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/**
* Copyright (C) 2020-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* 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
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* 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 Server Side 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 <boost/optional.hpp>
#include <fmt/format.h>
#if defined(__linux__)
#include <time.h>
#endif // defined(__linux__)
#include "mongo/db/operation_cpu_timer.h"
#include "mongo/base/error_codes.h"
#include "mongo/db/client.h"
#include "mongo/db/operation_context.h"
#include "mongo/stdx/thread.h"
#include "mongo/util/assert_util.h"
#include "mongo/util/errno_util.h"
#include "mongo/util/fail_point.h"
namespace mongo {
#if defined(__linux__)
namespace {
using namespace fmt::literals;
MONGO_FAIL_POINT_DEFINE(hangCPUTimerAfterOnThreadAttach);
MONGO_FAIL_POINT_DEFINE(hangCPUTimerAfterOnThreadDetach);
class PosixTimer final : public OperationCPUTimer {
public:
Nanoseconds getElapsed() const override;
void start() override;
void stop() override;
void onThreadAttach() override;
void onThreadDetach() override;
private:
bool _timerIsRunning() const;
bool _isAttachedToCurrentThread() const;
// Returns the elapsed time since the creation of the current thread.
Nanoseconds _getThreadTime() const;
// Holds the value returned by `_getThreadTime()` at the time of starting/resuming the timer.
boost::optional<Nanoseconds> _startedOn;
boost::optional<stdx::thread::id> _threadId;
Nanoseconds _elapsedBeforeInterrupted = Nanoseconds(0);
};
Nanoseconds PosixTimer::getElapsed() const {
invariant(_isAttachedToCurrentThread(), "Not attached to current thread");
auto elapsed = _elapsedBeforeInterrupted;
if (_timerIsRunning())
elapsed += _getThreadTime() - _startedOn.get();
return elapsed;
}
bool PosixTimer::_timerIsRunning() const {
return _startedOn.has_value();
}
bool PosixTimer::_isAttachedToCurrentThread() const {
return _threadId.has_value() && _threadId.get() == stdx::this_thread::get_id();
}
void PosixTimer::start() {
invariant(!_timerIsRunning(), "Timer has already started");
_startedOn = _getThreadTime();
_threadId = stdx::this_thread::get_id();
_elapsedBeforeInterrupted = Nanoseconds(0);
}
void PosixTimer::stop() {
invariant(_timerIsRunning(), "Timer is not running");
invariant(_isAttachedToCurrentThread());
_elapsedBeforeInterrupted = getElapsed();
_startedOn.reset();
}
void PosixTimer::onThreadAttach() {
if (!_timerIsRunning())
return;
invariant(!_threadId.has_value(), "Timer has already been attached");
_threadId = stdx::this_thread::get_id();
_startedOn = _getThreadTime();
hangCPUTimerAfterOnThreadAttach.pauseWhileSet();
}
void PosixTimer::onThreadDetach() {
if (!_timerIsRunning())
return;
invariant(_threadId.has_value(), "Timer is not attached");
_threadId.reset();
_elapsedBeforeInterrupted = _getThreadTime() - _startedOn.get();
hangCPUTimerAfterOnThreadDetach.pauseWhileSet();
}
Nanoseconds PosixTimer::_getThreadTime() const {
struct timespec t;
if (auto ret = clock_gettime(CLOCK_THREAD_CPUTIME_ID, &t); ret != 0) {
int ec = errno;
internalAssert(Status(ErrorCodes::InternalError,
"Unable to get time: {}"_format(errnoWithDescription(ec))));
}
return Seconds(t.tv_sec) + Nanoseconds(t.tv_nsec);
}
static auto getCPUTimer = OperationContext::declareDecoration<PosixTimer>();
} // namespace
OperationCPUTimer* OperationCPUTimer::get(OperationContext* opCtx) {
invariant(Client::getCurrent() && Client::getCurrent()->getOperationContext() == opCtx,
"Operation not attached to the current thread");
// Checks for time support on POSIX platforms. In particular, it checks for support in presence
// of SMP systems.
static bool isTimeSupported = [] {
clockid_t cid;
return clock_getcpuclockid(0, &cid) == 0;
}();
if (!isTimeSupported)
return nullptr;
return &getCPUTimer(opCtx);
}
#else // not defined(__linux__)
OperationCPUTimer* OperationCPUTimer::get(OperationContext*) {
return nullptr;
}
#endif // defined(__linux__)
} // namespace mongo
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