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// Copyright 2013 The Flutter 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 "flutter/shell/common/vsync_waiter.h"
#include "flutter/fml/task_runner.h"
#include "flutter/fml/trace_event.h"
namespace flutter {
static constexpr const char* kVsyncFlowName = "VsyncFlow";
#if defined(OS_FUCHSIA)
// ________ _________ ________ ________
// |\ ____\|\___ ___\\ __ \|\ __ \
// \ \ \___|\|___ \ \_\ \ \|\ \ \ \|\ \
// \ \_____ \ \ \ \ \ \ \\\ \ \ ____\
// \|____|\ \ \ \ \ \ \ \\\ \ \ \___|
// ____\_\ \ \ \__\ \ \_______\ \__\
// |\_________\ \|__| \|_______|\|__|
// \|_________|
//
// Fuchsia benchmarks depend on this trace event's name. Please do not change
// it without checking that the changes are compatible with Fuchsia benchmarks
// first!
static constexpr const char* kVsyncTraceName = "vsync callback";
#else
static constexpr const char* kVsyncTraceName = "VsyncProcessCallback";
#endif
VsyncWaiter::VsyncWaiter(TaskRunners task_runners)
: task_runners_(std::move(task_runners)) {}
VsyncWaiter::~VsyncWaiter() = default;
// Public method invoked by the animator.
void VsyncWaiter::AsyncWaitForVsync(const Callback& callback) {
if (!callback) {
return;
}
TRACE_EVENT0("flutter", "AsyncWaitForVsync");
{
std::scoped_lock lock(callback_mutex_);
if (callback_) {
// The animator may request a frame more than once within a frame
// interval. Multiple calls to request frame must result in a single
// callback per frame interval.
TRACE_EVENT_INSTANT0("flutter", "MultipleCallsToVsyncInFrameInterval");
return;
}
callback_ = std::move(callback);
if (!secondary_callbacks_.empty()) {
// Return directly as `AwaitVSync` is already called by
// `ScheduleSecondaryCallback`.
return;
}
}
AwaitVSync();
}
void VsyncWaiter::ScheduleSecondaryCallback(uintptr_t id,
const fml::closure& callback) {
FML_DCHECK(task_runners_.GetUITaskRunner()->RunsTasksOnCurrentThread());
if (!callback) {
return;
}
TRACE_EVENT0("flutter", "ScheduleSecondaryCallback");
{
std::scoped_lock lock(callback_mutex_);
auto [_, inserted] = secondary_callbacks_.emplace(id, std::move(callback));
if (!inserted) {
// Multiple schedules must result in a single callback per frame interval.
TRACE_EVENT_INSTANT0("flutter",
"MultipleCallsToSecondaryVsyncInFrameInterval");
return;
}
if (callback_) {
// Return directly as `AwaitVSync` is already called by
// `AsyncWaitForVsync`.
return;
}
}
AwaitVSync();
}
void VsyncWaiter::FireCallback(fml::TimePoint frame_start_time,
fml::TimePoint frame_target_time) {
Callback callback;
std::vector<fml::closure> secondary_callbacks;
{
std::scoped_lock lock(callback_mutex_);
callback = std::move(callback_);
for (auto& pair : secondary_callbacks_) {
secondary_callbacks.push_back(std::move(pair.second));
}
secondary_callbacks_.clear();
}
if (!callback && secondary_callbacks.empty()) {
// This means that the vsync waiter implementation fired a callback for a
// request we did not make. This is a paranoid check but we still want to
// make sure we catch misbehaving vsync implementations.
TRACE_EVENT_INSTANT0("flutter", "MismatchedFrameCallback");
return;
}
if (callback) {
auto flow_identifier = fml::tracing::TraceNonce();
// The base trace ensures that flows have a root to begin from if one does
// not exist. The trace viewer will ignore traces that have no base event
// trace. While all our message loops insert a base trace trace
// (MessageLoop::RunExpiredTasks), embedders may not.
TRACE_EVENT0("flutter", "VsyncFireCallback");
TRACE_FLOW_BEGIN("flutter", kVsyncFlowName, flow_identifier);
task_runners_.GetUITaskRunner()->PostTaskForTime(
[callback, flow_identifier, frame_start_time, frame_target_time]() {
FML_TRACE_EVENT("flutter", kVsyncTraceName, "StartTime",
frame_start_time, "TargetTime", frame_target_time);
callback(frame_start_time, frame_target_time);
TRACE_FLOW_END("flutter", kVsyncFlowName, flow_identifier);
},
frame_start_time);
}
for (auto& secondary_callback : secondary_callbacks) {
task_runners_.GetUITaskRunner()->PostTaskForTime(
std::move(secondary_callback), frame_start_time);
}
}
} // namespace flutter