Code:
/ Dotnetfx_Win7_3.5.1 / Dotnetfx_Win7_3.5.1 / 3.5.1 / DEVDIV / depot / DevDiv / releases / whidbey / NetFXspW7 / ndp / fx / src / xsp / System / Web / Cache / cache.cs / 1 / cache.cs
//------------------------------------------------------------------------------
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
//-----------------------------------------------------------------------------
/*
* Cache class
*
* Copyright (c) 1999 Microsoft Corporation
*/
namespace System.Web.Caching {
using System.Collections;
using System.Collections.Specialized;
using System.Configuration;
using System.Diagnostics.CodeAnalysis;
using System.Runtime.InteropServices;
using System.Threading;
using System.Web.Util;
using System.Web;
using Microsoft.Win32;
using System.Security.Permissions;
using System.Globalization;
using System.Web.Configuration;
using System.Web.Management;
///
/// Represents the method that will handle the
///
public delegate void CacheItemRemovedCallback(
string key, object value, CacheItemRemovedReason reason);
///
/// Represents the method that will handle the
///
[SuppressMessage("Microsoft.Design", "CA1021:AvoidOutParameters")]
public delegate void CacheItemUpdateCallback(
string key, CacheItemUpdateReason reason,
out object expensiveObject, out CacheDependency dependency, out DateTime absoluteExpiration, out TimeSpan slidingExpiration);
///
/// Specifies the relative priority of items stored in the System.Web.Caching.Cache. When the Web
/// server runs low on memory, the Cache selectively purges items to free system
/// memory. Items with higher priorities are less likely to be removed from the
/// cache when the server is under load. Web
/// applications can use these
/// values to prioritize cached items relative to one another. The default is
/// normal.
///
public enum CacheItemPriority {
///
/// The cahce items with this priority level will be the first
/// to be removed when the server frees system memory by deleting items from the
/// cache.
///
Low = 1,
///
/// The cache items with this priority level
/// are in the second group to be removed when the server frees system memory by
/// deleting items from the cache.
///
BelowNormal,
///
/// The cache items with this priority level are in
/// the third group to be removed when the server frees system memory by deleting items from the cache. This is the default.
///
Normal,
///
/// The cache items with this priority level are in the
/// fourth group to be removed when the server frees system memory by deleting items from the
/// cache.
///
AboveNormal,
///
/// The cache items with this priority level are in the fifth group to be removed
/// when the server frees system memory by deleting items from the cache.
///
High,
///
/// The cache items with this priority level will not be removed when the server
/// frees system memory by deleting items from the cache.
///
NotRemovable,
///
/// The default value is Normal.
///
Default = Normal
}
///
/// Specifies the reason that a cached item was removed.
///
public enum CacheItemRemovedReason {
///
/// The item was removed from the cache by the 'System.Web.Caching.Cache.Remove' method, or by an System.Web.Caching.Cache.Insert method call specifying the same key.
///
Removed = 1,
///
/// The item was removed from the cache because it expired.
///
Expired,
///
/// The item was removed from the cache because the value in the hitInterval
/// parameter was not met, or because the system removed it to free memory.
///
Underused,
///
/// The item was removed from the cache because a file or key dependency was
/// changed.
///
DependencyChanged
}
///
/// Specifies the reason why a cached item needs to be updated.
///
[SuppressMessage("Microsoft.Design", "CA1008:EnumsShouldHaveZeroValue",
Justification = "This enum should mirror CacheItemRemovedReason enum in design")]
public enum CacheItemUpdateReason {
///
/// The item needs to be updated because it expired.
///
Expired = 1,
///
/// The item needs to be updated because a file or key dependency was
/// changed.
///
DependencyChanged
}
enum CacheGetOptions {
None = 0,
ReturnCacheEntry = 0x1,
}
///
/// Implements the cache for a Web application. There is only one instance of
/// this class per application domain, and it remains valid only as long as the
/// application domain remains active. Information about an instance of this class
/// is available through the
///
//
// Extra notes:
// - The Cache object contains a CacheInternal object.
// - The CacheInternal object is either a CacheSingle, or a CacheMultiple which contains mulitple
// CacheSingle objects.
//
[AspNetHostingPermission(SecurityAction.LinkDemand, Level=AspNetHostingPermissionLevel.Minimal)]
public sealed class Cache : IEnumerable {
///
/// Sets the absolute expiration policy to, in essence,
/// never. When set, this field is equal to the the System.DateTime.MaxValue , which is a constant
/// representing the largest possible
///
public static readonly DateTime NoAbsoluteExpiration = DateTime.MaxValue;
///
/// Sets the amount of time for sliding cache expirations to
/// zero. When set, this field is equal to the System.TimeSpan.Zero field, which is a constant value of
/// zero. This field is read-only.
///
public static readonly TimeSpan NoSlidingExpiration = TimeSpan.Zero;
CacheInternal _cacheInternal;
static CacheItemRemovedCallback s_sentinelRemovedCallback = new CacheItemRemovedCallback(SentinelEntry.OnCacheItemRemovedCallback);
///
/// This constructor is for internal use only, and was accidentally made public - do not use.
///
[SecurityPermission(SecurityAction.Demand, Unrestricted=true)]
public Cache() {
}
//
// internal ctor used by CacheCommon that avoids the demand for UnmanagedCode.
//
internal Cache(int dummy) {
}
internal void SetCacheInternal(CacheInternal cacheInternal) {
_cacheInternal = cacheInternal;
}
///
/// Gets the number of items stored in the cache. This value can be useful when
/// monitoring your application's performance or when using the ASP.NET tracing
/// functionality.
///
public int Count {
get {
return _cacheInternal.PublicCount;
}
}
///
/// Returns a dictionary enumerator used for iterating through the key/value
/// pairs contained in the cache. Items can be added to or removed from the cache
/// while this method is enumerating through the cache items.
///
public IDictionaryEnumerator GetEnumerator() {
return _cacheInternal.GetEnumerator();
}
///
/// Gets or sets an item in the cache.
///
public object this[string key] {
get {
return Get(key);
}
set {
Insert(key, value);
}
}
private class SentinelEntry {
private string _key;
private CacheDependency _expensiveObjectDependency;
private CacheItemUpdateCallback _cacheItemUpdateCallback;
public SentinelEntry(string key, CacheDependency expensiveObjectDependency, CacheItemUpdateCallback callback) {
_key = key;
_expensiveObjectDependency = expensiveObjectDependency;
_cacheItemUpdateCallback = callback;
}
public string Key {
get { return _key; }
}
public CacheDependency ExpensiveObjectDependency {
get { return _expensiveObjectDependency; }
}
public CacheItemUpdateCallback CacheItemUpdateCallback {
get { return _cacheItemUpdateCallback; }
}
public static void OnCacheItemRemovedCallback(string key, object value, CacheItemRemovedReason reason) {
CacheItemUpdateReason updateReason;
SentinelEntry entry = value as SentinelEntry;
switch (reason) {
case CacheItemRemovedReason.Expired:
updateReason = CacheItemUpdateReason.Expired;
break;
case CacheItemRemovedReason.DependencyChanged:
updateReason = CacheItemUpdateReason.DependencyChanged;
if (entry.ExpensiveObjectDependency.HasChanged) {
// If the expensiveObject has been removed explicitly by Cache.Remove,
// return from the SentinelEntry removed callback
// thus effectively removing the SentinelEntry from the cache.
return;
}
break;
case CacheItemRemovedReason.Underused:
Debug.Fail("Reason should never be CacheItemRemovedReason.Underused since the entry was inserted as NotRemovable.");
return;
default:
// do nothing if reason is Removed
return;
}
CacheDependency cacheDependency;
DateTime absoluteExpiration;
TimeSpan slidingExpiration;
object expensiveObject;
CacheItemUpdateCallback callback = entry.CacheItemUpdateCallback;
// invoke update callback
try {
callback(entry.Key, updateReason, out expensiveObject, out cacheDependency, out absoluteExpiration, out slidingExpiration);
if (expensiveObject != null) {
HttpRuntime.Cache.Insert(entry.Key, expensiveObject, cacheDependency, absoluteExpiration, slidingExpiration, entry.CacheItemUpdateCallback);
}
else {
HttpRuntime.Cache.Remove(entry.Key);
}
}
catch (Exception e) {
HttpRuntime.Cache.Remove(entry.Key);
try {
WebBaseEvent.RaiseRuntimeError(e, value);
}
catch {
}
}
}
}
///
/// Retrieves an item from the cache.
///
public object Get(string key) {
return _cacheInternal.DoGet(true, key, CacheGetOptions.None);
}
internal object Get(string key, CacheGetOptions getOptions) {
return _cacheInternal.DoGet(true, key, getOptions);
}
///
/// Inserts an item into the Cache with default values.
///
public void Insert(string key, object value) {
_cacheInternal.DoInsert(
true,
key,
value,
null,
NoAbsoluteExpiration,
NoSlidingExpiration,
CacheItemPriority.Default,
null,
true);
}
///
/// Inserts an object into the System.Web.Caching.Cache that has file or key
/// dependencies.
///
public void Insert(string key, object value, CacheDependency dependencies) {
_cacheInternal.DoInsert(
true,
key,
value,
dependencies,
NoAbsoluteExpiration,
NoSlidingExpiration,
CacheItemPriority.Default,
null,
true);
}
///
/// Inserts an object into the System.Web.Caching.Cache that has file or key dependencies and
/// expires at the value set in the
///
public void Insert(string key, object value, CacheDependency dependencies, DateTime absoluteExpiration, TimeSpan slidingExpiration) {
DateTime utcAbsoluteExpiration = DateTimeUtil.ConvertToUniversalTime(absoluteExpiration);
_cacheInternal.DoInsert(
true,
key,
value,
dependencies,
utcAbsoluteExpiration,
slidingExpiration,
CacheItemPriority.Default,
null,
true);
}
public void Insert(
string key,
object value,
CacheDependency dependencies,
DateTime absoluteExpiration,
TimeSpan slidingExpiration,
CacheItemPriority priority,
CacheItemRemovedCallback onRemoveCallback) {
DateTime utcAbsoluteExpiration = DateTimeUtil.ConvertToUniversalTime(absoluteExpiration);
_cacheInternal.DoInsert(
true,
key,
value,
dependencies,
utcAbsoluteExpiration,
slidingExpiration,
priority,
onRemoveCallback,
true);
}
// DevDiv Bugs 162763:
// Add a an event that fires *before* an item is evicted from the ASP.NET Cache
public void Insert(
string key,
object value,
CacheDependency dependencies,
DateTime absoluteExpiration,
TimeSpan slidingExpiration,
CacheItemUpdateCallback onUpdateCallback) {
if (dependencies == null && absoluteExpiration == Cache.NoAbsoluteExpiration && slidingExpiration == Cache.NoSlidingExpiration) {
throw new ArgumentException(SR.GetString(SR.Invalid_Parameters_To_Insert));
}
if (onUpdateCallback == null) {
throw new ArgumentNullException("onUpdateCallback");
}
DateTime utcAbsoluteExpiration = DateTimeUtil.ConvertToUniversalTime(absoluteExpiration);
// Insert updatable cache entry
_cacheInternal.DoInsert (
true,
key,
value,
null,
Cache.NoAbsoluteExpiration,
Cache.NoSlidingExpiration,
CacheItemPriority.NotRemovable,
null,
true);
// Ensure the sentinel depends on its updatable entry
string[] cacheKeys = { key };
CacheDependency expensiveObjectDep = new CacheDependency(null, cacheKeys);
if (dependencies == null) {
dependencies = expensiveObjectDep;
}
else {
AggregateCacheDependency deps = new AggregateCacheDependency();
deps.Add(dependencies, expensiveObjectDep);
dependencies = deps;
}
// Insert sentinel entry for the updatable cache entry
_cacheInternal.DoInsert(
false,
CacheInternal.PrefixValidationSentinel + key,
new SentinelEntry(key, expensiveObjectDep, onUpdateCallback),
dependencies,
utcAbsoluteExpiration,
slidingExpiration,
CacheItemPriority.NotRemovable,
Cache.s_sentinelRemovedCallback,
true);
}
public object Add(
string key,
object value,
CacheDependency dependencies,
DateTime absoluteExpiration,
TimeSpan slidingExpiration,
CacheItemPriority priority,
CacheItemRemovedCallback onRemoveCallback) {
DateTime utcAbsoluteExpiration = DateTimeUtil.ConvertToUniversalTime(absoluteExpiration);
return _cacheInternal.DoInsert(
true,
key,
value,
dependencies,
utcAbsoluteExpiration,
slidingExpiration,
priority,
onRemoveCallback,
false);
}
///
/// Removes the specified item from the cache.
///
public object Remove(string key) {
CacheKey cacheKey = new CacheKey(key, true);
return _cacheInternal.DoRemove(cacheKey, CacheItemRemovedReason.Removed);
}
public long EffectivePrivateBytesLimit {
get {
return _cacheInternal.EffectivePrivateBytesLimit;
}
}
public long EffectivePercentagePhysicalMemoryLimit {
get {
return _cacheInternal.EffectivePercentagePhysicalMemoryLimit;
}
}
}
class CacheCommon {
const int MEMORYSTATUS_INTERVAL_5_SECONDS = 5 * Msec.ONE_SECOND;
const int MEMORYSTATUS_INTERVAL_30_SECONDS = 30 * Msec.ONE_SECOND;
const int GC_BACKOFF_INTERVAL = 60;
const int GC_INTERVAL = 5;
internal CacheInternal _cacheInternal;
internal Cache _cachePublic;
internal protected CacheMemoryStats _cacheMemoryStats;
internal object _timerMemoryStatsLock = new object();
internal Timer _timerMemoryStats;
internal int _currentPollInterval = MEMORYSTATUS_INTERVAL_30_SECONDS;
internal DateTime _timerSuspendTime = DateTime.MinValue;
internal int _inMemoryStatsUpdate;
internal bool _enableMemoryCollection;
internal bool _enableExpiration;
internal bool _internalConfigRead;
private int _gcCollectCount; /* count of calls to GC.Collect */
internal CacheCommon() {
_cachePublic = new Cache(0);
_cacheMemoryStats = new CacheMemoryStats();
_enableMemoryCollection = true;
_enableExpiration = true;
}
internal void Dispose(bool disposing) {
if (disposing) {
EnableCacheMemoryTimer(false);
}
}
internal void SetCacheInternal(CacheInternal cacheInternal) {
_cacheInternal = cacheInternal;
_cachePublic.SetCacheInternal(cacheInternal);
}
internal void ReadCacheInternalConfig(CacheSection cacheSection) {
if (_internalConfigRead) {
return;
}
lock (this) {
if (_internalConfigRead) {
return;
}
// Set it to true here so that even if we have to call ReadCacheInternalConfig
// from the code below, we won't get into an infinite loop.
