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// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_VIZ_SERVICE_FRAME_SINKS_BEGIN_FRAME_TRACKER_H_
#define COMPONENTS_VIZ_SERVICE_FRAME_SINKS_BEGIN_FRAME_TRACKER_H_
#include "components/viz/common/frame_sinks/begin_frame_args.h"
#include "components/viz/service/viz_service_export.h"
namespace viz {
// Keeps track of OnBeginFrame() messages sent the client and acks received back
// from the client in order to throttle unresponsive clients. This is to prevent
// sending a large number of IPCs to a client that is unresponsive and having
// the message queue balloon in size. Tolerates clients occasionally dropping
// an OnBeginFrame() message and not acking as long as they keep responding to
// the latest BeginFrameArgs.
class VIZ_SERVICE_EXPORT BeginFrameTracker {
public:
// Defines the number of begin frames that have been sent to a client without
// a response before we throttle or stop sending begin frames altogether.
static constexpr int kLimitStop = 100;
static constexpr int kLimitThrottle = 10;
// To be called every time OnBeginFrame() is sent.
void SentBeginFrame(const BeginFrameArgs& args);
// To be called every time a BeginFrameAck is received back from the client.
void ReceivedAck(const BeginFrameAck& ack);
bool ShouldThrottleBeginFrame() const;
bool ShouldStopBeginFrame() const;
private:
bool MatchesLastSent(const BeginFrameAck& ack);
int outstanding_begin_frames_ = 0;
BeginFrameId last_frame_id_;
};
} // namespace viz
#endif // COMPONENTS_VIZ_SERVICE_FRAME_SINKS_BEGIN_FRAME_TRACKER_H_
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