singleflight_test.go

package gcache

/*
Copyright 2012 Google Inc.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

import (
	"errors"
	"fmt"
	"sync"
	"sync/atomic"
	"testing"
	"time"
)

func TestDo(t *testing.T) {
	var g Group
	gc, err := New(32).Build()
	if err != nil {
		t.Error(err)
	}

	g.cache = gc

	v, _, err := g.Do("key", func() (interface{}, error) {
		return "bar", nil
	}, true)
	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
	gc, err := New(32).Build()
	if err != nil {
		t.Error(err)
	}
	g.cache = gc

	someErr := errors.New("Some error")
	v, _, err := g.Do("key", func() (interface{}, error) {
		return nil, someErr
	}, true)
	if err != someErr {
		t.Errorf("Do error = %v; want someErr", err)
	}
	if v != nil {
		t.Errorf("unexpected non-nil value %#v", v)
	}
}

func TestDoDupSuppress(t *testing.T) {
	var g Group
	gc, err := New(32).Build()
	if err != nil {
		t.Error(err)
	}
	g.cache = gc

	c := make(chan string)
	var calls int32
	fn := func() (interface{}, error) {
		atomic.AddInt32(&calls, 1)
		return <-c, nil
	}

	const n = 10
	var wg sync.WaitGroup
	for i := 0; i < n; i++ {
		wg.Add(1)
		go func() {
			v, _, err := g.Do("key", fn, true)
			if err != nil {
				t.Errorf("Do error: %v", err)
			}
			if v.(string) != "bar" {
				t.Errorf("got %q; want %q", v, "bar")
			}
			wg.Done()
		}()
	}
	time.Sleep(100 * time.Millisecond) // let goroutines above block
	c <- "bar"
	wg.Wait()
	if got := atomic.LoadInt32(&calls); got != 1 {
		t.Errorf("number of calls = %d; want 1", got)
	}
}