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- // Copyright 2013 The Go Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style
- // license that can be found in the LICENSE file.
-
- package singleflight
-
- import (
- "errors"
- "fmt"
- "sync"
- "sync/atomic"
- "testing"
- "time"
- )
-
- func TestDo(t *testing.T) {
- var g Group
- v, err, _ := g.Do("key", func() (interface{}, error) {
- return "bar", nil
- })
- if got, want := fmt.Sprintf("%v (%T)", v, v), "bar (string)"; got != want {
- t.Errorf("Do = %v; want %v", got, want)
- }
- if err != nil {
- t.Errorf("Do error = %v", err)
- }
- }
-
- func TestDoErr(t *testing.T) {
- var g Group
- someErr := errors.New("Some error")
- v, err, _ := g.Do("key", func() (interface{}, error) {
- return nil, someErr
- })
- if err != someErr {
- t.Errorf("Do error = %v; want someErr %v", err, someErr)
- }
- if v != nil {
- t.Errorf("unexpected non-nil value %#v", v)
- }
- }
-
- func TestDoDupSuppress(t *testing.T) {
- var g Group
- var wg1, wg2 sync.WaitGroup
- c := make(chan string, 1)
- var calls int32
- fn := func() (interface{}, error) {
- if atomic.AddInt32(&calls, 1) == 1 {
- // First invocation.
- wg1.Done()
- }
- v := <-c
- c <- v // pump; make available for any future calls
-
- time.Sleep(10 * time.Millisecond) // let more goroutines enter Do
-
- return v, nil
- }
-
- const n = 10
- wg1.Add(1)
- for i := 0; i < n; i++ {
- wg1.Add(1)
- wg2.Add(1)
- go func() {
- defer wg2.Done()
- wg1.Done()
- v, err, _ := g.Do("key", fn)
- if err != nil {
- t.Errorf("Do error: %v", err)
- return
- }
- if s, _ := v.(string); s != "bar" {
- t.Errorf("Do = %T %v; want %q", v, v, "bar")
- }
- }()
- }
- wg1.Wait()
- // At least one goroutine is in fn now and all of them have at
- // least reached the line before the Do.
- c <- "bar"
- wg2.Wait()
- if got := atomic.LoadInt32(&calls); got <= 0 || got >= n {
- t.Errorf("number of calls = %d; want over 0 and less than %d", got, n)
- }
- }
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