base

gms/LG/new_sh_statusd/test/incr3.c

@@ -0,0 +1,46 @@
+#include	"unpipc.h"
+
+struct shared {
+  sem_t	mutex;		/* the mutex: a Posix memory-based semaphore */
+  int	count;		/* and the counter */
+} shared;
+
+int
+main(int argc, char **argv)
+{
+	int		fd, i, nloop;
+	struct shared 	*ptr;
+	if (argc != 3)
+		err_quit("usage: incr3 <pathname> <#loops>");
+	nloop = atoi(argv[2]);
+	/* 4open file, initialize to 0, map into memory */
+	fd = Open(argv[1], O_RDWR | O_CREAT, FILE_MODE);
+	
+	Write(fd, &shared, sizeof(struct shared));
+	fprintf(stderr, "before ptr-->%x\n", ptr);
+	ptr = Mmap(NULL, sizeof(struct shared), PROT_READ | PROT_WRITE,
+			   MAP_SHARED, fd, 0);
+	Close(fd);
+	fprintf(stderr, "after ptr-->%x\n", ptr);
+	/* 4initialize semaphore that is shared between processes */
+	Sem_init(&ptr->mutex, 0, 0);
+	fprintf(stderr, "---- 5 ----\n");
+	setbuf(stdout, NULL);	/* stdout is unbuffered */
+	if (Fork() == 0) {		/* child */
+		for (i = 0; i < nloop; i++) {
+			Sem_wait(&ptr->mutex);
+			printf("child: %d\n", ptr->count++);
+			Sem_post(&ptr->mutex);
+		}
+		exit(0);
+	}
+
+	/* 4parent */
+	for (i = 0; i < nloop; i++) {
+		Sem_wait(&ptr->mutex);
+		printf("parent: %d\n", ptr->count++);
+		Sem_post(&ptr->mutex);
+	}
+	Sem_destroy(&ptr->mutex);
+	exit(0);
+}