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// @file timer.h
/* Copyright 2010 10gen Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#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 unsigned long long millisPerSecond = 1000;
static const unsigned long long microsPerSecond = 1000 * millisPerSecond;
static const unsigned 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() {
unsigned long long nextNow = now();
unsigned long long deltaMicros =
((nextNow - _old) * microsPerSecond) / _countsPerSecond;
_old = nextNow;
return static_cast<int>(deltaMicros / 1000);
}
inline unsigned long long micros() const {
return ((now() - _old) * microsPerSecond) / _countsPerSecond;
}
inline void reset() { _old = now(); }
/**
* 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.
*
* This value is initialized at program startup, and never changed after.
* It should be treated as private.
*/
static unsigned long long _countsPerSecond;
private:
inline unsigned long long now() const;
unsigned long long _old;
};
} // namespace mongo
#include "mongo/util/timer-inl.h"
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