Code:
/ Net / Net / 3.5.50727.3053 / DEVDIV / depot / DevDiv / releases / Orcas / SP / ndp / fx / src / DataWeb / Client / System / Data / Services / Client / BaseAsyncResult.cs / 1 / BaseAsyncResult.cs
//---------------------------------------------------------------------- //// Copyright (c) Microsoft Corporation. All rights reserved. // //// query object // //--------------------------------------------------------------------- namespace System.Data.Services.Client { using System; using System.Diagnostics; using System.IO; #if !ASTORIA_LIGHT // Data.Services http stack using System.Net; #else using System.Data.Services.Http; #endif ////// Implementation of IAsyncResult /// internal abstract class BaseAsyncResult : IAsyncResult { ///Originating object, used to validate End* internal readonly object Source; ///Originating method on source, to differentiate between different methods from same source internal readonly string Method; ///User callback passed to Begin* private readonly AsyncCallback userCallback; ///User state passed to Begin* private readonly object userState; ///wait handle for user to wait until done private System.Threading.ManualResetEvent asyncWait; ///Holding exception to throw as a nested exception during to End* private Exception failure; ///true unless something completes asynchronously private bool completedSynchronously = true; ///true when no more changes are pending private bool completed; ///verify we only invoke the user callback once private int userNotified; ///non-zero after End* private int done; ////// ctor /// /// source object of async request /// async method name on source object /// user callback to invoke when complete /// user state internal BaseAsyncResult(object source, string method, AsyncCallback callback, object state) { Debug.Assert(null != source, "null source"); this.Source = source; this.Method = method; this.userCallback = callback; this.userState = state; } #region IAsyncResult implmentation - AsyncState, AsyncWaitHandle, CompletedSynchronously, IsCompleted ///user state object parameter public object AsyncState { get { return this.userState; } } ///wait handle for when waiting is required ///if displayed by debugger, it undesirable to create the WaitHandle [DebuggerBrowsable(DebuggerBrowsableState.Never)] public System.Threading.WaitHandle AsyncWaitHandle { get { if (null == this.asyncWait) { // delay create the wait handle since the user may never use it // like asyncWait which will be GC'd, the losers in creating the asyncWait will also be GC'd System.Threading.Interlocked.CompareExchange(ref this.asyncWait, new System.Threading.ManualResetEvent(this.IsCompleted), null); // multi-thread condition // 1) thread 1 returned IAsyncResult and !IsCompleted so AsyncWaitHandle.WaitOne() // 2) thread 2 signals complete, however thread 1 has retrieved this.completed but not assigned asyncWait if (this.IsCompleted) { // yes, Set may be called multiple times - but user would have to assume ManualResetEvent and call Reset this.asyncWait.Set(); } } return this.asyncWait; } } ///did the result complete synchronously? public bool CompletedSynchronously { get { return this.completedSynchronously; } internal set { this.completedSynchronously = value; } } ///is the result complete? public bool IsCompleted { get { return this.completed; } internal set { this.completed = value; } } #endregion ///first exception that happened internal Exception Failure { get { return this.failure; } } ////// common handler for EndExecuteBatch & EndSaveChanges /// ///derived type of the AsyncResult /// source object of async request /// async method name on source object /// the asyncResult being ended ///data service response for batch internal static T EndExecute(object source, string method, IAsyncResult asyncResult) where T : BaseAsyncResult { Util.CheckArgumentNull(asyncResult, "asyncResult"); T result = (asyncResult as T); if ((null == result) || (source != result.Source) || (result.Method != method)) { throw Error.Argument(Strings.Context_DidNotOriginateAsync, "asyncResult"); } Debug.Assert((result.CompletedSynchronously && result.IsCompleted) || !result.CompletedSynchronously, "CompletedSynchronously && !IsCompleted"); if (!result.IsCompleted) { // if the user doesn't want to wait forever, they should explictly wait on the handle with a timeout result.AsyncWaitHandle.WaitOne(); Debug.Assert(result.IsCompleted, "not completed after waiting"); } if (System.Threading.Interlocked.Exchange(ref result.done, 1) != 0) { throw Error.Argument(Strings.Context_AsyncAlreadyDone, "asyncResult"); } if (null != result.failure) { throw Error.InvalidOperation(Strings.Context_SaveChangesError, result.failure); } return result; } /// Set the AsyncWait and invoke the user callback. internal void HandleCompleted() { if (Util.DoNotHandleException(this.failure)) { return; } if (this.IsCompleted && (System.Threading.Interlocked.Exchange(ref this.userNotified, 1) == 0)) { try { this.CompletedRequest(); } catch (Exception ex) { if (this.HandleFailure(ex)) { throw; } } if (null != this.asyncWait) { this.asyncWait.Set(); } if (null != this.userCallback) { // any exception thrown by user should be "unhandled" this.userCallback(this); } } } ///Cache the exception that happened on the background thread for the caller of EndSaveChanges. /// exception object from background thread ///true if the exception (like StackOverflow or ThreadAbort) should be rethrown internal bool HandleFailure(Exception e) { System.Threading.Interlocked.CompareExchange(ref this.failure, e, null); this.completed = true; return Util.DoNotHandleException(e); } ///invoked for derived classes to cleanup before callback is invoked protected abstract void