content/browser/android/synchronous_compositor_sync_call_bridge.cc

// Copyright 2018 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.

#include "content/browser/android/synchronous_compositor_sync_call_bridge.h"

#include "base/bind.h"
#include "base/task/post_task.h"
#include "content/browser/android/synchronous_compositor_host.h"
#include "content/browser/renderer_host/render_process_host_impl.h"
#include "content/public/browser/browser_task_traits.h"
#include "content/public/browser/browser_thread.h"
#include "content/public/common/content_features.h"
#include "ui/android/window_android.h"

namespace content {

SynchronousCompositorSyncCallBridge::SynchronousCompositorSyncCallBridge(
    SynchronousCompositorHost* host)
    : routing_id_(host->routing_id()),
      host_(host),
      begin_frame_condition_(&lock_) {
  DCHECK(host);
}

SynchronousCompositorSyncCallBridge::~SynchronousCompositorSyncCallBridge() {
  DCHECK(frame_futures_.empty());
}

void SynchronousCompositorSyncCallBridge::RemoteReady() {
  base::AutoLock lock(lock_);
  if (remote_state_ != RemoteState::INIT)
    return;
  remote_state_ = RemoteState::READY;
}

void SynchronousCompositorSyncCallBridge::RemoteClosedOnIOThread() {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  base::AutoLock lock(lock_);
  SignalRemoteClosedToAllWaitersOnIOThread();
}

bool SynchronousCompositorSyncCallBridge::ReceiveFrameOnIOThread(
    int layer_tree_frame_sink_id,
    uint32_t metadata_version,
    base::Optional<viz::CompositorFrame> compositor_frame) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  base::AutoLock lock(lock_);
  if (remote_state_ != RemoteState::READY || frame_futures_.empty())
    return false;
  auto frame_ptr = std::make_unique<SynchronousCompositor::Frame>();
  frame_ptr->layer_tree_frame_sink_id = layer_tree_frame_sink_id;
  scoped_refptr<SynchronousCompositor::FrameFuture> future =
      std::move(frame_futures_.front());
  DCHECK(future);
  frame_futures_.pop_front();

  if (compositor_frame) {
    base::PostTaskWithTraits(
        FROM_HERE, {BrowserThread::UI},
        base::BindOnce(&SynchronousCompositorSyncCallBridge::
                           ProcessFrameMetadataOnUIThread,
                       this, metadata_version,
                       compositor_frame->metadata.Clone()));
    frame_ptr->frame.reset(new viz::CompositorFrame);
    *frame_ptr->frame = std::move(*compositor_frame);
  }
  future->SetFrame(std::move(frame_ptr));
  return true;
}

bool SynchronousCompositorSyncCallBridge::BeginFrameResponseOnIOThread(
    const SyncCompositorCommonRendererParams& render_params) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  base::AutoLock lock(lock_);
  if (begin_frame_response_valid_)
    return false;
  begin_frame_response_valid_ = true;
  last_render_params_ = render_params;
  begin_frame_condition_.Signal();
  return true;
}

bool SynchronousCompositorSyncCallBridge::WaitAfterVSyncOnUIThread(
    ui::WindowAndroid* window_android) {
  DCHECK_CURRENTLY_ON(BrowserThread::UI);
  base::AutoLock lock(lock_);
  if (remote_state_ != RemoteState::READY)
    return false;
  CHECK(!begin_frame_response_valid_);
  window_android->AddBeginFrameCompletionCallback(base::BindOnce(
      &SynchronousCompositorSyncCallBridge::BeginFrameCompleteOnUIThread,
      this));
  return true;
}

bool SynchronousCompositorSyncCallBridge::SetFrameFutureOnUIThread(
    scoped_refptr<SynchronousCompositor::FrameFuture> frame_future) {
  DCHECK_CURRENTLY_ON(BrowserThread::UI);
  DCHECK(frame_future);
  base::AutoLock lock(lock_);
  if (remote_state_ != RemoteState::READY)
    return false;

  // Allowing arbitrary number of pending futures can lead to increase in frame
  // latency. Due to this, Android platform already ensures that here that there
  // can be at most 2 pending frames. Here, we rely on Android to do the
  // necessary blocking, which allows more parallelism without increasing
  // latency. But DCHECK Android blocking is working.
  DCHECK_LT(frame_futures_.size(), 2u);
  frame_futures_.emplace_back(std::move(frame_future));
  return true;
}

void SynchronousCompositorSyncCallBridge::HostDestroyedOnUIThread() {
  DCHECK_CURRENTLY_ON(BrowserThread::UI);
  DCHECK(host_);
  host_ = nullptr;
}

bool SynchronousCompositorSyncCallBridge::IsRemoteReadyOnUIThread() {
  DCHECK_CURRENTLY_ON(BrowserThread::UI);
  base::AutoLock lock(lock_);
  return remote_state_ == RemoteState::READY;
}

void SynchronousCompositorSyncCallBridge::BeginFrameCompleteOnUIThread() {
  DCHECK_CURRENTLY_ON(BrowserThread::UI);

  bool update_state = false;
  SyncCompositorCommonRendererParams render_params;
  {
    base::AutoLock lock(lock_);
    if (remote_state_ != RemoteState::READY)
      return;

    // If we haven't received a response yet. Wait for it.
    if (!begin_frame_response_valid_) {
      base::ScopedAllowBaseSyncPrimitivesOutsideBlockingScope
          allow_base_sync_primitives;
      begin_frame_condition_.Wait();
    }
    DCHECK(begin_frame_response_valid_ || remote_state_ != RemoteState::READY);
    begin_frame_response_valid_ = false;
    if (remote_state_ == RemoteState::READY) {
      update_state = true;
      render_params = last_render_params_;
    }
  }
  if (update_state)
    host_->UpdateState(render_params);
}

void SynchronousCompositorSyncCallBridge::ProcessFrameMetadataOnUIThread(
    uint32_t metadata_version,
    viz::CompositorFrameMetadata metadata) {
  DCHECK_CURRENTLY_ON(BrowserThread::UI);
  if (host_)
    host_->UpdateFrameMetaData(metadata_version, std::move(metadata));
}

void SynchronousCompositorSyncCallBridge::
    SignalRemoteClosedToAllWaitersOnIOThread() {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  lock_.AssertAcquired();
  remote_state_ = RemoteState::CLOSED;
  for (auto& future_ptr : frame_futures_) {
    future_ptr->SetFrame(nullptr);
  }
  frame_futures_.clear();
  begin_frame_condition_.Signal();
}

}  // namespace content