ReaderWriterLock.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / clr / src / BCL / System / Threading / ReaderWriterLock.cs / 1305376 / ReaderWriterLock.cs
                        
                        
                            // ==++== 
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ==--== 
//
// [....] 
/*============================================================ 
**
** Class:    RWLock 
**
**
** Purpose: Defines the lock that implements
**          single-writer/multiple-reader semantics 
**
** 
===========================================================*/ 

#if FEATURE_RWLOCK 
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;
    using System.Runtime.Versioning; 
    using System.Diagnostics.Contracts;

    [HostProtection(Synchronization=true, ExternalThreading=true)]
    [ComVisible(true)] 
    public sealed class ReaderWriterLock: CriticalFinalizerObject
    { 
        /* 
         * Constructor
         */ 
        [System.Security.SecuritySafeCritical]  // auto-generated
        public ReaderWriterLock()
        {
            PrivateInitialize(); 
        }
 
        /* 
         * Destructor
         */ 
        [System.Security.SecuritySafeCritical]  // auto-generated
        ~ReaderWriterLock()
        {
            PrivateDestruct(); 
        }
 
        /* 
         * Property that returns TRUE if the reader lock is held
         * by the current thread 
         */
        public bool IsReaderLockHeld {
            [System.Security.SecuritySafeCritical]  // auto-generated
            [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 {
            [System.Security.SecuritySafeCritical]  // auto-generated 
            [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 { 
            [System.Security.SecuritySafeCritical]  // auto-generated
            get {
                return(PrivateGetWriterSeqNum());
                } 
        }
 
        /* 
         * Acquires reader lock. The thread will block if a different
         * thread has writer lock. 
         */
        [System.Security.SecurityCritical]  // auto-generated
        [ResourceExposure(ResourceScope.None)]
        [MethodImplAttribute(MethodImplOptions.InternalCall)] 
        private extern void AcquireReaderLockInternal(int millisecondsTimeout);
 
        [System.Security.SecuritySafeCritical]  // auto-generated 
        public void AcquireReaderLock(int millisecondsTimeout)
        { 
            AcquireReaderLockInternal(millisecondsTimeout);
        }

 
        [System.Security.SecuritySafeCritical]  // auto-generated
        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 
         */
        [System.Security.SecurityCritical]  // auto-generated
        [ResourceExposure(ResourceScope.None)]
        [MethodImplAttribute(MethodImplOptions.InternalCall)] 
        private extern void AcquireWriterLockInternal(int millisecondsTimeout);
 
        [System.Security.SecuritySafeCritical]  // auto-generated 
        public void AcquireWriterLock(int millisecondsTimeout)
        { 
            AcquireWriterLockInternal(millisecondsTimeout);
        }

        [System.Security.SecuritySafeCritical]  // auto-generated 
        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. 
         */ 
        [System.Security.SecurityCritical]  // auto-generated
        [ResourceExposure(ResourceScope.None)] 
        [MethodImplAttribute(MethodImplOptions.InternalCall)]
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
        private extern void ReleaseReaderLockInternal();
 
        [System.Security.SecuritySafeCritical]  // auto-generated
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)] 
        public void ReleaseReaderLock() 
        {
            ReleaseReaderLockInternal(); 
        }

        /*
         * Releases writer lock. 
         */
        [System.Security.SecurityCritical]  // auto-generated 
        [ResourceExposure(ResourceScope.None)] 
        [MethodImplAttribute(MethodImplOptions.InternalCall)]
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)] 
        private extern void ReleaseWriterLockInternal();

        [System.Security.SecuritySafeCritical]  // auto-generated
        [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. 
         */
        [System.Security.SecuritySafeCritical]  // auto-generated 
        public LockCookie UpgradeToWriterLock(int millisecondsTimeout) 
        {
            LockCookie result = new LockCookie (); 
            FCallUpgradeToWriterLock (ref result, millisecondsTimeout);
            return result;
        }
 
        [System.Security.SecurityCritical]  // auto-generated
        [ResourceExposure(ResourceScope.None)] 
        [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.
         */
        [System.Security.SecurityCritical]  // auto-generated 
        [ResourceExposure(ResourceScope.None)]
        [MethodImplAttribute(MethodImplOptions.InternalCall)] 
        private extern void DowngradeFromWriterLockInternal(ref LockCookie lockCookie); 

        [System.Security.SecuritySafeCritical]  // auto-generated 
        public void DowngradeFromWriterLock(ref LockCookie lockCookie)
        {
            DowngradeFromWriterLockInternal(ref lockCookie);
        } 

        /* 
         * Releases the lock irrespective of the number of times the thread 
         * acquired the lock
         */ 
        [System.Security.SecuritySafeCritical]  // auto-generated
        public LockCookie ReleaseLock()
        {
            LockCookie result = new LockCookie (); 
            FCallReleaseLock (ref result);
            return result; 
        } 

        [System.Security.SecurityCritical]  // auto-generated 
        [ResourceExposure(ResourceScope.None)]
        [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. 
         */
        [System.Security.SecurityCritical]  // auto-generated 
        [ResourceExposure(ResourceScope.None)]
        [MethodImplAttribute(MethodImplOptions.InternalCall)]
        private extern void RestoreLockInternal(ref LockCookie lockCookie);
 
        [System.Security.SecuritySafeCritical]  // auto-generated
        public void RestoreLock(ref LockCookie lockCookie) 
        { 
            RestoreLockInternal(ref lockCookie);
        } 

        /*
         * Internal helper that returns TRUE if the reader lock is held
         * by the current thread 
         */
        [System.Security.SecurityCritical]  // auto-generated 
        [ResourceExposure(ResourceScope.None)] 
        [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
         */ 
        [System.Security.SecurityCritical]  // auto-generated 
        [ResourceExposure(ResourceScope.None)]
        [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 
         */
        [System.Security.SecurityCritical]  // auto-generated 
        [ResourceExposure(ResourceScope.None)]
        [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
         */ 
        [System.Security.SecuritySafeCritical]  // auto-generated
        [ResourceExposure(ResourceScope.None)]
        [MethodImplAttribute(MethodImplOptions.InternalCall)]
        public extern bool AnyWritersSince(int seqNum); 

        // Initialize state kept inside the lock 
        [System.Security.SecurityCritical]  // auto-generated 
        [ResourceExposure(ResourceScope.None)]
        [MethodImplAttribute(MethodImplOptions.InternalCall)] 
        private extern void PrivateInitialize();

        // Destruct resource associated with the lock
        [System.Security.SecurityCritical]  // auto-generated 
        [ResourceExposure(ResourceScope.None)]
        [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 
    }
} 
#endif //FEATURE_RWLOCK 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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