_internalConfigRead = true;
if (cacheSection != null) {
_enableMemoryCollection = (!cacheSection.DisableMemoryCollection);
_enableExpiration = (!cacheSection.DisableExpiration);
_cacheMemoryStats.ReadConfig(cacheSection);
_currentPollInterval = CacheMemoryPrivateBytesPressure.PollInterval;
ResetFromConfigSettings();
}
}
}
internal void ResetFromConfigSettings() {
EnableCacheMemoryTimer(_enableMemoryCollection);
_cacheInternal.EnableExpirationTimer(_enableExpiration);
}
internal void EnableCacheMemoryTimer(bool enable) {
lock (_timerMemoryStatsLock) {
#if DBG
if (Debug.IsTagPresent("Timer") && !Debug.IsTagEnabled("Timer")) {
enable = false;
}
#endif
if (enable) {
if (_timerMemoryStats == null) {
// has not been read yet
_timerMemoryStats = new Timer(new TimerCallback(this.MemoryStatusTimerCallback), null, _currentPollInterval, _currentPollInterval);
Debug.Trace("Cache", "Started CacheMemoryTimers");
}
else {
_timerMemoryStats.Change(_currentPollInterval, _currentPollInterval);
}
}
else {
Timer timer = _timerMemoryStats;
if (timer != null && Interlocked.CompareExchange(ref _timerMemoryStats, null, timer) == timer) {
timer.Dispose();
Debug.Trace("Cache", "Stopped CacheMemoryTimers");
}
}
}
if (!enable) {
// wait for MemoryStatusTimerCallback to finish
while(_inMemoryStatsUpdate != 0) {
Thread.Sleep(100);
}
}
}
void AdjustTimer() {
lock (_timerMemoryStatsLock) {
if (_timerMemoryStats == null)
return;
// the order of these if statements is important
// When above the high pressure mark, interval should be 5 seconds or less
if (_cacheMemoryStats.IsAboveHighPressure()) {
if (_currentPollInterval > MEMORYSTATUS_INTERVAL_5_SECONDS) {
_currentPollInterval = MEMORYSTATUS_INTERVAL_5_SECONDS;
_timerMemoryStats.Change(_currentPollInterval, _currentPollInterval);
}
return;
}
// When above half the low pressure mark, interval should be 30 seconds or less
if ((_cacheMemoryStats.PrivateBytesPressure.PressureLast > _cacheMemoryStats.PrivateBytesPressure.PressureLow/2)
|| (_cacheMemoryStats.TotalMemoryPressure.PressureLast > _cacheMemoryStats.TotalMemoryPressure.PressureLow/2)) {
// DevDivBugs 104034: allow interval to fall back down when memory pressure goes away
int newPollInterval = Math.Min(CacheMemoryPrivateBytesPressure.PollInterval, MEMORYSTATUS_INTERVAL_30_SECONDS);
if (_currentPollInterval != newPollInterval) {
_currentPollInterval = newPollInterval;
_timerMemoryStats.Change(_currentPollInterval, _currentPollInterval);
}
return;
}
// there is no pressure, interval should be the value from config
if (_currentPollInterval != CacheMemoryPrivateBytesPressure.PollInterval) {
_currentPollInterval = CacheMemoryPrivateBytesPressure.PollInterval;
_timerMemoryStats.Change(_currentPollInterval, _currentPollInterval);
}
}
}
void MemoryStatusTimerCallback(object state) {
if (Interlocked.Exchange(ref _inMemoryStatsUpdate, 1) != 0)
return;
Debug.Trace("CacheMemory", "MemoryStatusTimerCallback: appId=" + HttpRuntime.AppDomainAppIdInternal
+ ",time=" + DateTime.Now.ToString("T", CultureInfo.InvariantCulture));
try {
if (DateTime.UtcNow >= _timerSuspendTime) {
_cacheMemoryStats.Update();
AdjustTimer();
bool cacheTrimmed = _cacheInternal.ReviewMemoryStats();
// DevDivBugs 180639:
// Regression: ASP.NET Cache always calls GcCollect under higher memory pressure even if the cache hasn't been trimmed
// Do not call GcCollect if we didn't trim any cache items. CL2582117 unknowingly introduced this behavior that was a
// departure from what we had in ASP.NET 2.0. This caused a number of customers to experience poor performance after
// upgrading to 2.0 SP1.
if (_cacheMemoryStats.IsAboveHighPressure() && cacheTrimmed) {
GcCollect();
}
}
}
finally {
Interlocked.Exchange(ref _inMemoryStatsUpdate, 0);
}
}
// Call GcCollect if it's been a while since the last time we called.
// We wait an amount of time dependent on the memory pressure.
internal void GcCollect() {
Debug.Assert(_inMemoryStatsUpdate == 1, "GcCollect should only occur when we're updating memory statistics.");
Debug.Assert(_cacheMemoryStats.IsAboveHighPressure(), "_cacheMemoryStats.IsAboveHighPressure()");
// If we're under physical memory pressure, the GC is more aggressive and it is
// not necessary for us to call Collect. However, if we don't call Collect, we must ensure that
// we don't continue trimming--the memory statistics don't fall until the objects are collected.
// Here are the rules regarding calls to Collect:
// 1) Call Collect at most every GC_INTERVAL seconds.
// 2) If above high physical pressure, Collect at most every GC_BACKOFF_INTERVAL seconds and suspend
// MemoryStatusTimerCallback for GC_BACKOFF_INTERVAL seconds.
// 3) If we Trim but don't Collect, suspend the MemoryStatusTimerCallback for GC_BACKOFF_INTERVAL seconds.
// 4) If the configured poll interval is less than GC_BACKOFF_INTERVAL seconds, use it instead in 2) and 3), but always obey 1).
int pollIntervalInSeconds = CacheMemoryPrivateBytesPressure.PollInterval / Msec.ONE_SECOND;
int backoffInterval = Math.Max(Math.Min(pollIntervalInSeconds, GC_BACKOFF_INTERVAL), GC_INTERVAL);
bool isAboveHighPhysicalPressure = _cacheMemoryStats.TotalMemoryPressure.IsAboveHighPressure();
long totalMemoryChange = 0;
bool callCollect;
UnsafeNativeMethods.SetGCLastCalledTime(out callCollect, isAboveHighPhysicalPressure ? backoffInterval : GC_INTERVAL);
if (callCollect) {
#if DBG
DateTime utcNow1 = DateTime.UtcNow;
DateTime now1 = DateTime.Now;
#endif
// sometimes private bytes is the only one that changes significantly,
// and sometimes managed bytes is the one that changes significantly,
// so collect both and use the maximum difference to determine if the collection
// was effective
long privateBytesBefore = CacheMemoryPrivateBytesPressure.GetPrivateBytes(true);
long gcHeapBefore = GC.GetTotalMemory(false);
GC.Collect();
_gcCollectCount++;
long privateBytesAfter = CacheMemoryPrivateBytesPressure.GetPrivateBytes(true);
long gcHeapAfter = GC.GetTotalMemory(false);
totalMemoryChange = Math.Max(privateBytesBefore-privateBytesAfter, gcHeapBefore-gcHeapAfter);
#if DBG
DateTime utcNow2 = DateTime.UtcNow;
long shrunk;
if (privateBytesBefore > 0 && privateBytesBefore > privateBytesAfter) {
shrunk = (100 * (privateBytesBefore - privateBytesAfter) / privateBytesBefore );
}
else {
shrunk = 0;
}
long shrunk2;
if (gcHeapBefore > 0 && gcHeapBefore > gcHeapAfter) {
shrunk2 = (100 * (gcHeapBefore - gcHeapAfter) / gcHeapBefore );
}
else {
shrunk2 = 0;
}
Debug.Trace("CacheMemoryGcCollect", "GcCollect: appId=" + HttpRuntime.AppDomainAppIdInternal
+ ",time=" + now1.ToString("T", CultureInfo.InvariantCulture)
+ ",duration=" + (utcNow2 - utcNow1).TotalMilliseconds + " ms,shrunk=" + shrunk + "%;before="
+ (privateBytesBefore / (1024 * 1024)) + ",after=" + (privateBytesAfter / (1024 * 1024))
+ " ,shrunk2=" + shrunk2 + "%;before2="
+ (gcHeapBefore / (1024 * 1024)) + ",after2=" + (gcHeapAfter / (1024 * 1024)));
#endif
}
if (!callCollect || isAboveHighPhysicalPressure || _cacheMemoryStats.IsGcCollectIneffective(totalMemoryChange)) {
// VSWhidbey 478175: suspend memory status timer for to avoid successive GC calls when there is a memory leak
_timerSuspendTime = DateTime.UtcNow.AddSeconds(backoffInterval);
}
}
}
abstract class CacheInternal : IEnumerable, IDisposable {
// cache key prefixes - they keep cache keys short and prevent conflicts
// NOTE: Since we already used up all the lowercase letters from 'a' to 'z',
// we are now using uppercase letters from 'A' to 'Z'
internal const string PrefixFIRST = "A";
internal const string PrefixResourceProvider = "A";
// Next prefix goes here, until we get to 'Z'
internal const string PrefixOutputCache = "a";
internal const string PrefixSqlCacheDependency = "b";
internal const string PrefixMemoryBuildResult = "c";
internal const string PrefixPathData = "d";
internal const string PrefixHttpCapabilities = "e";
internal const string PrefixMapPath = "f";
internal const string PrefixHttpSys = "g";
internal const string PrefixFileSecurity = "h";
#if ORCAS
internal const string PrefixSiteCounters = "i";
#endif
internal const string PrefixInProcSessionState = "j";
internal const string PrefixStateApplication = "k";
internal const string PrefixPartialCachingControl = "l";
internal const string UNUSED = "m";
internal const string PrefixAdRotator = "n";
internal const string PrefixWebServiceDataSource = "o";
internal const string PrefixLoadXPath = "p";
internal const string PrefixLoadXml = "q";
internal const string PrefixLoadTransform = "r";
internal const string PrefixAspCompatThreading = "s";
internal const string PrefixDataSourceControl = "u";
internal const string PrefixValidationSentinel = "w";
internal const string PrefixWebEventResource = "x";
internal const string PrefixAssemblyPath = "y";
internal const string PrefixBrowserCapsHash = "z";
internal const string PrefixLAST = "z";
protected CacheCommon _cacheCommon;
// virtual methods requiring implementation
internal abstract int PublicCount {get;}
internal abstract IDictionaryEnumerator CreateEnumerator();
internal abstract CacheEntry UpdateCache(
CacheKey cacheKey,
CacheEntry newEntry,
bool replace,
CacheItemRemovedReason removedReason,
out object valueOld);
internal abstract bool ReviewMemoryStats();
internal abstract void EnableExpirationTimer(bool enable);
// common implementation
static internal CacheInternal Create() {
CacheCommon cacheCommon;
CacheInternal cacheInternal;
int numSubCaches = 0;
#if USE_CONFIG
String ver = VersionInfo.SystemWebVersion;
RegistryKey regKey = Registry.LocalMachine.OpenSubKey("Software\\Microsoft\\ASP.NET\\" + ver);
if (regKey != null) {
numSubCaches = (int) regKey.GetValue("numSubCaches", 0);
regKey.Close();
}
#endif
if (numSubCaches == 0) {
uint numCPUs = (uint) SystemInfo.GetNumProcessCPUs();
// the number of subcaches is the minimal power of 2 greater
// than or equal to the number of cpus
numSubCaches = 1;
numCPUs -= 1;
while (numCPUs > 0) {
numSubCaches <<= 1;
numCPUs >>= 1;
}
}
cacheCommon = new CacheCommon();
if (numSubCaches == 1) {
cacheInternal = new CacheSingle(cacheCommon, null, 0);
}
else {
cacheInternal = new CacheMultiple(cacheCommon, numSubCaches);
}
cacheCommon.SetCacheInternal(cacheInternal);
cacheCommon.ResetFromConfigSettings();
return cacheInternal;
}
protected CacheInternal(CacheCommon cacheCommon) {
_cacheCommon = cacheCommon;
}
protected virtual void Dispose(bool disposing) {
_cacheCommon.Dispose(disposing);
}
public void Dispose() {
Dispose(true);
// no destructor, don't need it.
// System.GC.SuppressFinalize(this);
}
internal void ReadCacheInternalConfig(CacheSection cacheSection) {
_cacheCommon.ReadCacheInternalConfig(cacheSection);
}
internal Cache CachePublic {
get {return _cacheCommon._cachePublic;}
}
#if UNUSED_CODE
internal CacheMemoryStats CacheMemoryStats {
get {return _cacheCommon._cacheMemoryStats;}
}
#endif
internal long EffectivePrivateBytesLimit {
get { return _cacheCommon._cacheMemoryStats.PrivateBytesPressure.PressureHighMemoryLimit; }
}
internal long EffectivePercentagePhysicalMemoryLimit {
get { return _cacheCommon._cacheMemoryStats.TotalMemoryPressure.MemoryLimit; }
}
IEnumerator IEnumerable.GetEnumerator() {
return CreateEnumerator();
}
public IDictionaryEnumerator GetEnumerator() {
return CreateEnumerator();
}
internal object this[string key] {
get {
return Get(key);
}
#if UNUSED_CODE
set {
UtcInsert(key, value);
}
#endif
}
internal object Get(string key) {
return DoGet(false, key, CacheGetOptions.None);
}
internal object Get(string key, CacheGetOptions getOptions) {
return DoGet(false, key, getOptions);
}
internal object DoGet(bool isPublic, string key, CacheGetOptions getOptions) {
CacheEntry entry;
CacheKey cacheKey;
object dummy;
cacheKey = new CacheKey(key, isPublic);
entry = UpdateCache(cacheKey, null, false, CacheItemRemovedReason.Removed, out dummy);
if (entry != null) {
if ((getOptions & CacheGetOptions.ReturnCacheEntry) != 0) {
return entry;
}
else {
return entry.Value;
}
}
else {
return null;
}
}
internal void UtcInsert(string key, object value) {
DoInsert(false,
key,
value,
null,
Cache.NoAbsoluteExpiration,
Cache.NoSlidingExpiration,
CacheItemPriority.Default,
null,
true);
}
internal void UtcInsert(string key, object value, CacheDependency dependencies) {
DoInsert(false,
key,
value,
dependencies,
Cache.NoAbsoluteExpiration,
Cache.NoSlidingExpiration,
CacheItemPriority.Default,
null,
true);
}
internal void UtcInsert(
string key,
object value,
CacheDependency dependencies,
DateTime utcAbsoluteExpiration,
TimeSpan slidingExpiration) {
DoInsert(false,
key,
value,
dependencies,
utcAbsoluteExpiration,
slidingExpiration,
CacheItemPriority.Default,
null,
true);
}
internal void UtcInsert(
string key,
object value,
CacheDependency dependencies,
DateTime utcAbsoluteExpiration,
TimeSpan slidingExpiration,
CacheItemPriority priority,
CacheItemRemovedCallback onRemoveCallback) {
DoInsert(false,
key,
value,
dependencies,
utcAbsoluteExpiration,
slidingExpiration,
priority,
onRemoveCallback,
true);
}
internal object UtcAdd(
string key,
object value,
CacheDependency dependencies,
DateTime utcAbsoluteExpiration,
TimeSpan slidingExpiration,
CacheItemPriority priority,
CacheItemRemovedCallback onRemoveCallback) {
return DoInsert(
false,
key,
value,
dependencies,
utcAbsoluteExpiration,
slidingExpiration,
priority,
onRemoveCallback,
false);
}
internal object DoInsert(
bool isPublic,
string key,
object value,
CacheDependency dependencies,
DateTime utcAbsoluteExpiration,
TimeSpan slidingExpiration,
CacheItemPriority priority,
CacheItemRemovedCallback onRemoveCallback,
bool replace) {
/*
* If we throw an exception, prevent a leak by a user who
* writes the following:
*
* Cache.Insert(key, value, new CacheDependency(file));
*/
using (dependencies) {
CacheEntry entry;
object dummy;
entry = new CacheEntry(
key,
value,
dependencies,
onRemoveCallback,
utcAbsoluteExpiration,
slidingExpiration,
priority,
isPublic);
entry = UpdateCache(entry, entry, replace, CacheItemRemovedReason.Removed, out dummy);
/*
* N.B. A set can fail if two or more threads set the same key
* at the same time.
*/
#if DBG
if (replace) {
string yesno = (entry != null) ? "succeeded" : "failed";
Debug.Trace("CacheAPIInsert", "Cache.Insert " + yesno + ": " + key);
}
else {
if (entry == null) {
Debug.Trace("CacheAPIAdd", "Cache.Add added new item: " + key);
}
else {
Debug.Trace("CacheAPIAdd", "Cache.Add returned existing item: " + key);
}
}
#endif
if (entry != null) {
return entry.Value;
}
else {
return null;
}
}
}
internal object Remove(string key) {
CacheKey cacheKey = new CacheKey(key, false);
return DoRemove(cacheKey, CacheItemRemovedReason.Removed);
}
#if UNUSED_CODE
internal object Remove(string key, CacheItemRemovedReason reason) {
CacheKey cacheKey = new CacheKey(key, false);
return DoRemove(cacheKey, reason);
}
#endif
internal object Remove(CacheKey cacheKey, CacheItemRemovedReason reason) {
return DoRemove(cacheKey, reason);
}
/*
* Remove an item from the cache, with a specific reason.
