#pragma warning restore 1998
#region UsingAsyncBuildingBlock
public Task Using(StringBuilder builder)
{
return(TaskBlocks.Using(
() => AcquireResourceAsync(builder),
task => task.Result.WriteAsync(SampleText)));
}
protected internal override Task <HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
if (disposed != 0)
{
throw new ObjectDisposedException(GetType().ToString());
}
Interlocked.Exchange(ref sentRequest, 1);
wrequest = CreateWebRequest(request);
Task intermediate;
if (request.Content != null)
{
AddContentHeaders(wrequest, request.Content.Headers);
intermediate = wrequest.GetRequestStreamAsync()
.Then(streamTask => request.Content.CopyToAsync(streamTask.Result).Finally(_ => streamTask.Result.Dispose()));
}
else if (HttpMethod.Post.Equals(request.Method) || HttpMethod.Put.Equals(request.Method) || HttpMethod.Delete.Equals(request.Method))
{
// Explicitly set this to make sure we're sending a "Content-Length: 0" header.
// This fixes the issue that's been reported on the forums:
// http://forums.xamarin.com/discussion/17770/length-required-error-in-http-post-since-latest-release
wrequest.ContentLength = 0;
intermediate = Task.FromResult(default(VoidResult));
}
else
{
intermediate = Task.FromResult(default(VoidResult));
}
HttpWebResponse wresponse = null;
Func <Task <IDisposable> > resource =
() => Task.FromResult <IDisposable>(cancellationToken.Register(l => ((HttpWebRequest)l).Abort(), wrequest));
Func <Task <IDisposable>, Task> body =
_ =>
{
return(wrequest.GetResponseAsync().Select(task => wresponse = (HttpWebResponse)task.Result)
.Catch <WebException>(
(task, we) =>
{
if (we.Status == WebExceptionStatus.ProtocolError)
{
// HttpClient shouldn't throw exceptions for these errors
wresponse = (HttpWebResponse)we.Response;
}
else if (we.Status != WebExceptionStatus.RequestCanceled)
{
// propagate the antecedent
return task;
}
return Task.FromResult(default(VoidResult));
})
.Then(
task =>
{
if (cancellationToken.IsCancellationRequested)
{
return Task.FromCanceled <HttpResponseMessage>(cancellationToken);
}
else
{
return Task.FromResult(default(VoidResult));
}
}));
};
return(intermediate
.Then(_ => TaskBlocks.Using(resource, body))
.Select(_ => CreateResponseMessage(wresponse, request, cancellationToken)));
}
protected internal override Task SerializeToStreamAsync(Stream stream, TransportContext context)
{
// RFC 2046
//
// The Content-Type field for multipart entities requires one parameter,
// "boundary". The boundary delimiter line is then defined as a line
// consisting entirely of two hyphen characters ("-", decimal value 45)
// followed by the boundary parameter value from the Content-Type header
// field, optional linear whitespace, and a terminating CRLF.
//
byte[] buffer;
var sb = new StringBuilder();
sb.Append('-').Append('-');
sb.Append(boundary);
sb.Append('\r').Append('\n');
int i = 0;
Func <bool> condition = () => i < nested_content.Count;
Func <Task> body =
() =>
{
var c = nested_content[i];
foreach (var h in c.Headers)
{
sb.Append(h.Key);
sb.Append(':').Append(' ');
foreach (var v in h.Value)
{
sb.Append(v);
}
sb.Append('\r').Append('\n');
}
sb.Append('\r').Append('\n');
buffer = Encoding.ASCII.GetBytes(sb.ToString());
sb.Length = 0;
return(stream.WriteAsync(buffer, 0, buffer.Length)
.Then(_ => c.SerializeToStreamAsync(stream, context))
.Select(
_ =>
{
if (i != nested_content.Count - 1)
{
sb.Append('\r').Append('\n');
sb.Append('-').Append('-');
sb.Append(boundary);
sb.Append('\r').Append('\n');
}
i++;
}));
};
Func <Task, Task> continuationFunction =
task =>
{
sb.Append('\r').Append('\n');
sb.Append('-').Append('-');
sb.Append(boundary);
sb.Append('-').Append('-');
sb.Append('\r').Append('\n');
buffer = Encoding.ASCII.GetBytes(sb.ToString());
return(stream.WriteAsync(buffer, 0, buffer.Length));
};
return(TaskBlocks.While(condition, body)
.Then(continuationFunction));
}
#pragma warning restore 1998
#region UsingWithResultAsyncBuildingBlock
public Task <string> UsingWithResult()
{
return(TaskBlocks.Using(
() => AcquireResourceAsync(),
task => task.Result.ReadToEndAsync()));
}