Code:
/ DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / clr / src / BCL / System / Threading / ReaderWriterLock.cs / 1 / ReaderWriterLock.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== /*============================================================ ** ** Class: RWLock ** ** ** Purpose: Defines the lock that implements ** single-writer/multiple-reader semantics ** ** ===========================================================*/ namespace System.Threading { using System.Threading; using System.Security.Permissions; using System.Runtime.Remoting; using System; using System.Runtime.CompilerServices; using System.Runtime.InteropServices; using System.Runtime.ConstrainedExecution; [HostProtection(Synchronization=true, ExternalThreading=true)] [ComVisible(true)] public sealed class ReaderWriterLock: CriticalFinalizerObject { /* * Constructor */ public ReaderWriterLock() { PrivateInitialize(); } /* * Destructor */ ~ReaderWriterLock() { PrivateDestruct(); } /* * Property that returns TRUE if the reader lock is held * by the current thread */ public bool IsReaderLockHeld { [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)] get { return(PrivateGetIsReaderLockHeld()); } } /* * Property that returns TRUE if the writer lock is held * by the current thread */ public bool IsWriterLockHeld { [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)] get { return(PrivateGetIsWriterLockHeld()); } } /* * Property that returns the current writer sequence number. * The caller should be a reader or writer for getting * meaningful results */ public int WriterSeqNum { get { return(PrivateGetWriterSeqNum()); } } /* * Acquires reader lock. The thread will block if a different * thread has writer lock. */ [MethodImplAttribute(MethodImplOptions.InternalCall)] private extern void AcquireReaderLockInternal(int millisecondsTimeout); public void AcquireReaderLock(int millisecondsTimeout) { AcquireReaderLockInternal(millisecondsTimeout); } public void AcquireReaderLock(TimeSpan timeout) { long tm = (long)timeout.TotalMilliseconds; if (tm < -1 || tm > (long) Int32.MaxValue) throw new ArgumentOutOfRangeException("timeout", Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegOrNegative1")); AcquireReaderLockInternal((int)tm); } /* * Acquires writer lock. The thread will block if a different * thread has reader lock. It will dead lock if this thread * has reader lock. Use UpgardeToWriterLock when you are not * sure if the thread has reader lock */ [MethodImplAttribute(MethodImplOptions.InternalCall)] private extern void AcquireWriterLockInternal(int millisecondsTimeout); public void AcquireWriterLock(int millisecondsTimeout) { AcquireWriterLockInternal(millisecondsTimeout); } public void AcquireWriterLock(TimeSpan timeout) { long tm = (long)timeout.TotalMilliseconds; if (tm < -1 || tm > (long) Int32.MaxValue) throw new ArgumentOutOfRangeException("timeout", Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegOrNegative1")); AcquireWriterLockInternal((int)tm); } /* * Releases reader lock. */ [MethodImplAttribute(MethodImplOptions.InternalCall)] [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)] private extern void ReleaseReaderLockInternal(); [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)] public void ReleaseReaderLock() { ReleaseReaderLockInternal(); } /* * Releases writer lock. */ [MethodImplAttribute(MethodImplOptions.InternalCall)] [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)] private extern void ReleaseWriterLockInternal(); [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)] public void ReleaseWriterLock() { ReleaseWriterLockInternal(); } /* * Upgardes the thread to a writer. If the thread has is a * reader, it is possible that the reader lock was * released before writer lock was acquired. */ public LockCookie UpgradeToWriterLock(int millisecondsTimeout) { LockCookie result = new LockCookie (); FCallUpgradeToWriterLock (ref result, millisecondsTimeout); return result; } [MethodImplAttribute(MethodImplOptions.InternalCall)] private extern void FCallUpgradeToWriterLock(ref LockCookie result, int millisecondsTimeout); public LockCookie UpgradeToWriterLock(TimeSpan timeout) { long tm = (long)timeout.TotalMilliseconds; if (tm < -1 || tm > (long) Int32.MaxValue) throw new ArgumentOutOfRangeException("timeout", Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegOrNegative1")); return UpgradeToWriterLock((int)tm); } /* * Restores the lock status of the thread to the one it was * in when it called UpgradeToWriterLock. */ [MethodImplAttribute(MethodImplOptions.InternalCall)] private extern void DowngradeFromWriterLockInternal(ref LockCookie lockCookie); public void DowngradeFromWriterLock(ref LockCookie lockCookie) { DowngradeFromWriterLockInternal(ref lockCookie); } /* * Releases the lock irrespective of the number of times the thread * acquired the lock */ public LockCookie ReleaseLock() { LockCookie result = new LockCookie (); FCallReleaseLock (ref result); return result; } [MethodImplAttribute(MethodImplOptions.InternalCall)] private extern void FCallReleaseLock(ref LockCookie result); /* * Restores the lock status of the thread to the one it was * in when it called ReleaseLock. */ [MethodImplAttribute(MethodImplOptions.InternalCall)] private extern void RestoreLockInternal(ref LockCookie lockCookie); public void RestoreLock(ref LockCookie lockCookie) { RestoreLockInternal(ref lockCookie); } /* * Internal helper that returns TRUE if the reader lock is held * by the current thread */ [MethodImplAttribute(MethodImplOptions.InternalCall)] [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)] private extern bool PrivateGetIsReaderLockHeld(); /* * Internal helper that returns TRUE if the writer lock is held * by the current thread */ [MethodImplAttribute(MethodImplOptions.InternalCall)] [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)] private extern bool PrivateGetIsWriterLockHeld(); /* * Internal helper that returns the current writer sequence * number. The caller should be a reader or writer for getting * meaningful results */ [MethodImplAttribute(MethodImplOptions.InternalCall)] private extern int PrivateGetWriterSeqNum(); /* * Returns true if there were intermediate writes since the * sequence number was obtained. The caller should be * a reader or writer for getting meaningful results */ [MethodImplAttribute(MethodImplOptions.InternalCall)] public extern bool AnyWritersSince(int seqNum); // Initialize state kept inside the lock [MethodImplAttribute(MethodImplOptions.InternalCall)] private extern void PrivateInitialize(); // Destruct resource associated with the lock [MethodImplAttribute(MethodImplOptions.InternalCall)] private extern void PrivateDestruct(); // State #pragma warning disable 169 #pragma warning disable 414 // These fields are not used from managed. private IntPtr _hWriterEvent; private IntPtr _hReaderEvent; private IntPtr _hObjectHandle; private int _dwState = 0; private int _dwULockID = 0; private int _dwLLockID = 0; private int _dwWriterID = 0; private int _dwWriterSeqNum = 0; private short _wWriterLevel; #if RWLOCK_STATISTICS // WARNING: You must explicitly #define RWLOCK_STATISTICS when you // build in both the VM and BCL directories if you want this. private int _dwReaderEntryCount = 0; private int _dwReaderContentionCount = 0; private int _dwWriterEntryCount = 0; private int _dwWriterContentionCount = 0; private int _dwEventsReleasedCount = 0; #endif // RWLOCK_STATISTICS #pragma warning restore 414 #pragma warning restore 169 } }
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