* This is package access so only the cache can specify
* a reason other than REMOVED.
*
* @param key The key for the item.
* @exception ArgumentException
*/
internal object DoRemove(CacheKey cacheKey, CacheItemRemovedReason reason) {
object valueOld;
UpdateCache(cacheKey, null, true, reason, out valueOld);
#if DBG
if (valueOld != null) {
Debug.Trace("CacheAPIRemove", "Cache.Remove succeeded, reason=" + reason + ": " + cacheKey);
}
else {
Debug.Trace("CacheAPIRemove", "Cache.Remove failed, reason=" + reason + ": " + cacheKey);
}
#endif
return valueOld;
}
}
sealed class CacheKeyComparer : IEqualityComparer {
static CacheKeyComparer s_comparerInstance;
static internal CacheKeyComparer GetInstance() {
if (s_comparerInstance == null) {
s_comparerInstance = new CacheKeyComparer();
}
return s_comparerInstance;
}
private CacheKeyComparer()
{
}
bool IEqualityComparer.Equals(Object x, Object y)
{
return Compare(x, y) == 0;
}
// Compares two objects. An implementation of this method must return a
// value less than zero if x is less than y, zero if x is equal to y, or a
// value greater than zero if x is greater than y.
private int Compare(Object x, Object y) {
CacheKey a, b;
Debug.Assert(x != null && x is CacheKey);
Debug.Assert(y != null && y is CacheKey);
a = (CacheKey) x;
b = (CacheKey) y;
if (a.IsPublic) {
if (b.IsPublic) {
return String.Compare(a.Key, b.Key, StringComparison.Ordinal);
}
else {
return 1;
}
}
else {
if (!b.IsPublic) {
return String.Compare(a.Key, b.Key, StringComparison.Ordinal);
}
else {
return -1;
}
}
}
// Returns a hash code for the given object.
//
int IEqualityComparer.GetHashCode(Object obj) {
Debug.Assert(obj != null && obj is CacheKey);
CacheKey cacheKey = (CacheKey) obj;
return cacheKey.GetHashCode();
}
}
/*
* The cache.
*/
sealed class CacheSingle : CacheInternal {
// cache stats
static readonly TimeSpan FLUSH_UNDERCOUNT_WAIT = new TimeSpan(0, 0, 1);
static readonly TimeSpan INSERT_BLOCK_WAIT = new TimeSpan(0, 0, 10);
const int MAX_COUNT = Int32.MaxValue / 2;
const int MIN_COUNT = 10;
const int MAX_OVERLOAD_COUNT = 50;
Hashtable _entries; /* lookup table of entries */
CacheExpires _expires; /* expires tables */
CacheUsage _usage; /* usage tables */
object _lock; /* read/write synchronization for _entries */
int _disposed; /* disposed */
int _totalCount; /* count of total entries */
int _publicCount; /* count of public entries */
int _maxCount; /* cache maximum count */
int _maxCountOverload; /* count at which an add triggers a trim */
bool _flushUndercount; /* was the last flush unable to flush items */
ManualResetEvent _insertBlock; /* event to block inserts during high mem usage */
bool _useInsertBlock; /* use insert block? */
int _insertBlockCalls; /* number of callers using insert block */
DateTime _utcLastTrimCompleted; /* the time we last collected */
int _iSubCache; /* index of this cache */
CacheMultiple _cacheMultiple; /* the CacheMultiple containing this cache */
/*
* Constructs a new Cache.
*/
internal CacheSingle(CacheCommon cacheCommon, CacheMultiple cacheMultiple, int iSubCache) : base(cacheCommon) {
_cacheMultiple = cacheMultiple;
_iSubCache = iSubCache;
_entries = new Hashtable(CacheKeyComparer.GetInstance());
_expires = new CacheExpires(this);
_usage = new CacheUsage(this);
_lock = new object();
_maxCount = MAX_COUNT;
_maxCountOverload = MAX_COUNT + MAX_OVERLOAD_COUNT;
_insertBlock = new ManualResetEvent(true);
}
/*
* Dispose the cache.
*/
protected override void Dispose(bool disposing) {
if (disposing) {
if (Interlocked.Exchange(ref _disposed, 1) == 0) {
if (_expires != null) {
_expires.EnableExpirationTimer(false);
}
// close all items
CacheEntry[] entries = null;
lock (_lock) {
entries = new CacheEntry[_entries.Count];
int i = 0;
foreach (DictionaryEntry d in _entries) {
entries[i++] = (CacheEntry) d.Value;
}
}
foreach (CacheEntry entry in entries) {
Remove(entry, CacheItemRemovedReason.Removed);
}
// force any waiters to complete their waits. Note
// that the insert block cannot be reacquired, as UseInsertBlock
// checks the _disposed field.
_insertBlock.Set();
// release the block, causing it to be disposed when there
// are no more callers.
ReleaseInsertBlock();
Debug.Trace("CacheDispose", "Cache disposed");
}
}
base.Dispose(disposing);
}
// Get the insert block manual reset event if it has not been disposed.
ManualResetEvent UseInsertBlock() {
for (;;) {
if (_disposed == 1)
return null;
int n = _insertBlockCalls;
if (n < 0) {
return null;
}
if (Interlocked.CompareExchange(ref _insertBlockCalls, n + 1, n) == n) {
return _insertBlock;
}
}
}
// Release the insert block event, and dispose it if it has been released
// more times than it has been used
void ReleaseInsertBlock() {
if (Interlocked.Decrement(ref _insertBlockCalls) < 0) {
ManualResetEvent e = _insertBlock;
_insertBlock = null;
// now close
e.Close();
}
}
// Set the insert block event.
void SetInsertBlock() {
ManualResetEvent e = null;
try {
e = UseInsertBlock();
if (e != null) {
e.Set();
}
}
finally {
if (e != null) {
ReleaseInsertBlock();
}
}
}
// Reset the insert block event.
void ResetInsertBlock() {
ManualResetEvent e = null;
try {
e = UseInsertBlock();
if (e != null) {
e.Reset();
}
}
finally {
if (e != null) {
ReleaseInsertBlock();
}
}
}
// Wait on the insert block event.
bool WaitInsertBlock() {
bool signaled = false;
ManualResetEvent e = null;
try {
e = UseInsertBlock();
if (e != null) {
Debug.Trace("CacheMemoryTrimInsertBlock", "WaitInsertBlock: Cache " + _iSubCache + ": _useInsertBlock=true");
signaled = e.WaitOne(INSERT_BLOCK_WAIT, false);
Debug.Trace("CacheMemoryTrimInsertBlock", "Done waiting");
}
}
finally {
if (e != null) {
ReleaseInsertBlock();
}
}
return signaled;
}
internal void BlockInsertIfNeeded() {
if (_cacheCommon._cacheMemoryStats.IsAboveHighPressure()) {
Debug.Trace("CacheMemoryTrimInsertBlock", "BlockInsertIfNeeded: Cache " + _iSubCache + ": _useInsertBlock=true");
_useInsertBlock = true;
ResetInsertBlock();
}
}
internal void UnblockInsert() {
if (_useInsertBlock) {
_useInsertBlock = false;
SetInsertBlock();
Debug.Trace("CacheMemoryTrimInsertBlock", "UnblockInsert: Cache " + _iSubCache + ": _useInsertBlock=false");
}
}
internal override int PublicCount {
get {return _publicCount;}
}
internal override IDictionaryEnumerator CreateEnumerator() {
Hashtable h = new Hashtable(_publicCount);
DateTime utcNow = DateTime.UtcNow;
lock (_lock) {
foreach (DictionaryEntry d in _entries) {
CacheEntry entry = (CacheEntry) d.Value;
// note that ASP.NET does not use this enumerator internally,
// so we just choose public items.
if (entry.IsPublic &&
entry.State == CacheEntry.EntryState.AddedToCache &&
((!_cacheCommon._enableExpiration) || (utcNow <= entry.UtcExpires))) {
h[entry.Key] = entry.Value;
}
}
}
return h.GetEnumerator();
}
/*
* Performs all operations on the cache, with the
* exception of Clear. The arguments indicate the type of operation:
*
* @param key The key of the object.
* @param newItem The new entry to be added to the cache.
* @param replace Whether or not newEntry should replace an existing object in the cache.
* @return The item requested. May be null.
*/
internal override CacheEntry UpdateCache(
CacheKey cacheKey,
CacheEntry newEntry,
bool replace,
CacheItemRemovedReason removedReason,
out object valueOld)
{
CacheEntry entry = null;
CacheEntry oldEntry = null;
bool expired = false;
DateTime utcNow;
CacheDependency newEntryDependency = null;
bool isGet, isAdd;
bool removeExpired = false;
bool updateExpires = false;
DateTime utcNewExpires = DateTime.MinValue;
CacheEntry.EntryState entryState = CacheEntry.EntryState.NotInCache;
bool newEntryNeedsClose = false;
CacheItemRemovedReason newEntryRemovedReason = CacheItemRemovedReason.Removed;
valueOld = null;
isGet = !replace && newEntry == null;
isAdd = !replace && newEntry != null;
/*
* Perform update of cache data structures in a series to
* avoid overlapping locks.
*
* First, update the hashtable. The hashtable is the place
* that guarantees what is in or out of the cache.
*
* Loop here to remove expired items in a Get or Add, where
* we can't otherwise delete an item.
*/
for (;;) {
if (removeExpired) {
Debug.Trace("CacheUpdate", "Removing expired item found in Get: " + cacheKey);
UpdateCache(cacheKey, null, true, CacheItemRemovedReason.Expired, out valueOld);
removeExpired = false;
}
entry = null;
utcNow = DateTime.UtcNow;
if (_useInsertBlock && newEntry != null && newEntry.HasUsage() /* HasUsage() means it's not NonRemovable */) {
bool insertBlockReleased = WaitInsertBlock();
#if DBG
if (!insertBlockReleased) {
Debug.Trace("CacheUpdateWaitFailed", "WaitInsertBlock failed.");
}
#endif
}
// the _entries hashtable supports multiple readers or one writer
bool isLockEntered = false;
if (!isGet) {
try {
}
finally {
// guarantee that there is no interruption between the following
// two statements by enclosing them within a finally block
Monitor.Enter(_lock);
isLockEntered = true;
}
}
try {
entry = (CacheEntry) _entries[cacheKey];
Debug.Trace("CacheUpdate", "Entry " + ((entry != null) ? "found" : "not found") + "in hashtable: " + cacheKey);
if (entry != null) {
entryState = entry.State;
// If isGet == true, we are not hold any lock and so entryState can be anything
Debug.Assert(
isGet ||
entryState == CacheEntry.EntryState.AddingToCache ||
entryState == CacheEntry.EntryState.AddedToCache,
"entryState == CacheEntry.EntryState.AddingToCache || entryState == CacheEntry.EntryState.AddedToCache");
expired = (_cacheCommon._enableExpiration) && (entry.UtcExpires < utcNow);
if (expired) {
if (isGet) {
/*
* If the expired item is Added to the cache, remove it now before
* its expiration timer fires up to a minute in the future.
* Otherwise, just return null to indicate the item is not available.
*/
if (entryState == CacheEntry.EntryState.AddedToCache) {
removeExpired = true;
continue;
}
entry = null;
}
else {
/*
* If it's a call to Add, replace the item
* when it has expired.
*/
replace = true;
/*
* Change the removed reason.
*/
removedReason = CacheItemRemovedReason.Expired;
}
}
else {
updateExpires = (_cacheCommon._enableExpiration) && (entry.SlidingExpiration > TimeSpan.Zero);
}
}
/*
* Avoid running unnecessary code in a Get request by this simple test:
*/
if (!isGet) {
/*
* Remove an item from the hashtable.
*/
if (replace && entry != null) {
bool doRemove = (entryState != CacheEntry.EntryState.AddingToCache);
if (doRemove) {
oldEntry = entry;
oldEntry.State = CacheEntry.EntryState.RemovingFromCache;
_entries.Remove(oldEntry);
Debug.Trace("CacheUpdate", "Entry removed from hashtable: " + cacheKey);
}
else {
/*
* If we're removing and couldn't remove the old item
* because its state was AddingToCache, return null
* to indicate failure.
*/
if (newEntry == null) {
Debug.Trace("CacheUpdate", "Removal from hashtable failed: " + cacheKey);
entry = null;
}
}
}
/*
* Add an item to the hashtable.
*/
if (newEntry != null) {
bool doAdd = true;
if (entry != null) {
if (oldEntry == null) {
/*
* We could not remove the existing entry,
* either because it simply exists and replace == false,
* or replace == true and it's state was AddingToCache when
* we tried to remove it.
*/
doAdd = false;
newEntryRemovedReason = CacheItemRemovedReason.Removed;
}
#if DBG
if (!doAdd) {
Debug.Trace("CacheUpdate", "Insertion into hashtable failed because old entry was not removed: " + cacheKey);
}
#endif
}
if (doAdd) {
/* non-definitive check */
newEntryDependency = newEntry.Dependency;
if (newEntryDependency != null) {
if (newEntryDependency.HasChanged) {
doAdd = false;
newEntryRemovedReason = CacheItemRemovedReason.DependencyChanged;
}
#if DBG
if (!doAdd) {
Debug.Trace("CacheUpdate", "Insertion into hashtable failed because dependency changed: " + cacheKey);
}
#endif
}
}
if (doAdd) {
newEntry.State = CacheEntry.EntryState.AddingToCache;
_entries.Add(newEntry, newEntry);
/*
* If this is an Add operation, indicate success
* by returning null.
*/
if (isAdd) {
Debug.Assert(entry == null || expired, "entry == null || expired");
entry = null;
}
else {
/*
* Indicate success by returning the inserted entry.
*/
entry = newEntry;
}
Debug.Trace("CacheUpdate", "Entry added to hashtable: " + cacheKey);
}
else {
if (!isAdd) {
/*
* If we failed for an Insert, indicate failure by returning null.
*/
entry = null;
newEntryNeedsClose = true;
}
else {
/*
* If we failed for an Add (e.g. Dependency has changed),
* return the existing value. If existing value is null,
* we have to close the newEntry ourselves. Otherwise, we'll
* return non-null and the caller should close the item.
*/
newEntryNeedsClose = (entry == null);
}
/*
* If newEntry cannot be inserted, and it does not need to be
* closed, set it to null so that we don't insert it later.
* Leave it non-null when it needs to be closed that that we
* can close it.
*/
if (!newEntryNeedsClose) {
newEntry = null;
}
}
}
}
break;
}
finally {
if (isLockEntered) {
Monitor.Exit(_lock);
}
}
}
/*
* Since we want Get to be fast, check here for a get without
* alteration to cache.
