flux_handle_watcher_create(3)

SYNOPSIS

#include <flux/core.h>

typedef void (*flux_watcher_f)(flux_reactor_t *r,
                               flux_watcher_t *w,
                               int revents,
                               void *arg);

flux_watcher_t *flux_handle_watcher_create (flux_reactor_t *r,
                                            flux_t *h,
                                            int events,
                                            flux_watcher_f callback,
                                            void *arg);

flux_t *flux_handle_watcher_get_flux (flux_watcher_t *w);

Link with -lflux-core.

DESCRIPTION

flux_handle_watcher_create() creates a flux_watcher_t object which monitors for events on a Flux broker handle h. When events occur, the user-supplied callback is invoked.

The events and revents arguments are a bitmask containing a logical OR of the following bits. If a bit is set in events, it indicates interest in this type of event. If a bit is set in revents, it indicates that this event has occurred.

FLUX_POLLIN: The handle is ready for reading.
FLUX_POLLOUT: The handle is ready for writing.
FLUX_POLLERR: The handle has encountered an error. This bit is ignored if it is set in events.

Events are processed in a level-triggered manner. That is, the callback will continue to be invoked as long as the event has not been fully consumed or cleared, and the watcher has not been stopped.

flux_handle_watcher_get_flux() is used to obtain the handle from within the callback.

RETURN VALUE

flux_handle_watcher_create() returns a flux_watcher_t object on success. On error, NULL is returned, and errno is set appropriately.

flux_handle_watcher_get_flux() returns the handle associated with the watcher.

ERRORS

ENOMEM: Out of memory.

RESOURCES

Flux: http://flux-framework.org

Flux RFC: https://flux-framework.readthedocs.io/projects/flux-rfc