chromium/cc/trees/presentation_time_callback_buffer.h

// 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 CC_TREES_PRESENTATION_TIME_CALLBACK_BUFFER_H_
#define CC_TREES_PRESENTATION_TIME_CALLBACK_BUFFER_H_

#include <vector>

#include "base/containers/circular_deque.h"
#include "base/functional/callback_forward.h"
#include "base/sequence_checker.h"
#include "base/time/time.h"
#include "cc/cc_export.h"
#include "components/viz/common/frame_timing_details.h"
#include "ui/gfx/presentation_feedback.h"

namespace cc {

// Maintains a queue of callbacks and compositor frame times that we want to
// buffer until a relevant frame is presented.
//
// Callbacks are queued through `RegisterMainThreadCallbacks()` or
// `RegisterMainThreadSuccessfulCallbacks()` if the they are to be run on the
// main thread and `RegisterCompositorThreadSuccessfulCallbacks()` if they are
// to be run on the compositor thread.
//
// Once a frame is presented, users of this class can call
// `PopPendingCallbacks()` to get their callbacks back. This class never runs
// callbacks itself so it's up to calling code to `PostTask()` or call `Run()`
// as needed.
//
// This class is thread unsafe so concurrent access would require external
// synchronization. In practice, however, instances of this class are only used
// on the compositor thread even though some of the buffered callbacks are
// intended to be run on the renderer main thread.
//
// CC_EXPORT is only needed for testing.
class CC_EXPORT PresentationTimeCallbackBuffer { … };

}  // namespace cc

#endif  // CC_TREES_PRESENTATION_TIME_CALLBACK_BUFFER_H_