92 lines
3.5 KiB
C#
92 lines
3.5 KiB
C#
namespace System.Threading
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{
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/// <summary>
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/// Provides extension methods for the <see cref="ReaderWriterLockSlim"/>.
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/// </summary>
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public static class ReaderWriterLockSlimExtensions
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{
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/// <summary>
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/// Acquires a read lock on a lock object that can be released with an
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/// <see cref="IDisposable"/> instance.
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/// </summary>
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/// <param name="rwLock">The lock object.</param>
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/// <param name="timeoutMilliseconds">The number of milliseconds to wait, or -1
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/// (<see cref="Timeout.Infinite"/>) to wait indefinitely.</param>
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/// <returns>An <see cref="IDisposable"/> instance to release the lock.</returns>
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public static IDisposable GetReadLock(this ReaderWriterLockSlim rwLock, int timeoutMilliseconds = -1)
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{
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if (!rwLock.TryEnterReadLock(timeoutMilliseconds))
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throw new TimeoutException("The read lock could not be acquired.");
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return new DisposableReadWriteLock(rwLock, LockMode.Read);
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}
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/// <summary>
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/// Acquires a upgradeable read lock on a lock object that can be released with an
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/// <see cref="IDisposable"/> instance. The lock can be upgraded to a write lock temporarily
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/// with <see cref="GetWriteLock"/> or until the lock is released with
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/// <see cref="ReaderWriterLockSlim.EnterWriteLock"/> alone.
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/// </summary>
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/// <param name="rwLock">The lock object.</param>
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/// <param name="timeoutMilliseconds">The number of milliseconds to wait, or -1
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/// (<see cref="Timeout.Infinite"/>) to wait indefinitely.</param>
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/// <returns>An <see cref="IDisposable"/> instance to release the lock. If the lock was
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/// upgraded to a write lock, that will be released as well.</returns>
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public static IDisposable GetUpgradeableReadLock(this ReaderWriterLockSlim rwLock, int timeoutMilliseconds = -1)
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{
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if (!rwLock.TryEnterUpgradeableReadLock(timeoutMilliseconds))
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throw new TimeoutException("The upgradeable read lock could not be acquired.");
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return new DisposableReadWriteLock(rwLock, LockMode.Upgradable);
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}
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/// <summary>
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/// Acquires a write lock on a lock object that can be released with an
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/// <see cref="IDisposable"/> instance.
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/// </summary>
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/// <param name="rwLock">The lock object.</param>
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/// <param name="timeoutMilliseconds">The number of milliseconds to wait, or -1
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/// (<see cref="Timeout.Infinite"/>) to wait indefinitely.</param>
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/// <returns>An <see cref="IDisposable"/> instance to release the lock.</returns>
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public static IDisposable GetWriteLock(this ReaderWriterLockSlim rwLock, int timeoutMilliseconds = -1)
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{
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if (!rwLock.TryEnterWriteLock(timeoutMilliseconds))
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throw new TimeoutException("The write lock could not be acquired.");
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return new DisposableReadWriteLock(rwLock, LockMode.Write);
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}
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private struct DisposableReadWriteLock(ReaderWriterLockSlim rwLock, LockMode lockMode)
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: IDisposable
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{
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private readonly ReaderWriterLockSlim _rwLock = rwLock;
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private LockMode _lockMode = lockMode;
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public void Dispose()
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{
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if (_lockMode == LockMode.Read)
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_rwLock.ExitReadLock();
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if (_lockMode == LockMode.Upgradable && _rwLock.IsWriteLockHeld) // Upgraded with EnterWriteLock alone
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_rwLock.ExitWriteLock();
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if (_lockMode == LockMode.Upgradable)
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_rwLock.ExitUpgradeableReadLock();
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if (_lockMode == LockMode.Write)
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_rwLock.ExitWriteLock();
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_lockMode = LockMode.None;
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}
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}
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private enum LockMode
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{
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None = 0,
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Read = 1,
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Upgradable = 2,
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Write = 3,
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}
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}
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}
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