75 lines
2.4 KiB
Go
75 lines
2.4 KiB
Go
// Copyright 2016 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package prometheus
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import "time"
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// Observer is the interface that wraps the Observe method, which is used by
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// Histogram and Summary to add observations.
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type Observer interface {
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Observe(float64)
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}
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// The ObserverFunc type is an adapter to allow the use of ordinary
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// functions as Observers. If f is a function with the appropriate
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// signature, ObserverFunc(f) is an Observer that calls f.
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//
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// This adapter is usually used in connection with the Timer type, and there are
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// two general use cases:
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//
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// The most common one is to use a Gauge as the Observer for a Timer.
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// See the "Batch" Timer example.
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//
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// The more advanced use case is to create a function that dynamically decides
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// which Observer to use for observing the duration. See the "Complex" Timer
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// example.
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type ObserverFunc func(float64)
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// Observe calls f(value). It implements Observer.
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func (f ObserverFunc) Observe(value float64) {
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f(value)
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}
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// Timer is a helper type to time functions. Use NewTimer to create new
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// instances.
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type Timer struct {
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begin time.Time
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observer Observer
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}
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// NewTimer creates a new Timer. The provided Observer is used to observe a
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// duration in seconds. Timer is usually used to time a function call in the
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// following way:
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// func TimeMe() {
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// timer := NewTimer(myHistogram)
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// defer timer.ObserveDuration()
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// // Do actual work.
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// }
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func NewTimer(o Observer) *Timer {
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return &Timer{
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begin: time.Now(),
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observer: o,
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}
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}
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// ObserveDuration records the duration passed since the Timer was created with
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// NewTimer. It calls the Observe method of the Observer provided during
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// construction with the duration in seconds as an argument. ObserveDuration is
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// usually called with a defer statement.
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func (t *Timer) ObserveDuration() {
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if t.observer != nil {
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t.observer.Observe(time.Since(t.begin).Seconds())
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}
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}
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