線程同步

線程同步的兩種方法：

1. 信號量

2. 互斥量

信號量：

<PRE class=cpp name="code"><SPAN style="FONT-SIZE: 14px">#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <semaphore.h>

void *thread_function(void *arg);
sem_t bin_sem;

#define WORK_SIZE 1024
char work_area[WORK_SIZE];

int main() {
	int res;
	pthread_t a_thread;
	void *thread_result;

	res = sem_init(&bin_sem, 0, 0);
	if(res != 0) {
		perror("Semaphore initialization failed");
		exit(EXIT_FAILURE);
	}
	res = pthread_create(&a_thread, NULL, thread_function, NULL);
	if(res != 0) {
		perror("Thread creation failed");
		exit(EXIT_FAILURE);
	}
	printf("Input some text. Enter 'end' to finish\n");
	while(strncmp("end",work_area, 3) != 0) {
		fgets(work_area, WORK_SIZE, stdin);
		sem_post(&bin_sem);
	}
	printf("\nWaiting for thread to finish....\n");
	res = pthread_join(a_thread, &thread_result);
	if(res !=0) {
		perror("Thread join failed");
		exit(EXIT_FAILURE);
	}
	printf("Thread join\n");
	sem_destroy(&bin_sem);
	exit(EXIT_SUCCESS);
}

void *thread_function(void *arg) {
	sem_wait(&bin_sem);
	while(strncmp("end", work_area, 3) != 0) {
		printf("You input %d characters\n", strlen(work_area) - 1);
		sem_wait(&bin_sem);
	}
	pthread_exit(NULL);
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