#include <flux/core.h> typedef void (*flux_msg_handler_f)(flux_t *h, flux_msg_handler_t *mh, const flux_msg_t *msg, void *arg); flux_msg_handler_t *flux_msg_handler_create ( flux_t *h, const struct flux_match match, flux_msg_handler_f callback, void *arg); void flux_msg_handler_destroy (flux_msg_handler_t *mh); void flux_msg_handler_start (flux_msg_handler_t *mh); void flux_msg_handler_stop (flux_msg_handler_t *mh);
Link with -lflux-core.
callback to be invoked when
a message meeting
match criteria, as described in flux_msg_cmp(3),
is received on Flux broker handle
The message handler must be started with
order to receive messages. Conversely,
the message handler to stop receiving messages. Starting and stopping
are idempotent operations.
h is monitored for FLUX_POLLIN events on the
flux_reactor_t associated with the handle as described in
flux_set_reactor(3). This internal "handle watcher" is started when the
first message handler is started, and stopped when the last message handler
Messages arriving on
h are internally read and dispatched to matching
message handlers. If multiple handlers match the message, the following
Requests are first delivered to a message handler whose
match.topic_globis set to an exact string match of the message topic glob. The most recently registered of these takes precedence. If an exact match is unavailable, the message is delivered to the most recently registered message handler for which flux_msg_cmp(3) returns true. If there is no match, an ENOSYS response is automatically generated by the dispatcher.
Responses are first delivered to a matching RPC response handler (
match.matchtag!= FLUX_MATCHTAG_NONE). If an RPC response handler does not match, responses are delivered to the most recently registered message handler for which flux_msg_cmp(3) returns true. If there is no match, the response is discarded.
Events are delivered to all matching message handlers.
flux_msg_handler_destroy() destroys a handler, after internally
Although it is possible to register a message handler in a given
handle for any topic string, flux-broker(1) does not automatically route
matching requests or events to the handle.
Requests are only routed if the handle has registered a matching service with flux_service_register(3), or for broker modules only, the service matches the module name.
Events are only routed if the topic matches a subscription registered with flux_event_subscribe(3).
flux_msg_handler_create() returns a
flux_msg_handler_t object on
success. On error, NULL is returned, and
errno is set appropriately.
Out of memory.