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// Copyright 2015 The Vanadium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package counter implements counters that keeps track of their recent values
// over different periods of time.
// Example:
// c := counter.New()
// c.Incr(n)
// ...
// delta1h := c.Delta1h()
// delta10m := c.Delta10m()
// delta1m := c.Delta1m()
// and:
// rate1h := c.Rate1h()
// rate10m := c.Rate10m()
// rate1m := c.Rate1m()
package counter
import (
"sync"
"time"
)
var (
// Used for testing.
TimeNow func() time.Time = time.Now
)
const (
hour = 0
tenminutes = 1
minute = 2
)
// Counter is a counter that keeps track of its recent values over a given
// period of time, and with a given resolution. Use New() to instantiate.
type Counter struct {
mu sync.RWMutex
ts [3]*timeseries
lastUpdate time.Time
}
// New returns a new Counter.
func New() *Counter {
now := TimeNow()
c := &Counter{}
c.ts[hour] = newTimeSeries(now, time.Hour, time.Minute)
c.ts[tenminutes] = newTimeSeries(now, 10*time.Minute, 10*time.Second)
c.ts[minute] = newTimeSeries(now, time.Minute, time.Second)
return c
}
func (c *Counter) advance() time.Time {
now := TimeNow()
for _, ts := range c.ts {
ts.advanceTime(now)
}
return now
}
// Value returns the current value of the counter.
func (c *Counter) Value() int64 {
c.mu.RLock()
defer c.mu.RUnlock()
return c.ts[minute].headValue()
}
// LastUpdate returns the last update time of the counter.
func (c *Counter) LastUpdate() time.Time {
c.mu.RLock()
defer c.mu.RUnlock()
return c.lastUpdate
}
// Set updates the current value of the counter.
func (c *Counter) Set(value int64) {
c.mu.Lock()
defer c.mu.Unlock()
c.lastUpdate = c.advance()
for _, ts := range c.ts {
ts.set(value)
}
}
// Incr increments the current value of the counter by 'delta'.
func (c *Counter) Incr(delta int64) {
c.mu.Lock()
defer c.mu.Unlock()
c.lastUpdate = c.advance()
for _, ts := range c.ts {
ts.incr(delta)
}
}
// Delta1h returns the delta for the last hour.
func (c *Counter) Delta1h() int64 {
c.mu.RLock()
defer c.mu.RUnlock()
c.advance()
return c.ts[hour].delta()
}
// Delta10m returns the delta for the last 10 minutes.
func (c *Counter) Delta10m() int64 {
c.mu.RLock()
defer c.mu.RUnlock()
c.advance()
return c.ts[tenminutes].delta()
}
// Delta1m returns the delta for the last minute.
func (c *Counter) Delta1m() int64 {
c.mu.RLock()
defer c.mu.RUnlock()
c.advance()
return c.ts[minute].delta()
}
// Rate1h returns the rate of change of the counter in the last hour.
func (c *Counter) Rate1h() float64 {
c.mu.RLock()
defer c.mu.RUnlock()
c.advance()
return c.ts[hour].rate()
}
// Rate10m returns the rate of change of the counter in the last 10 minutes.
func (c *Counter) Rate10m() float64 {
c.mu.RLock()
defer c.mu.RUnlock()
c.advance()
return c.ts[tenminutes].rate()
}
// Rate1m returns the rate of change of the counter in the last minute.
func (c *Counter) Rate1m() float64 {
c.mu.RLock()
defer c.mu.RUnlock()
c.advance()
return c.ts[minute].rate()
}
// Reset resets the counter to an empty state.
func (c *Counter) Reset() {
c.mu.Lock()
defer c.mu.Unlock()
now := TimeNow()
for _, ts := range c.ts {
ts.reset(now)
}
}