client_golang/metrics/timer.go

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2012-05-20 01:59:25 +04:00
// Copyright (c) 2012, Matt T. Proud
// All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// timer.go provides a scalar metric that times how long a given event takes.
package metrics
import (
"time"
)
// This callback is called upon the completion of the timer—i.e., when it stops.
type CompletionCallback func(duration time.Duration)
// This is meant to capture a function that a StopWatch can call for purposes
// of instrumentation.
type InstrumentableCall func()
type StopWatch struct {
startTime time.Time
endTime time.Time
onCompletion CompletionCallback
}
// Return a new StopWatch that is ready for instrumentation.
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.
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.
func InstrumentCall(instrumentable InstrumentableCall, onCompletion CompletionCallback) time.Duration {
s := Start(onCompletion)
instrumentable()
return s.Stop()
}