操作系统：ubuntu10.04
前言：
在嵌入式开发中，只要是带操作系统的，在其上开发产品应用，基本都需要用到多线程。
为了提高效率，尽可能的提高并发率。因此，线程之间的通信就是问题的核心。
根据当前产品需要，使用 环形缓冲区 解决。
一，环形缓冲区的实现
1，cbuf.h
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#ifndef __CBUF_H__
#define __CBUF_H__
#ifdef __cplusplus
extern "C" {
#endif
/* Define to prevent recursive inclusion
-------------------------------------*/
#include "types.h"
#include "thread.h"
typedef struct _cbuf
{
int32_t size; /* 当前缓冲区中存放的数据的个数 */
int32_t next_in; /* 缓冲区中下一个保存数据的位置 */
int32_t next_out; /* 从缓冲区中取出下一个数据的位置 */
int32_t capacity; /* 这个缓冲区的可保存的数据的总个数 */
mutex_t mutex; /* Lock the structure */
cond_t not_full; /* Full -> not full condition */
cond_t not_empty; /* Empty -> not empty condition */
void *data[CBUF_MAX];/* 缓冲区中保存的数据指针 */
}cbuf_t;
/* 初始化环形缓冲区 */
extern int32_t cbuf_init(cbuf_t *c);
/* 销毁环形缓冲区 */
extern void cbuf_destroy(cbuf_t *c);
/* 压入数据 */
extern int32_t cbuf_enqueue(cbuf_t *c,void *data);
/* 取出数据 */
extern void* cbuf_dequeue(cbuf_t *c);
/* 判断缓冲区是否为满 */
extern bool cbuf_full(cbuf_t *c);
/* 判断缓冲区是否为空 */
extern bool cbuf_empty(cbuf_t *c);
/* 获取缓冲区可存放的元素的总个数 */
extern int32_t cbuf_capacity(cbuf_t *c);
}
/* END OF FILE
---------------------------------------------------------------*/
2，cbuf.c
#include "cbuf.h"
int32_t cbuf_init(cbuf_t *c)
int32_t ret = OPER_OK;
if((ret = mutex_init(&c->mutex)) != OPER_OK)
{
#ifdef DEBUG_CBUF
debug("cbuf init fail ! mutex init fail !\n");
return ret;
}
if((ret = cond_init(&c->not_full)) != OPER_OK)
debug("cbuf init fail ! cond not full init fail !\n");
mutex_destroy(&c->mutex);
if((ret = cond_init(&c->not_empty)) != OPER_OK)
debug("cbuf init fail ! cond not empty init fail !\n");
cond_destroy(&c->not_full);
c->size = 0;
c->next_in = 0;
c->next_out = 0;
c->capacity = CBUF_MAX;
debug("cbuf init success !\n");
return ret;
void cbuf_destroy(cbuf_t *c)
cond_destroy(&c->not_empty);
cond_destroy(&c->not_full);
mutex_destroy(&c->mutex);
debug("cbuf destroy success \n");
int32_t cbuf_enqueue(cbuf_t *c,void *data)
if((ret = mutex_lock(&c->mutex)) != OPER_OK) return ret;
/*
* Wait while the buffer is full.
*/
while(cbuf_full(c))
debug("cbuf is full !!!\n");
cond_wait(&c->not_full,&c->mutex);
c->data[c->next_in++] = data;
c->size++;
c->next_in %= c->capacity;
mutex_unlock(&c->mutex);
* Let a waiting consumer know there is data.
cond_signal(&c->not_empty);
// debug("cbuf enqueue success ,data : %p\n",data);
debug("enqueue\n");
void* cbuf_dequeue(cbuf_t *c)
void *data = NULL;
int32_t ret = OPER_OK;
if((ret = mutex_lock(&c->mutex)) != OPER_OK) return NULL;
/*
* Wait while there is nothing in the buffer
while(cbuf_empty(c))
debug("cbuf is empty!!!\n");
cond_wait(&c->not_empty,&c->mutex);
data = c->data[c->next_out++];
c->size--;
c->next_out %= c->capacity;
* Let a waiting producer know there is room.
