From: Malcolm Beattie <mbeattie@sable.ox.ac.uk>
Date: Thu, 16 Oct 1997 16:26:53 +0000 (+0000)
Subject: Correct threads_mutex locking in main thread destruction.
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=0a00ffdb1e70eb883974513d0ee6f4afd54aca19;p=p5sagit%2Fp5-mst-13.2.git

Correct threads_mutex locking in main thread destruction.
Add per-interp thrsv to hold SV struct thread for main thread.
Move Thread.xs MUTEX_DESTROY from end of threadstart to remove_thread.
Add Thread/list.t test of Thread->list method.
Let Thread::Semaphore methods up and down take an extra argument.

p4raw-id: //depot/perlext/Thread@140
---

diff --git a/Thread.xs b/Thread.xs
index a5382d9..3dc2516 100644
--- a/Thread.xs
+++ b/Thread.xs
@@ -15,6 +15,7 @@ Thread t;
     DEBUG_L(WITH_THR(PerlIO_printf(PerlIO_stderr(),
 				   "%p: remove_thread %p\n", thr, t)));
     MUTEX_LOCK(&threads_mutex);
+    MUTEX_DESTROY(&t->mutex);
     nthreads--;
     t->prev->next = t->next;
     t->next->prev = t->prev;
@@ -181,7 +182,6 @@ void *arg;
 	croak("panic: illegal state %u at end of threadstart", ThrSTATE(thr));
 	/* NOTREACHED */
     }
-    MUTEX_DESTROY(&thr->mutex);
     return (void *) returnav;	/* Available for anyone to join with us */
 				/* unless we are detached in which case */
 				/* noone will see the value anyway. */
@@ -474,7 +474,6 @@ list(class)
 	do {
 	    n = nthreads;
 	    MUTEX_UNLOCK(&threads_mutex);
-	    DEBUG_L(PerlIO_printf(PerlIO_stderr(), "list: n = %d\n", n));
 	    if (AvFILL(av) < n - 1) {
 		int i = AvFILL(av);
 		for (i = AvFILL(av); i < n - 1; i++) {
@@ -498,14 +497,13 @@ list(class)
 	t = thr;
 	svp = AvARRAY(av);
 	do {
-	    SV *sv = SvRV(*svp++);
-	    DEBUG_L(PerlIO_printf(PerlIO_stderr(),
-  				  "list: filling in thread %p\n", t));
+	    SV *sv = (SV*)SvRV(*svp);
 	    sv_setiv(sv, t->tid);
 	    SvMAGIC(sv)->mg_obj = SvREFCNT_inc(t->Toursv);
 	    SvMAGIC(sv)->mg_flags |= MGf_REFCOUNTED;
 	    SvMAGIC(sv)->mg_private = Thread_MAGIC_SIGNATURE;
 	    t = t->next;
+	    svp++;
 	} while (t != thr);
 	/*  */
 	MUTEX_UNLOCK(&threads_mutex);
diff --git a/Thread/Semaphore.pm b/Thread/Semaphore.pm
index d34d6bd..9e5852f 100644
--- a/Thread/Semaphore.pm
+++ b/Thread/Semaphore.pm
@@ -10,14 +10,16 @@ sub new {
 sub down {
     use attrs qw(locked method);
     my $s = shift;
-    cond_wait $s until $$s > 0;
-    $$s--;
+    my $inc = @_ ? shift : 1;
+    cond_wait $s until $$s >= $inc;
+    $$s -= $inc;
 }
 
 sub up {
     use attrs qw(locked method);
     my $s = shift;
-    $$s++ > 0 and cond_broadcast $s;
+    my $inc = @_ ? shift : 1;
+    ($$s += $inc) > 0 and cond_broadcast $s;
 }
 
 1;
diff --git a/list.t b/list.t
new file mode 100644
index 0000000..f13f4b2
--- /dev/null
+++ b/list.t
@@ -0,0 +1,30 @@
+use Thread qw(async);
+use Thread::Semaphore;
+
+my $sem = Thread::Semaphore->new(0);
+
+$nthreads = 4;
+
+for (my $i = 0; $i < $nthreads; $i++) {
+    async {
+     	my $tid = Thread->self->tid;
+	print "thread $tid started...\n";
+	$sem->down;
+	print "thread $tid finishing\n";
+    };
+}
+
+print "main: started $nthreads threads\n";
+sleep 2;
+
+my @list = Thread->list;
+printf "main: Thread->list returned %d threads\n", scalar(@list);
+
+foreach my $t (@list) {
+    print "inspecting thread $t...\n";
+    print "...deref is $$t\n";
+    print "...flags = ", $t->flags, "\n";
+    print "...tid = ", $t->tid, "\n";
+}
+print "main thread telling workers to finish off...\n";
+$sem->up($nthreads);