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@@ -1,459 +0,0 @@
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-using System;
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-using System.IO;
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-using System.Threading;
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-using System.Threading.Tasks;
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-
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-namespace Emby.Server.Implementations.IO
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-{
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- public class AsyncStreamCopier : IDisposable
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- {
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- // size in bytes of the buffers in the buffer pool
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- private const int DefaultBufferSize = 81920;
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- private readonly int _bufferSize;
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- // number of buffers in the pool
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- private const int DefaultBufferCount = 4;
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- private readonly int _bufferCount;
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-
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- // indexes of the next buffer to read into/write from
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- private int _nextReadBuffer = -1;
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- private int _nextWriteBuffer = -1;
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-
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- // the buffer pool, implemented as an array, and used in a cyclic way
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- private readonly byte[][] _buffers;
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- // sizes in bytes of the available (read) data in the buffers
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- private readonly int[] _sizes;
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- // the streams...
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- private Stream _source;
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- private Stream _target;
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- private readonly bool _closeStreamsOnEnd;
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-
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- // number of buffers that are ready to be written
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- private int _buffersToWrite;
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- // flag indicating that there is still a read operation to be scheduled
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- // (source end of stream not reached)
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- private volatile bool _moreDataToRead;
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- // the result of the whole operation, returned by BeginCopy()
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- private AsyncResult _asyncResult;
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- // any exception that occurs during an async operation
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- // stored here for rethrow
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- private Exception _exception;
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-
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- public TaskCompletionSource<long> TaskCompletionSource;
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- private long _bytesToRead;
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- private long _totalBytesWritten;
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- private CancellationToken _cancellationToken;
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- public int IndividualReadOffset = 0;
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-
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- public AsyncStreamCopier(Stream source,
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- Stream target,
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- long bytesToRead,
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- CancellationToken cancellationToken,
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- bool closeStreamsOnEnd = false,
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- int bufferSize = DefaultBufferSize,
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- int bufferCount = DefaultBufferCount)
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- {
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- if (source == null)
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- throw new ArgumentNullException("source");
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- if (target == null)
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- throw new ArgumentNullException("target");
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- if (!source.CanRead)
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- throw new ArgumentException("Cannot copy from a non-readable stream.");
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- if (!target.CanWrite)
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- throw new ArgumentException("Cannot copy to a non-writable stream.");
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- _source = source;
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- _target = target;
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- _moreDataToRead = true;
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- _closeStreamsOnEnd = closeStreamsOnEnd;
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- _bufferSize = bufferSize;
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- _bufferCount = bufferCount;
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- _buffers = new byte[_bufferCount][];
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- _sizes = new int[_bufferCount];
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- _bytesToRead = bytesToRead;
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- _cancellationToken = cancellationToken;
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- }
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-
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- ~AsyncStreamCopier()
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- {
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- // ensure any exception cannot be ignored
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- ThrowExceptionIfNeeded();
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- }
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-
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- public static Task<long> CopyStream(Stream source, Stream target, int bufferSize, int bufferCount, CancellationToken cancellationToken)
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- {
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- return CopyStream(source, target, 0, bufferSize, bufferCount, cancellationToken);
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- }
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-
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- public static Task<long> CopyStream(Stream source, Stream target, long size, int bufferSize, int bufferCount, CancellationToken cancellationToken)
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- {
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- var copier = new AsyncStreamCopier(source, target, size, cancellationToken, false, bufferSize, bufferCount);
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- var taskCompletion = new TaskCompletionSource<long>();
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-
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- copier.TaskCompletionSource = taskCompletion;
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-
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- var result = copier.BeginCopy(StreamCopyCallback, copier);
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-
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- if (result.CompletedSynchronously)
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- {
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- StreamCopyCallback(result);
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- }
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-
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- cancellationToken.Register(() => taskCompletion.TrySetCanceled());
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-
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- return taskCompletion.Task;
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- }
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-
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- private static void StreamCopyCallback(IAsyncResult result)
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- {
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- var copier = (AsyncStreamCopier)result.AsyncState;
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- var taskCompletion = copier.TaskCompletionSource;
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-
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- try
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- {
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- copier.EndCopy(result);
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- taskCompletion.TrySetResult(copier._totalBytesWritten);
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- }
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- catch (Exception ex)
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- {
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- taskCompletion.TrySetException(ex);
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- }
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- }
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-
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- public void Dispose()
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- {
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- if (_asyncResult != null)
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- _asyncResult.Dispose();
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- if (_closeStreamsOnEnd)
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- {
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- if (_source != null)
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- {
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- _source.Dispose();
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- _source = null;
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- }
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- if (_target != null)
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- {
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- _target.Dispose();
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- _target = null;
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- }
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- }
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- GC.SuppressFinalize(this);
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- ThrowExceptionIfNeeded();
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- }
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-