*/
if (isGet) {
if (entry != null) {
if (updateExpires) {
utcNewExpires = utcNow + entry.SlidingExpiration;
if (utcNewExpires - entry.UtcExpires >= CacheExpires.MIN_UPDATE_DELTA || utcNewExpires < entry.UtcExpires) {
_expires.UtcUpdate(entry, utcNewExpires);
}
}
UtcUpdateUsageRecursive(entry, utcNow);
}
if (cacheKey.IsPublic) {
PerfCounters.IncrementCounter(AppPerfCounter.API_CACHE_RATIO_BASE);
if (entry != null) {
PerfCounters.IncrementCounter(AppPerfCounter.API_CACHE_HITS);
}
else {
PerfCounters.IncrementCounter(AppPerfCounter.API_CACHE_MISSES);
}
}
PerfCounters.IncrementCounter(AppPerfCounter.TOTAL_CACHE_RATIO_BASE);
if (entry != null) {
PerfCounters.IncrementCounter(AppPerfCounter.TOTAL_CACHE_HITS);
}
else {
PerfCounters.IncrementCounter(AppPerfCounter.TOTAL_CACHE_MISSES);
}
#if DBG
if (entry != null) {
Debug.Trace("CacheUpdate", "Cache hit: " + cacheKey);
}
else {
Debug.Trace("CacheUpdate", "Cache miss: " + cacheKey);
}
#endif
}
else {
int totalDelta = 0;
int publicDelta = 0;
int totalTurnover = 0;
int publicTurnover = 0;
if (oldEntry != null) {
if (oldEntry.InExpires()) {
_expires.Remove(oldEntry);
}
if (oldEntry.InUsage()) {
_usage.Remove(oldEntry);
}
Debug.Assert(oldEntry.State == CacheEntry.EntryState.RemovingFromCache, "oldEntry.State == CacheEntry.EntryState.RemovingFromCache");
oldEntry.State = CacheEntry.EntryState.RemovedFromCache;
valueOld = oldEntry.Value;
totalDelta--;
totalTurnover++;
if (oldEntry.IsPublic) {
publicDelta--;
publicTurnover++;
}
#if DBG
Debug.Trace("CacheUpdate", "Entry removed from cache, reason=" + removedReason + ": " + (CacheKey) oldEntry);
#endif
}
if (newEntry != null) {
if (newEntryNeedsClose) {
// Call close if newEntry could not be added.
newEntry.State = CacheEntry.EntryState.RemovedFromCache;
newEntry.Close(newEntryRemovedReason);
newEntry = null;
}
else {
Debug.Assert(!newEntry.InExpires());
Debug.Assert(!newEntry.InUsage());
if (_cacheCommon._enableExpiration && newEntry.HasExpiration()) {
_expires.Add(newEntry);
}
if ( _cacheCommon._enableMemoryCollection && newEntry.HasUsage() &&
( // Don't bother to set usage if it's going to expire very soon
!newEntry.HasExpiration() ||
newEntry.SlidingExpiration > TimeSpan.Zero ||
newEntry.UtcExpires - utcNow >= CacheUsage.MIN_LIFETIME_FOR_USAGE)) {
_usage.Add(newEntry);
}
newEntry.State = CacheEntry.EntryState.AddedToCache;
Debug.Trace("CacheUpdate", "Entry added to cache: " + (CacheKey)newEntry);
totalDelta++;
totalTurnover++;
if (newEntry.IsPublic) {
publicDelta++;
publicTurnover++;
}
}
}
// Call close after the newEntry has been fully added to the cache,
// so the OnRemoveCallback can take a dependency on the newly inserted item.
if (oldEntry != null) {
oldEntry.Close(removedReason);
}
// Delay monitoring change events until the oldEntry has been completely removed
// from the cache, and its OnRemoveCallback called. This way we won't call the
// OnRemoveCallback for newEntry before doing so for oldEntry.
if (newEntry != null) {
// listen to change events
newEntry.MonitorDependencyChanges();
/*
* NB: We have to check for dependency changes after we add the item
* to cache, because otherwise we may not remove it if it changes
* between the time we check for a dependency change and the time
* we set the AddedToCache bit. The worst that will happen is that
* a get can occur on an item that has changed, but that can happen
* anyway. The important thing is that we always remove an item that
* has changed.
*/
if (newEntryDependency != null && newEntryDependency.HasChanged) {
Remove(newEntry, CacheItemRemovedReason.DependencyChanged);
}
}
// update counts and counters
if (totalDelta == 1) {
Interlocked.Increment(ref _totalCount);
PerfCounters.IncrementCounter(AppPerfCounter.TOTAL_CACHE_ENTRIES);
}
else if (totalDelta == -1) {
Interlocked.Decrement(ref _totalCount);
PerfCounters.DecrementCounter(AppPerfCounter.TOTAL_CACHE_ENTRIES);
}
if (publicDelta == 1) {
Interlocked.Increment(ref _publicCount);
PerfCounters.IncrementCounter(AppPerfCounter.API_CACHE_ENTRIES);
}
else if (publicDelta == -1) {
Interlocked.Decrement(ref _publicCount);
PerfCounters.DecrementCounter(AppPerfCounter.API_CACHE_ENTRIES);
}
if (totalTurnover > 0) {
PerfCounters.IncrementCounterEx(AppPerfCounter.TOTAL_CACHE_TURNOVER_RATE, totalTurnover);
}
if (publicTurnover > 0) {
PerfCounters.IncrementCounterEx(AppPerfCounter.API_CACHE_TURNOVER_RATE, publicTurnover);
}
}
return entry;
}
void UtcUpdateUsageRecursive(CacheEntry entry, DateTime utcNow) {
CacheDependency dependency;
CacheEntry[] entries;
// Don't update if the last update is less than 1 sec away. This way we'll
// avoid over updating the usage in the scenario where a cache makes several
// update requests.
if (utcNow - entry.UtcLastUsageUpdate > CacheUsage.CORRELATED_REQUEST_TIMEOUT || utcNow < entry.UtcLastUsageUpdate) {
entry.UtcLastUsageUpdate = utcNow;
if (entry.InUsage()) {
CacheSingle cacheSingle;
if (_cacheMultiple == null) {
cacheSingle = this;
}
else {
cacheSingle = _cacheMultiple.GetCacheSingle(entry.Key.GetHashCode());
}
cacheSingle._usage.Update(entry);
}
dependency = entry.Dependency;
if (dependency != null) {
entries = dependency.CacheEntries;
if (entries != null) {
foreach (CacheEntry dependent in entries) {
UtcUpdateUsageRecursive(dependent, utcNow);
}
}
}
}
}
// calculate a new _maxCount based on the current memory pressure
int CalcMaxCount(CacheMemoryPressure pressure) {
int pressureLast = pressure.PressureLast;
int pressureAvg = pressure.PressureAvg;
int pressureHigh = pressure.PressureHigh;
int pressureLow = pressure.PressureLow;
int pressureMiddle = pressure.PressureMiddle;
int count = _totalCount;
int newMaxCount = -1;
if (pressureLast > pressureMiddle) {
// Possible scenarios:
// middle < high < Avg < Last : 50%
// middle < high < Last < Avg : 50%
// middle < Avg < high < Last : 50%
// Avg < middle < high < Last : 50%
// middle < Last < high < Avg : 5%
// middle < Avg < Last < high : 5%
// middle < Last < Avg < high : 5%
// Avg < middle < Last < high : 5%
if (pressureLast >= pressureHigh) {
// reduce by 50%
newMaxCount = (int)((long)count/ 2L);
}
else {
// reduce by MIN(5%, (pressureLast - pressureMiddle / pressureMiddle)%)
newMaxCount = (int)((long) count * (long)(2 * pressureMiddle - pressureLast) / (long)pressureMiddle);
newMaxCount = Math.Max((int)(19L * (long)count / 20L), newMaxCount);
}
}
else if (pressureLast == pressureMiddle) {
if (_maxCount < MAX_COUNT) {
newMaxCount = _maxCount;
}
else {
newMaxCount = count;
}
}
else if (pressureLast >= pressureLow) {
// Possible scenarios:
// Last < middle < high < Avg : no reduction
// Last < middle < Avg < high : no reduction
// Last < Avg < middle < high : increase by (middle - Last)/middle %
// Avg < Last < middle < high : increase by (middle - Last)/middle %
// When the pressure is between middle and low, ensure
// the count does not fall. If the average pressure is less
// than the middle, increase maxCount proportionally.
if (pressureAvg < pressureMiddle) {
// increase by (pressureMiddle - pressureLast / pressureMiddle)%
newMaxCount = (int)((long) count * (long)(2 * pressureMiddle - pressureLast) / (long)pressureMiddle);
}
else {
newMaxCount = count;
}
// ensure that _maxCount does not fall
if (_maxCount < MAX_COUNT) {
newMaxCount = Math.Max(newMaxCount, _maxCount);
}
}
else {
// Under low pressure, don't restrict count.
newMaxCount = MAX_COUNT;
}
#if DBG
Debug.Assert(newMaxCount != -1, "newMaxCount != -1");
if (HttpRuntime.AppDomainAppIdInternal != null && HttpRuntime.AppDomainAppIdInternal.Length > 0) {
Debug.Trace("CacheMemory", pressure.GetType().Name + ".CalcMaxCount: " + _iSubCache + ",last=" + pressureLast + ",avg=" + pressureAvg + ",count=" + count + ",_maxCount=" + _maxCount + ",newMaxCount=" + newMaxCount);
}
#endif
return newMaxCount;
}
internal override bool ReviewMemoryStats() {
int newMaxCount = CalcMaxCount(_cacheCommon._cacheMemoryStats.TotalMemoryPressure);
if (_cacheCommon._cacheMemoryStats.PrivateBytesPressure.HasLimit()) {
newMaxCount = Math.Min(newMaxCount, CalcMaxCount(_cacheCommon._cacheMemoryStats.PrivateBytesPressure));
}
newMaxCount = Math.Max(newMaxCount, MIN_COUNT);
newMaxCount = Math.Min(newMaxCount, MAX_COUNT);
_maxCount = newMaxCount;
_maxCountOverload = _maxCount + MAX_OVERLOAD_COUNT;
#if DBG
if (HttpRuntime.AppDomainAppIdInternal != null && HttpRuntime.AppDomainAppIdInternal.Length > 0) {
Debug.Trace("CacheMemory", "ReviewMemoryStats: _iSubCache= " + _iSubCache + ":_totalCount=" + _totalCount + ",_maxCount=" + _maxCount + ",_maxCountOverload=" + _maxCountOverload + " " + Debug.FormatLocalDate(DateTime.Now));
}
#endif
return TrimIfNeeded();
}
// We need to trim is the count is too high and we're able to flush
// items from the cache.
bool NeedsTrim() {
bool needsTrim = false;
if (_cacheCommon._enableMemoryCollection) {
if (_totalCount > _maxCountOverload || (_totalCount > _maxCount && _cacheCommon._cacheMemoryStats.IsAboveMediumPressure())) {
if (!_flushUndercount) {
needsTrim = true;
}
else {
needsTrim = (DateTime.UtcNow - _utcLastTrimCompleted >= FLUSH_UNDERCOUNT_WAIT);
}
}
}
return needsTrim;
}
bool TrimIfNeeded() {
// quick check
if (NeedsTrim()) {
Trim();
return true;
}
return false;
}
// This is the trim thread. Keep trimming while there are items to trim.
// Release the thread when there are no more items to trim.
void Trim() {
Debug.Assert(_cacheCommon._inMemoryStatsUpdate == 1, "Trim should only occur when we're updating memory statistics.");
Debug.Trace("CacheMemoryTrim", "Cache " + _iSubCache + ": Thread start");
int publicEntriesFlushed = 0; // number of public entries flushed
int totalFlushed = 0; // total number of entries flushed
try {
for (;;) {
int toFlush = _totalCount - _maxCount;
int flushed = 0;
if (toFlush > 0) {
#if DBG
DateTime start = DateTime.UtcNow;
Debug.Trace("CacheMemoryTrim", "Cache " + _iSubCache + ": start trimming " + toFlush +
" from cache at " + Debug.FormatUtcDate(start) + ",_totalCount=" + _totalCount);
#endif
flushed = _expires.FlushExpiredItems(true);
int underUsedFlushed = 0;
if (flushed < toFlush) {
underUsedFlushed = _usage.FlushUnderUsedItems(toFlush - flushed, ref publicEntriesFlushed);
flushed += underUsedFlushed;
totalFlushed += underUsedFlushed;
}
#if DBG
DateTime end = DateTime.UtcNow;
Debug.Trace("CacheMemoryTrim", "Cache " + _iSubCache + ": end trimming " + flushed +
" from cache at " + Debug.FormatUtcDate(end) +
" in " + (end - start).TotalMilliseconds + " msec,_totalCount=" + _totalCount);
#endif
}
_utcLastTrimCompleted = DateTime.UtcNow;
_flushUndercount = (flushed < toFlush);
if (!NeedsTrim())
break;
}
// Update values for perfcounters
PerfCounters.IncrementCounterEx(AppPerfCounter.CACHE_TOTAL_TRIMS, totalFlushed);
PerfCounters.IncrementCounterEx(AppPerfCounter.CACHE_API_TRIMS, publicEntriesFlushed);
PerfCounters.IncrementCounterEx(AppPerfCounter.CACHE_OUTPUT_TRIMS, totalFlushed - publicEntriesFlushed);
}
catch {
}
Debug.Trace("CacheMemoryTrim", "Cache " + _iSubCache + ": Thread end");
}
internal override void EnableExpirationTimer(bool enable) {
if (_expires != null) {
_expires.EnableExpirationTimer(enable);
}
}
}
class CacheMultiple : CacheInternal {
int _disposed;
CacheSingle[] _caches;
int _cacheIndexMask;
internal CacheMultiple(CacheCommon cacheCommon, int numSingleCaches) : base(cacheCommon) {
Debug.Assert(numSingleCaches > 1, "numSingleCaches is not greater than 1");
Debug.Assert((numSingleCaches & (numSingleCaches - 1)) == 0, "numSingleCaches is not a power of 2");
_cacheIndexMask = numSingleCaches - 1;
_caches = new CacheSingle[numSingleCaches];
for (int i = 0; i < numSingleCaches; i++) {
_caches[i] = new CacheSingle(cacheCommon, this, i);
}
}
protected override void Dispose(bool disposing) {
if (disposing) {
if (Interlocked.Exchange(ref _disposed, 1) == 0) {
foreach (CacheSingle cacheSingle in _caches) {
cacheSingle.Dispose();
}
}
}
base.Dispose(disposing);
}
internal override int PublicCount {
get {
int count = 0;
foreach (CacheSingle cacheSingle in _caches) {
count += cacheSingle.PublicCount;
}
return count;
}
}
internal override IDictionaryEnumerator CreateEnumerator() {
IDictionaryEnumerator[] enumerators = new IDictionaryEnumerator[_caches.Length];
for (int i = 0, c = _caches.Length; i < c; i++) {
enumerators[i] = _caches[i].CreateEnumerator();
}
return new AggregateEnumerator(enumerators);
}
internal CacheSingle GetCacheSingle(int hashCode) {
Debug.Assert(_caches != null && _caches.Length != 0);
hashCode = Math.Abs(hashCode);
int index = (hashCode & _cacheIndexMask);
return _caches[index];
}
internal override CacheEntry UpdateCache(
CacheKey cacheKey,
CacheEntry newEntry,
bool replace,
CacheItemRemovedReason removedReason,
out object valueOld) {
int hashCode = cacheKey.Key.GetHashCode();
CacheSingle cacheSingle = GetCacheSingle(hashCode);
return cacheSingle.UpdateCache(cacheKey, newEntry, replace, removedReason, out valueOld);
}
internal override bool ReviewMemoryStats() {
bool cacheTrimmed = false;
foreach (CacheSingle cacheSingle in _caches) {
cacheTrimmed |= cacheSingle.ReviewMemoryStats();
}
return cacheTrimmed;
}
internal override void EnableExpirationTimer(bool enable) {
foreach (CacheSingle cacheSingle in _caches) {
cacheSingle.EnableExpirationTimer(enable);
}
}
}
class AggregateEnumerator : IDictionaryEnumerator {
IDictionaryEnumerator [] _enumerators;
int _iCurrent;
internal AggregateEnumerator(IDictionaryEnumerator [] enumerators) {
_enumerators = enumerators;
}
public bool MoveNext() {
bool more;
for (;;) {
more = _enumerators[_iCurrent].MoveNext();
if (more)
break;
if (_iCurrent == _enumerators.Length - 1)
break;
_iCurrent++;
}
return more;
}
public void Reset() {
for (int i = 0; i <= _iCurrent; i++) {
_enumerators[i].Reset();
}
_iCurrent = 0;
}
public Object Current {
get {
return _enumerators[_iCurrent].Current;
}
}
public Object Key {
get {
return _enumerators[_iCurrent].Key;
}
}
public Object Value {
get {
return _enumerators[_iCurrent].Value;
}
}
public DictionaryEntry Entry {
get {
return _enumerators[_iCurrent].Entry;
}
}
}
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
//------------------------------------------------------------------------------
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
//-----------------------------------------------------------------------------
/*
* Cache class
*
* Copyright (c) 1999 Microsoft Corporation
*/
namespace System.Web.Caching {
using System.Collections;
using System.Collections.Specialized;
using System.Configuration;
using System.Diagnostics.CodeAnalysis;
using System.Runtime.InteropServices;
using System.Threading;
using System.Web.Util;
using System.Web;
using Microsoft.Win32;
using System.Security.Permissions;
using System.Globalization;
using System.Web.Configuration;
using System.Web.Management;
///
/// Represents the method that will handle the
///
public delegate void CacheItemRemovedCallback(
string key, object value, CacheItemRemovedReason reason);
///
/// Represents the method that will handle the
///
[SuppressMessage("Microsoft.Design", "CA1021:AvoidOutParameters")]
public delegate void CacheItemUpdateCallback(
string key, CacheItemUpdateReason reason,
out object expensiveObject, out CacheDependency dependency, out DateTime absoluteExpiration, out TimeSpan slidingExpiration);
///
/// Specifies the relative priority of items stored in the System.Web.Caching.Cache. When the Web
/// server runs low on memory, the Cache selectively purges items to free system
/// memory. Items with higher priorities are less likely to be removed from the
/// cache when the server is under load. Web
/// applications can use these
/// values to prioritize cached items relative to one another. The default is
/// normal.
