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src/share/vm/memory/referencePolicy.hpp@2c022e432e10 (annotated)

src/share/vm/memory/referencePolicy.hpp

Fri, 20 Sep 2013 10:53:28 +0200

author

stefank

date

Fri, 20 Sep 2013 10:53:28 +0200

changeset 5769

2c022e432e10

parent 4153

b9a9ed0f8eeb

child 6876

710a3c8b516e

permissions

-rw-r--r--

8024974: Incorrect use of GC_locker::is_active()
Summary: SymbolTable and StringTable can make calls to GC_locker::is_active() outside a safepoint. This isn't safe because the GC_locker active state (lock count) is only updated at a safepoint and only remains valid as long as _needs_gc is true. However, outside a safepoint_needs_gc can change to false at any time, which makes it impossible to do a correct call to is_active() in that context. In this case these calls can just be removed since the input argument to basic_add() should never be on the heap and so there's no need to check the GC_locker state. This change also adjusts the assert() in is_active() to makes sure all calls to this function are always done under a safepoint.
Reviewed-by: brutisso, dcubed
Contributed-by: per.liden@oracle.com

duke@435	1	/*
mikael@4153	2	* Copyright (c) 2000, 2012, Oracle and/or its affiliates. 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	*
trims@1907	19	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907	20	* or visit www.oracle.com if you need additional information or have any
trims@1907	21	* questions.
duke@435	22	*
duke@435	23	*/
duke@435	24
stefank@2314	25	#ifndef SHARE_VM_MEMORY_REFERENCEPOLICY_HPP
stefank@2314	26	#define SHARE_VM_MEMORY_REFERENCEPOLICY_HPP
stefank@2314	27
duke@435	28	// referencePolicy is used to determine when soft reference objects
duke@435	29	// should be cleared.
duke@435	30
duke@435	31
zgu@3900	32	class ReferencePolicy : public CHeapObj<mtGC> {
duke@435	33	public:
johnc@3188	34	virtual bool should_clear_reference(oop p, jlong timestamp_clock) {
johnc@3188	35	ShouldNotReachHere();
johnc@3188	36	return true;
johnc@3188	37	}
johnc@3188	38
ysr@888	39	// Capture state (of-the-VM) information needed to evaluate the policy
ysr@892	40	virtual void setup() { /* do nothing */ }
duke@435	41	};
duke@435	42
duke@435	43	class NeverClearPolicy : public ReferencePolicy {
duke@435	44	public:
johnc@3188	45	virtual bool should_clear_reference(oop p, jlong timestamp_clock) {
johnc@3188	46	return false;
johnc@3188	47	}
duke@435	48	};
duke@435	49
duke@435	50	class AlwaysClearPolicy : public ReferencePolicy {
duke@435	51	public:
johnc@3188	52	virtual bool should_clear_reference(oop p, jlong timestamp_clock) {
johnc@3188	53	return true;
johnc@3188	54	}
duke@435	55	};
duke@435	56
duke@435	57	class LRUCurrentHeapPolicy : public ReferencePolicy {
duke@435	58	private:
duke@435	59	jlong _max_interval;
duke@435	60
duke@435	61	public:
duke@435	62	LRUCurrentHeapPolicy();
duke@435	63
ysr@888	64	// Capture state (of-the-VM) information needed to evaluate the policy
ysr@892	65	void setup();
johnc@3188	66	virtual bool should_clear_reference(oop p, jlong timestamp_clock);
duke@435	67	};
duke@435	68
duke@435	69	class LRUMaxHeapPolicy : public ReferencePolicy {
duke@435	70	private:
duke@435	71	jlong _max_interval;
duke@435	72
duke@435	73	public:
duke@435	74	LRUMaxHeapPolicy();
duke@435	75
ysr@888	76	// Capture state (of-the-VM) information needed to evaluate the policy
ysr@892	77	void setup();
johnc@3188	78	virtual bool should_clear_reference(oop p, jlong timestamp_clock);
duke@435	79	};
stefank@2314	80
stefank@2314	81	#endif // SHARE_VM_MEMORY_REFERENCEPOLICY_HPP