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/*
* Copyright 2019 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "test/time_controller/simulated_time_controller.h"
#include <algorithm>
#include <list>
#include <memory>
#include <string>
#include <utility>
#include <vector>
#include "absl/strings/string_view.h"
#include "api/task_queue/task_queue_base.h"
#include "api/task_queue/task_queue_factory.h"
#include "api/units/time_delta.h"
#include "api/units/timestamp.h"
#include "rtc_base/checks.h"
#include "rtc_base/platform_thread_types.h"
#include "rtc_base/socket_server.h"
#include "rtc_base/synchronization/mutex.h"
#include "rtc_base/synchronization/yield_policy.h"
#include "rtc_base/thread.h"
#include "rtc_base/time_utils.h"
#include "system_wrappers/include/clock.h"
#include "test/time_controller/simulated_task_queue.h"
#include "test/time_controller/simulated_thread.h"
namespace webrtc {
namespace {
// Helper function to remove from a std container by value.
template <class C>
bool RemoveByValue(C* vec, typename C::value_type val) {
auto it = std::find(vec->begin(), vec->end(), val);
if (it == vec->end())
return false;
vec->erase(it);
return true;
}
} // namespace
namespace sim_time_impl {
SimulatedTimeControllerImpl::SimulatedTimeControllerImpl(Timestamp start_time)
: thread_id_(CurrentThreadId()), current_time_(start_time) {}
SimulatedTimeControllerImpl::~SimulatedTimeControllerImpl() = default;
std::unique_ptr<TaskQueueBase, TaskQueueDeleter>
SimulatedTimeControllerImpl::CreateTaskQueue(
absl::string_view name,
TaskQueueFactory::Priority priority) const {
// TODO(srte): Remove the const cast when the interface is made mutable.
auto mutable_this = const_cast<SimulatedTimeControllerImpl*>(this);
auto task_queue = std::unique_ptr<SimulatedTaskQueue, TaskQueueDeleter>(
new SimulatedTaskQueue(mutable_this, name));
mutable_this->Register(task_queue.get());
return task_queue;
}
std::unique_ptr<Thread> SimulatedTimeControllerImpl::CreateThread(
const std::string& name,
std::unique_ptr<SocketServer> socket_server) {
auto thread =
std::make_unique<SimulatedThread>(this, name, std::move(socket_server));
Register(thread.get());
return thread;
}
void SimulatedTimeControllerImpl::YieldExecution() {
if (CurrentThreadId() == thread_id_) {
TaskQueueBase* yielding_from = TaskQueueBase::Current();
// Since we might continue execution on a process thread, we should reset
// the thread local task queue reference. This ensures that thread checkers
// won't think we are executing on the yielding task queue. It also ensure
// that TaskQueueBase::Current() won't return the yielding task queue.
TokenTaskQueue::CurrentTaskQueueSetter reset_queue(nullptr);
// When we yield, we don't want to risk executing further tasks on the
// currently executing task queue. If there's a ready task that also yields,
// it's added to this set as well and only tasks on the remaining task
// queues are executed.
auto inserted = yielded_.insert(yielding_from);
RTC_DCHECK(inserted.second);
RunReadyRunners();
yielded_.erase(inserted.first);
}
}
void SimulatedTimeControllerImpl::RunReadyRunners() {
// Using a dummy thread rather than nullptr to avoid implicit thread creation
// by Thread::Current().
SimulatedThread::CurrentThreadSetter set_current(dummy_thread_.get());
MutexLock lock(&lock_);
RTC_DCHECK_EQ(CurrentThreadId(), thread_id_);
Timestamp current_time = CurrentTime();
// Clearing `ready_runners_` in case this is a recursive call:
// RunReadyRunners -> Run -> Event::Wait -> Yield ->RunReadyRunners
ready_runners_.clear();
// We repeat until we have no ready left to handle tasks posted by ready
// runners.
while (true) {
for (auto* runner : runners_) {
if (yielded_.find(runner->GetAsTaskQueue()) == yielded_.end() &&
runner->GetNextRunTime() <= current_time) {
ready_runners_.push_back(runner);
}
}
if (ready_runners_.empty())
break;
while (!ready_runners_.empty()) {
auto* runner = ready_runners_.front();
ready_runners_.pop_front();
lock_.Unlock();
// Note that the RunReady function might indirectly cause a call to
// Unregister() which will grab `lock_` again to remove items from
// `ready_runners_`.
