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/*
* 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");
if (PrintJNIGCStalls && PrintGCDetails) {
ResourceMark rm; // JavaThread::name() allocates to convert to UTF8
gclog_or_tty->print_cr(
"Allocation failed. Thread \"%s\" is stalled by JNI critical section.",
JavaThread::current()->name());
}
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
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