client_golang/metrics/timer.go

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/*
Copyright (c) 2012, Matt T. Proud
All rights reserved.
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Use of this source code is governed by a BSD-style
license that can be found in the LICENSE file.
*/
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package metrics
import (
"time"
)
/*
This callback is called upon the completion of the timeri.e., when it stops.
*/
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type CompletionCallback func(duration time.Duration)
/*
This is meant to capture a function that a StopWatch can call for purposes
of instrumentation.
*/
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type InstrumentableCall func()
/*
StopWatch is the structure that captures instrumentation for durations.
N.B.(mtp): A major limitation hereof is that the StopWatch protocol cannot
retain instrumentation if a panic percolates within the context that is
being measured.
*/
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type StopWatch struct {
startTime time.Time
endTime time.Time
onCompletion CompletionCallback
}
/*
Return a new StopWatch that is ready for instrumentation.
*/
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func Start(onCompletion CompletionCallback) *StopWatch {
return &StopWatch{
startTime: time.Now(),
onCompletion: onCompletion,
}
}
/*
Stop the StopWatch returning the elapsed duration of its lifetime while
firing an optional CompletionCallback in the background.
*/
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func (s *StopWatch) Stop() time.Duration {
s.endTime = time.Now()
duration := s.endTime.Sub(s.startTime)
if s.onCompletion != nil {
go s.onCompletion(duration)
}
return duration
}
/*
Provide a quick way of instrumenting a InstrumentableCall and emitting its
duration.
*/
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func InstrumentCall(instrumentable InstrumentableCall, onCompletion CompletionCallback) time.Duration {
s := Start(onCompletion)
instrumentable()
return s.Stop()
}