spin.c

<<c语言接口与实现>>一书源码,此书无疑是一部经典的c语言书籍,只可惜翻译的质量很差

static char rcsid[] = "$Id: H:/drh/idioms/book/RCS/thread.doc,v 1.11 1997/02/21 19:50:51 drh Exp $";
#include <stdio.h>
#include <stdlib.h>
#include "assert.h"
#include "fmt.h"
#include "thread.h"
#include "sem.h"
#define NBUMP 30000
struct args {
	Sem_T *mutex;
	int *ip;
};
int unsafe(void *cl) {
	int i, *ip = cl;
	for (i = 0; i < NBUMP; i++)
		*ip = *ip + 1;
	return EXIT_SUCCESS;
}
int safe(void *cl) {
	struct args *p = cl;
	int i;
	for (i = 0; i < NBUMP; i++)
		LOCK(*p->mutex)
			*p->ip = *p->ip + 1;
		END_LOCK;
	return EXIT_SUCCESS;
}
int n;
int main(int argc, char *argv[]) {
	int m = 5, preempt;
	preempt = Thread_init(1, NULL);
	assert(preempt == 1);
	if (argc >= 2)
		m = atoi(argv[1]);
	n = 0;
	{
		int i;
		for (i = 0; i < m; i++)
			Thread_new(unsafe, &n, 0, NULL);
		Thread_join(NULL);
	}
	Fmt_print("%d == %d\n", n, NBUMP*m);
	n = 0;
	{
		int i;
		struct args args;
		Sem_T mutex;
		Sem_init(&mutex, 1);
		args.mutex = &mutex;
		args.ip = &n;
		for (i = 0; i < m; i++)
			Thread_new(safe, &args, sizeof args, NULL);
		Thread_join(NULL);
	}
	Fmt_print("%d == %d\n", n, NBUMP*m);
	Thread_exit(EXIT_SUCCESS);
	return EXIT_SUCCESS;
}