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// @file timer.h
/* Copyright 2010 10gen 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.
*/
#pragma once
#include "mongo/client/export_macros.h"
namespace mongo {
/**
* Time tracking object.
*
* Should be of reasonably high performance, though the implementations are platform-specific.
* Each platform provides a distinct implementation of the now() method, and sets the
* _countsPerSecond static field to the constant number of ticks per second that now() counts
* in. The maximum span measurable by the counter and convertible to microseconds is about 10
* trillion ticks. As long as there are fewer than 100 ticks per nanosecond, timer durations of
* 2.5 years will be supported. Since a typical tick duration will be under 10 per nanosecond,
* if not below 1 per nanosecond, this should not be an issue.
*/
class MONGO_CLIENT_API Timer /*copyable*/ {
public:
static const long long millisPerSecond = 1000;
static const long long microsPerSecond = 1000 * millisPerSecond;
static const long long nanosPerSecond = 1000 * microsPerSecond;
Timer() {
reset();
}
int seconds() const {
return (int)(micros() / 1000000);
}
int millis() const {
return (int)(micros() / 1000);
}
int minutes() const {
return seconds() / 60;
}
/** Get the time interval and reset at the same time.
* @return time in milliseconds.
*/
inline int millisReset() {
const long long nextNow = now();
const long long deltaMicros = static_cast<long long>((nextNow - _old) * _microsPerCount);
_old = nextNow;
return static_cast<int>(deltaMicros / 1000);
}
inline long long micros() const {
return static_cast<long long>((now() - _old) * _microsPerCount);
}
inline void reset() {
_old = now();
}
inline static void setCountsPerSecond(long long countsPerSecond) {
_countsPerSecond = countsPerSecond;
_microsPerCount = static_cast<double>(microsPerSecond) / _countsPerSecond;
}
inline static long long getCountsPerSecond() {
return _countsPerSecond;
}
private:
/**
* Internally, the timer counts platform-dependent ticks of some sort, and
* must then convert those ticks to microseconds and their ilk. This field
* stores the frequency of the platform-dependent counter.
*/
static long long _countsPerSecond;
// Derived value from _countsPerSecond. This represents the conversion ratio
// from clock ticks to microseconds.
static double _microsPerCount;
long long now() const;
long long _old;
};
} // namespace mongo
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