100 lines
1.8 KiB
Go
100 lines
1.8 KiB
Go
package backoff
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import (
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"context"
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"sync"
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"time"
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)
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type controller struct {
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ctx context.Context
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cancel func()
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ig IntervalGenerator
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maxRetries int
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mu *sync.RWMutex
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next chan struct{} // user-facing channel
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resetTimer chan time.Duration
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retries int
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timer *time.Timer
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}
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func newController(ctx context.Context, ig IntervalGenerator, options ...ControllerOption) *controller {
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cctx, cancel := context.WithCancel(ctx) // DO NOT fire this cancel here
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maxRetries := 10
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for _, option := range options {
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switch option.Ident() {
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case identMaxRetries{}:
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maxRetries = option.Value().(int)
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}
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}
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c := &controller{
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cancel: cancel,
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ctx: cctx,
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ig: ig,
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maxRetries: maxRetries,
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mu: &sync.RWMutex{},
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next: make(chan struct{}, 1),
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resetTimer: make(chan time.Duration, 1),
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timer: time.NewTimer(ig.Next()),
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}
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// enqueue a single fake event so the user gets to retry once
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c.next <- struct{}{}
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go c.loop()
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return c
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}
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func (c *controller) loop() {
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for {
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select {
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case <-c.ctx.Done():
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return
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case d := <-c.resetTimer:
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if !c.timer.Stop() {
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select {
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case <-c.timer.C:
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default:
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}
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}
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c.timer.Reset(d)
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case <-c.timer.C:
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select {
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case <-c.ctx.Done():
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return
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case c.next <- struct{}{}:
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}
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if c.maxRetries > 0 {
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c.retries++
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}
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if !c.check() {
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c.cancel()
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return
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}
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c.resetTimer <- c.ig.Next()
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}
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}
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}
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func (c *controller) check() bool {
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if c.maxRetries > 0 && c.retries >= c.maxRetries {
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return false
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}
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return true
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}
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func (c *controller) Done() <-chan struct{} {
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c.mu.RLock()
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defer c.mu.RUnlock()
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return c.ctx.Done()
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}
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func (c *controller) Next() <-chan struct{} {
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c.mu.RLock()
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defer c.mu.RUnlock()
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return c.next
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}
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