// Copyright 2009 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.

// GOMAXPROCS=10 gotest

package sync_test

import (
	"runtime";
	. "sync";
	"testing";
)

func HammerSemaphore(s *uint32, loops int, cdone chan bool) {
	for i := 0; i < loops; i++ {
		runtime.Semacquire(s);
		runtime.Semrelease(s);
	}
	cdone <- true;
}

func TestSemaphore(t *testing.T) {
	s := new(uint32);
	*s = 1;
	c := make(chan bool);
	for i := 0; i < 10; i++ {
		go HammerSemaphore(s, 1000, c)
	}
	for i := 0; i < 10; i++ {
		<-c
	}
}

func BenchmarkUncontendedSemaphore(b *testing.B) {
	s := new(uint32);
	*s = 1;
	HammerSemaphore(s, b.N, make(chan bool, 2));
}

func BenchmarkContendedSemaphore(b *testing.B) {
	b.StopTimer();
	s := new(uint32);
	*s = 1;
	c := make(chan bool);
	runtime.GOMAXPROCS(2);
	b.StartTimer();

	go HammerSemaphore(s, b.N/2, c);
	go HammerSemaphore(s, b.N/2, c);
	<-c;
	<-c;
}


func HammerMutex(m *Mutex, loops int, cdone chan bool) {
	for i := 0; i < loops; i++ {
		m.Lock();
		m.Unlock();
	}
	cdone <- true;
}

func TestMutex(t *testing.T) {
	m := new(Mutex);
	c := make(chan bool);
	for i := 0; i < 10; i++ {
		go HammerMutex(m, 1000, c)
	}
	for i := 0; i < 10; i++ {
		<-c
	}
}

func BenchmarkUncontendedMutex(b *testing.B) {
	m := new(Mutex);
	HammerMutex(m, b.N, make(chan bool, 2));
}

func BenchmarkContendedMutex(b *testing.B) {
	b.StopTimer();
	m := new(Mutex);
	c := make(chan bool);
	runtime.GOMAXPROCS(2);
	b.StartTimer();

	go HammerMutex(m, b.N/2, c);
	go HammerMutex(m, b.N/2, c);
	<-c;
	<-c;
}