Basic HTTP pipelining support

net/http/http_pipelined_host.h

Index: net/http/http_pipelined_host.h
diff --git a/net/http/http_pipelined_host.h b/net/http/http_pipelined_host.h
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+// 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_H_
+#define NET_HTTP_HTTP_PIPELINED_HOST_H_
+#pragma once
+
+#include <set>
+#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"
+
+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 HttpPipelinedHost
+    : public HttpPipelinedConnection::Delegate {
+ public:
+  class Delegate {
+   public:
+    // Called when a pipelined host has no outstanding requests on any of its
+    // pipelined connections.
+    virtual void OnHostIdle(HttpPipelinedHost* host) = 0;
+
+    // Called when a pipelined host has newly available pipeline capacity, like
+    // when a request completes.
+    virtual void OnHostHasAdditionalCapacity(HttpPipelinedHost* host) = 0;
+  };
+
+  HttpPipelinedHost(Delegate* delegate, const HostPortPair& origin,
+                    HttpPipelinedConnection::Factory* factory);
+  virtual ~HttpPipelinedHost();
+
+  // Constructs a new pipeline on |connection| and returns a new
+  // HttpPipelinedStream that uses it.
+  HttpPipelinedStream* CreateStreamOnNewPipeline(
+      ClientSocketHandle* connection,
+      const SSLConfig& used_ssl_config,
+      const ProxyInfo& used_proxy_info,
+      const BoundNetLog& net_log,
+      bool was_npn_negotiated);
+
+  // Tries to find an existing pipeline with capacity for a new request. If
+  // successful, returns a new stream on that pipeline. Otherwise, returns NULL.
+  HttpPipelinedStream* CreateStreamOnExistingPipeline();
+
+  // Returns true if we have a pipelined connection that can accept new
+  // requests.
+  bool IsExistingPipelineAvailable();
+
+  // Callbacks for HttpPipelinedConnection.
+
+  // 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;
+
+  const HostPortPair& origin() const { return origin_; }
+
+ private:
+  // 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);
+
+  int max_pipeline_depth() const { return 3; }
+
+  Delegate* delegate_;
+  const HostPortPair origin_;
+  std::set<HttpPipelinedConnection*> pipelines_;
+  scoped_ptr<HttpPipelinedConnection::Factory> factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(HttpPipelinedHost);
+};
+
+}  // namespace net
+
+#endif  // NET_HTTP_HTTP_PIPELINED_HOST_H_