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// Package eventbus представляет собой асинхронную шину событий
package eventbus
import (
"context"
"strings"
"sync"
)
const (
defaultCapacity = 32
)
type Bus struct {
noCopy
listeners node[Listener]
nameSeparator string
wildcard string
}
func New(opts ...Opt) *Bus {
b := &Bus{
nameSeparator: ".",
wildcard: "*",
}
for _, o := range opts {
o.Apply(b)
}
if cap(b.listeners.values) == 0 {
b.listeners = node[Listener]{
children: make(map[string]*node[Listener], defaultCapacity),
values: make([]Listener, 0, defaultCapacity),
}
}
return b
}
type Listener chan Event
type Event interface {
Event() string
}
// Subscribe to an event at the specified path. Returns a listener channel for
// receiving events.
func (b *Bus) Subscribe(ctx context.Context, path string) Listener {
splitedPath := strings.Split(path, b.nameSeparator)
ch := make(Listener, 1)
b.listeners.Put(splitedPath, ch)
go func() {
<-ctx.Done()
close(ch)
b.listeners.Remove(ch)
}()
return ch
}
// Publish an event to all subscribers who are subscribed to the corresponding
// event path.
func (b *Bus) Publish(ev Event) {
splitedEventName := strings.Split(ev.Event(), b.nameSeparator)
listeners := b.listeners.Get(splitedEventName, b.wildcard)
wg := sync.WaitGroup{}
for _, l := range listeners {
wg.Go(func() {
select {
case l <- ev:
default:
}
})
}
wg.Wait()
}
// Close the event bus and all listener channels.
func (b *Bus) Close() {
b.listeners.Clear(func(value Listener) {
close(value)
})
}
type noCopy struct{}
func (*noCopy) Lock() {}
func (*noCopy) Unlock() {}
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