nursik / wake

Go signal and broadcast to wake waiting goroutines

Wake - wake goroutines and broadcast

Go library to wake goroutines. Thread-safe, small memory footprint, fast and simple API.

The library was written primarily as a dependency for safer sync.Cond.

You also might check go-broadcast to send/broadcast messages of any type and unlike this library you are able to not miss these messages/signals.

Features

• Signaller:
  • Wake N goroutines (Signal)
  • Wake exactly N goroutines with context (SignalWithContext)
  • Wake all goroutines (Broadcast)
  • Check how many goroutines are currently waiting (WaitCount)
  • Close signaller to unblock goroutines
• Receiver:
  • Wait with/without context (Wait/WaitWithContext). Receiver can check, if it was awoken due signal or context cancellation/closing.

Usage

go get github.com/nursik/wake

import (
	"context"
	"fmt"
	"time"

	"github.com/nursik/wake"
)

func Wait(r *wake.Receiver, id int) {
	// r.Wait() blocks until it is awoken. Returns true if it was awoken by signal or false if signaller was closed
	for r.Wait() {
		fmt.Printf("%v: received signal or broadcast\n", id)
	}
	fmt.Printf("%v: signaller is closed\n", id)
}

func main() {
	s, r := wake.New()
	defer s.Close()

	go Wait(r, 1)
	go Wait(r, 2)

	// Wait may start after Signal, sleep a little bit
	time.Sleep(time.Microsecond)

	_ = s.Signal(1) // wakes id 1 OR 2

	// Wait may start after Signal
	time.Sleep(time.Microsecond)

	s.Broadcast() // wakes id 1 and 2

	// Blocks until context is cancelled, signaller is closed or wakes 1 goroutine
	_, _ = s.SignalWithContext(context.Background(), 1) // wakes id 1 or 2
}