Added a net::BidirectionalStream to expose a bidirectional streaming interface

net/http/bidirectional_stream.h

Index: net/http/bidirectional_stream.h
diff --git a/net/http/bidirectional_stream.h b/net/http/bidirectional_stream.h
new file mode 100644
index 0000000000000000000000000000000000000000..470e6710017629929702dbfdc82dc8bcb5d4ba33
--- /dev/null
+++ b/net/http/bidirectional_stream.h
@@ -0,0 +1,89 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef NET_HTTP_BIDIRECTIONAL_STREAM_H_
+#define NET_HTTP_BIDIRECTIONAL_STREAM_H_
+
+#include "base/macros.h"
+#include "net/base/net_export.h"
+#include "net/base/request_priority.h"
+#include "net/http/http_request_info.h"
+#include "net/spdy/spdy_session.h"
+#include "net/spdy/spdy_stream.h"
+
+namespace net {
+
+struct HttpRequestInfo;
+class IOBuffer;
+class BoundNetLog;
+
+// An interface that exposes bidirectional streaming. Note that only one
+// ReadData or SendData should be in flight until the operation completes
+// synchronously or asynchronously.
+class NET_EXPORT BidirectionalStream {

[mmenke, 2015/11/03 20:32:13]

NET_EXPORT_PRIVATE (You'll need to make the helper class implement this class's
delegate, and make the helper's delegate match this one - the wrapper is a bit
of a hassle, but it makes lifetime semantics a little clearer, cancellation
cleaner, and works a bit more like URLRequests).

[xunjieli, 2015/11/05 23:17:13]

Done.

+ public:
+  // Delegate to handle BidirectionalStream events.
+  class Delegate {
+   public:
+    Delegate();
+
+    // Called when an error occurs. E.g. when a connection to the server cannot
+    // be established.
+    virtual void OnFailed(int error) = 0;

[mef, 2015/11/04 20:13:53]

UrlRequest has a status() method. Does this callback replace it?

[mmenke, 2015/11/04 20:42:41]

This and knowledge of whether you're waiting on it to call you or not.  I'd love
to be able to remove status() from UrlRequest - it makes for a weird API, and
lots of fun bugs in both the network stack and consumers of it.

+
+    // Called when the request headers have been sent.
+    virtual void OnRequestHeadersSent() = 0;

[mef, 2015/11/04 20:13:53]

We need to add something like HttpResponseInfo, with details about negotiated
protocol, etc.

[xunjieli, 2015/11/05 23:17:13]

Acknowledged. Added as a TODO.

+
+    // Called when response headers are received.
+    virtual void OnHeaders(const SpdyHeaderBlock& response_headers) = 0;

[mef, 2015/11/02 18:00:42]

Is this called only once or could it happen multiple times?

[mef, 2015/11/04 20:13:53]

Is there some way to get Http status code at this point?

[xunjieli, 2015/11/05 23:17:13]

Yes, we can get it from the header ":status"

[xunjieli, 2015/11/05 23:17:13]

It's called once. I've added comment.

+
+    // Called when read is completed asynchronously. |bytes_read| specifies how
+    // much data is available.
+    virtual void OnReadCompleted(int bytes_read) = 0;

[mef, 2015/11/04 20:13:52]

Is there some way to get running received bytes count (pre-decompression)?

[xunjieli, 2015/11/05 23:17:13]

This byte count here is pre-decompression. We can increment the counter cronet
side.

+
+    // Called when the entire buffer passed through SendData is sent.
+    virtual void OnDataSent() = 0;
+
+    // Called when trailers are received.
+    virtual void OnTrailers(const SpdyHeaderBlock& trailers) = 0;
+
+    // Called when the stream is closed. No other delegate functions will be
+    // called after this. |status| is an error code or OK.
+    virtual void OnClose(int status) = 0;
+
+   protected:
+    virtual ~Delegate();
+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(Delegate);
+  };
+
+  BidirectionalStream();
+  virtual ~BidirectionalStream();
+
+  // Starts the BidirectionalStream and sends request headers.
+  virtual void Start(const HttpRequestInfo& request_info,
+                     RequestPriority priority,
+                     const BoundNetLog& net_log,
+                     Delegate* delegate) = 0;
+
+  // Reads at most |buf_len| bytes into |buf|. Returns the number of bytes read,
+  // or ERR_IO_PENDING if the read is to be completed asynchronously.
+  virtual int ReadData(IOBuffer* buf, int buf_len) = 0;
+
+  // Sends data. This should not be called again until OnDataSent is invoked.
+  virtual void SendData(IOBuffer* data, int length, bool end_stream) = 0;
+
+  // Cancels the stream. No Delegate method will be called.
+  virtual void Cancel() = 0;
+
+  // TODO(xunjieli): implement a method to do flow control.

[mef, 2015/11/02 18:00:42]

We also need a method for ping, but fine to have it in another CL.

[xunjieli, 2015/11/05 23:17:13]

Acknowledged.

+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(BidirectionalStream);
+};
+
+}  // namespace net
+
+#endif  // NET_HTTP_BIDIRECTIONAL_STREAM_H_