[SPDY] Refactor SpdySession's write queue

net/spdy/spdy_write_queue.h

+// Copyright (c) 2013 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_SPDY_SPDY_WRITE_QUEUE_H_
+#define NET_SPDY_SPDY_WRITE_QUEUE_H_
+
+#include <deque>
+
+#include "base/basictypes.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "net/base/net_export.h"
+#include "net/base/request_priority.h"
+
+namespace net {
+
+class SpdyFrameProducer;
+class SpdyStream;
+
+// A queue of SpdyFrameProducers to produce frames to write. Ordered
+// by priority, and then FIFO.
+class NET_EXPORT_PRIVATE SpdyWriteQueue {
+ public:
+  SpdyWriteQueue();
+  ~SpdyWriteQueue();
+
+  // Enqueues the given frame producer at the given priority
+  // associated with the given stream, which may be NULL if the frame
+  // producer is not associated with a stream. If |stream| is
+  // non-NULL, its priority must be equal to |priority|.
+  void Enqueue(RequestPriority priority,
+               scoped_ptr<SpdyFrameProducer> frame_producer,
+               const scoped_refptr<SpdyStream>& stream);
+
+  // Dequeues the frame producer with the highest priority that was
+  // enqueued the earliest and its associated stream. Returns true and
+  // fills in |frame_producer| and |stream| if successful --
+  // otherwise, just returns false.
+  bool Dequeue(scoped_ptr<SpdyFrameProducer>* frame_producer,
+               scoped_refptr<SpdyStream>* stream);
+
+  // Removes all pending writes for the given stream, which must be
+  // non-NULL.
+  void RemovePendingWritesForStream(const scoped_refptr<SpdyStream>& stream);
+
+  // Removes all pending writes.
+  void Clear();
+
+ private:
+  // A struct holding a frame producer and its associated stream.
+  struct PendingWrite {
+    // This has to be a raw pointer since we store this in an STL
+    // container.
+    SpdyFrameProducer* frame_producer;
+    scoped_refptr<SpdyStream> stream;
+
+    PendingWrite();
+    PendingWrite(SpdyFrameProducer* frame_producer,
+                 const scoped_refptr<SpdyStream>& stream);
+    ~PendingWrite();
+  };
+
+  // The actual write queue, binned by priority.
+  std::deque<PendingWrite> queue_[NUM_PRIORITIES];
+
+  DISALLOW_COPY_AND_ASSIGN(SpdyWriteQueue);
+};
+
+}  // namespace net
+
+#endif  // NET_SPDY_SPDY_WRITE_QUEUE_H_