--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/memory/gcLocker.cpp Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,160 @@
+/*
+ * Copyright 1997-2007 Sun Microsystems, Inc. All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+# include "incls/_precompiled.incl"
+# include "incls/_gcLocker.cpp.incl"
+
+volatile jint GC_locker::_jni_lock_count = 0;
+volatile jint GC_locker::_lock_count = 0;
+volatile bool GC_locker::_needs_gc = false;
+volatile bool GC_locker::_doing_gc = false;
+
+void GC_locker::stall_until_clear() {
+ assert(!JavaThread::current()->in_critical(), "Would deadlock");
+ MutexLocker ml(JNICritical_lock);
+ // Wait for _needs_gc to be cleared
+ while (GC_locker::needs_gc()) {
+ JNICritical_lock->wait();
+ }
+}
+
+void GC_locker::jni_lock_slow() {
+ MutexLocker mu(JNICritical_lock);
+ // Block entering threads if we know at least one thread is in a
+ // JNI critical region and we need a GC.
+ // We check that at least one thread is in a critical region before
+ // blocking because blocked threads are woken up by a thread exiting
+ // a JNI critical region.
+ while ((is_jni_active() && needs_gc()) || _doing_gc) {
+ JNICritical_lock->wait();
+ }
+ jni_lock();
+}
+
+void GC_locker::jni_unlock_slow() {
+ MutexLocker mu(JNICritical_lock);
+ jni_unlock();
+ if (needs_gc() && !is_jni_active()) {
+ // We're the last thread out. Cause a GC to occur.
+ // GC will also check is_active, so this check is not
+ // strictly needed. It's added here to make it clear that
+ // the GC will NOT be performed if any other caller
+ // of GC_locker::lock() still needs GC locked.
+ if (!is_active()) {
+ _doing_gc = true;
+ {
+ // Must give up the lock while at a safepoint
+ MutexUnlocker munlock(JNICritical_lock);
+ Universe::heap()->collect(GCCause::_gc_locker);
+ }
+ _doing_gc = false;
+ }
+ clear_needs_gc();
+ JNICritical_lock->notify_all();
+ }
+}
+
+// Implementation of No_GC_Verifier
+
+#ifdef ASSERT
+
+No_GC_Verifier::No_GC_Verifier(bool verifygc) {
+ _verifygc = verifygc;
+ if (_verifygc) {
+ CollectedHeap* h = Universe::heap();
+ assert(!h->is_gc_active(), "GC active during No_GC_Verifier");
+ _old_invocations = h->total_collections();
+ }
+}
+
+
+No_GC_Verifier::~No_GC_Verifier() {
+ if (_verifygc) {
+ CollectedHeap* h = Universe::heap();
+ assert(!h->is_gc_active(), "GC active during No_GC_Verifier");
+ if (_old_invocations != h->total_collections()) {
+ fatal("collection in a No_GC_Verifier secured function");
+ }
+ }
+}
+
+Pause_No_GC_Verifier::Pause_No_GC_Verifier(No_GC_Verifier * ngcv) {
+ _ngcv = ngcv;
+ if (_ngcv->_verifygc) {
+ // if we were verifying, then make sure that nothing is
+ // wrong before we "pause" verification
+ CollectedHeap* h = Universe::heap();
+ assert(!h->is_gc_active(), "GC active during No_GC_Verifier");
+ if (_ngcv->_old_invocations != h->total_collections()) {
+ fatal("collection in a No_GC_Verifier secured function");
+ }
+ }
+}
+
+
+Pause_No_GC_Verifier::~Pause_No_GC_Verifier() {
+ if (_ngcv->_verifygc) {
+ // if we were verifying before, then reenable verification
+ CollectedHeap* h = Universe::heap();
+ assert(!h->is_gc_active(), "GC active during No_GC_Verifier");
+ _ngcv->_old_invocations = h->total_collections();
+ }
+}
+
+
+// JRT_LEAF rules:
+// A JRT_LEAF method may not interfere with safepointing by
+// 1) acquiring or blocking on a Mutex or JavaLock - checked
+// 2) allocating heap memory - checked
+// 3) executing a VM operation - checked
+// 4) executing a system call (including malloc) that could block or grab a lock
+// 5) invoking GC
+// 6) reaching a safepoint
+// 7) running too long
+// Nor may any method it calls.
+JRT_Leaf_Verifier::JRT_Leaf_Verifier()
+ : No_Safepoint_Verifier(true, JRT_Leaf_Verifier::should_verify_GC())
+{
+}
+
+JRT_Leaf_Verifier::~JRT_Leaf_Verifier()
+{
+}
+
+bool JRT_Leaf_Verifier::should_verify_GC() {
+ switch (JavaThread::current()->thread_state()) {
+ case _thread_in_Java:
+ // is in a leaf routine, there must be no safepoint.
+ return true;
+ case _thread_in_native:
+ // A native thread is not subject to safepoints.
+ // Even while it is in a leaf routine, GC is ok
+ return false;
+ default:
+ // Leaf routines cannot be called from other contexts.
+ ShouldNotReachHere();
+ return false;
+ }
+}
+#endif