如何退出简单的生产者－消费者问题
|
我正在尝试制定一个简单的生产者－消费者计划。我有以下代码：
//global variable g_lastImage is declared as:
volatile int g_lastImage = 0;
void producer(void) {
int i = 0;
while (1) {
sem_wait(&g_shm->PSem);
printf(\"I:%d\\n\",i);
if (i == 5) {
g_lastImage = 1;
printf(\"It\'s time to say goodbye!\\n\");
sem_post(&g_shm->ChSem);
return;
}
printf(\"producing\\n\");
i++;
sem_post(&g_shm->ChSem);
}
}
void consumer(void) {
while (1) {
sem_wait(&g_shm->ChSem);
if (g_lastImage) {
printf(\"Bye!\\n\");
return;
}
printf(\"consuming\\n\");
sem_post(&g_shm->PSem);
}
}
int main() {
alloc(); /*allocates shared memory and two semaphores,
ChSem on initial counter value 0 and PSem on value 1*/
int processes = 1; //let\'s start with one process only just for now
int id = 0, i = 0, status;
for (i = 0; i < processes; i++) {
id = fork();
if (id < 0) {
perror (\"error\\n\");
exit(1);
} else if (id == 0) {
consumer();
printf(\"child exits\\n\");
exit(0);
}
}
producer();
for (i = 0; i < processes; ++i) {
wait(&status);
}
return 1;
}
I:0
producing
consuming
I:1
producing
consuming
I:2
producing
consuming
I:3
producing
consuming
I:4
producing
consuming
I:5
It\'s time to say goodbye!
consuming
//deadlock - nothing written
没有找到相关结果
已邀请:
2 个回复
醒荒捆府绣
#include <semaphore.h> #include <stdio.h> #include <unistd.h> #include <stdlib.h> #include <sys/wait.h> #include <sys/mman.h> struct Shared { sem_t PSem ; sem_t ChSem ; int g_lastImage ; } * g_shm ; void producer(void) { int i = 0; while (1) { sem_wait(&g_shm->PSem); printf(\"I:%d\\n\",i); if (i == 5) { g_shm->g_lastImage = 1; printf(\"It\'s time to say goodbye!\\n\"); sem_post(&g_shm->ChSem); return; } printf(\"producing\\n\"); i++; sem_post(&g_shm->ChSem); } } void consumer(void) { while (1) { sem_wait(&g_shm->ChSem); if (g_shm->g_lastImage) { printf(\"Bye!\\n\"); return; } printf(\"consuming\\n\"); sem_post(&g_shm->PSem); } } int main() { g_shm = mmap( NULL , sizeof( struct Shared ) , PROT_READ | PROT_WRITE , MAP_SHARED | MAP_ANONYMOUS , -1 , 0 ); sem_init( & g_shm->PSem , 1 , 1 ); sem_init( & g_shm->ChSem , 1 , 0 ); g_shm->g_lastImage = 0 ; int processes = 1; int id = 0, i = 0, status; for (i = 0; i < processes; i++) { id = fork(); if (id < 0) { perror (\"error\\n\"); exit(1); } else if (id == 0) { consumer(); printf(\"child exits\\n\"); exit(0); } } producer(); for (i = 0; i < processes; ++i) { wait(&status); } return 1; }蹄寄噬非芹