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// ==++==
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// ==--==
//
// <OWNER>Microsoft</OWNER>
/*=============================================================================
**
** Class: Monitor
**
**
** Purpose: Synchronizes access to a shared resource or region of code in a multi-threaded
** program.
**
**
=============================================================================*/
namespace System.Threading {
using System;
using System.Security.Permissions;
using System.Runtime;
using System.Runtime.Remoting;
using System.Threading;
using System.Runtime.CompilerServices;
using System.Runtime.ConstrainedExecution;
using System.Runtime.Versioning;
using System.Diagnostics.Contracts;
[HostProtection(Synchronization=true, ExternalThreading=true)]
[System.Runtime.InteropServices.ComVisible(true)]
public static class Monitor
{
/*=========================================================================
** Obtain the monitor lock of obj. Will block if another thread holds the lock
** Will not block if the current thread holds the lock,
** however the caller must ensure that the same number of Exit
** calls are made as there were Enter calls.
**
** Exceptions: ArgumentNullException if object is null.
=========================================================================*/
[System.Security.SecuritySafeCritical]
[ResourceExposure(ResourceScope.None)]
[MethodImplAttribute(MethodImplOptions.InternalCall)]
public static extern void Enter(Object obj);
// Use a ref bool instead of out to ensure that unverifiable code must
// initialize this value to something. If we used out, the value
// could be uninitialized if we threw an exception in our prolog.
// The JIT should inline this method to allow check of lockTaken argument to be optimized out
// in the typical case. Note that the method has to be transparent for inlining to be allowed by the VM.
public static void Enter(Object obj, ref bool lockTaken)
{
if (lockTaken)
ThrowLockTakenException();
ReliableEnter(obj, ref lockTaken);
Contract.Assert(lockTaken);
}
private static void ThrowLockTakenException()
{
throw new ArgumentException(Environment.GetResourceString("Argument_MustBeFalse"), "lockTaken");
}
[System.Security.SecuritySafeCritical]
[ResourceExposure(ResourceScope.None)]
[MethodImplAttribute(MethodImplOptions.InternalCall)]
private static extern void ReliableEnter(Object obj, ref bool lockTaken);
/*=========================================================================
** Release the monitor lock. If one or more threads are waiting to acquire the
** lock, and the current thread has executed as many Exits as
** Enters, one of the threads will be unblocked and allowed to proceed.
**
** Exceptions: ArgumentNullException if object is null.
** SynchronizationLockException if the current thread does not
** own the lock.
=========================================================================*/
[System.Security.SecuritySafeCritical]
[ResourceExposure(ResourceScope.None)]
[MethodImplAttribute(MethodImplOptions.InternalCall)]
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
public static extern void Exit(Object obj);
/*=========================================================================
** Similar to Enter, but will never block. That is, if the current thread can
** acquire the monitor lock without blocking, it will do so and TRUE will
** be returned. Otherwise FALSE will be returned.
**
** Exceptions: ArgumentNullException if object is null.
=========================================================================*/
public static bool TryEnter(Object obj)
{
bool lockTaken = false;
TryEnter(obj, 0, ref lockTaken);
return lockTaken;
}
// The JIT should inline this method to allow check of lockTaken argument to be optimized out
// in the typical case. Note that the method has to be transparent for inlining to be allowed by the VM.
public static void TryEnter(Object obj, ref bool lockTaken)
{
if (lockTaken)
ThrowLockTakenException();
ReliableEnterTimeout(obj, 0, ref lockTaken);
}
/*=========================================================================
** Version of TryEnter that will block, but only up to a timeout period
** expressed in milliseconds. If timeout == Timeout.Infinite the method
** becomes equivalent to Enter.
**
** Exceptions: ArgumentNullException if object is null.
** ArgumentException if timeout < 0.
=========================================================================*/
// The JIT should inline this method to allow check of lockTaken argument to be optimized out
// in the typical case. Note that the method has to be transparent for inlining to be allowed by the VM.
