/
window.go
205 lines (170 loc) · 3.67 KB
/
window.go
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package circuitry
import (
"container/ring"
"errors"
"sync"
"sync/atomic"
"time"
)
var ErrBucketSize = errors.New("bucket duration and size must divide equally")
type bucket struct {
failures int64
successes int64
shortcircuits int64
}
func (b *bucket) MarkShortCircuited() {
atomic.AddInt64(&b.shortcircuits, 1)
}
func (b *bucket) MarkSuccess() {
atomic.AddInt64(&b.successes, 1)
}
func (b *bucket) MarkFailure() {
atomic.AddInt64(&b.failures, 1)
}
func (b *bucket) Total() int64 {
return b.Failures() + b.Successes() + b.ShortCircuited()
}
func (b *bucket) Errors() int64 {
return b.Failures() + b.ShortCircuited()
}
func (b *bucket) Successes() int64 {
return atomic.LoadInt64(&b.successes)
}
func (b *bucket) Failures() int64 {
return atomic.LoadInt64(&b.failures)
}
func (b *bucket) ShortCircuited() int64 {
return atomic.LoadInt64(&b.shortcircuits)
}
func (b *bucket) Reset() {
atomic.StoreInt64(&b.failures, 0)
atomic.StoreInt64(&b.successes, 0)
atomic.StoreInt64(&b.shortcircuits, 0)
}
type Window struct {
size int
ring *ring.Ring
m sync.RWMutex
}
// Create a new window of duration d containing n buckets.
func NewWindow(n int, d time.Duration) (*Window, error) {
if int(d.Nanoseconds())%n != 0 {
return nil, ErrBucketSize
}
w := &Window{
size: n,
ring: seed(ring.New(n)),
}
go w.tick(time.Duration(int(d) / n))
return w, nil
}
func (w *Window) tick(d time.Duration) {
for _ = range time.Tick(d) {
w.m.Lock()
w.ring = rollup(w.ring)
w.m.Unlock()
}
}
func rollup(r *ring.Ring) *ring.Ring {
n := r.Next()
return seed(n)
}
func seed(r *ring.Ring) *ring.Ring {
if r.Value == nil {
r.Value = new(bucket)
} else {
r.Value.(*bucket).Reset()
}
return r
}
// Record a short-circuit.
func (w *Window) markShortCircuited() {
w.m.RLock()
defer w.m.RUnlock()
bucket := w.ring.Value.(*bucket)
bucket.MarkShortCircuited()
}
// Record a success.
func (w *Window) markSuccess() {
w.m.RLock()
defer w.m.RUnlock()
bucket := w.ring.Value.(*bucket)
bucket.MarkSuccess()
}
// Record a failure.
func (w *Window) markFailure() {
w.m.RLock()
defer w.m.RUnlock()
bucket := w.ring.Value.(*bucket)
bucket.MarkFailure()
}
// Return the total number of access (failures, success and short-circuit).
func (w *Window) Total() (total int64) {
w.m.RLock()
defer w.m.RUnlock()
w.ring.Do(func(i interface{}) {
if b, ok := i.(*bucket); ok {
total += b.Total()
}
})
return total
}
// Return the percentage of errors (failures and short-circuit).
func (w *Window) Errors() int64 {
w.m.RLock()
defer w.m.RUnlock()
var total, failures int64
w.ring.Do(func(i interface{}) {
if b, ok := i.(*bucket); ok {
failures += b.Errors()
total += b.Total()
}
})
if total > 0 {
return int64((float64(failures) / float64(total)) * 100)
}
return 0
}
// Return the total of short-circuit.
func (w *Window) ShortCircuited() (shortcircuit int64) {
w.m.RLock()
defer w.m.RUnlock()
w.ring.Do(func(i interface{}) {
if b, ok := i.(*bucket); ok {
shortcircuit += b.ShortCircuited()
}
})
return shortcircuit
}
// Return the total of successes.
func (w *Window) Successes() (successes int64) {
w.m.RLock()
defer w.m.RUnlock()
w.ring.Do(func(i interface{}) {
if b, ok := i.(*bucket); ok {
successes += b.Successes()
}
})
return successes
}
// Return the total of failures.
func (w *Window) Failures() (failures int64) {
w.m.RLock()
defer w.m.RUnlock()
w.ring.Do(func(i interface{}) {
if b, ok := i.(*bucket); ok {
failures += b.Failures()
}
})
return failures
}
// Reset window statistics.
func (w *Window) Reset() {
w.m.Lock()
defer w.m.Unlock()
w.ring.Do(func(i interface{}) {
if b, ok := i.(*bucket); ok {
b.Reset()
}
})
}