77 lines
2.0 KiB
C#
77 lines
2.0 KiB
C#
using System;
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using System.Threading;
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using System.Threading.Tasks;
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namespace Barotrauma.LuaCs;
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// taken from: <https://gist.github.com/cajuncoding/a88f0d00847dcfc241ae80d1c7bafb1e?permalink_comment_id=4498792>
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public sealed class AsyncReaderWriterLock : IDisposable
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{
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readonly SemaphoreSlim _readSemaphore = new SemaphoreSlim(1, 1);
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readonly SemaphoreSlim _writeSemaphore = new SemaphoreSlim(1, 1);
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int _readerCount;
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public async Task<IDisposable> AcquireWriterLock(CancellationToken token = default)
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{
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await _writeSemaphore.WaitAsync(token).ConfigureAwait(false);
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try
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{
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await _readSemaphore.WaitAsync(token).ConfigureAwait(false);
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}
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catch
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{
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_writeSemaphore.Release();
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throw;
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}
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return new LockToken(ReleaseWriterLock);
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}
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private void ReleaseWriterLock()
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{
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_readSemaphore.Release();
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_writeSemaphore.Release();
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}
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public async Task<IDisposable> AcquireReaderLock(CancellationToken token = default)
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{
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await _writeSemaphore.WaitAsync(token).ConfigureAwait(false);
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if (Interlocked.Increment(ref _readerCount) == 1)
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{
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try
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{
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await _readSemaphore.WaitAsync(token).ConfigureAwait(false);
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}
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catch
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{
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Interlocked.Decrement(ref _readerCount);
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_writeSemaphore.Release();
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throw;
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}
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}
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_writeSemaphore.Release();
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return new LockToken(ReleaseReaderLock);
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}
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private void ReleaseReaderLock()
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{
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if (Interlocked.Decrement(ref _readerCount) == 0)
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_readSemaphore.Release();
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}
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public void Dispose()
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{
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_writeSemaphore.Dispose();
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_readSemaphore.Dispose();
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}
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private sealed class LockToken : IDisposable
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{
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private readonly Action _action;
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public LockToken(Action action) => _action = action;
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public void Dispose() => _action?.Invoke();
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}
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}
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