///
public enum CacheItemPriority {
///
/// The cahce items with this priority level will be the first
/// to be removed when the server frees system memory by deleting items from the
/// cache.
///
Low = 1,
///
/// The cache items with this priority level
/// are in the second group to be removed when the server frees system memory by
/// deleting items from the cache.
///
BelowNormal,
///
/// The cache items with this priority level are in
/// the third group to be removed when the server frees system memory by deleting items from the cache. This is the default.
///
Normal,
///
/// The cache items with this priority level are in the
/// fourth group to be removed when the server frees system memory by deleting items from the
/// cache.
///
AboveNormal,
///
/// The cache items with this priority level are in the fifth group to be removed
/// when the server frees system memory by deleting items from the cache.
///
High,
///
/// The cache items with this priority level will not be removed when the server
/// frees system memory by deleting items from the cache.
///
NotRemovable,
///
/// The default value is Normal.
///
Default = Normal
}
///
/// Specifies the reason that a cached item was removed.
///
public enum CacheItemRemovedReason {
///
/// The item was removed from the cache by the 'System.Web.Caching.Cache.Remove' method, or by an System.Web.Caching.Cache.Insert method call specifying the same key.
///
Removed = 1,
///
/// The item was removed from the cache because it expired.
///
Expired,
///
/// The item was removed from the cache because the value in the hitInterval
/// parameter was not met, or because the system removed it to free memory.
///
Underused,
///
/// The item was removed from the cache because a file or key dependency was
/// changed.
///
DependencyChanged
}
///
/// Specifies the reason why a cached item needs to be updated.
///
[SuppressMessage("Microsoft.Design", "CA1008:EnumsShouldHaveZeroValue",
Justification = "This enum should mirror CacheItemRemovedReason enum in design")]
public enum CacheItemUpdateReason {
///
/// The item needs to be updated because it expired.
///
Expired = 1,
///
/// The item needs to be updated because a file or key dependency was
/// changed.
///
DependencyChanged
}
enum CacheGetOptions {
None = 0,
ReturnCacheEntry = 0x1,
}
///
/// Implements the cache for a Web application. There is only one instance of
/// this class per application domain, and it remains valid only as long as the
/// application domain remains active. Information about an instance of this class
/// is available through the
///
//
// Extra notes:
// - The Cache object contains a CacheInternal object.
// - The CacheInternal object is either a CacheSingle, or a CacheMultiple which contains mulitple
// CacheSingle objects.
//
[AspNetHostingPermission(SecurityAction.LinkDemand, Level=AspNetHostingPermissionLevel.Minimal)]
public sealed class Cache : IEnumerable {
///
/// Sets the absolute expiration policy to, in essence,
/// never. When set, this field is equal to the the System.DateTime.MaxValue , which is a constant
/// representing the largest possible
///
public static readonly DateTime NoAbsoluteExpiration = DateTime.MaxValue;
///
/// Sets the amount of time for sliding cache expirations to
/// zero. When set, this field is equal to the System.TimeSpan.Zero field, which is a constant value of
/// zero. This field is read-only.
///
public static readonly TimeSpan NoSlidingExpiration = TimeSpan.Zero;
CacheInternal _cacheInternal;
static CacheItemRemovedCallback s_sentinelRemovedCallback = new CacheItemRemovedCallback(SentinelEntry.OnCacheItemRemovedCallback);
///
/// This constructor is for internal use only, and was accidentally made public - do not use.
///
[SecurityPermission(SecurityAction.Demand, Unrestricted=true)]
public Cache() {
}
//
// internal ctor used by CacheCommon that avoids the demand for UnmanagedCode.
//
internal Cache(int dummy) {
}
internal void SetCacheInternal(CacheInternal cacheInternal) {
_cacheInternal = cacheInternal;
}
///
/// Gets the number of items stored in the cache. This value can be useful when
/// monitoring your application's performance or when using the ASP.NET tracing
/// functionality.
///
public int Count {
get {
return _cacheInternal.PublicCount;
}
}
///
/// Returns a dictionary enumerator used for iterating through the key/value
/// pairs contained in the cache. Items can be added to or removed from the cache
/// while this method is enumerating through the cache items.
///
public IDictionaryEnumerator GetEnumerator() {
return _cacheInternal.GetEnumerator();
}
///
/// Gets or sets an item in the cache.
///
public object this[string key] {
get {
return Get(key);
}
set {
Insert(key, value);
}
}
private class SentinelEntry {
private string _key;
private CacheDependency _expensiveObjectDependency;
private CacheItemUpdateCallback _cacheItemUpdateCallback;
public SentinelEntry(string key, CacheDependency expensiveObjectDependency, CacheItemUpdateCallback callback) {
_key = key;
_expensiveObjectDependency = expensiveObjectDependency;
_cacheItemUpdateCallback = callback;
}
public string Key {
get { return _key; }
}
public CacheDependency ExpensiveObjectDependency {
get { return _expensiveObjectDependency; }
}
public CacheItemUpdateCallback CacheItemUpdateCallback {
get { return _cacheItemUpdateCallback; }
}
public static void OnCacheItemRemovedCallback(string key, object value, CacheItemRemovedReason reason) {
CacheItemUpdateReason updateReason;
SentinelEntry entry = value as SentinelEntry;
switch (reason) {
case CacheItemRemovedReason.Expired:
updateReason = CacheItemUpdateReason.Expired;
break;
case CacheItemRemovedReason.DependencyChanged:
updateReason = CacheItemUpdateReason.DependencyChanged;
if (entry.ExpensiveObjectDependency.HasChanged) {
// If the expensiveObject has been removed explicitly by Cache.Remove,
// return from the SentinelEntry removed callback
// thus effectively removing the SentinelEntry from the cache.
return;
}
break;
case CacheItemRemovedReason.Underused:
Debug.Fail("Reason should never be CacheItemRemovedReason.Underused since the entry was inserted as NotRemovable.");
return;
default:
// do nothing if reason is Removed
return;
}
CacheDependency cacheDependency;
DateTime absoluteExpiration;
TimeSpan slidingExpiration;
object expensiveObject;
CacheItemUpdateCallback callback = entry.CacheItemUpdateCallback;
// invoke update callback
try {
callback(entry.Key, updateReason, out expensiveObject, out cacheDependency, out absoluteExpiration, out slidingExpiration);
if (expensiveObject != null) {
HttpRuntime.Cache.Insert(entry.Key, expensiveObject, cacheDependency, absoluteExpiration, slidingExpiration, entry.CacheItemUpdateCallback);
}
else {
HttpRuntime.Cache.Remove(entry.Key);
}
}
catch (Exception e) {
HttpRuntime.Cache.Remove(entry.Key);
try {
WebBaseEvent.RaiseRuntimeError(e, value);
}
catch {
}
}
}
}
///
/// Retrieves an item from the cache.
///
public object Get(string key) {
return _cacheInternal.DoGet(true, key, CacheGetOptions.None);
}
internal object Get(string key, CacheGetOptions getOptions) {
return _cacheInternal.DoGet(true, key, getOptions);
}
///
/// Inserts an item into the Cache with default values.
///
public void Insert(string key, object value) {
_cacheInternal.DoInsert(
true,
key,
value,
null,
NoAbsoluteExpiration,
NoSlidingExpiration,
CacheItemPriority.Default,
null,
true);
}
///
/// Inserts an object into the System.Web.Caching.Cache that has file or key
/// dependencies.
///
public void Insert(string key, object value, CacheDependency dependencies) {
_cacheInternal.DoInsert(
true,
key,
value,
dependencies,
NoAbsoluteExpiration,
NoSlidingExpiration,
CacheItemPriority.Default,
null,
true);
}
///
/// Inserts an object into the System.Web.Caching.Cache that has file or key dependencies and
/// expires at the value set in the
///
public void Insert(string key, object value, CacheDependency dependencies, DateTime absoluteExpiration, TimeSpan slidingExpiration) {
DateTime utcAbsoluteExpiration = DateTimeUtil.ConvertToUniversalTime(absoluteExpiration);
_cacheInternal.DoInsert(
true,
key,
value,
dependencies,
utcAbsoluteExpiration,
slidingExpiration,
CacheItemPriority.Default,
null,
true);
}
public void Insert(
string key,
object value,
CacheDependency dependencies,
DateTime absoluteExpiration,
TimeSpan slidingExpiration,
CacheItemPriority priority,
CacheItemRemovedCallback onRemoveCallback) {
DateTime utcAbsoluteExpiration = DateTimeUtil.ConvertToUniversalTime(absoluteExpiration);
_cacheInternal.DoInsert(
true,
key,
value,
dependencies,
utcAbsoluteExpiration,
slidingExpiration,
priority,
onRemoveCallback,
true);
}
// DevDiv Bugs 162763:
// Add a an event that fires *before* an item is evicted from the ASP.NET Cache
public void Insert(
string key,
object value,
CacheDependency dependencies,
DateTime absoluteExpiration,
TimeSpan slidingExpiration,
CacheItemUpdateCallback onUpdateCallback) {
if (dependencies == null && absoluteExpiration == Cache.NoAbsoluteExpiration && slidingExpiration == Cache.NoSlidingExpiration) {
throw new ArgumentException(SR.GetString(SR.Invalid_Parameters_To_Insert));
}
if (onUpdateCallback == null) {
throw new ArgumentNullException("onUpdateCallback");
}
DateTime utcAbsoluteExpiration = DateTimeUtil.ConvertToUniversalTime(absoluteExpiration);
// Insert updatable cache entry
_cacheInternal.DoInsert (
true,
key,
value,
null,
Cache.NoAbsoluteExpiration,
Cache.NoSlidingExpiration,
CacheItemPriority.NotRemovable,
null,
true);
// Ensure the sentinel depends on its updatable entry
string[] cacheKeys = { key };
CacheDependency expensiveObjectDep = new CacheDependency(null, cacheKeys);
if (dependencies == null) {
dependencies = expensiveObjectDep;
}
else {
AggregateCacheDependency deps = new AggregateCacheDependency();
deps.Add(dependencies, expensiveObjectDep);
dependencies = deps;
}
// Insert sentinel entry for the updatable cache entry
_cacheInternal.DoInsert(
false,
CacheInternal.PrefixValidationSentinel + key,
new SentinelEntry(key, expensiveObjectDep, onUpdateCallback),
dependencies,
utcAbsoluteExpiration,
slidingExpiration,
CacheItemPriority.NotRemovable,
Cache.s_sentinelRemovedCallback,
true);
}
public object Add(
string key,
object value,
CacheDependency dependencies,
DateTime absoluteExpiration,
TimeSpan slidingExpiration,
CacheItemPriority priority,
CacheItemRemovedCallback onRemoveCallback) {
DateTime utcAbsoluteExpiration = DateTimeUtil.ConvertToUniversalTime(absoluteExpiration);
return _cacheInternal.DoInsert(
true,
key,
value,
dependencies,
utcAbsoluteExpiration,
slidingExpiration,
priority,
onRemoveCallback,
false);
}
///
/// Removes the specified item from the cache.
///
public object Remove(string key) {
CacheKey cacheKey = new CacheKey(key, true);
return _cacheInternal.DoRemove(cacheKey, CacheItemRemovedReason.Removed);
}
public long EffectivePrivateBytesLimit {
get {
return _cacheInternal.EffectivePrivateBytesLimit;
}
}
public long EffectivePercentagePhysicalMemoryLimit {
get {
return _cacheInternal.EffectivePercentagePhysicalMemoryLimit;
}
}
}
class CacheCommon {
const int MEMORYSTATUS_INTERVAL_5_SECONDS = 5 * Msec.ONE_SECOND;
const int MEMORYSTATUS_INTERVAL_30_SECONDS = 30 * Msec.ONE_SECOND;
const int GC_BACKOFF_INTERVAL = 60;
const int GC_INTERVAL = 5;
internal CacheInternal _cacheInternal;
internal Cache _cachePublic;
internal protected CacheMemoryStats _cacheMemoryStats;
internal object _timerMemoryStatsLock = new object();
internal Timer _timerMemoryStats;
internal int _currentPollInterval = MEMORYSTATUS_INTERVAL_30_SECONDS;
internal DateTime _timerSuspendTime = DateTime.MinValue;
internal int _inMemoryStatsUpdate;
internal bool _enableMemoryCollection;
internal bool _enableExpiration;
internal bool _internalConfigRead;
private int _gcCollectCount; /* count of calls to GC.Collect */
internal CacheCommon() {
_cachePublic = new Cache(0);
_cacheMemoryStats = new CacheMemoryStats();
_enableMemoryCollection = true;
_enableExpiration = true;
}
internal void Dispose(bool disposing) {
if (disposing) {
EnableCacheMemoryTimer(false);
}
}
internal void SetCacheInternal(CacheInternal cacheInternal) {
_cacheInternal = cacheInternal;
_cachePublic.SetCacheInternal(cacheInternal);
}
internal void ReadCacheInternalConfig(CacheSection cacheSection) {
if (_internalConfigRead) {
return;
}
lock (this) {
if (_internalConfigRead) {
return;
}
// Set it to true here so that even if we have to call ReadCacheInternalConfig
// from the code below, we won't get into an infinite loop.
