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/* Copyright (C) 1999-2007 Henry Cejtin, Matthew Fluet, Suresh
* Jagannathan, and Stephen Weeks.
* Copyright (C) 1997-2000 NEC Research Institute.
*
* MLton is released under a BSD-style license.
* See the file MLton-LICENSE for details.
*/
/* GC_startSignalHandler does not do an enter()/leave(), even though
* it is exported. The basis library uses it via _import, not _prim,
* and so does not treat it as a runtime call -- so the invariant in
* enter would fail miserably. It is OK because GC_startHandler must
* be called from within a critical section.
*
* Don't make it inline, because it is also called in basis/Thread.c,
* and when compiling with COMPILE_FAST, they may appear out of order.
*/
void GC_startSignalHandler (GC_state s) {
/* Switch to the signal handler thread. */
if (DEBUG_SIGNALS) {
fprintf (stderr, "GC_startSignalHandler\n");
}
assert (s->atomicState == 1);
assert (s->signalsInfo.signalIsPending);
s->signalsInfo.signalIsPending = FALSE;
s->signalsInfo.amInSignalHandler = TRUE;
assert (s->savedThread == BOGUS_OBJPTR);
s->savedThread = s->currentThread;
/* Set s->atomicState to 2 when switching to the signal handler
* thread; leaving the runtime will decrement s->atomicState to 1,
* the signal handler will then run atomically and will finish by
* switching to the thread to continue with, which will decrement
* s->atomicState to 0.
*/
s->atomicState = 2;
}
void GC_finishSignalHandler (GC_state s) {
if (DEBUG_SIGNALS)
fprintf (stderr, "GC_finishSignalHandler ()\n");
assert (s->atomicState == 1);
s->signalsInfo.amInSignalHandler = FALSE;
}
void switchToSignalHandlerThreadIfNonAtomicAndSignalPending (GC_state s) {
if (s->atomicState == 1
and s->signalsInfo.signalIsPending) {
GC_startSignalHandler (s);
switchToThread (s, s->signalHandlerThread);
}
}
/* GC_handler sets s->limit = 0 so that the next limit check will
* fail. Signals need to be blocked during the handler (i.e. it
* should run atomically) because sigaddset does both a read and a
* write of s->signalsInfo.signalsPending. The signals are blocked
* by Posix_Signal_handle (see Posix/Signal/Signal.c).
*/
void GC_handler (GC_state s, int signum) {
if (DEBUG_SIGNALS)
fprintf (stderr, "GC_handler signum = %d\n", signum);
assert (sigismember (&s->signalsInfo.signalsHandled, signum));
if (s->atomicState == 0)
s->limit = 0;
s->signalsInfo.signalIsPending = TRUE;
sigaddset (&s->signalsInfo.signalsPending, signum);
if (DEBUG_SIGNALS)
fprintf (stderr, "GC_handler done\n");
}
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