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authorErlang/OTP <[email protected]>2009-11-20 14:54:40 +0000
committerErlang/OTP <[email protected]>2009-11-20 14:54:40 +0000
commit84adefa331c4159d432d22840663c38f155cd4c1 (patch)
treebff9a9c66adda4df2106dfd0e5c053ab182a12bd /lib/erl_interface/src/legacy/erl_timeout.h
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The R13B03 release.OTP_R13B03
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+/*
+ * %CopyrightBegin%
+ *
+ * Copyright Ericsson AB 1997-2009. All Rights Reserved.
+ *
+ * The contents of this file are subject to the Erlang Public License,
+ * Version 1.1, (the "License"); you may not use this file except in
+ * compliance with the License. You should have received a copy of the
+ * Erlang Public License along with this software. If not, it can be
+ * retrieved online at http://www.erlang.org/.
+ *
+ * Software distributed under the License is distributed on an "AS IS"
+ * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+ * the License for the specific language governing rights and limitations
+ * under the License.
+ *
+ * %CopyrightEnd%
+ */
+#ifndef _ERL_TIMEOUT_H
+#define _ERL_TIMEOUT_H
+
+#if !defined (__WIN32__) && !defined (VXWORKS)
+
+#include <setjmp.h>
+
+/*
+ use timeout like this (delay in ms):
+
+ if (timeout(delay,fun(a,b,c))) {
+ printf("timeout occurred\n");
+ }
+ else {
+ ...
+ }
+
+If the call to fun() has not returned before 'delay' ms, it will be
+interrupted and and timeout() will return a non-zero value.
+
+If fun() finishes before 'delay' ms, then timeout will return 0.
+
+If you need the return value from fun then assign it like this:
+
+ if (timeout(delay,(x = fun(...)))) {
+ }
+
+These functions work by setting and catching SIGALRM, and although it
+saves and restores the signal handler, it may not work in situations
+where you are already using SIGALRM (this includes calls to sleep(3)).
+
+Note that although recursive calls to timeout will not fail, they may
+not give the expected results. All invocations of timeout use the same
+timer, which is set on entrance to timeout and restored on exit from
+timeout. So although an inner call to timeout will restart the timer
+for any pending outer call when it exits, any time that has already
+elapsed against the outer timeout is forgotten. In addition, the alarm
+signal will always go to the innermost (last called) timeout, which
+may or may not be the intention in recursive cases.
+
+*/
+
+#define JMPVAL 997 /* magic */
+
+#define timeout(ms,funcall) \
+ (setjmp(*timeout_setup(ms)) == JMPVAL ? -1: \
+ ((void)(funcall), timeout_cancel()))
+
+
+/* don't call any of these directly - use the macro! see above! */
+jmp_buf *timeout_setup(int ms);
+int timeout_cancel(void);
+
+#endif /* WIN32 && VXWORKS */
+
+#endif /* _ERL_TIMEOUT_H */