Send a message to workers. Sending a message returns
a message id, which can be used to poll for a response with the
other rrq_message_*
functions.
rrq_message_send(command, args = NULL, worker_ids = NULL, controller = NULL)
A command, such as PING
, PAUSE
; see the Messages
section of the Details for al messages.
Arguments to the command, if supported
Optional vector of worker ids to send the message
to. If NULL
then the message will be sent to all active workers.
The controller to use. If not given (or NULL
)
we'll use the controller registered with
rrq_default_controller_set()
.
Invisibly, a single identifier