flux_child_watcher_create.rst

flux_child_watcher_create(3)

c

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_child_watcher_create (flux_reactor_t *r,
                                           int pid,
                                           bool trace,
                                           flux_watcher_f cb,
                                           void *arg);

int flux_child_watcher_get_rpid (flux_watcher_t *w);

int flux_child_watcher_get_rstatus (flux_watcher_t *w);

Link with -lflux-core.

DESCRIPTION

flux_child_watcher_create creates a reactor watcher that monitors state transitions of child processes. If trace is false, only child termination will trigger an event; otherwise, stop and start events may be generated.

The callback revents argument should be ignored.

The process id that had a transition may be obtained by calling flux_child_watcher_get_rpid.

The status value returned by :linux:man2:waitpid may be obtained by calling flux_child_watcher_get_rstatus.

Only a Flux reactor created with the FLUX_REACTOR_SIGCHLD flag can be used with child watchers, as the reactor must register a SIGCHLD signal watcher before any processes are spawned. Only one reactor instance per program may be created with this capability.

RETURN VALUE

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

ERRORS

ENOMEM

Out of memory.

EINVAL

Reactor was not created with FLUX_REACTOR_SIGCHLD.

RESOURCES

libev: http://software.schmorp.de/pkg/libev.html

SEE ALSO

:man3:flux_watcher_start, :man3:flux_reactor_run