libflux: drop child watchers

Problem: child watchers have no users, are likely not required in the
public API, and inhibit changing the internal reactor to libuv.

Drop them.

Fixes #6512

Author: garlick

src/common/libflux/test/reactor.c

@@ -553,52 +553,6 @@ static void test_signal (flux_reactor_t *reactor)
     flux_watcher_destroy (idle);
 }
 
-static pid_t child_pid = -1;
-static void child_cb (flux_reactor_t *r,
-                      flux_watcher_t *w,
-                      int revents,
-                      void *arg)
-{
-    int pid = flux_child_watcher_get_rpid (w);
-    int rstatus = flux_child_watcher_get_rstatus (w);
-    ok (pid == child_pid,
-        "child watcher called with expected rpid");
-    ok (WIFSIGNALED (rstatus) && WTERMSIG (rstatus) == SIGHUP,
-        "child watcher called with expected rstatus");
-    flux_watcher_stop (w);
-}
-
-static void test_child  (flux_reactor_t *reactor)
-{
-    flux_watcher_t *w;
-    flux_reactor_t *r;
-
-    child_pid = fork ();
-    if (child_pid == 0) {
-        pause ();
-        exit (0);
-    }
-    errno = 0;
-    w = flux_child_watcher_create (reactor, child_pid, false, child_cb, NULL);
-    ok (w == NULL && errno == EINVAL,
-        "child watcher failed with EINVAL on non-SIGCHLD reactor");
-    ok ((r = flux_reactor_create (FLUX_REACTOR_SIGCHLD)) != NULL,
-        "created reactor with SIGCHLD flag");
-    w = flux_child_watcher_create (r, child_pid, false, child_cb, NULL);
-    ok (w != NULL,
-        "created child watcher");
-    generic_watcher_check (w, "signal");
-
-    ok (kill (child_pid, SIGHUP) == 0,
-        "sent child SIGHUP");
-    flux_watcher_start (w);
-
-    ok (flux_reactor_run (r, 0) == 0,
-        "reactor ran successfully");
-    flux_watcher_destroy (w);
-    flux_reactor_destroy (r);
-}
-
 struct stat_ctx {
     int fd;
     char *path;
@@ -953,7 +907,6 @@ int main (int argc, char *argv[])
     test_idle (reactor);
     test_prepcheck (reactor);
     test_signal (reactor);
-    test_child (reactor);
     test_stat (reactor);
     test_handle (reactor);
     test_unref (reactor);

src/common/libflux/watcher.h

@@ -107,17 +107,6 @@ flux_watcher_t *flux_idle_watcher_create (flux_reactor_t *r,
                                           flux_watcher_f cb,
                                           void *arg);
 
-/* child
- */
-
-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);
-
 /* signal
  */
 

src/common/libflux/watcher_wrap.c

@@ -642,93 +642,6 @@ flux_watcher_t *flux_idle_watcher_create (flux_reactor_t *r,
     return w;
 }
 
-/* Child
- */
-
-struct child_watcher {
-    ev_child evw;
-};
-
-static void child_watcher_start (flux_watcher_t *w)
-{
-    struct ev_loop *loop = watcher_get_ev (w);
-    struct child_watcher *cw = watcher_get_data (w);
-    bool active = ev_is_active (&cw->evw);
-    ev_child_start (loop, &cw->evw);
-    watcher_start_post_ev (w, active);
-}
-
-static void child_watcher_stop (flux_watcher_t *w)
-{
-    struct ev_loop *loop = watcher_get_ev (w);
-    struct child_watcher *cw = watcher_get_data (w);
-    watcher_stop_pre_ev (w);
-    ev_child_stop (loop, &cw->evw);
-}
-
-static bool child_watcher_is_active (flux_watcher_t *w)
-{
-    struct child_watcher *cw = watcher_get_data (w);
-    return ev_is_active (&cw->evw);
-}
-
-static void child_watcher_cb (struct ev_loop *loop, ev_child *evw, int revents)
-{
-    struct flux_watcher *w = evw->data;
-    watcher_call_ev (w, revents);
-}
-
-static struct flux_watcher_ops child_watcher_ops = {
-    .start = child_watcher_start,
-    .stop = child_watcher_stop,
-    .ref = watcher_ref_ev,
-    .unref = watcher_unref_ev,
-    .is_active = child_watcher_is_active,
-    .destroy = NULL,
-};
-
-flux_watcher_t *flux_child_watcher_create (flux_reactor_t *r,
-                                           int pid,
-                                           bool trace,
-                                           flux_watcher_f cb,
-                                           void *arg)
-{
-    flux_watcher_t *w;
-    struct child_watcher *cw;
-
-    if (!ev_is_default_loop (reactor_get_loop (r))) {
-        errno = EINVAL;
-        return NULL;
-    }
-    if (!(w = watcher_create (r, sizeof (*cw), &child_watcher_ops, cb, arg)))
-        return NULL;
-    cw = watcher_get_data (w);
-    ev_child_init (&cw->evw, child_watcher_cb, pid, trace ? 1 : 0);
-    cw->evw.data = w;
-
-    return w;
-}
-
-int flux_child_watcher_get_rpid (flux_watcher_t *w)
-{
-    if (watcher_get_ops (w) != &child_watcher_ops) {
-        errno = EINVAL;
-        return -1;
-    }
-    struct child_watcher *cw = watcher_get_data (w);
-    return cw->evw.rpid;
-}
-
-int flux_child_watcher_get_rstatus (flux_watcher_t *w)
-{
-    if (watcher_get_ops (w) != &child_watcher_ops) {
-        errno = EINVAL;
-        return -1;
-    }
-    struct child_watcher *cw = watcher_get_data (w);
-    return cw->evw.rstatus;
-}
-
 /* Signal
  */