Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Services / Messaging / System / Messaging / MessageEnumerator.cs / 1305376 / MessageEnumerator.cs
//------------------------------------------------------------------------------ //// Copyright (c) Microsoft Corporation. All rights reserved. // //----------------------------------------------------------------------------- namespace System.Messaging { using System.Diagnostics; using System; using System.ComponentModel; using System.Collections; using System.Messaging.Interop; ////// /// public class MessageEnumerator : MarshalByRefObject, IEnumerator, IDisposable { private MessageQueue owner; private CursorHandle handle = System.Messaging.Interop.CursorHandle.NullHandle; private int index = 0; private bool disposed = false; private bool useCorrectRemoveCurrent = false;//needed in fix for 88615 internal MessageEnumerator(MessageQueue owner, bool useCorrectRemoveCurrent) { this.owner = owner; this.useCorrectRemoveCurrent = useCorrectRemoveCurrent; } ///Provides (forward-only) /// cursor semantics to enumerate the messages contained in /// a queue. ////// Translate into English? /// ////// /// public Message Current { get { if (this.index == 0) throw new InvalidOperationException(Res.GetString(Res.NoCurrentMessage)); return this.owner.ReceiveCurrent(TimeSpan.Zero, NativeMethods.QUEUE_ACTION_PEEK_CURRENT, this.Handle, this.owner.MessageReadPropertyFilter, null, MessageQueueTransactionType.None); } } ///Gets the current ///pointed to /// by this enumerator. /// object IEnumerator.Current { get { return this.Current; } } /// /// /// public IntPtr CursorHandle{ get { return this.Handle.DangerousGetHandle(); } } internal CursorHandle Handle { get{ //Cursor handle doesn't demand permissions since GetEnumerator will demand somehow. if (this.handle.IsInvalid) { //Cannot allocate the a new cursor if the object has been disposed, since finalization has been suppressed. if (this.disposed) throw new ObjectDisposedException(GetType().Name); CursorHandle result; int status = SafeNativeMethods.MQCreateCursor(this.owner.MQInfo.ReadHandle, out result); if (MessageQueue.IsFatalError(status)) throw new MessageQueueException(status); this.handle = result; } return this.handle; } } ///Gets the native Message Queuing cursor handle used to browse messages /// in the queue. ////// /// public void Close() { this.index = 0; if (!this.handle.IsInvalid) { this.handle.Close(); } } ////// Frees the resources associated with the enumerator. /// ////// /// [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2213:DisposableFieldsShouldBeDisposed")] public void Dispose() { Dispose(true); GC.SuppressFinalize(this); } ////// /// protected virtual void Dispose(bool disposing) { this.Close(); this.disposed = true; } ////// ////// /// /// ~MessageEnumerator() { Dispose(false); } ////// /// public bool MoveNext() { return MoveNext(TimeSpan.Zero); } ///Advances the enumerator to the next message in the queue, if one /// is currently available. ////// /// public unsafe bool MoveNext(TimeSpan timeout) { long timeoutInMilliseconds = (long)timeout.TotalMilliseconds; if (timeoutInMilliseconds < 0 || timeoutInMilliseconds > UInt32.MaxValue) throw new ArgumentException(Res.GetString(Res.InvalidParameter, "timeout", timeout.ToString())); int status = 0; int action = NativeMethods.QUEUE_ACTION_PEEK_NEXT; //Peek current or next? if (this.index == 0) action = NativeMethods.QUEUE_ACTION_PEEK_CURRENT; status = owner.StaleSafeReceiveMessage((uint)timeoutInMilliseconds, action, null, null, null, this.Handle, (IntPtr)NativeMethods.QUEUE_TRANSACTION_NONE); //If the cursor reached the end of the queue. if (status == (int)MessageQueueErrorCode.IOTimeout) { this.Close(); return false; } //If all messages were removed. else if (status == (int)MessageQueueErrorCode.IllegalCursorAction) { this.index = 0; this.Close(); return false; } if (MessageQueue.IsFatalError(status)) throw new MessageQueueException(status); ++ this.index; return true; } ///Advances the enumerator to the next message in the /// queue. If the enumerator is positioned at the end of the queue, ///waits until a message is available or the /// given /// expires. /// /// public Message RemoveCurrent() { return RemoveCurrent(TimeSpan.Zero, null, MessageQueueTransactionType.None); } ///Removes the current message from /// the queue and returns the message to the calling application. ////// /// public Message RemoveCurrent(MessageQueueTransaction transaction) { if (transaction == null) throw new ArgumentNullException("transaction"); return RemoveCurrent(TimeSpan.Zero, transaction, MessageQueueTransactionType.None); } ///Removes the current message from /// the queue and returns the message to the calling application. ////// /// public Message RemoveCurrent(MessageQueueTransactionType transactionType) { if (!ValidationUtility.ValidateMessageQueueTransactionType(transactionType)) throw new InvalidEnumArgumentException("transactionType", (int)transactionType, typeof(MessageQueueTransactionType)); return RemoveCurrent(TimeSpan.Zero, null, transactionType); } ///Removes the current message from /// the queue and returns the message to the calling application. ////// /// public Message RemoveCurrent(TimeSpan timeout) { return RemoveCurrent(timeout, null, MessageQueueTransactionType.None); } ///Removes the current message from /// the queue and returns the message to the calling application within the timeout specified. ////// /// public Message RemoveCurrent(TimeSpan timeout, MessageQueueTransaction transaction) { if (transaction == null) throw new ArgumentNullException("transaction"); return RemoveCurrent(timeout, transaction, MessageQueueTransactionType.None); } ///Removes the current message from /// the queue and returns the message to the calling application within the timeout specified. ////// /// public Message RemoveCurrent(TimeSpan timeout, MessageQueueTransactionType transactionType) { if (!ValidationUtility.ValidateMessageQueueTransactionType(transactionType)) throw new InvalidEnumArgumentException("transactionType", (int)transactionType, typeof(MessageQueueTransactionType)); return RemoveCurrent(timeout, null, transactionType); } private Message RemoveCurrent(TimeSpan timeout, MessageQueueTransaction transaction, MessageQueueTransactionType transactionType) { long timeoutInMilliseconds = (long)timeout.TotalMilliseconds; if (timeoutInMilliseconds < 0 || timeoutInMilliseconds > UInt32.MaxValue) throw new ArgumentException(Res.GetString(Res.InvalidParameter, "timeout", timeout.ToString())); if (this.index == 0) return null; Message message = this.owner.ReceiveCurrent(timeout, NativeMethods.QUEUE_ACTION_RECEIVE, this.Handle, this.owner.MessageReadPropertyFilter, transaction, transactionType); if (!useCorrectRemoveCurrent) --this.index; return message; } ///Removes the current message from /// the queue and returns the message to the calling application within the timeout specified. ////// /// public void Reset() { this.Close(); } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007.Resets the current enumerator, so it points to /// the head of the queue. ///
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