Method Do

pkg/singleflight/singleflight.go:94–118

Do executes and returns the results of the given function, making sure that only one execution is in-flight for a given key at a time. If a duplicate comes in, the duplicate caller waits for the original to complete and receives the same results. The return value shared indicates whether v was given

(key K, fn func() (V, error))

//
//nolint:revive
func (g *Group[K, V]) Do(key K, fn func() (V, error)) (v V, err error, shared bool) {
	g.mu.Lock()
	if g.m == nil {
		g.m = make(map[K]*call[V])
	}
	if c, ok := g.m[key]; ok {
		c.dups++
		g.mu.Unlock()
		c.wg.Wait()

		if e, ok := c.err.(*panicError); ok {
			panic(e)
		} else if c.err == errGoexit {
			runtime.Goexit()
		}
		return c.val, c.err, true
	}
	c := new(call[V])
	c.wg.Add(1)
	g.m[key] = c
	g.mu.Unlock()

	g.doCall(c, key, fn)
	return c.val, c.err, c.dups > 0
}

// DoChan is like Do but returns a channel that will receive the
// results when they are ready.