* 取出了一个元素，又有空间来保存接下来需要存储的元素
cond_signal(&c->not_full);
// debug("cbuf dequeue success ,data : %p\n",data);
debug("dequeue\n");
return data;
bool cbuf_full(cbuf_t *c)
return (c->size == c->capacity);
bool cbuf_empty(cbuf_t *c)
return (c->size == 0);
int32_t cbuf_capacity(cbuf_t *c)
return c->capacity;
二，辅助文件
为了提高程序的移植性，对线程相关进行封装。
1，thread.h
#ifndef __THREAD_H__
#define __THREAD_H__
typedef struct _mutex
pthread_mutex_t mutex;
}mutex_t;
typedef struct _cond
pthread_cond_t cond;
}cond_t;
typedef pthread_t tid_t;
typedef pthread_attr_t attr_t;
typedef void* (* thread_fun_t)(void*);
typedef struct _thread
tid_t tid;
cond_t *cv;
int32_t state;
int32_t stack_size;
attr_t attr;
thread_fun_t fun;
}thread_t;
/* mutex */
extern int32_t mutex_init(mutex_t *m);
extern int32_t mutex_destroy(mutex_t *m);
extern int32_t mutex_lock(mutex_t *m);
extern int32_t mutex_unlock(mutex_t *m);
/* cond */
extern int32_t cond_init(cond_t *c);
extern int32_t cond_destroy(cond_t *c);
extern int32_t cond_signal(cond_t *c);
extern int32_t cond_wait(cond_t *c,mutex_t *m);
/* thread */
/* 线程的创建，其属性的设置等都封装在里面 */
extern int32_t thread_create(thread_t *t);
//extern int32_t thread_init(thread_t *t);
#define thread_join(t, p) pthread_join(t, p)
#define thread_self() pthread_self()
#define thread_sigmask pthread_sigmask
2，thread.c
int32_t mutex_init(mutex_t *m)
int32_t ret = OPER_OK;
if((ret = pthread_mutex_init(&m->mutex, NULL)) != 0)
ret = -THREAD_MUTEX_INIT_ERROR;
int32_t mutex_destroy(mutex_t *m)
if((ret = pthread_mutex_destroy(&m->mutex)) != 0)
ret = -MUTEX_DESTROY_ERROR;
int32_t mutex_lock(mutex_t *m)
if((ret = pthread_mutex_lock(&m->mutex)) != 0)
ret = -THREAD_MUTEX_LOCK_ERROR;
int32_t mutex_unlock(mutex_t *m)
if((ret = pthread_mutex_unlock(&m->mutex)) != 0)
ret = -THREAD_MUTEX_UNLOCK_ERROR;
int32_t cond_init(cond_t *c)
if((ret = pthread_cond_init(&c->cond, NULL)) != 0)
ret = -THREAD_COND_INIT_ERROR;
int32_t cond_destroy(cond_t *c)
if((ret = pthread_cond_destroy(&c->cond)) != 0)
ret = -COND_DESTROY_ERROR;
int32_t cond_signal(cond_t *c)
if((ret = pthread_cond_signal(&c->cond)) != 0)
ret = -COND_SIGNAL_ERROR;
int32_t cond_wait(cond_t *c,mutex_t *m)
if((ret = pthread_cond_wait(&c->cond, &m->mutex)) != 0)
ret = -COND_WAIT_ERROR;
三，测试
1，测试代码
/*
* cbuf begin
*/
#define OVER (-1)
static cbuf_t cmd;
static int line_1[200];
static int line_2[200];
//static int temp = 0;
static bool line1_finish = false;
static bool line2_finish = false;
void* producer_1(void *data)
int32_t i = 0;
for(i = 0; i < 200; i++)
line_1[i] = i+1000;
cbuf_enqueue(&cmd, &line_1[i]);
if(0 == (i % 9)) sleep(1);
line1_finish = true;
return NULL;
void* producer_2(void *data)
line_2[i] = i+20000;
cbuf_enqueue(&cmd, &line_2[i]);
line2_finish = true;
void* consumer(void *data)
int32_t *ptr = NULL;
while(1)
ptr = cbuf_dequeue(&cmd);
printf("%d\n",*ptr);
if(cbuf_empty(&cmd) && line2_finish && line1_finish)
{
printf("quit\n");
break;
}
void test_cbuf_oper(void)
pthread_t l_1;
pthread_t l_2;
pthread_t c;
cbuf_init(&cmd);
pthread_create(&l_1,NULL,producer_1,0);
pthread_create(&l_2,NULL,producer_2,0);
pthread_create(&c,NULL,consumer,0);
pthread_join(l_1,NULL);
pthread_join(l_2,NULL);
pthread_join(c,NULL);
cbuf_destroy(&cmd);
void test_cbuf(void)
test_cbuf_oper();
* cbuf end
2，测试结果
四，参考文件
1，《bareos-master》源码
2，《nginx》源码
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