public static bool TryEnter(Object obj, int millisecondsTimeout)
{
bool lockTaken = false;
TryEnter(obj, millisecondsTimeout, ref lockTaken);
return lockTaken;
}
private static int MillisecondsTimeoutFromTimeSpan(TimeSpan timeout)
{
long tm = (long)timeout.TotalMilliseconds;
if (tm < -1 || tm > (long)Int32.MaxValue)
throw new ArgumentOutOfRangeException("timeout", Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegOrNegative1"));
return (int)tm;
}
public static bool TryEnter(Object obj, TimeSpan timeout)
{
return TryEnter(obj, MillisecondsTimeoutFromTimeSpan(timeout));
}
// The JIT should inline this method to allow check of lockTaken argument to be optimized out
// in the typical case. Note that the method has to be transparent for inlining to be allowed by the VM.
public static void TryEnter(Object obj, int millisecondsTimeout, ref bool lockTaken)
{
if (lockTaken)
ThrowLockTakenException();
ReliableEnterTimeout(obj, millisecondsTimeout, ref lockTaken);
}
public static void TryEnter(Object obj, TimeSpan timeout, ref bool lockTaken)
{
if (lockTaken)
ThrowLockTakenException();
ReliableEnterTimeout(obj, MillisecondsTimeoutFromTimeSpan(timeout), ref lockTaken);
}
[System.Security.SecuritySafeCritical]
[ResourceExposure(ResourceScope.None)]
[MethodImplAttribute(MethodImplOptions.InternalCall)]
private static extern void ReliableEnterTimeout(Object obj, int timeout, ref bool lockTaken);
[System.Security.SecuritySafeCritical]
public static bool IsEntered(object obj)
{
if (obj == null)
throw new ArgumentNullException("obj");
return IsEnteredNative(obj);
}
[System.Security.SecurityCritical]
[ResourceExposure(ResourceScope.None)]
[MethodImplAttribute(MethodImplOptions.InternalCall)]
private static extern bool IsEnteredNative(Object obj);
/*========================================================================
** Waits for notification from the object (via a Pulse/PulseAll).
** timeout indicates how long to wait before the method returns.
** This method acquires the monitor waithandle for the object
** If this thread holds the monitor lock for the object, it releases it.
** On exit from the method, it obtains the monitor lock back.
** If exitContext is true then the synchronization domain for the context
** (if in a synchronized context) is exited before the wait and reacquired
**
** Exceptions: ArgumentNullException if object is null.
========================================================================*/
[System.Security.SecurityCritical] // auto-generated
[ResourceExposure(ResourceScope.None)]
[MethodImplAttribute(MethodImplOptions.InternalCall)]
private static extern bool ObjWait(bool exitContext, int millisecondsTimeout, Object obj);
[System.Security.SecuritySafeCritical] // auto-generated
public static bool Wait(Object obj, int millisecondsTimeout, bool exitContext)
{
if (obj == null)
throw (new ArgumentNullException("obj"));
return ObjWait(exitContext, millisecondsTimeout, obj);
}
public static bool Wait(Object obj, TimeSpan timeout, bool exitContext)
{
return Wait(obj, MillisecondsTimeoutFromTimeSpan(timeout), exitContext);
}
public static bool Wait(Object obj, int millisecondsTimeout)
{
return Wait(obj, millisecondsTimeout, false);
}
public static bool Wait(Object obj, TimeSpan timeout)
{
return Wait(obj, MillisecondsTimeoutFromTimeSpan(timeout), false);
}
public static bool Wait(Object obj)
{
return Wait(obj, Timeout.Infinite, false);
}
/*========================================================================
** Sends a notification to a single waiting object.
* Exceptions: SynchronizationLockException if this method is not called inside
* a synchronized block of code.
========================================================================*/
[System.Security.SecurityCritical] // auto-generated
[ResourceExposure(ResourceScope.None)]
[MethodImplAttribute(MethodImplOptions.InternalCall)]
private static extern void ObjPulse(Object obj);
[System.Security.SecuritySafeCritical] // auto-generated
public static void Pulse(Object obj)
{
if (obj == null)
{
throw new ArgumentNullException("obj");
}
Contract.EndContractBlock();
ObjPulse(obj);
}
/*========================================================================
** Sends a notification to all waiting objects.
========================================================================*/
[System.Security.SecurityCritical] // auto-generated
[ResourceExposure(ResourceScope.None)]
[MethodImplAttribute(MethodImplOptions.InternalCall)]
private static extern void ObjPulseAll(Object obj);
[System.Security.SecuritySafeCritical] // auto-generated
public static void PulseAll(Object obj)
{
if (obj == null)
{
throw new ArgumentNullException("obj");
}
Contract.EndContractBlock();
ObjPulseAll(obj);
}
}
}
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