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/*
* Copyright (C) 2020 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <chrono>
#include <thread>
#include <vibratorservice/VibratorCallbackScheduler.h>
namespace android {
namespace vibrator {
// -------------------------------------------------------------------------------------------------
bool DelayedCallback::isExpired() const {
return mExpiration <= std::chrono::steady_clock::now();
}
std::chrono::milliseconds DelayedCallback::getWaitForExpirationDuration() const {
std::chrono::milliseconds delta = std::chrono::duration_cast<std::chrono::milliseconds>(
mExpiration - std::chrono::steady_clock::now());
// Return zero if this is already expired.
return delta > delta.zero() ? delta : delta.zero();
}
void DelayedCallback::run() const {
mCallback();
}
bool DelayedCallback::operator<(const DelayedCallback& other) const {
return mExpiration < other.mExpiration;
}
bool DelayedCallback::operator>(const DelayedCallback& other) const {
return mExpiration > other.mExpiration;
}
// -------------------------------------------------------------------------------------------------
CallbackScheduler::~CallbackScheduler() {
{
std::lock_guard<std::mutex> lock(mMutex);
mFinished = true;
}
mCondition.notify_all();
if (mCallbackThread && mCallbackThread->joinable()) {
mCallbackThread->join();
}
}
void CallbackScheduler::schedule(std::function<void()> callback, std::chrono::milliseconds delay) {
{
std::lock_guard<std::mutex> lock(mMutex);
if (mCallbackThread == nullptr) {
mCallbackThread = std::make_unique<std::thread>(&CallbackScheduler::loop, this);
}
mQueue.emplace(DelayedCallback(callback, delay));
}
mCondition.notify_all();
}
void CallbackScheduler::loop() {
while (true) {
std::unique_lock<std::mutex> lock(mMutex);
if (mFinished) {
// Destructor was called, so let the callback thread die.
break;
}
while (!mQueue.empty() && mQueue.top().isExpired()) {
DelayedCallback callback = mQueue.top();
mQueue.pop();
lock.unlock();
callback.run();
lock.lock();
}
if (mQueue.empty()) {
// Wait until a new callback is scheduled.
mCondition.wait(mMutex);
} else {
// Wait until next callback expires, or a new one is scheduled.
// Use the monotonic steady clock to wait for the measured delay interval via wait_for
// instead of using a wall clock via wait_until.
mCondition.wait_for(mMutex, mQueue.top().getWaitForExpirationDuration());
}
}
}
// -------------------------------------------------------------------------------------------------
}; // namespace vibrator
}; // namespace android
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