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/**
* Copyright (C) 2017 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/stdx/thread.h"
#include "mongo/util/clock_source.h"
namespace mongo {
stdx::cv_status ClockSource::waitForConditionUntil(stdx::condition_variable& cv,
stdx::unique_lock<stdx::mutex>& m,
Date_t deadline) {
if (_tracksSystemClock) {
return cv.wait_until(m, deadline.toSystemTimePoint());
}
// The rest of this function only runs during testing, when the clock source is virtualized and
// does not track the system clock.
if (deadline <= now()) {
return stdx::cv_status::timeout;
}
struct AlarmInfo {
stdx::mutex controlMutex;
stdx::mutex* waitMutex;
stdx::condition_variable* waitCV;
stdx::cv_status cvWaitResult = stdx::cv_status::no_timeout;
};
auto alarmInfo = std::make_shared<AlarmInfo>();
alarmInfo->waitCV = &cv;
alarmInfo->waitMutex = m.mutex();
const auto waiterThreadId = stdx::this_thread::get_id();
bool invokedAlarmInline = false;
invariantOK(setAlarm(deadline, [alarmInfo, waiterThreadId, &invokedAlarmInline] {
stdx::lock_guard<stdx::mutex> controlLk(alarmInfo->controlMutex);
alarmInfo->cvWaitResult = stdx::cv_status::timeout;
if (!alarmInfo->waitMutex) {
return;
}
if (stdx::this_thread::get_id() == waiterThreadId) {
// In NetworkInterfaceMock, setAlarm may invoke its callback immediately if the deadline
// has expired, so we detect that case and avoid self-deadlock by returning early, here.
// It is safe to set invokedAlarmInline without synchronization in this case, because it
// is exactly the case where the same thread is writing and consulting the value.
invokedAlarmInline = true;
return;
}
stdx::lock_guard<stdx::mutex> waitLk(*alarmInfo->waitMutex);
alarmInfo->waitCV->notify_all();
}));
if (!invokedAlarmInline) {
cv.wait(m);
}
m.unlock();
stdx::lock_guard<stdx::mutex> controlLk(alarmInfo->controlMutex);
m.lock();
alarmInfo->waitMutex = nullptr;
alarmInfo->waitCV = nullptr;
return alarmInfo->cvWaitResult;
}
} // namespace mongo
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