Code:
/ DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / Net / System / Net / SecureProtocols / _HelperAsyncResults.cs / 1 / _HelperAsyncResults.cs
/*++ Copyright (c) 2000 Microsoft Corporation Module Name: _HelperAsyncResults.cs Abstract: These are simple helpers to keep track of protocol IO requests Author: Alexei Vopilov Aug 18 2003 Revision History: --*/ namespace System.Net { using System; using System.IO; using System.Threading; // // Simply said whenever we want to wrap a user IO request we need // to preserve the original request buffer & sizes. // // Usually we would return this class as IAsyncResult to application // internal class BufferAsyncResult: LazyAsyncResult { public byte[] Buffer; public BufferOffsetSize[] Buffers; public int Offset; public int Count; public bool IsWrite; // MultipleWriteOnly // public BufferAsyncResult(object asyncObject, BufferOffsetSize[] buffers, object asyncState, AsyncCallback asyncCallback) :base (asyncObject, asyncState, asyncCallback) { Buffers = buffers; IsWrite = true; } public BufferAsyncResult(object asyncObject, byte[] buffer, int offset, int count, object asyncState, AsyncCallback asyncCallback) :this(asyncObject, buffer, offset, count, false, asyncState, asyncCallback) { } public BufferAsyncResult(object asyncObject, byte[] buffer, int offset, int count, bool isWrite, object asyncState, AsyncCallback asyncCallback) :base (asyncObject, asyncState, asyncCallback) { Buffer = buffer; Offset = offset; Count = count; IsWrite = isWrite; } } // The callback type used with below AsyncProtocolRequest class internal delegate void AsyncProtocolCallback(AsyncProtocolRequest asyncRequest); // // The class mimics LazyAsyncResult although it does not need to be thread safe nor it does need an Event. // Usually we would use this class to implement iterative protocol logic // // The beauty is that // 1) it can be reused for handshake-like or multi-IO request protocols // 2) it is proven to not block async IO since there is NO event handler exposed // // UserAsyncResult property is a link into original user IO request (could be a BufferAsyncResult). // When underlined protocol is done this guy gets completed // internal class AsyncProtocolRequest { #if DEBUG internal object _DebugAsyncChain; // Optionally used to track chains of async calls. #endif private AsyncProtocolCallback _Callback; private int _CompletionStatus; const int StatusNotStarted = 0; const int StatusCompleted = 1; const int StatusCheckedOnSyncCompletion = 2; public LazyAsyncResult UserAsyncResult; public int Result; // it's always about read bytes or alike public object AsyncState; // sometime it's needed to communicate additional info. // Note that AsyncObject is just a link to UserAsyncResult.AsyncObject public byte[] Buffer; // temp buffer reused by a protocol. public int Offset; // ditto public int Count; // ditto // // public AsyncProtocolRequest(LazyAsyncResult userAsyncResult) { GlobalLog.Assert(userAsyncResult != null, "AsyncProtocolRequest()|userAsyncResult == null"); GlobalLog.Assert(!userAsyncResult.InternalPeekCompleted, "AsyncProtocolRequest()|userAsyncResult is already completed."); UserAsyncResult = userAsyncResult; } // // public void SetNextRequest(byte[] buffer, int offset, int count, AsyncProtocolCallback callback) { if (_CompletionStatus != StatusNotStarted) throw new InternalException(); // pending op is in progress Buffer = buffer; Offset = offset; Count = count; _Callback = callback; } // // internal object AsyncObject { get { return UserAsyncResult.AsyncObject; } } // // Notify protocol so a next stage could be started // internal void CompleteRequest(int result) { Result = result; int status = Interlocked.Exchange(ref _CompletionStatus, StatusCompleted); if (status == StatusCompleted) throw new InternalException(); // only allow one call if (status == StatusCheckedOnSyncCompletion) { _CompletionStatus = StatusNotStarted; _Callback(this); } } // public bool MustCompleteSynchronously { get { int status = Interlocked.Exchange(ref _CompletionStatus, StatusCheckedOnSyncCompletion); if (status == StatusCheckedOnSyncCompletion) throw new InternalException(); // only allow one call if (status == StatusCompleted) { _CompletionStatus = StatusNotStarted; return true; } return false; } } // // NB: This will abandon _Callback and directly notify UserAsyncResult. // internal void CompleteWithError(Exception e) { UserAsyncResult.InvokeCallback(e); } // internal void CompleteUser() { UserAsyncResult.InvokeCallback(); } // internal void CompleteUser(object userResult) { UserAsyncResult.InvokeCallback(userResult); } // internal bool IsUserCompleted { get {return UserAsyncResult.InternalPeekCompleted;} } } }
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