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- public IAsyncResult BeginCopy(AsyncCallback callback, object state)
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- {
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- // avoid concurrent start of the copy on separate threads
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- if (Interlocked.CompareExchange(ref _asyncResult, new AsyncResult(callback, state), null) != null)
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- throw new InvalidOperationException("A copy operation has already been started on this object.");
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- // allocate buffers
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- for (int i = 0; i < _bufferCount; i++)
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- _buffers[i] = new byte[_bufferSize];
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-
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- // we pass false to BeginRead() to avoid completing the async result
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- // immediately which would result in invoking the callback
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- // when the method fails synchronously
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- BeginRead(false);
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- // throw exception synchronously if there is one
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- ThrowExceptionIfNeeded();
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- return _asyncResult;
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- }
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-
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- public void EndCopy(IAsyncResult ar)
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- {
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- if (ar != _asyncResult)
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- throw new InvalidOperationException("Invalid IAsyncResult object.");
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-
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- if (!_asyncResult.IsCompleted)
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- _asyncResult.AsyncWaitHandle.WaitOne();
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-
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- if (_closeStreamsOnEnd)
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- {
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- _source.Close();
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- _source = null;
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- _target.Close();
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- _target = null;
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- }
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-
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- //_logger.Info("AsyncStreamCopier {0} bytes requested. {1} bytes transferred", _bytesToRead, _totalBytesWritten);
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- ThrowExceptionIfNeeded();
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- }
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-
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- /// <summary>
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- /// Here we'll throw a pending exception if there is one,
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- /// and remove it from our instance, so we know it has been consumed.
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- /// </summary>
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- private void ThrowExceptionIfNeeded()
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- {
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- if (_exception != null)
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- {
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- var exception = _exception;
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- _exception = null;
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- throw exception;
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- }
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- }
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-
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- private void BeginRead(bool completeOnError = true)
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- {
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- if (!_moreDataToRead)
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- {
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- return;
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- }
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- if (_asyncResult.IsCompleted)
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- return;
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- int bufferIndex = Interlocked.Increment(ref _nextReadBuffer) % _bufferCount;
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-
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- try
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- {
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- _source.BeginRead(_buffers[bufferIndex], 0, _bufferSize, EndRead, bufferIndex);
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- }
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- catch (Exception exception)
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- {
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- _exception = exception;
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- if (completeOnError)
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- _asyncResult.Complete(false);
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- }
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- }
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-
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- private void BeginWrite()
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- {
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- if (_asyncResult.IsCompleted)
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- return;
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- // this method can actually be called concurrently!!
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- // indeed, let's say we call a BeginWrite, and the thread gets interrupted
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- // just after making the IO request.
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- // At that moment, the thread is still in the method. And then the IO request
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- // ends (extremely fast io, or caching...), EndWrite gets called
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- // on another thread, and calls BeginWrite again! There we have it!
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- // That is the reason why an Interlocked is needed here.
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- int bufferIndex = Interlocked.Increment(ref _nextWriteBuffer) % _bufferCount;
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-
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- try
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- {
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- int bytesToWrite;
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- if (_bytesToRead > 0)
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- {
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- var bytesLeftToWrite = _bytesToRead - _totalBytesWritten;
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- bytesToWrite = Convert.ToInt32(Math.Min(_sizes[bufferIndex], bytesLeftToWrite));
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- }
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- else
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- {
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- bytesToWrite = _sizes[bufferIndex];
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- }
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-
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- _target.BeginWrite(_buffers[bufferIndex], IndividualReadOffset, bytesToWrite - IndividualReadOffset, EndWrite, null);
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-
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- _totalBytesWritten += bytesToWrite;
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- }
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- catch (Exception exception)
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- {
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- _exception = exception;
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- _asyncResult.Complete(false);
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- }
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- }
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-
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- private void EndRead(IAsyncResult ar)
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- {
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- try
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- {
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- int read = _source.EndRead(ar);
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- _moreDataToRead = read > 0;
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- var bufferIndex = (int)ar.AsyncState;
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- _sizes[bufferIndex] = read;
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- }
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- catch (Exception exception)
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- {
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- _exception = exception;
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- _asyncResult.Complete(false);
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- return;
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- }
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-
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- if (_moreDataToRead && !_cancellationToken.IsCancellationRequested)
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- {
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- int usedBuffers = Interlocked.Increment(ref _buffersToWrite);
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- // if we incremented from zero to one, then it means we just
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- // added the single buffer to write, so a writer could not
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- // be busy, and we have to schedule one.
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- if (usedBuffers == 1)
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- BeginWrite();
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- // test if there is at least a free buffer, and schedule
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- // a read, as we have read some data
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- if (usedBuffers < _bufferCount)
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- BeginRead();
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- }
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- else
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- {
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- // we did not add a buffer, because no data was read, and
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- // there is no buffer left to write so this is the end...
