From 6367f0a0521c4aa65f3e5af85569ff19ee503484 Mon Sep 17 00:00:00 2001
From: root <root>
Date: Sat, 8 Mar 2008 07:04:55 +0000
Subject: *** empty log message ***

---
 Changes |  1 +
 ev.c    | 10 +++++-----
 ev.pod  | 56 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 61 insertions(+), 6 deletions(-)

diff --git a/Changes b/Changes
index e5d53d1..6f1e9e0 100644
--- a/Changes
+++ b/Changes
@@ -4,6 +4,7 @@ Revision history for libev, a high-performance and full-featured event loop
 	- implement ev_async watchers.
         - only initialise signal pipe on demand.
 	- make use of sig_atomic_t configurable.
+        - improved ev_child documentation.
 
 3.0  Mon Jan 28 13:14:47 CET 2008
 	- API/ABI bump to version 3.0.
diff --git a/ev.c b/ev.c
index 34e3fd9..4e8deda 100644
--- a/ev.c
+++ b/ev.c
@@ -914,7 +914,7 @@ static ev_signal childev;
 #endif
 
 void inline_speed
-child_reap (EV_P_ ev_signal *sw, int chain, int pid, int status)
+child_reap (EV_P_ int chain, int pid, int status)
 {
   ev_child *w;
   int traced = WIFSTOPPED (status) || WIFCONTINUED (status);
@@ -924,7 +924,7 @@ child_reap (EV_P_ ev_signal *sw, int chain, int pid, int status)
       if ((w->pid == pid || !w->pid)
           && (!traced || (w->flags & 1)))
         {
-          ev_set_priority (w, ev_priority (sw)); /* need to do it *now* */
+          ev_set_priority (w, EV_MAXPRI); /* need to do it *now*, this *must* be the same prio as the signal watcher itself */
           w->rpid    = pid;
           w->rstatus = status;
           ev_feed_event (EV_A_ (W)w, EV_CHILD);
@@ -948,13 +948,13 @@ childcb (EV_P_ ev_signal *sw, int revents)
         || 0 >= (pid = waitpid (-1, &status, WNOHANG | WUNTRACED)))
       return;
 
-  /* make sure we are called again until all childs have been reaped */
+  /* make sure we are called again until all children have been reaped */
   /* we need to do it this way so that the callback gets called before we continue */
   ev_feed_event (EV_A_ (W)sw, EV_SIGNAL);
 
-  child_reap (EV_A_ sw, pid, pid, status);
+  child_reap (EV_A_ pid, pid, status);
   if (EV_PID_HASHSIZE > 1)
-    child_reap (EV_A_ sw, 0, pid, status); /* this might trigger a watcher twice, but feed_event catches that */
+    child_reap (EV_A_ 0, pid, status); /* this might trigger a watcher twice, but feed_event catches that */
 }
 
 #endif
diff --git a/ev.pod b/ev.pod
index 812978b..b41cc3d 100644
--- a/ev.pod
+++ b/ev.pod
@@ -1456,7 +1456,32 @@ Example: Try to exit cleanly on SIGINT and SIGTERM.
 =head2 C<ev_child> - watch out for process status changes
 
 Child watchers trigger when your process receives a SIGCHLD in response to
-some child status changes (most typically when a child of yours dies).
+some child status changes (most typically when a child of yours dies). It
+is permissible to install a child watcher I<after> the child has been
+forked (which implies it might have already exited), as long as the event
+loop isn't entered (or is continued from a watcher).
+
+Only the default event loop is capable of handling signals, and therefore
+you can only rgeister child watchers in the default event loop.
+
+=head3 Process Interaction
+
+Libev grabs C<SIGCHLD> as soon as the default event loop is
+initialised. This is necessary to guarantee proper behaviour even if
+the first child watcher is started after the child exits. The occurance
+of C<SIGCHLD> is recorded asynchronously, but child reaping is done
+synchronously as part of the event loop processing. Libev always reaps all
+children, even ones not watched.
+
+=head3 Overriding the Built-In Processing
+
+Libev offers no special support for overriding the built-in child
+processing, but if your application collides with libev's default child
+handler, you can override it easily by installing your own handler for
+C<SIGCHLD> after initialising the default loop, and making sure the
+default loop never gets destroyed. You are encouraged, however, to use an
+event-based approach to child reaping and thus use libev's support for
+that, so other libev users can use C<ev_child> watchers freely.
 
 =head3 Watcher-Specific Functions and Data Members
 
@@ -1490,6 +1515,35 @@ C<waitpid> and C<sys/wait.h> documentation for details).
 
 =back
 
+=head3 Examples
+
+Example: C<fork()> a new process and install a child handler to wait for
+its completion.
+
+  ev_child cw;
+
+  static void
+  child_cb (EV_P_ struct ev_child *w, int revents)
+  {
+    ev_child_stop (EV_A_ w);
+    printf ("process %d exited with status %x\n", w->rpid, w->rstatus);
+  }
+
+  pid_t pid = fork ();
+
+  if (pid < 0)
+    // error
+  else if (pid == 0)
+    {
+      // the forked child executes here
+      exit (1);
+    }
+  else
+    {
+      ev_child_init (&cw, child_cb, pid, 0);
+      ev_child_start (EV_DEFAULT_ &cw);
+    }
+
 
 =head2 C<ev_stat> - did the file attributes just change?
 
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