HTTP retry support.

net/http/http_stream_base.h

 // Copyright (c) 2012 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.
 //
 // HttpStreamBase is an interface for reading and writing data to an
 // HTTP-like stream that keeps the client agnostic of the actual underlying
 // transport layer.  This provides an abstraction for HttpStream and
 // WebSocketHandshakeStreamBase.
 
 #ifndef NET_HTTP_HTTP_STREAM_BASE_H_
@@ skipping 104 matching lines @@
   virtual bool IsConnectionReused() const = 0;
   virtual void SetConnectionReused() = 0;
 
   // Checks whether the current state of the underlying connection
   // allows it to be reused.
   virtual bool IsConnectionReusable() const = 0;
 
   // Get the total number of bytes received from network for this stream.
   virtual int64 GetTotalReceivedBytes() const = 0;
 
+  // Get the total number of body bytes received from network for this stream.
+  virtual int64 GetReceivedBodyLength() const = 0;

[mmenke, 2014/07/22 14:57:41]

Why are these in the HttpStreamBase class, and not in HttpNetworkTransaction? 
Then you get QUIC and SPDY support for free, if we want them.

[jonnyr, 2014/07/23 08:43:05]

I could not do this in HttpNetworkTransaction since io_callback_ is used for
returning data. No actual data passes through HttpNetworkTransaction as far as I
can see.

[mmenke, 2014/07/23 15:08:40]

I'm not following why this doesn't work.  In
HttpNetworkTransaction::DoReadBodyComplete, we have result, which is the number
of body bytes read (or an error), and we have |read_buf_|.  Am I missing
something?

+
   // Populates the connection establishment part of |load_timing_info|, and
   // socket ID.  |load_timing_info| must have all null times when called.
   // Returns false and does nothing if there is no underlying connection, either
   // because one has yet to be assigned to the stream, or because the underlying
   // socket has been closed.
   //
   // In practice, this means that this function will always succeed any time
   // between when the full headers have been received and the stream has been
   // closed.
   virtual bool GetLoadTimingInfo(LoadTimingInfo* load_timing_info) const = 0;
@@ skipping 14 matching lines @@
 
   // In the case of an HTTP error or redirect, flush the response body (usually
   // a simple error or "this page has moved") so that we can re-use the
   // underlying connection. This stream is responsible for deleting itself when
   // draining is complete.
   virtual void Drain(HttpNetworkSession* session) = 0;
 
   // Called when the priority of the parent transaction changes.
   virtual void SetPriority(RequestPriority priority) = 0;
 
+  // If restarting a request where a part of the body has already been
+  // received, set where we should start reading from, previous content length
+  // and hash of previous response.
+  virtual void SetRestartInfo(int64 read_offset, const void* hash,
+                              size_t hash_length) = 0;
+
+  // If restarting a request where a part of the body has already been received,
+  // retrieve the hash so that this can be verified on retry.
+  virtual void GetHash(void* output, size_t hash_length) = 0;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(HttpStreamBase);
 };
 
 }  // namespace net
 
 #endif  // NET_HTTP_HTTP_STREAM_BASE_H_