/// <summary>
/// Acquires the write lock if it is not held by another thread
/// within the given waiting time and <see cref="System.Threading.Thread.Interrupt()"/> has not been called on the current thread
/// </summary>
/// <remarks>
/// Acquires the write lock if neither the read nor write lock
/// are held by another thread
/// and returns immediately with the value <see lang="true"/>,
/// setting the write lock hold count to one. If this lock has been
/// set to use a fair ordering policy then an available lock
/// <b>will not</b> be acquired if any other threads are
/// waiting for the write lock. This is in contrast to the <see cref="Spring.Threading.Locks.WriterLock.TryLock()"/>
/// If you want a timed <see cref="Spring.Threading.Locks.WriterLock.TryLock()"/>
/// that does permit barging on a fair lock, then combine the
/// timed and un-timed forms together:
///
/// <code>
/// if (lock.TryLock() || lock.tryLock(timeSpan) ) { ... }
/// </code>
///
/// <p/>
/// If the current thread already holds this lock then the
/// hold count is incremented by one and the method returns
/// <see lang="true"/>.
///
/// <p/>
/// If the lock is held by another thread then the current
/// thread becomes disabled for thread scheduling purposes and
/// lies dormant until one of three things happens:
///
/// <ul>
/// <li>The write lock is acquired by the current thread</li>
/// <li>Some other thread calls <see cref="System.Threading.Thread.Interrupt()"/>
/// on the current thread</li>
/// <li>The specified <see cref="System.TimeSpan"/> elapses</li>
/// </ul>
///
/// <p/>
/// If the write lock is acquired then the value <see lang="true"/> is
/// returned and the write lock hold count is set to one.
///
/// <p/>
/// If the current thread has <see cref="System.Threading.Thread.Interrupt()"/> called on it while acquiring
/// the write lock, then a <see cref="System.Threading.ThreadInterruptedException"/> is thrown.
///
/// <p/>
/// If the specified <see cref="System.TimeSpan"/> elapses then the value
/// <see lang="false"/> is returned. If the time is less than or
/// equal to zero, the method will not wait at all.
///
/// <p/>
/// In this implementation, as this method is an explicit
/// interruption point, preference is given to responding to
/// the interrupt over normal or reentrant acquisition of the
/// lock, and over reporting the elapse of the waiting time.
///
/// </remarks>
/// <param name="durationToWait">the time to wait for the write lock</param>
/// <returns> <see lang="true"/> if the lock was free and was acquired
/// by the current thread, or the write lock was already held by the
/// current thread; and <see lang="false"/> if the waiting time
/// elapsed before the lock could be acquired.
/// </returns>
///
/// <exception cref="System.Threading.ThreadInterruptedException">if the current thread is interrupted.</exception>
public override bool TryLock(TimeSpan durationToWait)
{
ThreadInterruptedException ie = null;
lock (this)
{
if (durationToWait.TotalMilliseconds <= 0)
{
return(ReentrantReadWriteLock.StartWrite());
}
else if (ReentrantReadWriteLock.StartWriteFromNewWriter())
{
return(true);
}
else
{
DateTime deadline = DateTime.Now.Add(durationToWait);
for (;;)
{
try
{
Monitor.Wait(this, durationToWait);
}
catch (ThreadInterruptedException ex)
{
ReentrantReadWriteLock.CancelWaitingWriter();
Monitor.Pulse(this);
ie = ex;
break;
}
if (ReentrantReadWriteLock.StartWriteFromWaitingWriter())
{
return(true);
}
else
{
if (deadline.Subtract(DateTime.Now).TotalMilliseconds <= 0)
{
ReentrantReadWriteLock.CancelWaitingWriter();
Monitor.Pulse(this);
break;
}
}
}
}
}
ReentrantReadWriteLock.SignallerReaderLock.SignalWaiters();
if (ie != null)
{
throw ie;
}
else
{
return(false);
}
}
/// <summary>
/// Acquires the write lock unless <see cref="System.Threading.Thread.Interrupt()"/> is called on the current thread
/// </summary>
/// <remarks>
/// Acquires the write lock if neither the read nor write locks
/// are held by another thread
/// and returns immediately, setting the write lock hold count to
/// one.
///
/// <p/>
/// If the current thread already holds this lock then the
/// hold count is incremented by one and the method returns
/// immediately.
///
/// <p/>
/// If the lock is held by another thread then the current
/// thread becomes disabled for thread scheduling purposes and
/// lies dormant until one of two things happens:
///
/// <ul>
/// <li>The write lock is acquired by the current thread.</li>
/// <li>Some other thread calls <see cref="System.Threading.Thread.Interrupt()"/> on the current thread.</li>
/// </ul>
///
/// <p/>
/// If the write lock is acquired by the current thread then the
/// lock hold count is set to one.
///
/// <p/>
/// If the current thread:
/// <ul>
/// <li>has its interrupted status set on entry to this method</li>
/// <li><see cref="System.Threading.Thread.Interrupt()"/> is called on the thread while acquiring the write lock.</li>
/// </ul>
///
/// then a <see cref="System.Threading.ThreadInterruptedException"/> is thrown and the current
/// thread's interrupted status is cleared.
///
/// <p/>
/// In this implementation, as this method is an explicit
/// interruption point, preference is given to responding to
/// the interrupt over normal or reentrant acquisition of the
/// lock.
///
/// </remarks>
/// <exception cref="System.Threading.ThreadInterruptedException">if the current thread is interrupted.</exception>
public override IDisposable LockInterruptibly()
{
ThreadInterruptedException ie = null;
lock (this)
{
if (!ReentrantReadWriteLock.StartWriteFromNewWriter())
{
for (;;)
{
try
{
Monitor.Wait(this);
if (ReentrantReadWriteLock.StartWriteFromWaitingWriter())
{
return(this);
}
}
catch (ThreadInterruptedException ex)
{
ReentrantReadWriteLock.CancelWaitingWriter();
Monitor.Pulse(this);
ie = ex;
break;
}
}
}
}
if (ie != null)
{
// Fall through outside synch on interrupt.
// On exception, we may need to signal readers.
// It is not worth checking here whether it is strictly necessary.
ReentrantReadWriteLock.SignallerReaderLock.SignalWaiters();
throw ie;
}
return(this);
}
