From 6f329fd6404650011ce8124a9c504e880ecc5a6b Mon Sep 17 00:00:00 2001
From: Martin Mares <mj@ucw.cz>
Date: Mon, 14 Nov 2005 20:06:49 +0000
Subject: [PATCH] Changed main_loop shutdown logic once again. The former
 mechanism with a single global main_shutdown variable was too inflexible. I
 have given all hooks a possibility to either invoke an immediate shutdown or
 a "soft" shutdown which is activated if all hooks agree on it (the idea is
 that different parts of a single program can have their local opinion on
 whether there is more to do or not).

---
 lib/mainloop.c | 31 +++++++++++++++----------------
 lib/mainloop.h | 11 +++++++++--
 2 files changed, 24 insertions(+), 18 deletions(-)

diff --git a/lib/mainloop.c b/lib/mainloop.c
index 544a7b7d..5b5fb45a 100644
--- a/lib/mainloop.c
+++ b/lib/mainloop.c
@@ -345,7 +345,7 @@ main_rebuild_poll_table(void)
   main_poll_table_obsolete = 0;
 }
 
-int
+void
 main_loop(void)
 {
   DBG("MAIN: Entering main_loop");
@@ -366,12 +366,24 @@ main_loop(void)
 	  DBG("MAIN: Timer %p expired at %Ld", tm, (long long) tm->expires);
 	  tm->handler(tm);
 	}
+      int hook_min = HOOK_RETRY;
+      int hook_max = HOOK_SHUTDOWN;
       CLIST_WALK_DELSAFE(ho, main_hook_list, tmp)
 	{
 	  DBG("MAIN: Hook %p", ho);
-	  if (ho->handler(ho))
-	    wake = 0;
+	  int ret = ho->handler(ho);
+	  hook_min = MIN(hook_min, ret);
+	  hook_max = MAX(hook_max, ret);
 	}
+      if (hook_min == HOOK_SHUTDOWN ||
+	  hook_min == HOOK_DONE && hook_max == HOOK_DONE ||
+	  main_shutdown)
+	{
+	  DBG("MAIN: Shut down by %s", main_shutdown ? "main_shutdown" : "a hook");
+	  return;
+	}
+      if (hook_max == HOOK_RETRY)
+	wake = 0;
       if (main_poll_table_obsolete)
 	main_rebuild_poll_table();
       if (!clist_empty(&main_process_list))
@@ -395,19 +407,6 @@ main_loop(void)
 	      wake = 0;
 	    }
 	}
-      if (clist_empty(&main_file_list) &&
-	  clist_empty(&main_timer_list) &&
-	  clist_empty(&main_hook_list) &&
-	  clist_empty(&main_process_list))
-	{
-	  DBG("MAIN: Nothing to do, exiting");
-	  return 0;
-	}
-      if (main_shutdown)
-	{
-	  DBG("MAIN: Shutdown");
-	  return 1;
-	}
       /* FIXME: Here is a small race window where SIGCHLD can come unnoticed. */
       if ((tm = clist_head(&main_timer_list)) && tm->expires < wake)
 	wake = tm->expires;
diff --git a/lib/mainloop.h b/lib/mainloop.h
index a8626f03..f321c2b5 100644
--- a/lib/mainloop.h
+++ b/lib/mainloop.h
@@ -71,10 +71,17 @@ void file_close_all(void);			/* Close all known main_file's; frequently used bef
 
 struct main_hook {
   cnode n;
-  int (*handler)(struct main_hook *ho);		/* [*] Hook function; returns 1 if should be called again */
+  int (*handler)(struct main_hook *ho);		/* [*] Hook function; returns HOOK_xxx */
   void *data;					/* [*] For use by the handler */
 };
 
+enum main_hook_return {
+  HOOK_IDLE,					/* Call again when the main loop becomes idle again */
+  HOOK_RETRY,					/* Call again as soon as possible */
+  HOOK_DONE = -1,				/* Shut down the main loop if all hooks return this value */
+  HOOK_SHUTDOWN = -2				/* Shut down the main loop immediately */
+};
+
 void hook_add(struct main_hook *ho);
 void hook_del(struct main_hook *ho);
 
@@ -96,7 +103,7 @@ int process_fork(struct main_process *mp);
 /* The main loop */
 
 void main_init(void);
-int main_loop(void);
+void main_loop(void);
 void main_debug(void);
 
 #endif
-- 
2.39.2