c - 从消息队列中读取(如果为空则非阻塞)

Question

我正在写消息队列

if (msgsnd(q, &msg, sizeof(message), slaves_list[to]) == -1)

阅读

if (msgrcv(q, &msg, sizeof(message), id, 0) == -1)

但是如果这个队列是空的呢？如何检查？如果没有我想在循环中执行下一条指令

Answer 1

使用IPC_NOWAIT。来自documentation :

If (msgflg & IPC_NOWAIT) is non-zero, the calling thread will return immediately with a return value of -1 and errno set to [ENOMSG].