flux_child_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_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);

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 waitpid(2) 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.

SEE ALSO

flux_watcher_start(3), flux_reactor_start(3)

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