_internalConfigRead = true;
if (cacheSection != null) {
_enableMemoryCollection = (!cacheSection.DisableMemoryCollection);
_enableExpiration = (!cacheSection.DisableExpiration);
_cacheMemoryStats.ReadConfig(cacheSection);
_currentPollInterval = CacheMemoryPrivateBytesPressure.PollInterval;
ResetFromConfigSettings();
}
}
}
internal void ResetFromConfigSettings() {
EnableCacheMemoryTimer(_enableMemoryCollection);
_cacheInternal.EnableExpirationTimer(_enableExpiration);
}
internal void EnableCacheMemoryTimer(bool enable) {
lock (_timerMemoryStatsLock) {
#if DBG
if (Debug.IsTagPresent("Timer") && !Debug.IsTagEnabled("Timer")) {
enable = false;
}
#endif
if (enable) {
if (_timerMemoryStats == null) {
// has not been read yet
_timerMemoryStats = new Timer(new TimerCallback(this.MemoryStatusTimerCallback), null, _currentPollInterval, _currentPollInterval);
Debug.Trace("Cache", "Started CacheMemoryTimers");
}
else {
_timerMemoryStats.Change(_currentPollInterval, _currentPollInterval);
}
}
else {
Timer timer = _timerMemoryStats;
if (timer != null && Interlocked.CompareExchange(ref _timerMemoryStats, null, timer) == timer) {
timer.Dispose();
Debug.Trace("Cache", "Stopped CacheMemoryTimers");
}
}
}
if (!enable) {
// wait for MemoryStatusTimerCallback to finish
while(_inMemoryStatsUpdate != 0) {
Thread.Sleep(100);
}
}
}
void AdjustTimer() {
lock (_timerMemoryStatsLock) {
if (_timerMemoryStats == null)
return;
// the order of these if statements is important
// When above the high pressure mark, interval should be 5 seconds or less
if (_cacheMemoryStats.IsAboveHighPressure()) {
if (_currentPollInterval > MEMORYSTATUS_INTERVAL_5_SECONDS) {
_currentPollInterval = MEMORYSTATUS_INTERVAL_5_SECONDS;
_timerMemoryStats.Change(_currentPollInterval, _currentPollInterval);
}
return;
}
// When above half the low pressure mark, interval should be 30 seconds or less
if ((_cacheMemoryStats.PrivateBytesPressure.PressureLast > _cacheMemoryStats.PrivateBytesPressure.PressureLow/2)
|| (_cacheMemoryStats.TotalMemoryPressure.PressureLast > _cacheMemoryStats.TotalMemoryPressure.PressureLow/2)) {
// DevDivBugs 104034: allow interval to fall back down when memory pressure goes away
int newPollInterval = Math.Min(CacheMemoryPrivateBytesPressure.PollInterval, MEMORYSTATUS_INTERVAL_30_SECONDS);
if (_currentPollInterval != newPollInterval) {
_currentPollInterval = newPollInterval;
_timerMemoryStats.Change(_currentPollInterval, _currentPollInterval);
}
return;
}
// there is no pressure, interval should be the value from config
if (_currentPollInterval != CacheMemoryPrivateBytesPressure.PollInterval) {
_currentPollInterval = CacheMemoryPrivateBytesPressure.PollInterval;
_timerMemoryStats.Change(_currentPollInterval, _currentPollInterval);
}
}
}
void MemoryStatusTimerCallback(object state) {
if (Interlocked.Exchange(ref _inMemoryStatsUpdate, 1) != 0)
return;
Debug.Trace("CacheMemory", "MemoryStatusTimerCallback: appId=" + HttpRuntime.AppDomainAppIdInternal
+ ",time=" + DateTime.Now.ToString("T", CultureInfo.InvariantCulture));
try {
if (DateTime.UtcNow >= _timerSuspendTime) {
_cacheMemoryStats.Update();
AdjustTimer();
bool cacheTrimmed = _cacheInternal.ReviewMemoryStats();
// DevDivBugs 180639:
// Regression: ASP.NET Cache always calls GcCollect under higher memory pressure even if the cache hasn't been trimmed
// Do not call GcCollect if we didn't trim any cache items. CL2582117 unknowingly introduced this behavior that was a
// departure from what we had in ASP.NET 2.0. This caused a number of customers to experience poor performance after
// upgrading to 2.0 SP1.
if (_cacheMemoryStats.IsAboveHighPressure() && cacheTrimmed) {
GcCollect();
}
}
}
finally {
Interlocked.Exchange(ref _inMemoryStatsUpdate, 0);
}
}
// Call GcCollect if it's been a while since the last time we called.
// We wait an amount of time dependent on the memory pressure.
internal void GcCollect() {
Debug.Assert(_inMemoryStatsUpdate == 1, "GcCollect should only occur when we're updating memory statistics.");
Debug.Assert(_cacheMemoryStats.IsAboveHighPressure(), "_cacheMemoryStats.IsAboveHighPressure()");
// If we're under physical memory pressure, the GC is more aggressive and it is
// not necessary for us to call Collect. However, if we don't call Collect, we must ensure that
// we don't continue trimming--the memory statistics don't fall until the objects are collected.
// Here are the rules regarding calls to Collect:
// 1) Call Collect at most every GC_INTERVAL seconds.
// 2) If above high physical pressure, Collect at most every GC_BACKOFF_INTERVAL seconds and suspend
// MemoryStatusTimerCallback for GC_BACKOFF_INTERVAL seconds.
// 3) If we Trim but don't Collect, suspend the MemoryStatusTimerCallback for GC_BACKOFF_INTERVAL seconds.
// 4) If the configured poll interval is less than GC_BACKOFF_INTERVAL seconds, use it instead in 2) and 3), but always obey 1).
int pollIntervalInSeconds = CacheMemoryPrivateBytesPressure.PollInterval / Msec.ONE_SECOND;
int backoffInterval = Math.Max(Math.Min(pollIntervalInSeconds, GC_BACKOFF_INTERVAL), GC_INTERVAL);
bool isAboveHighPhysicalPressure = _cacheMemoryStats.TotalMemoryPressure.IsAboveHighPressure();
long totalMemoryChange = 0;
bool callCollect;
UnsafeNativeMethods.SetGCLastCalledTime(out callCollect, isAboveHighPhysicalPressure ? backoffInterval : GC_INTERVAL);
if (callCollect) {
#if DBG
DateTime utcNow1 = DateTime.UtcNow;
DateTime now1 = DateTime.Now;
#endif
// sometimes private bytes is the only one that changes significantly,
// and sometimes managed bytes is the one that changes significantly,
// so collect both and use the maximum difference to determine if the collection
// was effective
long privateBytesBefore = CacheMemoryPrivateBytesPressure.GetPrivateBytes(true);
long gcHeapBefore = GC.GetTotalMemory(false);
GC.Collect();
_gcCollectCount++;
long privateBytesAfter = CacheMemoryPrivateBytesPressure.GetPrivateBytes(true);
long gcHeapAfter = GC.GetTotalMemory(false);
totalMemoryChange = Math.Max(privateBytesBefore-privateBytesAfter, gcHeapBefore-gcHeapAfter);
#if DBG
DateTime utcNow2 = DateTime.UtcNow;
long shrunk;
if (privateBytesBefore > 0 && privateBytesBefore > privateBytesAfter) {
shrunk = (100 * (privateBytesBefore - privateBytesAfter) / privateBytesBefore );
}
else {
shrunk = 0;
}
long shrunk2;
if (gcHeapBefore > 0 && gcHeapBefore > gcHeapAfter) {
shrunk2 = (100 * (gcHeapBefore - gcHeapAfter) / gcHeapBefore );
}
else {
shrunk2 = 0;
}
Debug.Trace("CacheMemoryGcCollect", "GcCollect: appId=" + HttpRuntime.AppDomainAppIdInternal
+ ",time=" + now1.ToString("T", CultureInfo.InvariantCulture)
+ ",duration=" + (utcNow2 - utcNow1).TotalMilliseconds + " ms,shrunk=" + shrunk + "%;before="
+ (privateBytesBefore / (1024 * 1024)) + ",after=" + (privateBytesAfter / (1024 * 1024))
+ " ,shrunk2=" + shrunk2 + "%;before2="
+ (gcHeapBefore / (1024 * 1024)) + ",after2=" + (gcHeapAfter / (1024 * 1024)));
#endif
}
if (!callCollect || isAboveHighPhysicalPressure || _cacheMemoryStats.IsGcCollectIneffective(totalMemoryChange)) {
// VSWhidbey 478175: suspend memory status timer for to avoid successive GC calls when there is a memory leak
_timerSuspendTime = DateTime.UtcNow.AddSeconds(backoffInterval);
}
}
}
abstract class CacheInternal : IEnumerable, IDisposable {
// cache key prefixes - they keep cache keys short and prevent conflicts
// NOTE: Since we already used up all the lowercase letters from 'a' to 'z',
// we are now using uppercase letters from 'A' to 'Z'
internal const string PrefixFIRST = "A";
internal const string PrefixResourceProvider = "A";
// Next prefix goes here, until we get to 'Z'
internal const string PrefixOutputCache = "a";
internal const string PrefixSqlCacheDependency = "b";
internal const string PrefixMemoryBuildResult = "c";
internal const string PrefixPathData = "d";
internal const string PrefixHttpCapabilities = "e";
internal const string PrefixMapPath = "f";
internal const string PrefixHttpSys = "g";
internal const string PrefixFileSecurity = "h";
#if ORCAS
internal const string PrefixSiteCounters = "i";
#endif
internal const string PrefixInProcSessionState = "j";
internal const string PrefixStateApplication = "k";
internal const string PrefixPartialCachingControl = "l";
internal const string UNUSED = "m";
internal const string PrefixAdRotator = "n";
internal const string PrefixWebServiceDataSource = "o";
internal const string PrefixLoadXPath = "p";
internal const string PrefixLoadXml = "q";
internal const string PrefixLoadTransform = "r";
internal const string PrefixAspCompatThreading = "s";
internal const string PrefixDataSourceControl = "u";
internal const string PrefixValidationSentinel = "w";
internal const string PrefixWebEventResource = "x";
internal const string PrefixAssemblyPath = "y";
internal const string PrefixBrowserCapsHash = "z";
internal const string PrefixLAST = "z";
protected CacheCommon _cacheCommon;
// virtual methods requiring implementation
internal abstract int PublicCount {get;}
internal abstract IDictionaryEnumerator CreateEnumerator();
internal abstract CacheEntry UpdateCache(
CacheKey cacheKey,
CacheEntry newEntry,
bool replace,
CacheItemRemovedReason removedReason,
out object valueOld);
internal abstract bool ReviewMemoryStats();
internal abstract void EnableExpirationTimer(bool enable);
// common implementation
static internal CacheInternal Create() {
CacheCommon cacheCommon;
CacheInternal cacheInternal;
int numSubCaches = 0;
#if USE_CONFIG
String ver = VersionInfo.SystemWebVersion;
RegistryKey regKey = Registry.LocalMachine.OpenSubKey("Software\\Microsoft\\ASP.NET\\" + ver);
if (regKey != null) {
numSubCaches = (int) regKey.GetValue("numSubCaches", 0);
regKey.Close();
}
#endif
if (numSubCaches == 0) {
uint numCPUs = (uint) SystemInfo.GetNumProcessCPUs();
// the number of subcaches is the minimal power of 2 greater
// than or equal to the number of cpus
numSubCaches = 1;
numCPUs -= 1;
while (numCPUs > 0) {
numSubCaches <<= 1;
numCPUs >>= 1;
}
}
cacheCommon = new CacheCommon();
if (numSubCaches == 1) {
cacheInternal = new CacheSingle(cacheCommon, null, 0);
}
else {
cacheInternal = new CacheMultiple(cacheCommon, numSubCaches);
}
cacheCommon.SetCacheInternal(cacheInternal);
cacheCommon.ResetFromConfigSettings();
return cacheInternal;
}
protected CacheInternal(CacheCommon cacheCommon) {
_cacheCommon = cacheCommon;
}
protected virtual void Dispose(bool disposing) {
_cacheCommon.Dispose(disposing);
}
public void Dispose() {
Dispose(true);
// no destructor, don't need it.
// System.GC.SuppressFinalize(this);
}
internal void ReadCacheInternalConfig(CacheSection cacheSection) {
_cacheCommon.ReadCacheInternalConfig(cacheSection);
}
internal Cache CachePublic {
get {return _cacheCommon._cachePublic;}
}
#if UNUSED_CODE
internal CacheMemoryStats CacheMemoryStats {
get {return _cacheCommon._cacheMemoryStats;}
}
#endif
internal long EffectivePrivateBytesLimit {
get { return _cacheCommon._cacheMemoryStats.PrivateBytesPressure.PressureHighMemoryLimit; }
}
internal long EffectivePercentagePhysicalMemoryLimit {
get { return _cacheCommon._cacheMemoryStats.TotalMemoryPressure.MemoryLimit; }
}
IEnumerator IEnumerable.GetEnumerator() {
return CreateEnumerator();
}
public IDictionaryEnumerator GetEnumerator() {
return CreateEnumerator();
}
internal object this[string key] {
get {
return Get(key);
}
#if UNUSED_CODE
set {
UtcInsert(key, value);
}
#endif
}
internal object Get(string key) {
return DoGet(false, key, CacheGetOptions.None);
}
internal object Get(string key, CacheGetOptions getOptions) {
return DoGet(false, key, getOptions);
}
internal object DoGet(bool isPublic, string key, CacheGetOptions getOptions) {
CacheEntry entry;
CacheKey cacheKey;
object dummy;
cacheKey = new CacheKey(key, isPublic);
entry = UpdateCache(cacheKey, null, false, CacheItemRemovedReason.Removed, out dummy);
if (entry != null) {
if ((getOptions & CacheGetOptions.ReturnCacheEntry) != 0) {
return entry;
}
else {
return entry.Value;
}
}
else {
return null;
}
}
internal void UtcInsert(string key, object value) {
DoInsert(false,
key,
value,
null,
Cache.NoAbsoluteExpiration,
Cache.NoSlidingExpiration,
CacheItemPriority.Default,
null,
true);
}
internal void UtcInsert(string key, object value, CacheDependency dependencies) {
DoInsert(false,
key,
value,
dependencies,
Cache.NoAbsoluteExpiration,
Cache.NoSlidingExpiration,
CacheItemPriority.Default,
null,
true);
}
internal void UtcInsert(
string key,
object value,
CacheDependency dependencies,
DateTime utcAbsoluteExpiration,
TimeSpan slidingExpiration) {
DoInsert(false,
key,
value,
dependencies,
utcAbsoluteExpiration,
slidingExpiration,
CacheItemPriority.Default,
null,
true);
}
internal void UtcInsert(
string key,
object value,
CacheDependency dependencies,
DateTime utcAbsoluteExpiration,
TimeSpan slidingExpiration,
CacheItemPriority priority,
CacheItemRemovedCallback onRemoveCallback) {
DoInsert(false,
key,
value,
dependencies,
utcAbsoluteExpiration,
slidingExpiration,
priority,
onRemoveCallback,
true);
}
internal object UtcAdd(
string key,
object value,
CacheDependency dependencies,
DateTime utcAbsoluteExpiration,
TimeSpan slidingExpiration,
CacheItemPriority priority,
CacheItemRemovedCallback onRemoveCallback) {
return DoInsert(
false,
key,
value,
dependencies,
utcAbsoluteExpiration,
slidingExpiration,
priority,
onRemoveCallback,
false);
}
internal object DoInsert(
bool isPublic,
string key,
object value,
CacheDependency dependencies,
DateTime utcAbsoluteExpiration,
TimeSpan slidingExpiration,
CacheItemPriority priority,
CacheItemRemovedCallback onRemoveCallback,
bool replace) {
/*
* If we throw an exception, prevent a leak by a user who
* writes the following:
*
* Cache.Insert(key, value, new CacheDependency(file));
*/
using (dependencies) {
CacheEntry entry;
object dummy;
entry = new CacheEntry(
key,
value,
dependencies,
onRemoveCallback,
utcAbsoluteExpiration,
slidingExpiration,
priority,
isPublic);
entry = UpdateCache(entry, entry, replace, CacheItemRemovedReason.Removed, out dummy);
/*
* N.B. A set can fail if two or more threads set the same key
* at the same time.
*/
#if DBG
if (replace) {
string yesno = (entry != null) ? "succeeded" : "failed";
Debug.Trace("CacheAPIInsert", "Cache.Insert " + yesno + ": " + key);
}
else {
if (entry == null) {
Debug.Trace("CacheAPIAdd", "Cache.Add added new item: " + key);
}
else {
Debug.Trace("CacheAPIAdd", "Cache.Add returned existing item: " + key);
}
}
#endif
if (entry != null) {
return entry.Value;
}
else {
return null;
}
}
}
internal object Remove(string key) {
CacheKey cacheKey = new CacheKey(key, false);
return DoRemove(cacheKey, CacheItemRemovedReason.Removed);
}
#if UNUSED_CODE
internal object Remove(string key, CacheItemRemovedReason reason) {
CacheKey cacheKey = new CacheKey(key, false);
return DoRemove(cacheKey, reason);
}
#endif
internal object Remove(CacheKey cacheKey, CacheItemRemovedReason reason) {
return DoRemove(cacheKey, reason);
}
/*
* Remove an item from the cache, with a specific reason.
