tracker

A small Go library for cancelling trees of goroutines and waiting for them to finish.

On projects with many goroutines it gets hard to keep track of a growing "cancel-tree" and wire up a WaitGroup for every layer. tracker combines a context.Context and a sync.WaitGroup behind one interface, with an API for starting goroutines similar to errgroup from golang.org/x/sync.

Install

go get github.com/s00500/tracker

Usage

t := tracker.Root()

t.Go(func(tkr tracker.Tracker) {
    for {
        select {
        case <-tkr.Done():
            return // cancelled — clean up and exit
        default:
            // do work
        }
    }
})

// Create a sub-group whose goroutines are cancelled together with the parent.
sub := t.NewSubGroup()
sub.Go(func(tkr tracker.Tracker) {
    <-tkr.Done()
})

// Cancel everything and block until all goroutines have returned.
t.CancelAndWait()

Key operations:

• Root() / FromContext(ctx) — create a top-level tracker.
• Go / GoRef — start a tracked goroutine; Run runs synchronously.
• NewSubGroup — derive a child tracker that cancels with its parent.
• Cancel, Wait, CancelAndWait — stop and/or wait for goroutines.
• Context() — get the underlying context.Context for external libraries.

See the full API on pkg.go.dev.

Feedback on the design is welcome.

License

MIT — see LICENSE. You may use, modify, and distribute the software freely; the only requirement is that the copyright notice and author attribution be retained in copies.