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..2d6f7b3e59e0452b8cf8ee686ba9e5fafd32ce30
--- /dev/null
+++ b/net/http/bidirectional_stream.h
@@ -0,0 +1,82 @@
+// 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 "base/memory/weak_ptr.h"

[mmenke, 2015/10/07 18:43:33]

Not needed

[xunjieli, 2015/10/19 21:07:46]

Done.

+#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;
+
+class NET_EXPORT BidirectionalStream {
+ public:
+  // Delegate to handle BidirectionalStream events.
+  class Delegate {
+   public:
+    Delegate() {}

[mmenke, 2015/10/07 18:43:33]

nit:  Blank line after constructor.

[xunjieli, 2015/10/19 21:07:46]

Done.

+    // Called when an error occurs. E.g. when an connection to the server cannot
+    // be established.
+    virtual void OnFailed(int error) = 0;
+
+    // Called when the request headers have been sent.
+    virtual void OnRequestHeadersSent() = 0;
+
+    // Called when response headers are received.
+    virtual void OnHeaders(const SpdyHeaderBlock& response_headers) = 0;
+
+    // Called when read is completed asynchronously. |bytes_read| specifies how
+    // much data is available.
+    virtual void OnReadCompleted(int bytes_read) = 0;
+
+    // Called when data is sent.
+    virtual void OnDataSent() = 0;

[mmenke, 2015/10/07 18:43:33]

This is called when all data from the last SendData call is sent?

[xunjieli, 2015/10/19 21:07:46]

I think it is called for every SendData.

[mmenke, 2015/10/19 21:27:53]

Right...But it's called when *all* of the data is sent.  Note that this isn't
how low level socket methods work, so I think it's worth noting that we send it
when everything is sent, not just some subset of the data.

[xunjieli, 2015/10/19 21:34:31]

Ah, I see! I will modify the comment to reflect this in the next patch set.

+
+    // 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.

[mef, 2015/10/07 23:44:56]

Add a comment about values of |status|.

[xunjieli, 2015/10/19 21:07:46]

Done.

+    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.
+  virtual void SendData(IOBuffer* data, int length, bool end_stream) = 0;

[mmenke, 2015/10/07 18:43:33]

I assume it's not legal to call again until OnDataSent is called?

[xunjieli, 2015/10/19 21:07:46]

Yes, that's my understanding too. I added a comment.

+
+  // TODO(xunjieli): implement a method to do flow control.

[mef, 2015/10/07 23:44:56]

Do we also need a method to explicitly close / cancel stream from the client
side? For example if timeout has expired waiting for pending Send or Read?

[xunjieli, 2015/10/19 21:07:46]

Done.

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