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// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "third_party/blink/renderer/platform/scheduler/common/thread_scheduler_base.h"
#include "base/trace_event/trace_event.h"
#include "third_party/blink/renderer/platform/scheduler/common/auto_advancing_virtual_time_domain.h"
namespace blink {
namespace scheduler {
void ThreadSchedulerBase::ExecuteAfterCurrentTask(
base::OnceClosure on_completion_task) {
GetOnTaskCompletionCallbacks().push_back(std::move(on_completion_task));
}
void ThreadSchedulerBase::Shutdown() {
GetHelper().ResetTimeDomain();
virtual_time_domain_.reset();
}
base::TimeTicks ThreadSchedulerBase::EnableVirtualTime(
base::Time initial_time) {
if (virtual_time_domain_)
return virtual_time_domain_->InitialTicks();
if (initial_time.is_null())
initial_time = base::Time::Now();
// TODO(caseq): Considering we're not enabling override atomically with
// capturing current ticks, provide a safety margin to assure the emulated
// ticks never get behind real clock, while the override is being enabled.
base::TimeTicks initial_ticks = GetTickClock()->NowTicks();
virtual_time_domain_ = std::make_unique<AutoAdvancingVirtualTimeDomain>(
initial_time, initial_ticks, &GetHelper());
GetHelper().SetTimeDomain(virtual_time_domain_.get());
OnVirtualTimeEnabled();
DCHECK(!virtual_time_stopped_);
virtual_time_domain_->SetCanAdvanceVirtualTime(true);
return virtual_time_domain_->InitialTicks();
}
void ThreadSchedulerBase::DisableVirtualTimeForTesting() {
if (!IsVirtualTimeEnabled())
return;
// Reset virtual time and all tasks queues back to their initial state.
SetVirtualTimeStopped(false);
// This can only happen during test tear down, in which case there is no need
// to notify the pages that virtual time was disabled.
GetHelper().ResetTimeDomain();
virtual_time_domain_.reset();
OnVirtualTimeDisabled();
}
bool ThreadSchedulerBase::VirtualTimeAllowedToAdvance() const {
DCHECK(!virtual_time_stopped_ || virtual_time_domain_);
return !virtual_time_stopped_;
}
void ThreadSchedulerBase::GrantVirtualTimeBudget(
base::TimeDelta budget,
base::OnceClosure budget_exhausted_callback) {
GetVirtualTimeTaskRunner()->PostDelayedTask(
FROM_HERE, std::move(budget_exhausted_callback), budget);
// This can shift time forwards if there's a pending MaybeAdvanceVirtualTime,
// so it's important this is called second.
virtual_time_domain_->SetVirtualTimeFence(GetTickClock()->NowTicks() +
budget);
}
void ThreadSchedulerBase::SetVirtualTimePolicy(VirtualTimePolicy policy) {
DCHECK(IsVirtualTimeEnabled());
virtual_time_policy_ = policy;
ApplyVirtualTimePolicy();
}
void ThreadSchedulerBase::SetMaxVirtualTimeTaskStarvationCount(
int max_task_starvation_count) {
DCHECK(IsVirtualTimeEnabled());
max_virtual_time_task_starvation_count_ = max_task_starvation_count;
ApplyVirtualTimePolicy();
}
WebScopedVirtualTimePauser
ThreadSchedulerBase::CreateWebScopedVirtualTimePauser(
const WTF::String& name,
WebScopedVirtualTimePauser::VirtualTaskDuration duration) {
return WebScopedVirtualTimePauser(this, duration, name);
}
bool ThreadSchedulerBase::IsVirtualTimeEnabled() const {
return !!virtual_time_domain_;
}
base::TimeTicks ThreadSchedulerBase::IncrementVirtualTimePauseCount() {
virtual_time_pause_count_++;
if (IsVirtualTimeEnabled())
ApplyVirtualTimePolicy();
return GetTickClock()->NowTicks();
}
