Slow start pipelining.

net/http/http_pipelined_host_impl.h

+// Copyright (c) 2011 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_HTTP_PIPELINED_HOST_IMPL_H_
+#define NET_HTTP_HTTP_PIPELINED_HOST_IMPL_H_
+#pragma once
+
+#include <map>
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+#include "net/base/host_port_pair.h"
+#include "net/base/net_export.h"
+#include "net/http/http_pipelined_connection.h"
+#include "net/http/http_pipelined_host.h"
+
+namespace net {
+
+class BoundNetLog;
+class ClientSocketHandle;
+class HttpPipelinedStream;
+class ProxyInfo;
+struct SSLConfig;
+
+// Manages all of the pipelining state for specific host with active pipelined
+// HTTP requests. Manages connection jobs, constructs pipelined streams, and
+// assigns requests to the least loaded pipelined connection.
+class NET_EXPORT_PRIVATE HttpPipelinedHostImpl
+    : public HttpPipelinedHost,
+      public HttpPipelinedConnection::Delegate {
+ public:
+  HttpPipelinedHostImpl(HttpPipelinedHost::Delegate* delegate,
+                        const HostPortPair& origin,
+                        HttpPipelinedConnection::Factory* factory,
+                        Capability capability);
+  virtual ~HttpPipelinedHostImpl();
+
+  // HttpPipelinedHost interface
+  virtual HttpPipelinedStream* CreateStreamOnNewPipeline(
+      ClientSocketHandle* connection,
+      const SSLConfig& used_ssl_config,
+      const ProxyInfo& used_proxy_info,
+      const BoundNetLog& net_log,
+      bool was_npn_negotiated) OVERRIDE;
+
+  virtual HttpPipelinedStream* CreateStreamOnExistingPipeline() OVERRIDE;
+
+  virtual bool IsExistingPipelineAvailable() const OVERRIDE;
+
+  // HttpPipelinedConnection::Delegate interface
+
+  // Called when a pipelined connection completes a request. Adds a pending
+  // request to the pipeline if the pipeline is still usable.
+  virtual void OnPipelineHasCapacity(
+      HttpPipelinedConnection* pipeline) OVERRIDE;
+
+  virtual void OnPipelineFeedback(
+      HttpPipelinedConnection* pipeline,
+      HttpPipelinedConnection::Feedback feedback) OVERRIDE;
+
+  virtual const HostPortPair& origin() const OVERRIDE;
+
+  // Returns the maximum number of in-flight pipelined requests we'll allow on a
+  // single connection.
+  static int max_pipeline_depth() { return 3; }

[mmenke, 2011/12/01 17:22:48]

Think you'll need a NET_EXPORT_PRIVATE here.

[James Simonsen, 2011/12/01 20:36:42]

Done.

+
+ private:
+  struct PipelineInfo {
+    PipelineInfo();
+
+    int num_successes;
+  };
+  typedef std::map<HttpPipelinedConnection*, PipelineInfo> PipelineInfoMap;
+
+  // Called when a pipeline is empty and there are no pending requests. Closes
+  // the connection.
+  void OnPipelineEmpty(HttpPipelinedConnection* pipeline);
+
+  // Adds the next pending request to the pipeline if it's still usuable.
+  void AddRequestToPipeline(HttpPipelinedConnection* connection);
+
+  // Returns the current pipeline capacity based on |capability_|.

[mmenke, 2011/12/01 17:22:48]

Maybe add a note that it can't be called when capability is INCAPABLE?  Don't
think that's obvious from the description.

[James Simonsen, 2011/12/01 20:36:42]

Done.

+  int GetPipelineCapacity() const;
+
+  HttpPipelinedHost::Delegate* delegate_;
+  const HostPortPair origin_;
+  PipelineInfoMap pipelines_;
+  scoped_ptr<HttpPipelinedConnection::Factory> factory_;
+  Capability capability_;
+
+  DISALLOW_COPY_AND_ASSIGN(HttpPipelinedHostImpl);
+};
+
+}  // namespace net
+
+#endif  // NET_HTTP_HTTP_PIPELINED_HOST_IMPL_H_