flux_recv(3)¶
SYNOPSIS¶
#include <flux/core.h>
flux_msg_t *flux_recv (flux_t *h, struct flux_match match, int flags);
DESCRIPTION¶
flux_recv()
receives a message using the Flux Message broker,
previously opened with flux_open()
on handle h.
The message should eventually be destroyed with flux_msg_destroy()
.
match is a message match structure which limits which messages can be received.
struct flux_match {
int typemask; // bitmask of matching message types
uint32_t matchtag; // matchtag
char *topic_glob; // glob matching topic string
};
The following initializers are available for match:
- FLUX_MATCH_ANY
Match any message.
- FLUX_MATCH_EVENT
Match any event message.
For additional details on how to use match, see flux_msg_cmp(3).
flags is the logical "or" of zero or more of the following flags:
- FLUX_O_TRACE
Dumps msg to stderr.
- FLUX_O_NONBLOCK
If unable to receive a matching message, return an error rather than block.
Internally, flags are the logical "or" of flags and the flags provided
to flux_open()
when the handle was created.
Messages that do not meet match criteria, are requeued with
flux_requeue()
for later consumption.
RETURN VALUE¶
flux_recv()
returns a message on success. On error, NULL is returned,
and errno is set appropriately.
ERRORS¶
- ENOSYS
Handle has no recv operation.
- EINVAL
Some arguments were invalid.
- EAGAIN
FLUX_O_NONBLOCK
was selected andflux_send()
would block.
EXAMPLES¶
This example opens the Flux broker and displays event messages as they arrive.
#include <flux/core.h>
#include "src/common/libutil/log.h"
int main (int argc, char **argv)
{
flux_t *h;
flux_msg_t *msg;
const char *topic;
if (!(h = flux_open (NULL, 0)))
log_err_exit ("flux_open");
if (flux_event_subscribe (h, "") < 0)
log_err_exit ("flux_event_subscribe");
for (;;) {
if ((msg = flux_recv (h, FLUX_MATCH_EVENT, 0)))
log_err_exit ("flux_recv");
if (flux_msg_get_topic (msg, &topic) < 0)
log_err_exit ("flux_msg_get_topic");
printf ("Event: %s\n", topic);
flux_msg_destroy (msg);
}
flux_close (h);
return (0);
}
RESOURCES¶
SEE ALSO¶
flux_open(3), flux_send(3), flux_requeue(3), flux_msg_cmp(3)