/// <summary>
/// Copies bytes from the stream provided in our constructor into the target <paramref name="stream"/>.
/// </summary>
/// <remarks>
/// This is used internally by HttpClient.SendAsync to send the request body.
/// Here's the sequence of events as of commit 17300169760c61a90cab8d913636c1058a30a8c1 (https://github.com/dotnet/corefx -- tag v3.1.1).
///
/// <code>
/// HttpClient.SendAsync -->
/// HttpMessageInvoker.SendAsync -->
/// HttpClientHandler.SendAsync -->
/// SocketsHttpHandler.SendAsync -->
/// HttpConnectionHandler.SendAsync -->
/// HttpConnectionPoolManager.SendAsync -->
/// HttpConnectionPool.SendAsync --> ... -->
/// {
/// HTTP/1.1: HttpConnection.SendAsync -->
/// HttpConnection.SendAsyncCore -->
/// HttpConnection.SendRequestContentAsync -->
/// HttpContent.CopyToAsync
///
/// HTTP/2: Http2Connection.SendAsync -->
/// Http2Stream.SendRequestBodyAsync -->
/// HttpContent.CopyToAsync
///
/// /* Only in .NET 5:
/// HTTP/3: Http3Connection.SendAsync -->
/// Http3Connection.SendWithoutWaitingAsync -->
/// Http3RequestStream.SendAsync -->
/// Http3RequestStream.SendContentAsync -->
/// HttpContent.CopyToAsync
/// */
/// }
///
/// HttpContent.CopyToAsync -->
/// HttpContent.SerializeToStreamAsync (bingo!)
/// </code>
///
/// Conclusion: by overriding HttpContent.SerializeToStreamAsync,
/// we have full control over pumping bytes to the target stream for all protocols
/// (except Web Sockets, which is handled separately).
/// </remarks>
protected override async Task SerializeToStreamAsync(Stream stream, TransportContext context)
{
if (Started)
{
throw new InvalidOperationException("Stream was already consumed.");
}
Started = true;
try
{
if (_autoFlushHttpClientOutgoingStream)
{
// HttpClient's machinery keeps an internal buffer that doesn't get flushed to the socket on every write.
// Some protocols (e.g. gRPC) may rely on specific bytes being sent, and HttpClient's buffering would prevent it.
// AutoFlushingStream delegates to the provided stream, adding calls to FlushAsync on every WriteAsync.
// Note that HttpClient does NOT call Flush on the underlying socket, so the perf impact of this is expected to be small.
// This statement is based on current knowledge as of .NET Core 3.1.201.
stream = new AutoFlushingStream(stream);
}
// Immediately flush request stream to send headers
// https://github.com/dotnet/corefx/issues/39586#issuecomment-516210081
await stream.FlushAsync();
await _streamCopier.CopyAsync(_source, stream, _cancellation);
_tcs.TrySetResult(true);
}
catch (Exception ex)
{
_tcs.TrySetException(ex);
throw;
}
}
/// <summary>
/// Copies bytes from the stream provided in our constructor into the target <paramref name="stream"/>.
/// </summary>
/// <remarks>
/// This is used internally by HttpClient.SendAsync to send the request body.
/// Here's the sequence of events as of commit 17300169760c61a90cab8d913636c1058a30a8c1 (https://github.com/dotnet/corefx -- tag v3.1.1).
///
/// <code>
/// HttpClient.SendAsync -->
/// HttpMessageInvoker.SendAsync -->
/// HttpClientHandler.SendAsync -->
/// SocketsHttpHandler.SendAsync -->
/// HttpConnectionHandler.SendAsync -->
/// HttpConnectionPoolManager.SendAsync -->
/// HttpConnectionPool.SendAsync --> ... -->
/// {
/// HTTP/1.1: HttpConnection.SendAsync -->
/// HttpConnection.SendAsyncCore -->
/// HttpConnection.SendRequestContentAsync -->
/// HttpContent.CopyToAsync
///
/// HTTP/2: Http2Connection.SendAsync -->
/// Http2Stream.SendRequestBodyAsync -->
/// HttpContent.CopyToAsync
///
/// /* Only in .NET 5:
/// HTTP/3: Http3Connection.SendAsync -->
/// Http3Connection.SendWithoutWaitingAsync -->
/// Http3RequestStream.SendAsync -->
/// Http3RequestStream.SendContentAsync -->
/// HttpContent.CopyToAsync
/// */
/// }
///
/// HttpContent.CopyToAsync -->
/// HttpContent.SerializeToStreamAsync (bingo!)
/// </code>
///
/// Conclusion: by overriding HttpContent.SerializeToStreamAsync,
/// we have full control over pumping bytes to the target stream for all protocols
/// (except Web Sockets, which is handled separately).
/// </remarks>
protected override async Task SerializeToStreamAsync(Stream stream, TransportContext context)
{
if (Started)
{
throw new InvalidOperationException("Stream was already consumed.");
}
Started = true;
try
{
// Immediately flush request stream to send headers
// https://github.com/dotnet/corefx/issues/39586#issuecomment-516210081
await stream.FlushAsync();
await _streamCopier.CopyAsync(_source, stream, _cancellation);
_tcs.TrySetResult(true);
}
catch (Exception ex)
{
_tcs.TrySetException(ex);
throw;
}
}