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- if (Thread.VolatileRead(ref _buffersToWrite) == 0)
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- {
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- _asyncResult.Complete(false);
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- }
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- }
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- }
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-
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- private void EndWrite(IAsyncResult ar)
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- {
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- try
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- {
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- _target.EndWrite(ar);
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- }
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- catch (Exception exception)
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- {
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- _exception = exception;
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- _asyncResult.Complete(false);
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- return;
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- }
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-
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- int buffersLeftToWrite = Interlocked.Decrement(ref _buffersToWrite);
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- // no reader could be active if all buffers were full of data waiting to be written
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- bool noReaderIsBusy = buffersLeftToWrite == _bufferCount - 1;
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- // note that it is possible that both a reader and
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- // a writer see the end of the copy and call Complete
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- // on the _asyncResult object. That race condition is handled by
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- // Complete that ensures it is only executed fully once.
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-
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- long bytesLeftToWrite;
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- if (_bytesToRead > 0)
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- {
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- bytesLeftToWrite = _bytesToRead - _totalBytesWritten;
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- }
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- else
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- {
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- bytesLeftToWrite = 1;
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- }
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-
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- if (!_moreDataToRead || bytesLeftToWrite <= 0 || _cancellationToken.IsCancellationRequested)
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- {
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- // at this point we know no reader can schedule a read or write
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- if (Thread.VolatileRead(ref _buffersToWrite) == 0)
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- {
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- // nothing left to write, so it is the end
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- _asyncResult.Complete(false);
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- return;
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- }
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- }
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- else
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- // here, we know we have something left to read,
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- // so schedule a read if no read is busy
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- if (noReaderIsBusy)
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- BeginRead();
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-
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- // also schedule a write if we are sure we did not write the last buffer
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- // note that if buffersLeftToWrite is zero and a reader has put another
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- // buffer to write between the time we decremented _buffersToWrite
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- // and now, that reader will also schedule another write,
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- // as it will increment _buffersToWrite from zero to one
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- if (buffersLeftToWrite > 0)
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- BeginWrite();
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- }
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- }
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-
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- internal class AsyncResult : IAsyncResult, IDisposable
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- {
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- // Fields set at construction which never change while
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- // operation is pending
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- private readonly AsyncCallback _asyncCallback;
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- private readonly object _asyncState;
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-
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- // Fields set at construction which do change after
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- // operation completes
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- private const int StatePending = 0;
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- private const int StateCompletedSynchronously = 1;
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- private const int StateCompletedAsynchronously = 2;
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- private int _completedState = StatePending;
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-
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- // Field that may or may not get set depending on usage
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- private ManualResetEvent _waitHandle;
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-
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- internal AsyncResult(
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- AsyncCallback asyncCallback,
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- object state)
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- {
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- _asyncCallback = asyncCallback;
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- _asyncState = state;
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- }
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-
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- internal bool Complete(bool completedSynchronously)
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- {
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- bool result = false;
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-
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- // The _completedState field MUST be set prior calling the callback
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- int prevState = Interlocked.CompareExchange(ref _completedState,
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- completedSynchronously ? StateCompletedSynchronously :
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- StateCompletedAsynchronously, StatePending);
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- if (prevState == StatePending)
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- {
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- // If the event exists, set it
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- if (_waitHandle != null)
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- _waitHandle.Set();
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-
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- if (_asyncCallback != null)
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- _asyncCallback(this);
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-
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- result = true;
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- }
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-
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- return result;
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- }
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-
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- #region Implementation of IAsyncResult
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-
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- public Object AsyncState { get { return _asyncState; } }
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-
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- public bool CompletedSynchronously
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- {
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- get
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- {
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- return Thread.VolatileRead(ref _completedState) ==
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- StateCompletedSynchronously;
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- }
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- }
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-
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- public WaitHandle AsyncWaitHandle
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- {
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- get
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- {
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- if (_waitHandle == null)
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- {
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- bool done = IsCompleted;
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- var mre = new ManualResetEvent(done);
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- if (Interlocked.CompareExchange(ref _waitHandle,
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- mre, null) != null)
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- {
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- // Another thread created this object's event; dispose
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- // the event we just created
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- mre.Close();
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- }
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- else
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- {
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- if (!done && IsCompleted)
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- {
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- // If the operation wasn't done when we created
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- // the event but now it is done, set the event
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- _waitHandle.Set();
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- }
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- }
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- }
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- return _waitHandle;
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- }
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- }
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-
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- public bool IsCompleted
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- {
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- get
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- {
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- return Thread.VolatileRead(ref _completedState) !=
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- StatePending;
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- }
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- }
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- #endregion
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-
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- public void Dispose()
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|
- {
|
|
|
- if (_waitHandle != null)
|
|
|
- {
|
|
|
- _waitHandle.Dispose();
|
|
|
- _waitHandle = null;
|
|
|
- }
|
|
|
- }
|
|
|
- }
|
|
|
-}
|
Luke Pulverenti