/// <summary>
/// Asynchronously enters the lock in read mode and returns a <see cref="IDisposableLock"/> that
/// will release the lock when disposed.
/// </summary>
/// <param name="lockInstance">The <see cref="AsyncReaderWriterLockSlim"/> instance.</param>
/// <param name="cancellationToken">The <see cref="CancellationToken"/> to observe.</param>
/// <returns>A task that will complete with a <see cref="IDisposableLock"/> when the lock has been entered,
/// which will release the lock when disposed.</returns>
/// <exception cref="OperationCanceledException"><paramref name="cancellationToken"/> was canceled.</exception>
/// <exception cref="ObjectDisposedException">The current instance has already been disposed.</exception>
public static async Task <IDisposableLock> GetReadLockAsync(
this AsyncReaderWriterLockSlim lockInstance,
CancellationToken cancellationToken = default(CancellationToken))
{
await lockInstance.EnterReadLockAsync(cancellationToken);
return(new ActionDisposableLock(lockInstance.ExitReadLock, lockInstance, false));
}
/// <summary>
/// Enters the lock in write mode.
/// </summary>
/// <param name="lockInstance">The <see cref="AsyncReaderWriterLockSlim"/> instance.</param>
/// <param name="cancellationToken">The <see cref="CancellationToken"/> to observe.</param>
/// <returns>A <see cref="IDisposableLock"/> that will release the lock when disposed.</returns>
/// <exception cref="OperationCanceledException"><paramref name="cancellationToken"/> was canceled.</exception>
/// <exception cref="ObjectDisposedException">The current instance has already been disposed.</exception>
public static IDisposableLock GetWriteLock(
this AsyncReaderWriterLockSlim lockInstance,
CancellationToken cancellationToken = default(CancellationToken))
{
lockInstance.EnterWriteLock(cancellationToken);
return(new ActionDisposableLock(lockInstance.ExitWriteLock, lockInstance, true));
}
public ActionDisposableLock(
Action action,
AsyncReaderWriterLockSlim lockOrigin,
bool isWriteLock)
{
this.action = action;
this.lockOrigin = lockOrigin;
this.isWriteLock = isWriteLock;
}
/// <summary>
/// Tries to asynchronously enter the lock in read mode, with an optional integer time-out.
/// </summary>
/// <param name="lockInstance">The <see cref="AsyncReaderWriterLockSlim"/> instance.</param>
/// <param name="millisecondsTimeout">The number of milliseconds to wait, or -1
/// (<see cref="Timeout.Infinite"/>) to wait indefinitely.</param>
/// <param name="cancellationToken">The <see cref="CancellationToken"/> to observe.</param>
/// <returns>A task that will complete with a <see cref="IDisposableLock"/> that will release the lock
/// when disposed if the lock could be entered, or with <c>null</c> otherwise.</returns>
/// <exception cref="ArgumentOutOfRangeException"><paramref name="millisecondsTimeout"/> is a negative number
/// other than -1, which represents an infinite time-out.</exception>
/// <exception cref="OperationCanceledException"><paramref name="cancellationToken"/> was canceled.</exception>
/// <exception cref="ObjectDisposedException">The current instance has already been disposed.</exception>
public static async Task <IDisposableLock> TryGetReadLockAsync(
this AsyncReaderWriterLockSlim lockInstance,
int millisecondsTimeout,
CancellationToken cancellationToken = default(CancellationToken))
{
bool returnValue = await lockInstance.TryEnterReadLockAsync(
millisecondsTimeout, cancellationToken);
if (returnValue)
{
return(new ActionDisposableLock(lockInstance.ExitReadLock, lockInstance, false));
}
else
{
return(null);
}
}
/// <summary>
/// Tries to enter the lock in write mode, with an optional integer time-out.
/// </summary>
/// <param name="lockInstance">The <see cref="AsyncReaderWriterLockSlim"/> instance.</param>
/// <param name="millisecondsTimeout">The number of milliseconds to wait, or -1
/// (<see cref="Timeout.Infinite"/>) to wait indefinitely.</param>
/// <param name="cancellationToken">The <see cref="CancellationToken"/> to observe.</param>
/// <returns>A <see cref="IDisposableLock"/> that will release the lock when disposed if the lock
/// could be entered, or <c>null</c> otherwise.</returns>
/// <exception cref="ArgumentOutOfRangeException"><paramref name="millisecondsTimeout"/> is a negative number
/// other than -1, which represents an infinite time-out.</exception>
/// <exception cref="OperationCanceledException"><paramref name="cancellationToken"/> was canceled.</exception>
/// <exception cref="ObjectDisposedException">The current instance has already been disposed.</exception>
public static IDisposableLock TryGetWriteLock(
this AsyncReaderWriterLockSlim lockInstance,
int millisecondsTimeout,
CancellationToken cancellationToken = default(CancellationToken))
{
bool returnValue = lockInstance.TryEnterWriteLock(
millisecondsTimeout, cancellationToken);
if (returnValue)
{
return(new ActionDisposableLock(lockInstance.ExitWriteLock, lockInstance, true));
}
else
{
return(null);
}
}
/// <summary>
/// Downgrades the lock from write mode to read mode.
/// </summary>
/// <param name="lockInstance">The <see cref="AsyncReaderWriterLockSlim"/> instance.</param>
/// <param name="readLock">The <see cref="IDisposableLock"/> which should be downgraded.</param>
/// <exception cref="ObjectDisposedException">The current instance has already been disposed.</exception>
public static void DowngradeWriteLockToReadLock(
this AsyncReaderWriterLockSlim lockInstance,
IDisposableLock readLock)
{
if (readLock == null)
{
throw new ArgumentNullException(nameof(readLock));
}
var myReadLock = readLock as ActionDisposableLock;
if (myReadLock == null || myReadLock.LockOrigin != lockInstance ||
!myReadLock.IsWriteLock || myReadLock.IsDisposed)
{
throw new ArgumentException();
}
// Downgrade the lock.
lockInstance.DowngradeWriteLockToReadLock();
// Now mark the lock as being a read lock.
myReadLock.IsWriteLock = false;
}