Provided batched input delivery with a BufferedInputRouter

content/browser/renderer_host/input/input_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 CONTENT_BROWSER_RENDERER_HOST_INPUT_INPUT_QUEUE_H_
+#define CONTENT_BROWSER_RENDERER_HOST_INPUT_INPUT_QUEUE_H_
+
+#include <vector>

[aelias_OOO_until_Jul13, 2013/08/15 00:52:15]

Delete this include.

[jdduke (slow), 2013/08/15 23:22:26]

Done.

+
+#include "base/basictypes.h"
+#include "base/callback.h"

[aelias_OOO_until_Jul13, 2013/08/15 00:52:15]

Delete this include.

[jdduke (slow), 2013/08/15 23:22:26]

Done.

+#include "content/common/content_export.h"
+
+namespace content {
+
+class EventPacket;
+class InputAckObserver;
+class InputEvent;
+class InputQueueClient;
+
+class CONTENT_EXPORT InputQueue {
+ public:
+
+  // The |client| must outlive this object.
+  InputQueue(InputQueueClient* client);
+  virtual ~InputQueue();
+
+  // If |ack_handler| is non-null, it must live at least until |event| has been

[aelias_OOO_until_Jul13, 2013/08/15 00:52:15]

This comment is out of date.

[jdduke (slow), 2013/08/15 23:22:26]

Done.

+  // ack'ed. If null, no ack response is made for |event|.
+  // If |event| is flagged for follow-up, its |ack_handler| will receive
+  // an EventInjector capable of inserting events into the current flush stream.
+  void QueueEvent(const InputEvent& event, InputAckObserver* ack_observer);
+
+  // Initiates the flush of the pending event packet to |client_|, if necessary.
+  // This should only be called in response to |client_->SetNeedsFlush()|
+  // Note: Events queued after this call, but before the flush completes, will
+  // not be sent until the following flush. If a flush is still in progress, the
+  // call will be ignored.
+  void FlushEventsInCurrentFrame();
+
+
+  // Called by the owner upon EventPacket responses from the sender target. This
+  // will dispatch event acks for events with a corresponding |ack_handler|.
+  enum AckResult {
+    ACK_OK,          // |acked_packet| was processed successfully.
+    ACK_UNEXPECTED,  // |acked_packet| was unexpected; no flush was in-progress.
+    ACK_INVALID,     // |acked_packet| contains invalid data.
+    ACK_SHUTDOWN     // |acked_packet| processing triggered queue shutdown.
+  };
+  AckResult OnEventPacketAck(const EventPacket& acked_packet);
+
+  // Total number of evenst in the queue, both being flushed and pending flush.
+  size_t QueuedEventCount() const;
+
+ protected:
+  friend class InputQueueTest;
+
+  // If we have a current, non-empty EventPacket, deliver it to |client_|.
+  // Otherwise, finish the flush by signalling flush completion, and requesting
+  // an additional flush, if necessary.
+  void TryFinishFlush();
+
+  // Requests a flush via the |client_|, but only if a flush is required and has
+  // not yet been requested.
+  void RequestFlushIfNecessary();
+
+  // Signal flush completion to the |client_| if not yet sent for this flush.
+  void SignalFlushedIfNecessary();

[aelias_OOO_until_Jul13, 2013/08/15 00:52:15]

Rename to SignalFlushCompleteIfNecessary

[jdduke (slow), 2013/08/15 23:22:26]

See comment below about flush_complete_signalled_: we can remove this
completely.

+
+  // True when |current_frame_| is non-empty.
+  bool IsFlushing() const;
+
+private:
+  InputQueueClient* client_;
+
+  // Used to assign unique ID's to each EventPacket that is generated.
+  int64 last_packet_id_;

[aelias_OOO_until_Jul13, 2013/08/15 00:52:15]

Nit: next_packet_id_

[jdduke (slow), 2013/08/15 23:22:26]

Done.

+
+  // Avoid spamming the client with redundant flush requests.
+  bool flush_requested_;
+
+  // Allows a DidFlush() signal before the packet has been ack'ed.
+  bool flush_signalled_;

[aelias_OOO_until_Jul13, 2013/08/15 00:52:15]

Rename to flush_complete_signalled_.

[jdduke (slow), 2013/08/15 23:22:26]

Hmm, I think this is a relic from when I had the awkward timeout logic.  This
should no longer be necessary, as we will only ever send a DidFlush when the
flush actually completes.

+
+  class EventFrame;
+
+  // Events currently being flushed.
+  scoped_ptr<EventFrame> current_frame_;
+
+  // Events pending flush.
+  scoped_ptr<EventFrame> pending_frame_;
+
+  DISALLOW_COPY_AND_ASSIGN(InputQueue);
+};
+
+} // namespace content
+
+#endif // CONTENT_BROWSER_RENDERER_HOST_INPUT_INPUT_QUEUE_H_