* This is package access so only the cache can specify
* a reason other than REMOVED.
*
* @param key The key for the item.
* @exception ArgumentException
*/
internal object DoRemove(CacheKey cacheKey, CacheItemRemovedReason reason) {
object valueOld;
UpdateCache(cacheKey, null, true, reason, out valueOld);
#if DBG
if (valueOld != null) {
Debug.Trace("CacheAPIRemove", "Cache.Remove succeeded, reason=" + reason + ": " + cacheKey);
}
else {
Debug.Trace("CacheAPIRemove", "Cache.Remove failed, reason=" + reason + ": " + cacheKey);
}
#endif
return valueOld;
}
}
sealed class CacheKeyComparer : IEqualityComparer {
static CacheKeyComparer s_comparerInstance;
static internal CacheKeyComparer GetInstance() {
if (s_comparerInstance == null) {
s_comparerInstance = new CacheKeyComparer();
}
return s_comparerInstance;
}
private CacheKeyComparer()
{
}
bool IEqualityComparer.Equals(Object x, Object y)
{
return Compare(x, y) == 0;
}
// Compares two objects. An implementation of this method must return a
// value less than zero if x is less than y, zero if x is equal to y, or a
// value greater than zero if x is greater than y.
private int Compare(Object x, Object y) {
CacheKey a, b;
Debug.Assert(x != null && x is CacheKey);
Debug.Assert(y != null && y is CacheKey);
a = (CacheKey) x;
b = (CacheKey) y;
if (a.IsPublic) {
if (b.IsPublic) {
return String.Compare(a.Key, b.Key, StringComparison.Ordinal);
}
else {
return 1;
}
}
else {
if (!b.IsPublic) {
return String.Compare(a.Key, b.Key, StringComparison.Ordinal);
}
else {
return -1;
}
}
}
// Returns a hash code for the given object.
//
int IEqualityComparer.GetHashCode(Object obj) {
Debug.Assert(obj != null && obj is CacheKey);
CacheKey cacheKey = (CacheKey) obj;
return cacheKey.GetHashCode();
}
}
/*
* The cache.
*/
sealed class CacheSingle : CacheInternal {
// cache stats
static readonly TimeSpan FLUSH_UNDERCOUNT_WAIT = new TimeSpan(0, 0, 1);
static readonly TimeSpan INSERT_BLOCK_WAIT = new TimeSpan(0, 0, 10);
const int MAX_COUNT = Int32.MaxValue / 2;
const int MIN_COUNT = 10;
const int MAX_OVERLOAD_COUNT = 50;
Hashtable _entries; /* lookup table of entries */
CacheExpires _expires; /* expires tables */
CacheUsage _usage; /* usage tables */
object _lock; /* read/write synchronization for _entries */
int _disposed; /* disposed */
int _totalCount; /* count of total entries */
int _publicCount; /* count of public entries */
int _maxCount; /* cache maximum count */
int _maxCountOverload; /* count at which an add triggers a trim */
bool _flushUndercount; /* was the last flush unable to flush items */
ManualResetEvent _insertBlock; /* event to block inserts during high mem usage */
bool _useInsertBlock; /* use insert block? */
int _insertBlockCalls; /* number of callers using insert block */
DateTime _utcLastTrimCompleted; /* the time we last collected */
int _iSubCache; /* index of this cache */
CacheMultiple _cacheMultiple; /* the CacheMultiple containing this cache */
/*
* Constructs a new Cache.
*/
internal CacheSingle(CacheCommon cacheCommon, CacheMultiple cacheMultiple, int iSubCache) : base(cacheCommon) {
_cacheMultiple = cacheMultiple;
_iSubCache = iSubCache;
_entries = new Hashtable(CacheKeyComparer.GetInstance());
_expires = new CacheExpires(this);
_usage = new CacheUsage(this);
_lock = new object();
_maxCount = MAX_COUNT;
_maxCountOverload = MAX_COUNT + MAX_OVERLOAD_COUNT;
_insertBlock = new ManualResetEvent(true);
}
/*
* Dispose the cache.
*/
protected override void Dispose(bool disposing) {
if (disposing) {
if (Interlocked.Exchange(ref _disposed, 1) == 0) {
if (_expires != null) {
_expires.EnableExpirationTimer(false);
}
// close all items
CacheEntry[] entries = null;
lock (_lock) {
entries = new CacheEntry[_entries.Count];
int i = 0;
foreach (DictionaryEntry d in _entries) {
entries[i++] = (CacheEntry) d.Value;
}
}
foreach (CacheEntry entry in entries) {
Remove(entry, CacheItemRemovedReason.Removed);
}
// force any waiters to complete their waits. Note
// that the insert block cannot be reacquired, as UseInsertBlock
// checks the _disposed field.
_insertBlock.Set();
// release the block, causing it to be disposed when there
// are no more callers.
ReleaseInsertBlock();
Debug.Trace("CacheDispose", "Cache disposed");
}
}
base.Dispose(disposing);
}
// Get the insert block manual reset event if it has not been disposed.
ManualResetEvent UseInsertBlock() {
for (;;) {
if (_disposed == 1)
return null;
int n = _insertBlockCalls;
if (n < 0) {
return null;
}
if (Interlocked.CompareExchange(ref _insertBlockCalls, n + 1, n) == n) {
return _insertBlock;
}
}
}
// Release the insert block event, and dispose it if it has been released
// more times than it has been used
void ReleaseInsertBlock() {
if (Interlocked.Decrement(ref _insertBlockCalls) < 0) {
ManualResetEvent e = _insertBlock;
_insertBlock = null;
// now close
e.Close();
}
}
// Set the insert block event.
void SetInsertBlock() {
ManualResetEvent e = null;
try {
e = UseInsertBlock();
if (e != null) {
e.Set();
}
}
finally {
if (e != null) {
ReleaseInsertBlock();
}
}
}
// Reset the insert block event.
void ResetInsertBlock() {
ManualResetEvent e = null;
try {
e = UseInsertBlock();
if (e != null) {
e.Reset();
}
}
finally {
if (e != null) {
ReleaseInsertBlock();
}
}
}
// Wait on the insert block event.
bool WaitInsertBlock() {
bool signaled = false;
ManualResetEvent e = null;
try {
e = UseInsertBlock();
if (e != null) {
Debug.Trace("CacheMemoryTrimInsertBlock", "WaitInsertBlock: Cache " + _iSubCache + ": _useInsertBlock=true");
signaled = e.WaitOne(INSERT_BLOCK_WAIT, false);
Debug.Trace("CacheMemoryTrimInsertBlock", "Done waiting");
}
}
finally {
if (e != null) {
ReleaseInsertBlock();
}
}
return signaled;
}
internal void BlockInsertIfNeeded() {
if (_cacheCommon._cacheMemoryStats.IsAboveHighPressure()) {
Debug.Trace("CacheMemoryTrimInsertBlock", "BlockInsertIfNeeded: Cache " + _iSubCache + ": _useInsertBlock=true");
_useInsertBlock = true;
ResetInsertBlock();
}
}
internal void UnblockInsert() {
if (_useInsertBlock) {
_useInsertBlock = false;
SetInsertBlock();
Debug.Trace("CacheMemoryTrimInsertBlock", "UnblockInsert: Cache " + _iSubCache + ": _useInsertBlock=false");
}
}
internal override int PublicCount {
get {return _publicCount;}
}
internal override IDictionaryEnumerator CreateEnumerator() {
Hashtable h = new Hashtable(_publicCount);
DateTime utcNow = DateTime.UtcNow;
lock (_lock) {
foreach (DictionaryEntry d in _entries) {
CacheEntry entry = (CacheEntry) d.Value;
// note that ASP.NET does not use this enumerator internally,
// so we just choose public items.
if (entry.IsPublic &&
entry.State == CacheEntry.EntryState.AddedToCache &&
((!_cacheCommon._enableExpiration) || (utcNow <= entry.UtcExpires))) {
h[entry.Key] = entry.Value;
}
}
}
return h.GetEnumerator();
}
/*
* Performs all operations on the cache, with the
* exception of Clear. The arguments indicate the type of operation:
*
* @param key The key of the object.
* @param newItem The new entry to be added to the cache.
* @param replace Whether or not newEntry should replace an existing object in the cache.
* @return The item requested. May be null.
*/
internal override CacheEntry UpdateCache(
CacheKey cacheKey,
CacheEntry newEntry,
bool replace,
CacheItemRemovedReason removedReason,
out object valueOld)
{
CacheEntry entry = null;
CacheEntry oldEntry = null;
bool expired = false;
DateTime utcNow;
CacheDependency newEntryDependency = null;
bool isGet, isAdd;
bool removeExpired = false;
bool updateExpires = false;
DateTime utcNewExpires = DateTime.MinValue;
CacheEntry.EntryState entryState = CacheEntry.EntryState.NotInCache;
bool newEntryNeedsClose = false;
CacheItemRemovedReason newEntryRemovedReason = CacheItemRemovedReason.Removed;
valueOld = null;
isGet = !replace && newEntry == null;
isAdd = !replace && newEntry != null;
/*
* Perform update of cache data structures in a series to
* avoid overlapping locks.
*
* First, update the hashtable. The hashtable is the place
* that guarantees what is in or out of the cache.
*
* Loop here to remove expired items in a Get or Add, where
* we can't otherwise delete an item.
*/
for (;;) {
if (removeExpired) {
Debug.Trace("CacheUpdate", "Removing expired item found in Get: " + cacheKey);
UpdateCache(cacheKey, null, true, CacheItemRemovedReason.Expired, out valueOld);
removeExpired = false;
}
entry = null;
utcNow = DateTime.UtcNow;
if (_useInsertBlock && newEntry != null && newEntry.HasUsage() /* HasUsage() means it's not NonRemovable */) {
bool insertBlockReleased = WaitInsertBlock();
#if DBG
if (!insertBlockReleased) {
Debug.Trace("CacheUpdateWaitFailed", "WaitInsertBlock failed.");
}
#endif
}
// the _entries hashtable supports multiple readers or one writer
bool isLockEntered = false;
if (!isGet) {
try {
}
finally {
// guarantee that there is no interruption between the following
// two statements by enclosing them within a finally block
Monitor.Enter(_lock);
isLockEntered = true;
}
}
try {
entry = (CacheEntry) _entries[cacheKey];
Debug.Trace("CacheUpdate", "Entry " + ((entry != null) ? "found" : "not found") + "in hashtable: " + cacheKey);
if (entry != null) {
entryState = entry.State;
// If isGet == true, we are not hold any lock and so entryState can be anything
Debug.Assert(
isGet ||
entryState == CacheEntry.EntryState.AddingToCache ||
entryState == CacheEntry.EntryState.AddedToCache,
"entryState == CacheEntry.EntryState.AddingToCache || entryState == CacheEntry.EntryState.AddedToCache");
expired = (_cacheCommon._enableExpiration) && (entry.UtcExpires < utcNow);
if (expired) {
if (isGet) {
/*
* If the expired item is Added to the cache, remove it now before
* its expiration timer fires up to a minute in the future.
* Otherwise, just return null to indicate the item is not available.
*/
if (entryState == CacheEntry.EntryState.AddedToCache) {
removeExpired = true;
continue;
}
entry = null;
}
else {
/*
* If it's a call to Add, replace the item
* when it has expired.
*/
replace = true;
/*
* Change the removed reason.
*/
removedReason = CacheItemRemovedReason.Expired;
}
}
else {
updateExpires = (_cacheCommon._enableExpiration) && (entry.SlidingExpiration > TimeSpan.Zero);
}
}
/*
* Avoid running unnecessary code in a Get request by this simple test:
*/
if (!isGet) {
/*
* Remove an item from the hashtable.
*/
if (replace && entry != null) {
bool doRemove = (entryState != CacheEntry.EntryState.AddingToCache);
if (doRemove) {
oldEntry = entry;
oldEntry.State = CacheEntry.EntryState.RemovingFromCache;
_entries.Remove(oldEntry);
Debug.Trace("CacheUpdate", "Entry removed from hashtable: " + cacheKey);
}
else {
/*
* If we're removing and couldn't remove the old item
* because its state was AddingToCache, return null
* to indicate failure.
*/
if (newEntry == null) {
Debug.Trace("CacheUpdate", "Removal from hashtable failed: " + cacheKey);
entry = null;
}
}
}
/*
* Add an item to the hashtable.
*/
if (newEntry != null) {
bool doAdd = true;
if (entry != null) {
if (oldEntry == null) {
/*
* We could not remove the existing entry,
* either because it simply exists and replace == false,
* or replace == true and it's state was AddingToCache when
* we tried to remove it.
*/
doAdd = false;
newEntryRemovedReason = CacheItemRemovedReason.Removed;
}
#if DBG
if (!doAdd) {
Debug.Trace("CacheUpdate", "Insertion into hashtable failed because old entry was not removed: " + cacheKey);
}
#endif
}
if (doAdd) {
/* non-definitive check */
newEntryDependency = newEntry.Dependency;
if (newEntryDependency != null) {
if (newEntryDependency.HasChanged) {
doAdd = false;
newEntryRemovedReason = CacheItemRemovedReason.DependencyChanged;
}
#if DBG
if (!doAdd) {
Debug.Trace("CacheUpdate", "Insertion into hashtable failed because dependency changed: " + cacheKey);
}
#endif
}
}
if (doAdd) {
newEntry.State = CacheEntry.EntryState.AddingToCache;
_entries.Add(newEntry, newEntry);
/*
* If this is an Add operation, indicate success
* by returning null.
*/
if (isAdd) {
Debug.Assert(entry == null || expired, "entry == null || expired");
entry = null;
}
else {
/*
* Indicate success by returning the inserted entry.
*/
entry = newEntry;
}
Debug.Trace("CacheUpdate", "Entry added to hashtable: " + cacheKey);
}
else {
if (!isAdd) {
/*
* If we failed for an Insert, indicate failure by returning null.
*/
entry = null;
newEntryNeedsClose = true;
}
else {
/*
* If we failed for an Add (e.g. Dependency has changed),
* return the existing value. If existing value is null,
* we have to close the newEntry ourselves. Otherwise, we'll
* return non-null and the caller should close the item.
*/
newEntryNeedsClose = (entry == null);
}
/*
* If newEntry cannot be inserted, and it does not need to be
* closed, set it to null so that we don't insert it later.
* Leave it non-null when it needs to be closed that that we
* can close it.
*/
if (!newEntryNeedsClose) {
newEntry = null;
}
}
}
}
break;
}
finally {
if (isLockEntered) {
Monitor.Exit(_lock);
}
}
}
/*
* Since we want Get to be fast, check here for a get without
* alteration to cache.
