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/**
* Copyright (C) 2016 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#include "mongo/platform/basic.h"
#include "mongo/util/background_thread_clock_source.h"
#include <chrono>
#include <thread>
#include "mongo/stdx/memory.h"
#include "mongo/stdx/thread.h"
#include "mongo/util/time_support.h"
namespace mongo {
BackgroundThreadClockSource::BackgroundThreadClockSource(std::unique_ptr<ClockSource> clockSource,
Milliseconds granularity)
: _clockSource(std::move(clockSource)), _granularity(granularity), _shutdownTimer(false) {
_updateCurrent();
_startTimerThread();
}
BackgroundThreadClockSource::~BackgroundThreadClockSource() {
{
stdx::unique_lock<stdx::mutex> lock(_mutex);
_shutdownTimer = true;
_condition.notify_one();
}
_timer.join();
}
Milliseconds BackgroundThreadClockSource::getPrecision() {
return _granularity;
}
Date_t BackgroundThreadClockSource::now() {
return Date_t::fromMillisSinceEpoch(_current.load());
}
void BackgroundThreadClockSource::_startTimerThread() {
// Start the background thread that repeatedly sleeps for the specified duration of milliseconds
// and wakes up to store the current time.
_timer = stdx::thread([&]() {
stdx::unique_lock<stdx::mutex> lock(_mutex);
while (!_shutdownTimer) {
if (_condition.wait_for(lock, _granularity.toSystemDuration()) ==
stdx::cv_status::timeout) {
_updateCurrent();
}
}
});
}
void BackgroundThreadClockSource::_updateCurrent() {
_current.store(_clockSource->now().toMillisSinceEpoch());
}
} // namespace mongo
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