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MHSanaei
66b239da7d
The fan-out loop called every subscriber's handler sequentially on the single dispatch goroutine. The email and Telegram notifiers block on network I/O for tens of seconds (or minutes when the remote is slow), so one slow subscriber stalled the whole loop: the 256-slot channel then filled and Publish silently dropped later events — including high-value xray.crash and node.down notifications unrelated to the slow handler. Hand each delivered event to every handler in its own goroutine so a blocking subscriber can no longer stall delivery to the others. safeCall already recovers panics, so a detached handler cannot take down the bus.
127 lines
3.1 KiB
Go
127 lines
3.1 KiB
Go
package eventbus
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import (
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"sync"
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"time"
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"github.com/mhsanaei/3x-ui/v3/internal/logger"
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)
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// DefaultBufferSize is the number of events the bus can hold before Publish starts dropping.
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const DefaultBufferSize = 256
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// subscriber pairs an ID with its event handler.
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type subscriber struct {
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id string
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handler func(Event)
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}
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// Bus is a minimal in-process pub/sub event bus backed by a buffered channel.
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// Producers call Publish (non-blocking) and every event is fanned out to all
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// subscribers; per-event filtering is the subscriber's responsibility.
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type Bus struct {
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ch chan Event
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subs []subscriber
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mu sync.RWMutex
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done chan struct{}
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wg sync.WaitGroup
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}
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// New creates a Bus with the given buffer size. Use 0 for DefaultBufferSize.
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func New(bufSize int) *Bus {
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if bufSize <= 0 {
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bufSize = DefaultBufferSize
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}
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b := &Bus{
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ch: make(chan Event, bufSize),
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done: make(chan struct{}),
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}
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b.wg.Add(1)
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go b.dispatch()
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return b
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}
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// Subscribe registers a handler that receives every published event.
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// The id is used for Unsubscribe; it must be unique across active subscribers.
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// Subscribing with an already-registered id replaces the previous handler.
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func (b *Bus) Subscribe(id string, handler func(Event)) {
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b.mu.Lock()
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defer b.mu.Unlock()
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for i, s := range b.subs {
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if s.id == id {
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b.subs[i].handler = handler
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return
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}
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}
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b.subs = append(b.subs, subscriber{id: id, handler: handler})
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}
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// Unsubscribe removes a subscriber by id. Safe to call with unknown id.
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func (b *Bus) Unsubscribe(id string) {
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b.mu.Lock()
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defer b.mu.Unlock()
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for i, s := range b.subs {
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if s.id == id {
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b.subs = append(b.subs[:i], b.subs[i+1:]...)
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return
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}
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}
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}
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// Publish sends an event to all subscribers. Non-blocking — if the buffer is
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// full the event is dropped and a warning is logged.
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func (b *Bus) Publish(e Event) {
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if e.Timestamp.IsZero() {
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e.Timestamp = time.Now()
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}
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select {
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case b.ch <- e:
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default:
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logger.Warning("eventbus: buffer full, dropping event ", e.Type)
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}
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}
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// dispatch is the fan-out loop. It reads events from the channel and hands each
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// one to every subscriber's handler in its own goroutine, so a subscriber whose
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// handler blocks on network I/O (the email and Telegram notifiers can block for
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// tens of seconds) cannot stall delivery of unrelated, higher-value events such
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// as xray.crash or node.down.
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func (b *Bus) dispatch() {
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defer b.wg.Done()
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for {
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select {
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case e, ok := <-b.ch:
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if !ok {
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return
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}
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b.mu.RLock()
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subs := make([]subscriber, len(b.subs))
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copy(subs, b.subs)
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b.mu.RUnlock()
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for _, s := range subs {
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go safeCall(s.handler, e)
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}
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case <-b.done:
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return
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}
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}
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}
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// safeCall invokes handler with panic recovery.
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func safeCall(fn func(Event), e Event) {
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defer func() {
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if r := recover(); r != nil {
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logger.Errorf("eventbus: subscriber panicked on %s: %v", e.Type, r)
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}
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}()
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fn(e)
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}
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// Stop shuts down the bus: the dispatch goroutine exits and any events still
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// buffered may be dropped. Handler goroutines already spawned for delivered
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// events run to completion on their own. Safe to call once.
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func (b *Bus) Stop() {
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close(b.done)
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b.wg.Wait()
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}
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