CompletedRequest(); } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. //---------------------------------------------------------------------- //// Copyright (c) Microsoft Corporation. All rights reserved. // //// query object // //--------------------------------------------------------------------- namespace System.Data.Services.Client { using System; using System.Diagnostics; using System.IO; #if !ASTORIA_LIGHT // Data.Services http stack using System.Net; #else using System.Data.Services.Http; #endif ////// Implementation of IAsyncResult /// internal abstract class BaseAsyncResult : IAsyncResult { ///Originating object, used to validate End* internal readonly object Source; ///Originating method on source, to differentiate between different methods from same source internal readonly string Method; ///User callback passed to Begin* private readonly AsyncCallback userCallback; ///User state passed to Begin* private readonly object userState; ///wait handle for user to wait until done private System.Threading.ManualResetEvent asyncWait; ///Holding exception to throw as a nested exception during to End* private Exception failure; ///true unless something completes asynchronously private bool completedSynchronously = true; ///true when no more changes are pending private bool completed; ///verify we only invoke the user callback once private int userNotified; ///non-zero after End* private int done; ////// ctor /// /// source object of async request /// async method name on source object /// user callback to invoke when complete /// user state internal BaseAsyncResult(object source, string method, AsyncCallback callback, object state) { Debug.Assert(null != source, "null source"); this.Source = source; this.Method = method; this.userCallback = callback; this.userState = state; } #region IAsyncResult implmentation - AsyncState, AsyncWaitHandle, CompletedSynchronously, IsCompleted ///user state object parameter public object AsyncState { get { return this.userState; } } ///wait handle for when waiting is required ///if displayed by debugger, it undesirable to create the WaitHandle [DebuggerBrowsable(DebuggerBrowsableState.Never)] public System.Threading.WaitHandle AsyncWaitHandle { get { if (null == this.asyncWait) { // delay create the wait handle since the user may never use it // like asyncWait which will be GC'd, the losers in creating the asyncWait will also be GC'd System.Threading.Interlocked.CompareExchange(ref this.asyncWait, new System.Threading.ManualResetEvent(this.IsCompleted), null); // multi-thread condition // 1) thread 1 returned IAsyncResult and !IsCompleted so AsyncWaitHandle.WaitOne() // 2) thread 2 signals complete, however thread 1 has retrieved this.completed but not assigned asyncWait if (this.IsCompleted) { // yes, Set may be called multiple times - but user would have to assume ManualResetEvent and call Reset this.asyncWait.Set(); } } return this.asyncWait; } } ///did the result complete synchronously? public bool CompletedSynchronously { get { return this.completedSynchronously; } internal set { this.completedSynchronously = value; } } ///is the result complete? public bool IsCompleted { get { return this.completed; } internal set { this.completed = value; } } #endregion ///first exception that happened internal Exception Failure { get { return this.failure; } } ////// common handler for EndExecuteBatch & EndSaveChanges /// ///derived type of the AsyncResult /// source object of async request /// async method name on source object /// the asyncResult being ended ///data service response for batch internal static T EndExecute(object source, string method, IAsyncResult asyncResult) where T : BaseAsyncResult { Util.CheckArgumentNull(asyncResult, "asyncResult"); T result = (asyncResult as T); if ((null == result) || (source != result.Source) || (result.Method != method)) { throw Error.Argument(Strings.Context_DidNotOriginateAsync, "asyncResult"); } Debug.Assert((result.CompletedSynchronously && result.IsCompleted) || !result.CompletedSynchronously, "CompletedSynchronously && !IsCompleted"); if (!result.IsCompleted) { // if the user doesn't want to wait forever, they should explictly wait on the handle with a timeout result.AsyncWaitHandle.WaitOne(); Debug.Assert(result.IsCompleted, "not completed after waiting"); } if (System.Threading.Interlocked.Exchange(ref result.done, 1) != 0) { throw Error.Argument(Strings.Context_AsyncAlreadyDone, "asyncResult"); } if (null != result.failure) { throw Error.InvalidOperation(Strings.Context_SaveChangesError, result.failure); } return result; } /// Set the AsyncWait and invoke the user callback. internal void HandleCompleted() { if (Util.DoNotHandleException(this.failure)) { return; } if (this.IsCompleted && (System.Threading.Interlocked.Exchange(ref this.userNotified, 1) == 0)) { try { this.CompletedRequest(); } catch (Exception ex) { if (this.HandleFailure(ex)) { throw; } } if (null != this.asyncWait) { this.asyncWait.Set(); } if (null != this.userCallback) { // any exception thrown by user should be "unhandled" this.userCallback(this); } } } ///Cache the exception that happened on the background thread for the caller of EndSaveChanges. /// exception object from background thread ///true if the exception (like StackOverflow or ThreadAbort) should be rethrown internal bool HandleFailure(Exception e) { System.Threading.Interlocked.CompareExchange(ref this.failure, e, null); this.completed = true; return Util.DoNotHandleException(e); } ///invoked for derived classes to cleanup before callback is invoked protected abstract void CompletedRequest(); } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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