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src/share/vm/memory/gcLocker.cpp@a61af66fc99e (annotated)

src/share/vm/memory/gcLocker.cpp

Sat, 01 Dec 2007 00:00:00 +0000

author

duke

date

Sat, 01 Dec 2007 00:00:00 +0000

changeset 435

a61af66fc99e

child 574

c0492d52d55b

permissions

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duke@435	1	/*
duke@435	2	* Copyright 1997-2007 Sun Microsystems, Inc. All Rights Reserved.
duke@435	3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435	4	*
duke@435	5	* This code is free software; you can redistribute it and/or modify it
duke@435	6	* under the terms of the GNU General Public License version 2 only, as
duke@435	7	* published by the Free Software Foundation.
duke@435	8	*
duke@435	9	* This code is distributed in the hope that it will be useful, but WITHOUT
duke@435	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@435	12	* version 2 for more details (a copy is included in the LICENSE file that
duke@435	13	* accompanied this code).
duke@435	14	*
duke@435	15	* You should have received a copy of the GNU General Public License version
duke@435	16	* 2 along with this work; if not, write to the Free Software Foundation,
duke@435	17	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435	18	*
duke@435	19	* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
duke@435	20	* CA 95054 USA or visit www.sun.com if you need additional information or
duke@435	21	* have any questions.
duke@435	22	*
duke@435	23	*/
duke@435	24
duke@435	25	# include "incls/_precompiled.incl"
duke@435	26	# include "incls/_gcLocker.cpp.incl"
duke@435	27
duke@435	28	volatile jint GC_locker::_jni_lock_count = 0;
duke@435	29	volatile jint GC_locker::_lock_count = 0;
duke@435	30	volatile bool GC_locker::_needs_gc = false;
duke@435	31	volatile bool GC_locker::_doing_gc = false;
duke@435	32
duke@435	33	void GC_locker::stall_until_clear() {
duke@435	34	assert(!JavaThread::current()->in_critical(), "Would deadlock");
duke@435	35	MutexLocker ml(JNICritical_lock);
duke@435	36	// Wait for _needs_gc to be cleared
duke@435	37	while (GC_locker::needs_gc()) {
duke@435	38	JNICritical_lock->wait();
duke@435	39	}
duke@435	40	}
duke@435	41
duke@435	42	void GC_locker::jni_lock_slow() {
duke@435	43	MutexLocker mu(JNICritical_lock);
duke@435	44	// Block entering threads if we know at least one thread is in a
duke@435	45	// JNI critical region and we need a GC.
duke@435	46	// We check that at least one thread is in a critical region before
duke@435	47	// blocking because blocked threads are woken up by a thread exiting
duke@435	48	// a JNI critical region.
duke@435	49	while ((is_jni_active() && needs_gc()) || _doing_gc) {
duke@435	50	JNICritical_lock->wait();
duke@435	51	}
duke@435	52	jni_lock();
duke@435	53	}
duke@435	54
duke@435	55	void GC_locker::jni_unlock_slow() {
duke@435	56	MutexLocker mu(JNICritical_lock);
duke@435	57	jni_unlock();
duke@435	58	if (needs_gc() && !is_jni_active()) {
duke@435	59	// We're the last thread out. Cause a GC to occur.
duke@435	60	// GC will also check is_active, so this check is not
duke@435	61	// strictly needed. It's added here to make it clear that
duke@435	62	// the GC will NOT be performed if any other caller
duke@435	63	// of GC_locker::lock() still needs GC locked.
duke@435	64	if (!is_active()) {
duke@435	65	_doing_gc = true;
duke@435	66	{
duke@435	67	// Must give up the lock while at a safepoint
duke@435	68	MutexUnlocker munlock(JNICritical_lock);
duke@435	69	Universe::heap()->collect(GCCause::_gc_locker);