*/
if (isGet) {
if (entry != null) {
if (updateExpires) {
utcNewExpires = utcNow + entry.SlidingExpiration;
if (utcNewExpires - entry.UtcExpires >= CacheExpires.MIN_UPDATE_DELTA || utcNewExpires < entry.UtcExpires) {
_expires.UtcUpdate(entry, utcNewExpires);
}
}
UtcUpdateUsageRecursive(entry, utcNow);
}
if (cacheKey.IsPublic) {
PerfCounters.IncrementCounter(AppPerfCounter.API_CACHE_RATIO_BASE);
if (entry != null) {
PerfCounters.IncrementCounter(AppPerfCounter.API_CACHE_HITS);
}
else {
PerfCounters.IncrementCounter(AppPerfCounter.API_CACHE_MISSES);
}
}
PerfCounters.IncrementCounter(AppPerfCounter.TOTAL_CACHE_RATIO_BASE);
if (entry != null) {
PerfCounters.IncrementCounter(AppPerfCounter.TOTAL_CACHE_HITS);
}
else {
PerfCounters.IncrementCounter(AppPerfCounter.TOTAL_CACHE_MISSES);
}
#if DBG
if (entry != null) {
Debug.Trace("CacheUpdate", "Cache hit: " + cacheKey);
}
else {
Debug.Trace("CacheUpdate", "Cache miss: " + cacheKey);
}
#endif
}
else {
int totalDelta = 0;
int publicDelta = 0;
int totalTurnover = 0;
int publicTurnover = 0;
if (oldEntry != null) {
if (oldEntry.InExpires()) {
_expires.Remove(oldEntry);
}
if (oldEntry.InUsage()) {
_usage.Remove(oldEntry);
}
Debug.Assert(oldEntry.State == CacheEntry.EntryState.RemovingFromCache, "oldEntry.State == CacheEntry.EntryState.RemovingFromCache");
oldEntry.State = CacheEntry.EntryState.RemovedFromCache;
valueOld = oldEntry.Value;
totalDelta--;
totalTurnover++;
if (oldEntry.IsPublic) {
publicDelta--;
publicTurnover++;
}
#if DBG
Debug.Trace("CacheUpdate", "Entry removed from cache, reason=" + removedReason + ": " + (CacheKey) oldEntry);
#endif
}
if (newEntry != null) {
if (newEntryNeedsClose) {
// Call close if newEntry could not be added.
newEntry.State = CacheEntry.EntryState.RemovedFromCache;
newEntry.Close(newEntryRemovedReason);
newEntry = null;
}
else {
Debug.Assert(!newEntry.InExpires());
Debug.Assert(!newEntry.InUsage());
if (_cacheCommon._enableExpiration && newEntry.HasExpiration()) {
_expires.Add(newEntry);
}
if ( _cacheCommon._enableMemoryCollection && newEntry.HasUsage() &&
( // Don't bother to set usage if it's going to expire very soon
!newEntry.HasExpiration() ||
newEntry.SlidingExpiration > TimeSpan.Zero ||
newEntry.UtcExpires - utcNow >= CacheUsage.MIN_LIFETIME_FOR_USAGE)) {
_usage.Add(newEntry);
}
newEntry.State = CacheEntry.EntryState.AddedToCache;
Debug.Trace("CacheUpdate", "Entry added to cache: " + (CacheKey)newEntry);
totalDelta++;
totalTurnover++;
if (newEntry.IsPublic) {
publicDelta++;
publicTurnover++;
}
}
}
// Call close after the newEntry has been fully added to the cache,
// so the OnRemoveCallback can take a dependency on the newly inserted item.
if (oldEntry != null) {
oldEntry.Close(removedReason);
}
// Delay monitoring change events until the oldEntry has been completely removed
// from the cache, and its OnRemoveCallback called. This way we won't call the
// OnRemoveCallback for newEntry before doing so for oldEntry.
if (newEntry != null) {
// listen to change events
newEntry.MonitorDependencyChanges();
/*
* NB: We have to check for dependency changes after we add the item
* to cache, because otherwise we may not remove it if it changes
* between the time we check for a dependency change and the time
* we set the AddedToCache bit. The worst that will happen is that
* a get can occur on an item that has changed, but that can happen
* anyway. The important thing is that we always remove an item that
* has changed.
*/
if (newEntryDependency != null && newEntryDependency.HasChanged) {
Remove(newEntry, CacheItemRemovedReason.DependencyChanged);
}
}
// update counts and counters
if (totalDelta == 1) {
Interlocked.Increment(ref _totalCount);
PerfCounters.IncrementCounter(AppPerfCounter.TOTAL_CACHE_ENTRIES);
}
else if (totalDelta == -1) {
Interlocked.Decrement(ref _totalCount);
PerfCounters.DecrementCounter(AppPerfCounter.TOTAL_CACHE_ENTRIES);
}
if (publicDelta == 1) {
Interlocked.Increment(ref _publicCount);
PerfCounters.IncrementCounter(AppPerfCounter.API_CACHE_ENTRIES);
}
else if (publicDelta == -1) {
Interlocked.Decrement(ref _publicCount);
PerfCounters.DecrementCounter(AppPerfCounter.API_CACHE_ENTRIES);
}
if (totalTurnover > 0) {
PerfCounters.IncrementCounterEx(AppPerfCounter.TOTAL_CACHE_TURNOVER_RATE, totalTurnover);
}
if (publicTurnover > 0) {
PerfCounters.IncrementCounterEx(AppPerfCounter.API_CACHE_TURNOVER_RATE, publicTurnover);
}
}
return entry;
}
void UtcUpdateUsageRecursive(CacheEntry entry, DateTime utcNow) {
CacheDependency dependency;
CacheEntry[] entries;
// Don't update if the last update is less than 1 sec away. This way we'll
// avoid over updating the usage in the scenario where a cache makes several
// update requests.
if (utcNow - entry.UtcLastUsageUpdate > CacheUsage.CORRELATED_REQUEST_TIMEOUT || utcNow < entry.UtcLastUsageUpdate) {
entry.UtcLastUsageUpdate = utcNow;
if (entry.InUsage()) {
CacheSingle cacheSingle;
if (_cacheMultiple == null) {
cacheSingle = this;
}
else {
cacheSingle = _cacheMultiple.GetCacheSingle(entry.Key.GetHashCode());
}
cacheSingle._usage.Update(entry);
}
dependency = entry.Dependency;
if (dependency != null) {
entries = dependency.CacheEntries;
if (entries != null) {
foreach (CacheEntry dependent in entries) {
UtcUpdateUsageRecursive(dependent, utcNow);
}
}
}
}
}
// calculate a new _maxCount based on the current memory pressure
int CalcMaxCount(CacheMemoryPressure pressure) {
int pressureLast = pressure.PressureLast;
int pressureAvg = pressure.PressureAvg;
int pressureHigh = pressure.PressureHigh;
int pressureLow = pressure.PressureLow;
int pressureMiddle = pressure.PressureMiddle;
int count = _totalCount;
int newMaxCount = -1;
if (pressureLast > pressureMiddle) {
// Possible scenarios:
// middle < high < Avg < Last : 50%
// middle < high < Last < Avg : 50%
// middle < Avg < high < Last : 50%
// Avg < middle < high < Last : 50%
// middle < Last < high < Avg : 5%
// middle < Avg < Last < high : 5%
// middle < Last < Avg < high : 5%
// Avg < middle < Last < high : 5%
if (pressureLast >= pressureHigh) {
// reduce by 50%
newMaxCount = (int)((long)count/ 2L);
}
else {
// reduce by MIN(5%, (pressureLast - pressureMiddle / pressureMiddle)%)
newMaxCount = (int)((long) count * (long)(2 * pressureMiddle - pressureLast) / (long)pressureMiddle);
newMaxCount = Math.Max((int)(19L * (long)count / 20L), newMaxCount);
}
}
else if (pressureLast == pressureMiddle) {
if (_maxCount < MAX_COUNT) {
newMaxCount = _maxCount;
}
else {
newMaxCount = count;
}
}
else if (pressureLast >= pressureLow) {
// Possible scenarios:
// Last < middle < high < Avg : no reduction
// Last < middle < Avg < high : no reduction
// Last < Avg < middle < high : increase by (middle - Last)/middle %
// Avg < Last < middle < high : increase by (middle - Last)/middle %
// When the pressure is between middle and low, ensure
// the count does not fall. If the average pressure is less
// than the middle, increase maxCount proportionally.
if (pressureAvg < pressureMiddle) {
// increase by (pressureMiddle - pressureLast / pressureMiddle)%
newMaxCount = (int)((long) count * (long)(2 * pressureMiddle - pressureLast) / (long)pressureMiddle);
}
else {
newMaxCount = count;
}
// ensure that _maxCount does not fall
if (_maxCount < MAX_COUNT) {
newMaxCount = Math.Max(newMaxCount, _maxCount);
}
}
else {
// Under low pressure, don't restrict count.
newMaxCount = MAX_COUNT;
}
#if DBG
Debug.Assert(newMaxCount != -1, "newMaxCount != -1");
if (HttpRuntime.AppDomainAppIdInternal != null && HttpRuntime.AppDomainAppIdInternal.Length > 0) {
Debug.Trace("CacheMemory", pressure.GetType().Name + ".CalcMaxCount: " + _iSubCache + ",last=" + pressureLast + ",avg=" + pressureAvg + ",count=" + count + ",_maxCount=" + _maxCount + ",newMaxCount=" + newMaxCount);
}
#endif
return newMaxCount;
}
internal override bool ReviewMemoryStats() {
int newMaxCount = CalcMaxCount(_cacheCommon._cacheMemoryStats.TotalMemoryPressure);
if (_cacheCommon._cacheMemoryStats.PrivateBytesPressure.HasLimit()) {
newMaxCount = Math.Min(newMaxCount, CalcMaxCount(_cacheCommon._cacheMemoryStats.PrivateBytesPressure));
}
newMaxCount = Math.Max(newMaxCount, MIN_COUNT);
newMaxCount = Math.Min(newMaxCount, MAX_COUNT);
_maxCount = newMaxCount;
_maxCountOverload = _maxCount + MAX_OVERLOAD_COUNT;
#if DBG
if (HttpRuntime.AppDomainAppIdInternal != null && HttpRuntime.AppDomainAppIdInternal.Length > 0) {
Debug.Trace("CacheMemory", "ReviewMemoryStats: _iSubCache= " + _iSubCache + ":_totalCount=" + _totalCount + ",_maxCount=" + _maxCount + ",_maxCountOverload=" + _maxCountOverload + " " + Debug.FormatLocalDate(DateTime.Now));
}
#endif
return TrimIfNeeded();
}
// We need to trim is the count is too high and we're able to flush
// items from the cache.
bool NeedsTrim() {
bool needsTrim = false;
if (_cacheCommon._enableMemoryCollection) {
if (_totalCount > _maxCountOverload || (_totalCount > _maxCount && _cacheCommon._cacheMemoryStats.IsAboveMediumPressure())) {
if (!_flushUndercount) {
needsTrim = true;
}
else {
needsTrim = (DateTime.UtcNow - _utcLastTrimCompleted >= FLUSH_UNDERCOUNT_WAIT);
}
}
}
return needsTrim;
}
bool TrimIfNeeded() {
// quick check
if (NeedsTrim()) {
Trim();
return true;
}
return false;
}
// This is the trim thread. Keep trimming while there are items to trim.
// Release the thread when there are no more items to trim.
void Trim() {
Debug.Assert(_cacheCommon._inMemoryStatsUpdate == 1, "Trim should only occur when we're updating memory statistics.");
Debug.Trace("CacheMemoryTrim", "Cache " + _iSubCache + ": Thread start");
int publicEntriesFlushed = 0; // number of public entries flushed
int totalFlushed = 0; // total number of entries flushed
try {
for (;;) {
int toFlush = _totalCount - _maxCount;
int flushed = 0;
if (toFlush > 0) {
#if DBG
DateTime start = DateTime.UtcNow;
Debug.Trace("CacheMemoryTrim", "Cache " + _iSubCache + ": start trimming " + toFlush +
" from cache at " + Debug.FormatUtcDate(start) + ",_totalCount=" + _totalCount);
#endif
flushed = _expires.FlushExpiredItems(true);
int underUsedFlushed = 0;
if (flushed < toFlush) {
underUsedFlushed = _usage.FlushUnderUsedItems(toFlush - flushed, ref publicEntriesFlushed);
flushed += underUsedFlushed;
totalFlushed += underUsedFlushed;
}
#if DBG
DateTime end = DateTime.UtcNow;
Debug.Trace("CacheMemoryTrim", "Cache " + _iSubCache + ": end trimming " + flushed +
" from cache at " + Debug.FormatUtcDate(end) +
" in " + (end - start).TotalMilliseconds + " msec,_totalCount=" + _totalCount);
#endif
}
_utcLastTrimCompleted = DateTime.UtcNow;
_flushUndercount = (flushed < toFlush);
if (!NeedsTrim())
break;
}
// Update values for perfcounters
PerfCounters.IncrementCounterEx(AppPerfCounter.CACHE_TOTAL_TRIMS, totalFlushed);
PerfCounters.IncrementCounterEx(AppPerfCounter.CACHE_API_TRIMS, publicEntriesFlushed);
PerfCounters.IncrementCounterEx(AppPerfCounter.CACHE_OUTPUT_TRIMS, totalFlushed - publicEntriesFlushed);
}
catch {
}
Debug.Trace("CacheMemoryTrim", "Cache " + _iSubCache + ": Thread end");
}
internal override void EnableExpirationTimer(bool enable) {
if (_expires != null) {
_expires.EnableExpirationTimer(enable);
}
}
}
class CacheMultiple : CacheInternal {
int _disposed;
CacheSingle[] _caches;
int _cacheIndexMask;
internal CacheMultiple(CacheCommon cacheCommon, int numSingleCaches) : base(cacheCommon) {
Debug.Assert(numSingleCaches > 1, "numSingleCaches is not greater than 1");
Debug.Assert((numSingleCaches & (numSingleCaches - 1)) == 0, "numSingleCaches is not a power of 2");
_cacheIndexMask = numSingleCaches - 1;
_caches = new CacheSingle[numSingleCaches];
for (int i = 0; i < numSingleCaches; i++) {
_caches[i] = new CacheSingle(cacheCommon, this, i);
}
}
protected override void Dispose(bool disposing) {
if (disposing) {
if (Interlocked.Exchange(ref _disposed, 1) == 0) {
foreach (CacheSingle cacheSingle in _caches) {
cacheSingle.Dispose();
}
}
}
base.Dispose(disposing);
}
internal override int PublicCount {
get {
int count = 0;
foreach (CacheSingle cacheSingle in _caches) {
count += cacheSingle.PublicCount;
}
return count;
}
}
internal override IDictionaryEnumerator CreateEnumerator() {
IDictionaryEnumerator[] enumerators = new IDictionaryEnumerator[_caches.Length];
for (int i = 0, c = _caches.Length; i < c; i++) {
enumerators[i] = _caches[i].CreateEnumerator();
}
return new AggregateEnumerator(enumerators);
}
internal CacheSingle GetCacheSingle(int hashCode) {
Debug.Assert(_caches != null && _caches.Length != 0);
hashCode = Math.Abs(hashCode);
int index = (hashCode & _cacheIndexMask);
return _caches[index];
}
internal override CacheEntry UpdateCache(
CacheKey cacheKey,
CacheEntry newEntry,
bool replace,
CacheItemRemovedReason removedReason,
out object valueOld) {
int hashCode = cacheKey.Key.GetHashCode();
CacheSingle cacheSingle = GetCacheSingle(hashCode);
return cacheSingle.UpdateCache(cacheKey, newEntry, replace, removedReason, out valueOld);
}
internal override bool ReviewMemoryStats() {
bool cacheTrimmed = false;
foreach (CacheSingle cacheSingle in _caches) {
cacheTrimmed |= cacheSingle.ReviewMemoryStats();
}
return cacheTrimmed;
}
internal override void EnableExpirationTimer(bool enable) {
foreach (CacheSingle cacheSingle in _caches) {
cacheSingle.EnableExpirationTimer(enable);
}
}
}
class AggregateEnumerator : IDictionaryEnumerator {
IDictionaryEnumerator [] _enumerators;
int _iCurrent;
internal AggregateEnumerator(IDictionaryEnumerator [] enumerators) {
_enumerators = enumerators;
}
public bool MoveNext() {
bool more;
for (;;) {
more = _enumerators[_iCurrent].MoveNext();
if (more)
break;
if (_iCurrent == _enumerators.Length - 1)
break;
_iCurrent++;
}
return more;
}
public void Reset() {
for (int i = 0; i <= _iCurrent; i++) {
_enumerators[i].Reset();
}
_iCurrent = 0;
}
public Object Current {
get {
return _enumerators[_iCurrent].Current;
}
}
public Object Key {
get {
return _enumerators[_iCurrent].Key;
}
}
public Object Value {
get {
return _enumerators[_iCurrent].Value;
}
}
public DictionaryEntry Entry {
get {
return _enumerators[_iCurrent].Entry;
}
}
}
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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