分Cas和Block模式实现了demo, 供入门学习使用，代码全部是远程实现。
直接上代码：
/* ============================================================================ Name : Producer.c Author : qionghui.fang Version : 1.0 Date : 2019年6月11日 下午2:32:30 Copyright : Your copyright notice Description : Main ============================================================================ */ #include <stdio.h> #include <stdlib.h> #include <pthread.h> #include <semaphore.h> #include <unistd.h> #include "header.h" int main(void) { printf("Start...\n"); // 在阻塞模式下初始化信号量 if(TC > 3){ pthread_mutex_init(&mutex_add,NULL); pthread_mutex_init(&mutex_take,NULL); } printf("Producer1 Thread init ...\n"); pthread_t producer1; ThreadParam p1Params = {"Producer1", &mutex_add}; pthread_create(&producer1, NULL, (void *)addBean, &p1Params); printf("Producer2 Thread init ...\n"); pthread_t producer2; ThreadParam p2Params = { "Producer2", &mutex_add}; pthread_create(&producer2, NULL, (void *)addBean, &p2Params); printf("Consumer1 Thread init ...\n"); pthread_t consumer1; ThreadParam c1Params = { "Consumer1", &mutex_take}; pthread_create(&consumer1, NULL, (void *)takeBean, &c1Params); printf("Consumer2 Thread init ...\n"); pthread_t consumer2; ThreadParam c2Params = { "Consumer2", &mutex_take}; pthread_create(&consumer2, NULL, (void *)takeBean, &c2Params); printf("Consumer3 Thread init ...\n"); pthread_t consumer3; ThreadParam c3Params = { "Consumer3", &mutex_take}; pthread_create(&consumer3, NULL, (void *)takeBean, &c3Params); pthread_join(producer1, NULL); printf("\n\nhere 1"); pthread_join(producer2, NULL); printf("\nhere2"); pthread_join(consumer1, NULL); pthread_join(consumer2, NULL); pthread_join(consumer3, NULL); printf("\n\nhere3"); printf("\nEnd."); return EXIT_SUCCESS; }
/* * header.h * * Created on: 2019年6月11日 * Author: fangdahui */ #include <pthread.h> #include <semaphore.h> #ifndef HEADER_H_ #define HEADER_H_ typedef int boolean; #define TRUE 1 #define FALSE 0 // 队列数量 BeanCount #define BC 10 // thread count: <=3 为CAS模式 大于3为阻塞模式 #define TC 3 typedef struct bean{ int no; char* msg; }Bean_t; typedef struct threadParam{ char* threadName; pthread_mutex_t* mutex; }ThreadParam; // 队列 Bean_t beanList[100]; volatile int beanListSize; // 原子操作 cmpxchg boolean cmpxchg(volatile int* dest, int compareValue, int newValue); // 加入元素 void *addBean(ThreadParam* params); // 互斥信号 pthread_mutex_t mutex_add; // 获取元素 void *takeBean(ThreadParam* params); // 互斥信号 pthread_mutex_t mutex_take; #endif /* HEADER_H_ */
/* ============================================================================ Name : Atom.c Author : qionghui.fang Version : 1.0 Date : 2019年6月12日 上午8:53:35 Copyright : Your copyright notice Description : CAS原子实现 ============================================================================ */ #include "header.h" // Adding a lock prefix to an instruction on MP machine #define LOCK_IF_MP(mp) "cmp $0, " #mp "; je 1f; lock; 1: " boolean cmpxchg(volatile int* dest, int compareValue, int newValue){ // 暂存旧值 int oldValue = *dest; // 默认多核 boolean mp = TRUE; // 调用 cmpxchgl 指令 __asm__ volatile (LOCK_IF_MP(%4) "cmpxchgl %1,(%3)" : "=a" (newValue) : "r" (newValue), "a" (compareValue), "r" (dest), "r" (mp) : "cc", "memory"); // 调用结束后 若地址目标值发生变更，则说明替换成功 if(*dest != oldValue){ return TRUE; } // 其它为失败 return FALSE; }
