Code:
/ FX-1434 / FX-1434 / 1.0 / untmp / whidbey / REDBITS / ndp / fx / src / Data / System / Data / ProviderBase / DbConnectionPoolGroup.cs / 3 / DbConnectionPoolGroup.cs
//------------------------------------------------------------------------------ //// Copyright (c) Microsoft Corporation. All rights reserved. // //[....] //----------------------------------------------------------------------------- namespace System.Data.ProviderBase { using System; using System.Collections; using System.Collections.Specialized; using System.Data.Common; #if ORACLE using System.Data.OracleClient; #endif using System.Diagnostics; using System.Threading; // set_ConnectionString calls DbConnectionFactory.GetConnectionPoolGroup // when not found a new pool entry is created and potentially added // DbConnectionPoolGroup starts in the Active state // Open calls DbConnectionFactory.GetConnectionPool // if the existing pool entry is Disabled, GetConnectionPoolGroup is called for a new entry // DbConnectionFactory.GetConnectionPool calls DbConnectionPoolGroup.GetConnectionPool // DbConnectionPoolGroup.GetConnectionPool will return pool for the current identity // or null if identity is restricted or pooling is disabled or state is disabled at time of add // state changes are Active->Active, Idle->Active // DbConnectionFactory.PruneConnectionPoolGroups calls Prune // which will QueuePoolForRelease on all empty pools // and once no pools remain, change state from Active->Idle->Disabled // Once Disabled, factory can remove its reference to the pool entry sealed internal class DbConnectionPoolGroup { private readonly DbConnectionOptions _connectionOptions; private readonly DbConnectionPoolGroupOptions _poolGroupOptions; private HybridDictionary _poolCollection; private int _poolCount; // number of pools private int _state; // see PoolGroupState* below private DbConnectionPoolGroupProviderInfo _providerInfo; private DbMetaDataFactory _metaDataFactory; private static int _objectTypeCount; // Bid counter internal readonly int _objectID = System.Threading.Interlocked.Increment(ref _objectTypeCount); // always lock this before changing _state, we don't want to move out of `the disabled state // PoolGroupStateUninitialized = 0; private const int PoolGroupStateActive = 1; // initial state, GetPoolGroup from cache, connection Open private const int PoolGroupStateIdle = 2; // all pools are pruned via Clear private const int PoolGroupStateDisabled = 4; // factory pool entry prunning method internal DbConnectionPoolGroup (DbConnectionOptions connectionOptions, DbConnectionPoolGroupOptions poolGroupOptions) { Debug.Assert(null != connectionOptions, "null connection options"); Debug.Assert(null == poolGroupOptions || ADP.IsWindowsNT, "should not have pooling options on Win9x"); _connectionOptions = connectionOptions; _poolGroupOptions = poolGroupOptions; // always lock this object before changing state // HybridDictionary does not create any sub-objects until add // so it is safe to use for non-pooled connection as long as // we check _poolGroupOptions first _poolCollection = new HybridDictionary(1, false); _state = PoolGroupStateActive; // VSWhidbey 112102 } internal DbConnectionOptions ConnectionOptions { get { return _connectionOptions; } } internal int Count { get { // NOTE: the use of this property does not indicate activity, // on the pool entry because it only it is only used to identify // empty pool entries when we're pruning them. return _poolCount; } } internal DbConnectionPoolGroupProviderInfo ProviderInfo { get { return _providerInfo; } set { _providerInfo = value; if(null!=value) { _providerInfo.PoolGroup = this; } } } internal bool IsDisabled { get { return (PoolGroupStateDisabled == _state); } } internal int ObjectID { get { return _objectID; } } internal DbConnectionPoolGroupOptions PoolGroupOptions { get { return _poolGroupOptions; } } internal DbMetaDataFactory MetaDataFactory{ get { return _metaDataFactory; } set { _metaDataFactory = value; } } internal void Clear() { ClearInternal(true); } private bool ClearInternal(bool clearing) { // must be multi-thread safe with competing calls by Clear and Prune via background thread // will return true for Prune on if the pool entry is Disabled or not lock (this) { HybridDictionary poolCollection = _poolCollection; if (0 < poolCollection.Count) { HybridDictionary newPoolCollection = new HybridDictionary(poolCollection.Count, false); foreach (DictionaryEntry entry in poolCollection) { if (null != entry.Value) { DbConnectionPool pool = (DbConnectionPool)entry.Value; // // Actually prune the pool if the user requested it (clearing == true) // or if there are no connections in the pool and no errors occurred. // Empty pool during pruning indicates zero or low activity, but // an error state indicates the pool needs to stay around to // throttle new connection attempts. if (clearing || (!pool.ErrorOccurred && 0 == pool.Count)) { // Order is important here. First we remove the pool // from the collection of pools so no one will try // to use it while we're processing and finally we put the // pool into a list of pools to be released when they // are completely empty. DbConnectionFactory connectionFactory = pool.ConnectionFactory; connectionFactory.PerformanceCounters.NumberOfActiveConnectionPools.Decrement(); connectionFactory.QueuePoolForRelease(pool, clearing); } else { newPoolCollection.Add(entry.Key, entry.Value); } } } _poolCollection = newPoolCollection; _poolCount = newPoolCollection.Count; } // must be pruning thread to change state and no connections // otherwise pruning thread risks making entry disabled soon after user calls ClearPool if (!clearing && (0 == _poolCount)) { if (PoolGroupStateActive == _state) { _state = PoolGroupStateIdle; Bid.Trace("%d#, Idle\n", ObjectID); } else if (PoolGroupStateIdle == _state) { _state = PoolGroupStateDisabled; Bid.Trace(" %d#, Disabled\n", ObjectID); } } return (PoolGroupStateDisabled == _state); } } internal DbConnectionPool GetConnectionPool(DbConnectionFactory connectionFactory) { // When this method returns null it indicates that the connection // factory should not use pooling. // We don't support connection pooling on Win9x; it lacks too // many of the APIs we require. // PoolGroupOptions will only be null when we're not supposed to pool // connections. object pool = null; if (null != _poolGroupOptions) { Debug.Assert(ADP.IsWindowsNT, "should not be pooling on Win9x"); DbConnectionPoolIdentity currentIdentity = DbConnectionPoolIdentity.NoIdentity; if (_poolGroupOptions.PoolByIdentity) { // if we're pooling by identity (because integrated security is // being used for these connections) then we need to go out and // search for the connectionPool that matches the current identity. currentIdentity = DbConnectionPoolIdentity.GetCurrent(); // If the current token is restricted in some way, then we must // not attempt to pool these connections. if (currentIdentity.IsRestricted) { currentIdentity = null; } } if (null != currentIdentity) { HybridDictionary poolCollection = _poolCollection; pool = poolCollection[currentIdentity]; // find the pool if (null == pool) { DbConnectionPoolProviderInfo connectionPoolProviderInfo = connectionFactory.CreateConnectionPoolProviderInfo(this.ConnectionOptions); // optimistically create pool, but its callbacks are delayed until after actual add DbConnectionPool newPool = new DbConnectionPool(connectionFactory, this, currentIdentity, connectionPoolProviderInfo); lock (this) { // Did someone already add it to the list? poolCollection = _poolCollection; pool = poolCollection[currentIdentity]; // find the pool if (null == pool) { if (MarkPoolGroupAsActive()) { // If we get here, we know for certain that we there isn't // a pool that matches the current identity, so we have to // add the optimistically created one newPool.Startup(); // must start pool before usage HybridDictionary newPoolCollection = new HybridDictionary(1+poolCollection.Count, false); foreach(DictionaryEntry entry in poolCollection) { newPoolCollection.Add(entry.Key, entry.Value); } newPoolCollection.Add(currentIdentity, newPool); connectionFactory.PerformanceCounters.NumberOfActiveConnectionPools.Increment(); _poolCollection = newPoolCollection; _poolCount = newPoolCollection.Count; pool = newPool; newPool = null; } else { // else pool entry has been disabled so don't create new pools Debug.Assert(PoolGroupStateDisabled == _state, "state should be disabled"); } } else { // else found an existing pool to use instead Debug.Assert(PoolGroupStateActive == _state, "state should be active since a pool exists and lock holds"); } } if (null != newPool) { // don't need to call connectionFactory.QueuePoolForRelease(newPool) because // pool callbacks were delayed and no risk of connections being created newPool.Shutdown(); } } // the found pool could be in any state } } if (null == pool) { lock(this) { // keep the pool entry state active when not pooling MarkPoolGroupAsActive(); } } return (DbConnectionPool)pool; } private bool MarkPoolGroupAsActive() { // when getting a connection, make the entry active if it was idle (but not disabled) // must always lock this before calling if (PoolGroupStateIdle == _state) { _state = PoolGroupStateActive; Bid.Trace(" %d#, Active\n", ObjectID); } return (PoolGroupStateActive == _state); } internal bool Prune() { // must only call from DbConnectionFactory.PruneConnectionPoolGroups on background timer thread // must lock(DbConnectionFactory._connectionPoolGroups.SyncRoot) before calling ReadyToRemove // to avoid conflict with DbConnectionFactory.CreateConnectionPoolGroup replacing pool entry return ClearInternal(false); } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. 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