看到golang 标准库 sync package 提供了传统的mutex, once, cond, rwmutex 等基于共享内存的同步原语，就想写个代码实验一下。
type Cond struct {
// L is held while observing or changing the condition
L Locker
// contains filtered or unexported fields
}
Cond 结构包含一个可导出的Locker 对象
func NewCond(l Locker) *Cond
NewCond 函数 接受一个实现Locker 接口的对象， 返回一个指向Cond 的指针; pthread_cond_t 对应于此
func (c *Cond) Broadcast()
Brocast 唤醒所有在这个cond 对象上等待的 goroutine； pthread_cond_brocast() 对应于此
func (c *Cond) Signal()
Signal 唤醒一个再此cond 对象上等待的goroutine； pthread_cond_signal() 对应于此
type Mutex struct { // contains filtered or unexported fields }
func (m *Mutex) Lock()
func (m *Mutex) Unlock()
Mutex 拥有Lock，Unlock 方法， 所以实现了
type Locker interface {
Lock()
Unlock()
}
#include <stdio.h>
#include <pthread.h>
pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
int condition = 0;
int count = 0;
int consume( void )
{
while( 1 )
{
pthread_mutex_lock( &mutex );
while( condition == 0 )
pthread_cond_wait( &cond, &mutex );
printf( "Consumed %d\n", count );
condition = 0;
pthread_cond_signal( &cond );
pthread_mutex_unlock( &mutex );
}
return( 0 );
}
void* produce( void * arg )
{
while( 1 )
{
pthread_mutex_lock( &mutex );
while( condition == 1 )
pthread_cond_wait( &cond, &mutex );
printf( "Produced %d\n", count++ );
condition = 1;
pthread_cond_signal( &cond );
pthread_mutex_unlock( &mutex );
}
return( 0 );
}
int main( void )
{
pthread_t thr;
pthread_create( &thr, NULL, &produce, NULL );
return consume();
}
接着等价的golang 实现：
package main
import (
"fmt"
"sync"
)
var count = 0
var condition = 0
func main(){
lock := new(sync.Mutex)
cond := sync.NewCond(lock)
go func (){
for {
lock.Lock()
for condition == 0 {
cond.Wait()
}
fmt.Printf("Consumed %d\n", count )
condition = 0
cond.Signal()
lock.Unlock()
}
}()
for {
lock.Lock()
for condition == 1 {
cond.Wait()
}
fmt.Printf("Produced %d\n", count )
count++
condition = 1
cond.Signal()
lock.Unlock()
}
}
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