rendezvous

Overview

rendezvous is a Go module that implements a synchronisation mechanism where multiple goroutines must regroup and wait at a specific point before any of them can proceed.

Usage

Creating a rendezvous point

Since a rendezvous.Point needs to know how many goroutines must be synchronised, we must create one by calling rendezvous.NewPoint:

point := rendezvous.NewPoint(n)

You can also configure the behaviour of an rendezvous.Point by providing some rendezvous.Configurer's to the rendezvous.NewPoint function. For example:

var locker sync.Locker

// ...
// assign a custom sync.Locker implementation to locker
// ...

point := rendezvous.NewPoint(n, rendezvous.WithLocker(locker))

Regrouping goroutines

Once you have created a rendezvous.Point, you can call rendezvous.Point.Regroup to ensure that group of goroutines can only proceed once they have all reached the same point:

var (
    wg    sync.WaitGroup
    point = rendezvous.NewPoint(n)
    ctx   = context.Background()
)
for i := range n {
    wg.Add(1)
    go func(i int) {
        defer wg.Done()
        
        sleepDuration := rand.N(200 * time.Millisecond)
        time.Sleep(sleepDuration)
        
        fmt.Printf("[Goroutine %d] arrived at rendezvous point.\n", i)
        
        err := point.Regroup(ctx)
        if err != nil {
            fmt.Printf("[Goroutine %d] %s\n", i, err)
            return
        }
        
        fmt.Printf("[Goroutine %d] regrouped and proceeded.\n", i)
    }(i)
}

wg.Wait()

/*
Example output for n = 5:

    [Goroutine 4] arrived at rendezvous point.
    [Goroutine 0] arrived at rendezvous point.
    [Goroutine 1] arrived at rendezvous point.
    [Goroutine 2] arrived at rendezvous point.
    [Goroutine 3] arrived at rendezvous point.
    [Goroutine 3] regrouped and proceeded.
    [Goroutine 2] regrouped and proceeded.
    [Goroutine 0] regrouped and proceeded.
    [Goroutine 1] regrouped and proceeded.
    [Goroutine 4] regrouped and proceeded.
*/

Documentation

Documentation for rendezvous can be found here.