private void InitializeGraph()
{
if (_CompressGraph == null)
{
Debug.Assert(_Stream != null);
_CompressGraph = new CompressGraph(_Stream, _CompressionLevel);
}
}
public async Task FlushAsync(CancellationToken cancellationToken)
{
if (_CompressGraph != null)
{
await SendBufferAsync(cancellationToken).ConfigureAwait(false);
try
{
_CompressGraph.Complete();
await _CompressGraph.Completion.ConfigureAwait(false);
}
finally
{
_CompressGraph = null;
}
}
}
/// <summary>
/// Reads the bytes from the <paramref name="source"/> stream and
/// writes them compressed to the <paramref name="destination"/> stream,
/// using a specified <paramref name="compressionLevel"/> and <paramref name="bufferSize"/>.
/// <para/>
/// This operation is optimized by using parallel algorithms.
/// </summary>
/// <param name="source">The stream from which the content will be read.</param>
/// <param name="destination">The stream to which the content will be compressed.</param>
/// <param name="compressionLevel">The applied compression level.</param>
/// <param name="bufferSize">The size of the buffer. This value must be greater than zero.</param>
/// <param name="progress">The progress that is used for progress reporting.</param>
/// <param name="cancellationToken">The cancellation token with which to request cancellation of the operation.</param>
/// <returns>The awaitable <see cref="Task"/> to synchronize the operation.</returns>
/// <exception cref="System.ArgumentNullException"><paramref name="source"/>, <paramref name="destination"/> or <paramref name="progress"/> is null.</exception>
/// <exception cref="System.NotSupportedException"><paramref name="source"/> does not support reading or <paramref name="destination"/> does not support writing.</exception>
/// <exception cref="System.ArgumentOutOfRangeException"><paramref name="bufferSize"/> is negative or zero.</exception>
/// <remarks>
/// To decompress the content the method <see cref="DecompressParallelToAsync(System.IO.Stream, System.IO.Stream, System.IProgress{double})"/> must be used.
/// <para/>
/// The specified <paramref name="bufferSize"/> affects the parallelization potential and
/// and should be selected in dependency of the size of the <paramref name="source"/> stream.
/// <para/>
/// Copying begins at the current position in the <paramref name="source"/> stream,
/// and does not reset the position of the <paramref name="destination"/> stream after the copy operation is complete.
/// </remarks>
public static async Task CompressParallelToAsync(this Stream source, Stream destination, CompressionLevel compressionLevel, int bufferSize, IProgress <double> progress, CancellationToken cancellationToken)
{
#region Contracts
if (source == null)
{
throw new ArgumentNullException(nameof(source));
}
if (!source.CanRead)
{
throw new NotSupportedException("source does not support reading");
}
if (destination == null)
{
throw new ArgumentNullException(nameof(destination));
}
if (!destination.CanWrite)
{
throw new NotSupportedException("destination does not support writing");
}
if (bufferSize <= 0)
{
throw new ArgumentOutOfRangeException(nameof(bufferSize), "bufferSize is negative or zero");
}
if (progress == null)
{
throw new ArgumentNullException(nameof(progress));
}
Contract.EndContractBlock();
#endregion
var compressGraph = new CompressGraph(destination, compressionLevel, progress);
try
{
while (true)
{
var buffer = Buffer.ReadFrom(source, bufferSize);
if (buffer.Size == 0)
{
break;
}
await compressGraph.SendAsync(buffer, cancellationToken).ConfigureAwait(false);
}
}
finally
{
compressGraph.Complete();
await compressGraph.Completion.ConfigureAwait(false);
}
progress.Report(1.0);
}