duke@435	70	}
duke@435	71	_doing_gc = false;
duke@435	72	}
duke@435	73	clear_needs_gc();
duke@435	74	JNICritical_lock->notify_all();
duke@435	75	}
duke@435	76	}
duke@435	77
duke@435	78	// Implementation of No_GC_Verifier
duke@435	79
duke@435	80	#ifdef ASSERT
duke@435	81
duke@435	82	No_GC_Verifier::No_GC_Verifier(bool verifygc) {
duke@435	83	_verifygc = verifygc;
duke@435	84	if (_verifygc) {
duke@435	85	CollectedHeap* h = Universe::heap();
duke@435	86	assert(!h->is_gc_active(), "GC active during No_GC_Verifier");
duke@435	87	_old_invocations = h->total_collections();
duke@435	88	}
duke@435	89	}
duke@435	90
duke@435	91
duke@435	92	No_GC_Verifier::~No_GC_Verifier() {
duke@435	93	if (_verifygc) {
duke@435	94	CollectedHeap* h = Universe::heap();
duke@435	95	assert(!h->is_gc_active(), "GC active during No_GC_Verifier");
duke@435	96	if (_old_invocations != h->total_collections()) {
duke@435	97	fatal("collection in a No_GC_Verifier secured function");
duke@435	98	}
duke@435	99	}
duke@435	100	}
duke@435	101
duke@435	102	Pause_No_GC_Verifier::Pause_No_GC_Verifier(No_GC_Verifier * ngcv) {
duke@435	103	_ngcv = ngcv;
duke@435	104	if (_ngcv->_verifygc) {
duke@435	105	// if we were verifying, then make sure that nothing is
duke@435	106	// wrong before we "pause" verification
duke@435	107	CollectedHeap* h = Universe::heap();
duke@435	108	assert(!h->is_gc_active(), "GC active during No_GC_Verifier");
duke@435	109	if (_ngcv->_old_invocations != h->total_collections()) {
duke@435	110	fatal("collection in a No_GC_Verifier secured function");
duke@435	111	}
duke@435	112	}
duke@435	113	}
duke@435	114
duke@435	115
duke@435	116	Pause_No_GC_Verifier::~Pause_No_GC_Verifier() {
duke@435	117	if (_ngcv->_verifygc) {
duke@435	118	// if we were verifying before, then reenable verification
duke@435	119	CollectedHeap* h = Universe::heap();
duke@435	120	assert(!h->is_gc_active(), "GC active during No_GC_Verifier");
duke@435	121	_ngcv->_old_invocations = h->total_collections();
duke@435	122	}
duke@435	123	}
duke@435	124
duke@435	125
duke@435	126	// JRT_LEAF rules:
duke@435	127	// A JRT_LEAF method may not interfere with safepointing by
duke@435	128	// 1) acquiring or blocking on a Mutex or JavaLock - checked
duke@435	129	// 2) allocating heap memory - checked
duke@435	130	// 3) executing a VM operation - checked
duke@435	131	// 4) executing a system call (including malloc) that could block or grab a lock
duke@435	132	// 5) invoking GC
duke@435	133	// 6) reaching a safepoint
duke@435	134	// 7) running too long
duke@435	135	// Nor may any method it calls.
duke@435	136	JRT_Leaf_Verifier::JRT_Leaf_Verifier()
duke@435	137	: No_Safepoint_Verifier(true, JRT_Leaf_Verifier::should_verify_GC())
duke@435	138	{
duke@435	139	}
duke@435	140
duke@435	141	JRT_Leaf_Verifier::~JRT_Leaf_Verifier()
duke@435	142	{
duke@435	143	}
duke@435	144
duke@435	145	bool JRT_Leaf_Verifier::should_verify_GC() {
duke@435	146	switch (JavaThread::current()->thread_state()) {
duke@435	147	case _thread_in_Java:
duke@435	148	// is in a leaf routine, there must be no safepoint.
duke@435	149	return true;
duke@435	150	case _thread_in_native:
duke@435	151	// A native thread is not subject to safepoints.
duke@435	152	// Even while it is in a leaf routine, GC is ok
duke@435	153	return false;
duke@435	154	default:
duke@435	155	// Leaf routines cannot be called from other contexts.
duke@435	156	ShouldNotReachHere();
duke@435	157	return false;
duke@435	158	}
duke@435	159	}
duke@435	160	#endif