/// <summary>
/// Reads the compressed bytes from the <paramref name="source"/> stream and
/// writes them decompressed to the <paramref name="destination"/> stream.
/// <para/>
/// This operation is optimized by using parallel algorithms.
/// </summary>
/// <param name="source">The stream from which the compressed content will be read.</param>
/// <param name="destination">The stream to which the decompressed content will be written.</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>
/// <remarks>
/// The compressed content must be created by the method <see cref="CompressParallelToAsync(System.IO.Stream, System.IO.Stream, System.IO.Compression.CompressionLevel, int, System.IProgress{double})"/>.
/// <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 DecompressParallelToAsync(this Stream source, Stream destination, 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 (progress == null)
{
throw new ArgumentNullException(nameof(progress));
}
Contract.EndContractBlock();
#endregion
var decompressGraph = new DecompressGraph(source);
try
{
while (await decompressGraph.OutputAvailableAsync(cancellationToken).ConfigureAwait(false))
{
var buffer = await decompressGraph.ReceiveAsync(cancellationToken).ConfigureAwait(false);
buffer.WriteTo(destination, progress);
}
}
finally
{
decompressGraph.Complete();
await decompressGraph.Completion.ConfigureAwait(false);
}
progress.Report(1.0);
}
private async Task <bool> ReceiveBufferAsync(CancellationToken cancellationToken)
{
if (await _DecompressGraph.OutputAvailableAsync(cancellationToken).ConfigureAwait(false))
{
_Buffer = await _DecompressGraph.ReceiveAsync(cancellationToken).ConfigureAwait(false);
_BufferPosition = 0;
return(true);
}
_Buffer = Buffer.Empty;
_BufferPosition = 0;
return(false);
}