1.14 互斥与同步

1.思维导图

2.有一个隧道，长1000m，有一辆高铁，每秒100米；有一辆快车，每秒50米；要求模拟这两列火车通过隧道的场景。

1>程序代码：

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <pthread.h>
#include <semaphore.h>
#include <wait.h>
#include <signal.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <semaphore.h>
#include <sys/msg.h>
#include <sys/shm.h>
#include <sys/un.h>typedef struct sockaddr_in addr_in_t;
typedef struct sockaddr addr_t;
typedef struct sockaddr_un addr_un_t;#define LENGTH 1000  //隧道的长度typedef struct
{const char *name;int speed;int position;
}Train;void *simulate_train(void *arg) 
{Train *train = (Train *)arg;while (train->position < LENGTH) {train->position += train->speed;  // 火车前进if (train->position > LENGTH)train->position = LENGTH;  // 防止超出隧道长度printf("%s正在 %d 米处\n", train->name, train->position);sleep(1); }printf("%s已出隧道\n", train->name);return NULL;
}
int main(int argc, const char *argv[])
{pthread_t high_speed_thread, fast_train_thread;// 初始化两列火车Train high_speed_train = {"高铁", 100, 0};Train fast_train = {"快车", 50, 0};// 创建线程模拟火车运行pthread_create(&high_speed_thread, NULL, simulate_train, &high_speed_train);pthread_create(&fast_train_thread, NULL, simulate_train, &fast_train);// 等待两列火车完成运行pthread_join(high_speed_thread, NULL);pthread_join(fast_train_thread, NULL);printf("两列火车都已出隧道\n");return 0;
}

2>运行效果：

3.有一条隧道，长1000m，有一辆高铁，每秒100米；有一辆快车，每秒50米；有一辆慢车，每秒25米；模拟它们通过隧道的场景，要求：高铁最先过隧道，快车其次，慢车最后。

1>程序代码：

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <pthread.h>
#include <semaphore.h>
#include <wait.h>
#include <signal.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <semaphore.h>
#include <sys/msg.h>
#include <sys/shm.h>
#include <sys/un.h>typedef struct sockaddr_in addr_in_t;
typedef struct sockaddr addr_t;
typedef struct sockaddr_un addr_un_t;#define LENGTH 1000  // 隧道长度typedef struct 
{const char *name;  int speed;         int position;      int order;        //火车顺序 
} Train;pthread_mutex_t mutex;
pthread_cond_t cond;
int current_order = 1; // 当前允许进入隧道的火车顺序void *simulate_train(void *arg) 
{Train *train = (Train *)arg;pthread_mutex_lock(&mutex);while (train->order != current_order) {pthread_cond_wait(&cond, &mutex);}pthread_mutex_unlock(&mutex);while (train->position < LENGTH) {train->position += train->speed;  // 火车前进if (train->position > LENGTH) {train->position = LENGTH;  // 防止超出隧道长度}printf("%s正在%d米处\n", train->name, train->position);sleep(1);  // 模拟每秒前进}printf("%s已出隧道\n", train->name);pthread_mutex_lock(&mutex);current_order++;pthread_cond_broadcast(&cond);pthread_mutex_unlock(&mutex);return NULL;
}int main(int argc, const char *argv[])
{pthread_t id1,id2,id3;// 初始化三列火车Train high_speed_train = {"高铁", 100, 0, 1};Train fast_train = {"快车", 50, 0, 2};Train slow_train = {"慢车", 25, 0, 3};// 创建线程模拟火车运行pthread_create(&id1, NULL, simulate_train, &high_speed_train);pthread_create(&id2, NULL, simulate_train, &fast_train);pthread_create(&id3, NULL, simulate_train, &slow_train);// 等待所有线程完成pthread_join(id1, NULL);pthread_join(id2, NULL);pthread_join(id3, NULL);printf("所有火车都已出隧道\n");return 0;
}

2>运行效果：

4.使用条件变量实现一个生产消费模型（pv模型）。生产者线程：每秒生成2个苹果；消费者线程：每3秒消费5~9个苹果。

1>程序代码：

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <pthread.h>
#include <semaphore.h>
#include <wait.h>
#include <signal.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <semaphore.h>
#include <sys/msg.h>
#include <sys/shm.h>
#include <sys/un.h>typedef struct sockaddr_in addr_in_t;
typedef struct sockaddr addr_t;
typedef struct sockaddr_un addr_un_t;#define MAX_APPLES 100  //定义仓库最大容量
int apple_count = 0; //当前苹果的数量//使用条件变量
pthread_mutex_t mutex;
pthread_cond_t cond;//生产者线程
void* producer(void* arg)
{while(1){pthread_mutex_lock(&mutex);//生产苹果if(apple_count+2 <= MAX_APPLES){apple_count += 2;printf("生产者生产2个苹果，目前苹果总数为:%d\n",apple_count);}else{printf("仓库已满，生产者等待生产中...\n");}//唤醒消费者线程pthread_cond_signal(&cond);pthread_mutex_unlock(&mutex);sleep(1);}return NULL;
}//消费者线程
void* consumer(void* arg)
{while(1){pthread_mutex_lock(&mutex);int consumption = rand() % 5 + 5;  //随机消费5~9个苹果while(apple_count < consumption){printf("消费者想要消费 %d 个苹果，但是只剩 %d 个苹果，等待...\n",consumption,apple_count);pthread_cond_wait(&cond,&mutex);  //等待生产者生产}//消费苹果apple_count -= consumption;printf("消费者消费 %d 个苹果，剩余苹果： %d个\n",consumption,apple_count);pthread_mutex_unlock(&mutex);sleep(3);}return NULL;
}int main(int argc, const char *argv[])
{pthread_t id_producer,id_consumer;pthread_create(&id_producer,0,producer,0);pthread_create(&id_consumer,0,consumer,0);pthread_join(id_producer,NULL);pthread_join(id_consumer,NULL);return 0;
}