mirror of https://github.com/k3s-io/k3s
84 lines
1.3 KiB
Go
84 lines
1.3 KiB
Go
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package broadcaster
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import (
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"context"
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"sync"
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)
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type ConnectFunc func() (chan interface{}, error)
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type Broadcaster struct {
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sync.Mutex
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running bool
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subs map[chan interface{}]struct{}
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}
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func (b *Broadcaster) Subscribe(ctx context.Context, connect ConnectFunc) (<-chan interface{}, error) {
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b.Lock()
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defer b.Unlock()
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if !b.running {
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if err := b.start(connect); err != nil {
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return nil, err
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}
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}
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sub := make(chan interface{}, 100)
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if b.subs == nil {
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b.subs = map[chan interface{}]struct{}{}
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}
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b.subs[sub] = struct{}{}
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go func() {
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<-ctx.Done()
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b.unsub(sub, true)
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}()
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return sub, nil
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}
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func (b *Broadcaster) unsub(sub chan interface{}, lock bool) {
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if lock {
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b.Lock()
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}
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if _, ok := b.subs[sub]; ok {
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close(sub)
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delete(b.subs, sub)
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}
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if lock {
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b.Unlock()
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}
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}
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func (b *Broadcaster) start(connect ConnectFunc) error {
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c, err := connect()
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if err != nil {
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return err
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}
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go b.stream(c)
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b.running = true
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return nil
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}
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func (b *Broadcaster) stream(input chan interface{}) {
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for item := range input {
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b.Lock()
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for sub := range b.subs {
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select {
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case sub <- item:
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default:
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// Slow consumer, drop
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go b.unsub(sub, true)
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}
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}
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b.Unlock()
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}
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b.Lock()
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for sub := range b.subs {
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b.unsub(sub, false)
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}
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b.running = false
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b.Unlock()
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}
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