libdill: Structured Concurrency for C

NAME

chrecv - receives a message from a channel

SYNOPSIS

#include <libdill.h>

int chrecv(
    int ch,
    void* val,
    size_t len,
    int64_t deadline);

DESCRIPTION

Receives a message from a channel.

The size of the message requested from the channel must match the size of the message sent to the channel. Otherwise, both peers fail with EMSGSIZE error.

If there's no one sending a message at the moment, the function blocks until someone shows up or until the deadline expires.

ch: The channel.

val: The buffer to receive the message to.

len: Size of the buffer, in bytes.

deadline: A point in time when the operation should time out, in milliseconds. Use the now function to get your current point in time. 0 means immediate timeout, i.e., perform the operation if possible or return without blocking if not. -1 means no deadline, i.e., the call will block forever if the operation cannot be performed.

RETURN VALUE

In case of success the function returns 0. In case of error it returns -1 and sets errno to one of the values below.

ERRORS

EBADF: Invalid handle.
ECANCELED: Current coroutine was canceled.
EINVAL: Invalid argument.
EMSGSIZE: The peer sent a message of different size.
ENOTSUP: The handle does not support this operation.
EPIPE: Channel has been closed with chdone.
ETIMEDOUT: Deadline was reached.

EXAMPLE

int val;
int rc = chrecv(ch, &val, sizeof(val), now() + 1000);
if(rc != 0) {
    perror("Cannot receive message");
    exit(1);
}
printf("Value %d received.\n", val);