ClickHouse/dbms/include/DB/Common/Stopwatch.h

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#pragma once
#include <time.h>
#include <mutex>
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#include <Poco/ScopedLock.h>
#include <common/Common.h>
#ifdef __APPLE__
#include <common/apple_rt.h>
#endif
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/** Отличается от Poco::Stopwatch только тем, что использует clock_gettime вместо gettimeofday,
* возвращает наносекунды вместо микросекунд, а также другими незначительными отличиями.
*/
class Stopwatch
{
public:
/** CLOCK_MONOTONIC работает сравнительно эффективно (~15 млн. вызовов в сек.) и не приводит к системному вызову.
* Поставьте CLOCK_MONOTONIC_COARSE, если нужна больше производительность, но достаточно погрешности в несколько мс.
*/
Stopwatch(clockid_t clock_type_ = CLOCK_MONOTONIC) : clock_type(clock_type_) { restart(); }
void start() { setStart(); is_running = true; }
void stop() { updateElapsed(); is_running = false; }
void restart() { elapsed_ns = 0; start(); }
UInt64 elapsed() const { updateElapsed(); return elapsed_ns; }
double elapsedSeconds() const { updateElapsed(); return static_cast<double>(elapsed_ns) / 1000000000ULL; }
private:
mutable UInt64 start_ns;
mutable UInt64 elapsed_ns;
clockid_t clock_type;
bool is_running;
void setStart()
{
struct timespec ts;
clock_gettime(clock_type, &ts);
start_ns = ts.tv_sec * 1000000000ULL + ts.tv_nsec;
}
void updateElapsed() const
{
if (is_running)
{
struct timespec ts;
clock_gettime(clock_type, &ts);
UInt64 current_ns = ts.tv_sec * 1000000000ULL + ts.tv_nsec;
elapsed_ns += current_ns - start_ns;
start_ns = current_ns;
}
}
};
class StopwatchWithLock : public Stopwatch
{
public:
/** If specified amount of time has passed and timer is not locked right now, then restarts timer and returns true.
* Otherwise returns false.
* This is done atomically.
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*/
bool lockTestAndRestart(double seconds)
{
std::unique_lock<std::mutex> lock(mutex, std::defer_lock);
if (!lock.try_lock())
return false;
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if (elapsedSeconds() >= seconds)
{
restart();
return true;
}
else
return false;
}
struct Lock
{
StopwatchWithLock * parent = nullptr;
std::unique_lock<std::mutex> lock;
Lock() {}
operator bool() const { return parent != nullptr; }
Lock(StopwatchWithLock * parent, std::unique_lock<std::mutex> && lock)
: parent(parent), lock(std::move(lock))
{
}
Lock(Lock &&) = default;
~Lock()
{
if (parent)
parent->restart();
}
};
/** If specified amount of time has passed and timer is not locked right now, then returns Lock object,
* which locks timer and, on destruction, restarts timer and releases the lock.
* Otherwise returns object, that is implicitly casting to false.
* This is done atomically.
*
* Usage:
* if (auto lock = timer.lockTestAndRestartAfter(1))
* /// do some work, that must be done in one thread and not more frequently than each second.
*/
Lock lockTestAndRestartAfter(double seconds)
{
std::unique_lock<std::mutex> lock(mutex, std::defer_lock);
if (!lock.try_lock())
return {};
if (elapsedSeconds() >= seconds)
return Lock(this, std::move(lock));
return {};
}
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private:
std::mutex mutex;
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};