chromium/third_party/blink/renderer/platform/widget/input/main_thread_event_queue.h

// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_WIDGET_INPUT_MAIN_THREAD_EVENT_QUEUE_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_WIDGET_INPUT_MAIN_THREAD_EVENT_QUEUE_H_

#include <memory>
#include <optional>

#include "base/feature_list.h"
#include "base/memory/raw_ptr.h"
#include "base/memory/weak_ptr.h"
#include "base/task/single_thread_task_runner.h"
#include "base/time/time.h"
#include "base/timer/timer.h"
#include "cc/input/touch_action.h"
#include "third_party/blink/public/common/input/web_input_event.h"
#include "third_party/blink/public/common/input/web_input_event_attribution.h"
#include "third_party/blink/public/mojom/input/input_event_result.mojom-shared.h"
#include "third_party/blink/public/mojom/input/input_handler.mojom-blink.h"
#include "third_party/blink/renderer/platform/platform_export.h"
#include "third_party/blink/renderer/platform/scheduler/public/widget_scheduler.h"
#include "third_party/blink/renderer/platform/widget/input/input_event_prediction.h"
#include "third_party/blink/renderer/platform/widget/input/main_thread_event_queue_task_list.h"
#include "ui/latency/latency_info.h"

namespace cc {
class EventMetrics;
}

namespace blink {

HandledEventCallback;

// All interaction with the MainThreadEventQueueClient will occur
// on the main thread.
class PLATFORM_EXPORT MainThreadEventQueueClient { … };

// MainThreadEventQueue implements a queue for events that need to be
// queued between the compositor and main threads. This queue is managed
// by a lock where events are enqueued by the compositor thread
// and dequeued by the main thread.
//
// Below some example flows are how the code behaves.
// Legend: B=Browser, C=Compositor, M=Main Thread, NB=Non-blocking
//         BL=Blocking, PT=Post Task, ACK=Acknowledgement
//
// Normal blocking event sent to main thread.
//   B        C        M
//   ---(BL)-->
//         (queue)
//            ---(PT)-->
//                  (deque)
//   <-------(ACK)------
//
// Non-blocking event sent to main thread.
//   B        C        M
//   ---(NB)-->
//         (queue)
//            ---(PT)-->
//                  (deque)
//
// Non-blocking followed by blocking event sent to main thread.
//   B        C        M
//   ---(NB)-->
//         (queue)
//            ---(PT)-->
//   ---(BL)-->
//         (queue)
//            ---(PT)-->
//                  (deque)
//                  (deque)
//   <-------(ACK)------
//
class PLATFORM_EXPORT MainThreadEventQueue
    : public ThreadSafeRefCounted<MainThreadEventQueue> { … };

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_PLATFORM_WIDGET_INPUT_MAIN_THREAD_EVENT_QUEUE_H_