From f3e4148511643afb5a7dbeed4be8ec693430732b Mon Sep 17 00:00:00 2001
From: Vitor Santos Costa <vsc@dcc.fc.up.pt>
Date: Thu, 21 May 2009 00:39:57 -0500
Subject: [PATCH] fix bad behavior of time_out by making sure interrupts are
 disabled during critical operation, up to setting a throw.

---
 library/timeout.yap | 33 ++++++++++++++++++++++++++++-----
 1 file changed, 28 insertions(+), 5 deletions(-)

diff --git a/library/timeout.yap b/library/timeout.yap
index 607e73f20..c821f06d9 100644
--- a/library/timeout.yap
+++ b/library/timeout.yap
@@ -24,15 +24,38 @@
 %
 % not the nicest program I've ever seen.
 %
+%
+% I cannot use setup_call_cleanup because I can only take interrupts *after* I set up
+% the catcher, so I have to do the dirty deed myself.
+%
 time_out(Goal, Time, Result) :-
 	T is Time//1000,
 	UT is (Time mod 1000)*1000,
+	yap_hacks:disable_interrupts,
 	% enable alarm
 	alarm(T.UT,throw(time_out),_),
 	% launch goal and wait for signal
-	call_cleanup(
-		catch( ( Result0 = success, once(Goal) ),
-		       time_out,
-		       Result0 = time_out ),
-		alarm(0,_,_) ),
+	catch( run_goal(Goal, Result0),
+	       time_out,
+	       Result0 = time_out ),
 	Result = Result0.
+
+run_goal(Goal, Result0) :-
+	% we can only enable interrupts after alarm was been enabled.
+	yap_hacks:enable_interrupts,
+	Result0 = success,
+	call(Goal),
+	!,
+	% make sure we're not getting an extraneous interrupt if we terminate early....
+	yap_hacks:disable_interrupts.
+	alarm(0,_,_),
+	true.
+run_goal(Goal, Result0) :-
+	yap_hacks:disable_interrupts,
+	% make sure we're not getting an extraneous interrupt if we terminate early....
+	alarm(0,_,_),
+	fail.
+
+complete_time_out :-
+	alarm(0,_,_),
+	yap_hacks:enable_interrupts.