/* ============================================================================ Name : Producer.c Author : qionghui.fang Version : 1.0 Date : 2019年6月11日 下午2:32:30 Copyright : Your copyright notice Description : 生产者 ============================================================================ */ #include "header.h" #include <stdio.h> #include <unistd.h> #include <semaphore.h> void *addBean(ThreadParam * params){ while(TRUE){ // 生产1次 休眠1秒 sleep(1); // 走CAS模式 if(TC <= 3){ int oldSize = beanListSize; int newSize = oldSize + 1; if(newSize >= BC){ printf("\n[CasMode]%s: 队列已达最大长度，本次不加入，当前长度为：%d", params->threadName, beanListSize); sleep(1); //continue; break; } if(cmpxchg(&beanListSize, oldSize, newSize)){ // 队列长度+1 beanListSize = newSize; Bean_t bean = {beanListSize, "beanListSize"}; beanList[beanListSize] = bean; printf("\n[CasMode]%s: CAS成功，当前长度为：%d", params->threadName, beanListSize); } else{ printf("\n[CasMode]%s: CAS失败，进行下一轮尝试，当前长度为：%d", params->threadName, beanListSize); } } else{ // 加锁 pthread_mutex_lock(params->mutex); beanListSize ++; if(beanListSize >= 10){ printf("\n[BlockMode]%s: 队列已达最大长度，本次不加入，当前长度为：%d", params->threadName, beanListSize); sleep(1); //continue; //释放锁 pthread_mutex_unlock(params->mutex); break; } Bean_t bean = {beanListSize, "beanListSize"}; beanList[beanListSize] = bean; printf("\n[BlockMode]%s: 加锁成功，添加元素，当前长度为：%d", params->threadName, beanListSize); //释放锁 pthread_mutex_unlock(params->mutex); } } printf("\n%s: 线程终止，当前长度为：%d\n", params->threadName, beanListSize); return 0; }
/* ============================================================================ Name : Consumer.c Author : qionghui.fang Version : 1.0 Date : 2019年6月21日 上午9:56:30 Copyright : Your copyright notice Description : 消费者 ============================================================================ */ #include "header.h" #include <stdio.h> #include <unistd.h> #include <semaphore.h> void *takeBean(ThreadParam* params){ sleep(5); while(TRUE){ // 消费一次 休眠2秒 sleep(2); // 走CAS模式 if(TC <= 3){ int oldSize = beanListSize; int newSize = oldSize - 1; if(newSize < 1){ printf("\n[CasMode]%s: 消息已消费完，本次不能消费，当前长度为：%d", params->threadName, beanListSize); //continue; break; } if(cmpxchg(&beanListSize, oldSize, newSize)){ // 队列长度-1 beanListSize = newSize; printf("\n[CasMode]__%s: CAS成功，当前长度为：%d",params->threadName, beanListSize); int i; for(i=1; i<BC;i++){ Bean_t *bean = &beanList[i]; if(bean->no != 0){ bean->no = 0; bean->msg = NULL; break; } } } else{ printf("\n[CasMode]%s:CAS失败，进行下一轮尝试，当前长度为：%d", params->threadName, beanListSize); } } else{ // 加锁 pthread_mutex_lock(params->mutex); beanListSize --; if(beanListSize < 1){ printf("\n[BlockMode]__%s: 消息已消费完，本次不能消费，当前长度为：%d", params->threadName, beanListSize); sleep(1); //continue; //释放锁 pthread_mutex_unlock(params->mutex); break; } int i; for(i=1; i<100;i++){ Bean_t *bean = &beanList[i]; if(bean->no != 0){ bean->no = 0; bean->msg = NULL; break; } } printf("\n[BlockMode]__%s: 加锁成功, 消费元素，当前长度为：%d", params->threadName, beanListSize); //释放锁 pthread_mutex_unlock(params->mutex); } } printf("\n%s: 线程终止，当前长度为：%d\n", params->threadName, beanListSize); return 0; }
运行结果：
CAS模式：
阻塞Block模式（头文件里TC改为3以上，如5）：
逐行写的代码，收获不小。
这个适用于初学者，还是要在本地跑一跑。
祝好运。