void ThreadSchedulerBase::DecrementVirtualTimePauseCount() {
virtual_time_pause_count_--;
DCHECK_GE(virtual_time_pause_count_, 0);
if (IsVirtualTimeEnabled())
ApplyVirtualTimePolicy();
}
void ThreadSchedulerBase::MaybeAdvanceVirtualTime(
base::TimeTicks new_virtual_time) {
if (virtual_time_domain_)
virtual_time_domain_->MaybeAdvanceVirtualTime(new_virtual_time);
}
AutoAdvancingVirtualTimeDomain* ThreadSchedulerBase::GetVirtualTimeDomain() {
return virtual_time_domain_.get();
}
ThreadSchedulerBase::ThreadSchedulerBase() = default;
ThreadSchedulerBase::~ThreadSchedulerBase() = default;
void ThreadSchedulerBase::DispatchOnTaskCompletionCallbacks() {
for (auto& closure : GetOnTaskCompletionCallbacks()) {
std::move(closure).Run();
}
GetOnTaskCompletionCallbacks().clear();
}
namespace {
const char* VirtualTimePolicyToString(
VirtualTimeController::VirtualTimePolicy virtual_time_policy) {
switch (virtual_time_policy) {
case VirtualTimeController::VirtualTimePolicy::kAdvance:
return "ADVANCE";
case VirtualTimeController::VirtualTimePolicy::kPause:
return "PAUSE";
case VirtualTimeController::VirtualTimePolicy::kDeterministicLoading:
return "DETERMINISTIC_LOADING";
}
}
} // namespace
void ThreadSchedulerBase::WriteVirtualTimeInfoIntoTrace(
perfetto::TracedDictionary& dict) const {
dict.Add("virtual_time_stopped", virtual_time_stopped_);
dict.Add("virtual_time_pause_count", virtual_time_pause_count_);
dict.Add("virtual_time_policy",
VirtualTimePolicyToString(virtual_time_policy_));
dict.Add("virtual_time", !!virtual_time_domain_);
}
void ThreadSchedulerBase::SetVirtualTimeStopped(bool virtual_time_stopped) {
DCHECK(virtual_time_domain_);
if (virtual_time_stopped_ == virtual_time_stopped)
return;
virtual_time_stopped_ = virtual_time_stopped;
virtual_time_domain_->SetCanAdvanceVirtualTime(!virtual_time_stopped);
if (virtual_time_stopped)
OnVirtualTimePaused();
else
OnVirtualTimeResumed();
}
void ThreadSchedulerBase::ApplyVirtualTimePolicy() {
DCHECK(virtual_time_domain_);
switch (virtual_time_policy_) {
case VirtualTimePolicy::kAdvance:
virtual_time_domain_->SetMaxVirtualTimeTaskStarvationCount(
GetHelper().IsInNestedRunloop()
? 0
: max_virtual_time_task_starvation_count_);
virtual_time_domain_->SetVirtualTimeFence(base::TimeTicks());
SetVirtualTimeStopped(false);
break;
case VirtualTimePolicy::kPause:
virtual_time_domain_->SetMaxVirtualTimeTaskStarvationCount(0);
virtual_time_domain_->SetVirtualTimeFence(GetTickClock()->NowTicks());
SetVirtualTimeStopped(true);
break;
case VirtualTimePolicy::kDeterministicLoading:
virtual_time_domain_->SetMaxVirtualTimeTaskStarvationCount(
GetHelper().IsInNestedRunloop()
? 0
: max_virtual_time_task_starvation_count_);
// We pause virtual time while the run loop is nested because that implies
// something modal is happening such as the DevTools debugger pausing the
// system. We also pause while the renderer is waiting for various
// asynchronous things e.g. resource load or navigation.
SetVirtualTimeStopped(virtual_time_pause_count_ != 0 ||
GetHelper().IsInNestedRunloop());
break;
}
}
void ThreadSchedulerBase::OnBeginNestedRunLoop() {
if (IsVirtualTimeEnabled())
ApplyVirtualTimePolicy();
}
void ThreadSchedulerBase::OnExitNestedRunLoop() {
if (IsVirtualTimeEnabled())
ApplyVirtualTimePolicy();
}
} // namespace scheduler
} // namespace blink
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