runner->RunReady(current_time);
lock_.Lock();
}
}
}
Timestamp SimulatedTimeControllerImpl::CurrentTime() const {
MutexLock lock(&time_lock_);
return current_time_;
}
Timestamp SimulatedTimeControllerImpl::NextRunTime() const {
Timestamp current_time = CurrentTime();
Timestamp next_time = Timestamp::PlusInfinity();
MutexLock lock(&lock_);
for (auto* runner : runners_) {
Timestamp next_run_time = runner->GetNextRunTime();
if (next_run_time <= current_time)
return current_time;
next_time = std::min(next_time, next_run_time);
}
return next_time;
}
void SimulatedTimeControllerImpl::AdvanceTime(Timestamp target_time) {
MutexLock time_lock(&time_lock_);
RTC_DCHECK_GE(target_time, current_time_);
current_time_ = target_time;
}
void SimulatedTimeControllerImpl::Register(SimulatedSequenceRunner* runner) {
MutexLock lock(&lock_);
runners_.push_back(runner);
}
void SimulatedTimeControllerImpl::Unregister(SimulatedSequenceRunner* runner) {
MutexLock lock(&lock_);
bool removed = RemoveByValue(&runners_, runner);
RTC_CHECK(removed);
RemoveByValue(&ready_runners_, runner);
}
void SimulatedTimeControllerImpl::StartYield(TaskQueueBase* yielding_from) {
auto inserted = yielded_.insert(yielding_from);
RTC_DCHECK(inserted.second);
}
void SimulatedTimeControllerImpl::StopYield(TaskQueueBase* yielding_from) {
yielded_.erase(yielding_from);
}
} // namespace sim_time_impl
GlobalSimulatedTimeController::GlobalSimulatedTimeController(
Timestamp start_time)
: sim_clock_(start_time.us()), impl_(start_time), yield_policy_(&impl_) {
global_clock_.SetTime(start_time);
auto main_thread = std::make_unique<SimulatedMainThread>(&impl_);
impl_.Register(main_thread.get());
main_thread_ = std::move(main_thread);
}
GlobalSimulatedTimeController::~GlobalSimulatedTimeController() = default;
Clock* GlobalSimulatedTimeController::GetClock() {
return &sim_clock_;
}
TaskQueueFactory* GlobalSimulatedTimeController::GetTaskQueueFactory() {
return &impl_;
}
std::unique_ptr<Thread> GlobalSimulatedTimeController::CreateThread(
const std::string& name,
std::unique_ptr<SocketServer> socket_server) {
return impl_.CreateThread(name, std::move(socket_server));
}
Thread* GlobalSimulatedTimeController::GetMainThread() {
return main_thread_.get();
}
void GlobalSimulatedTimeController::AdvanceTime(TimeDelta duration) {
ScopedYieldPolicy yield_policy(&impl_);
Timestamp current_time = impl_.CurrentTime();
Timestamp target_time = current_time + duration;
RTC_DCHECK_EQ(current_time.us(), TimeMicros());
while (current_time < target_time) {
impl_.RunReadyRunners();
Timestamp next_time = std::min(impl_.NextRunTime(), target_time);
impl_.AdvanceTime(next_time);
auto delta = next_time - current_time;
current_time = next_time;
sim_clock_.AdvanceTimeMicroseconds(delta.us());
global_clock_.AdvanceTime(delta);
}
// After time has been simulated up until `target_time` we also need to run
// tasks meant to be executed at `target_time`.
impl_.RunReadyRunners();
}
void GlobalSimulatedTimeController::SkipForwardBy(TimeDelta duration) {
ScopedYieldPolicy yield_policy(&impl_);
Timestamp current_time = impl_.CurrentTime();
Timestamp target_time = current_time + duration;
impl_.AdvanceTime(target_time);
sim_clock_.AdvanceTimeMicroseconds(duration.us());
global_clock_.AdvanceTime(duration);
}
void GlobalSimulatedTimeController::Register(
sim_time_impl::SimulatedSequenceRunner* runner) {
impl_.Register(runner);
}
void GlobalSimulatedTimeController::Unregister(
sim_time_impl::SimulatedSequenceRunner* runner) {
impl_.Unregister(runner);
}
} // namespace webrtc
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