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src/share/vm/runtime/jniHandles.hpp@63147986a428 (annotated)

src/share/vm/runtime/jniHandles.hpp

Wed, 18 Sep 2013 07:02:10 -0700

author

dcubed

date

Wed, 18 Sep 2013 07:02:10 -0700

changeset 5743

63147986a428

parent 4037

da91efe96a93

child 6876

710a3c8b516e

child 7627

d68158e12cea

permissions

-rw-r--r--

8019835: Strings interned in different threads equal but does not ==
Summary: Add -XX:+VerifyStringTableAtExit option and code to verify StringTable invariants.
Reviewed-by: rdurbin, sspitsyn, coleenp

duke@435	1	/*
coleenp@4037	2	* Copyright (c) 1998, 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_RUNTIME_JNIHANDLES_HPP
stefank@2314	26	#define SHARE_VM_RUNTIME_JNIHANDLES_HPP
stefank@2314	27
stefank@2314	28	#include "runtime/handles.hpp"
stefank@2314	29	#include "utilities/top.hpp"
stefank@2314	30
duke@435	31	class JNIHandleBlock;
duke@435	32
duke@435	33
duke@435	34	// Interface for creating and resolving local/global JNI handles
duke@435	35
duke@435	36	class JNIHandles : AllStatic {
duke@435	37	friend class VMStructs;
duke@435	38	private:
duke@435	39	static JNIHandleBlock* _global_handles; // First global handle block
duke@435	40	static JNIHandleBlock* _weak_global_handles; // First weak global handle block
duke@435	41	static oop _deleted_handle; // Sentinel marking deleted handles
duke@435	42
duke@435	43	public:
duke@435	44	// Resolve handle into oop
duke@435	45	inline static oop resolve(jobject handle);
duke@435	46	// Resolve externally provided handle into oop with some guards
duke@435	47	inline static oop resolve_external_guard(jobject handle);
duke@435	48	// Resolve handle into oop, result guaranteed not to be null
duke@435	49	inline static oop resolve_non_null(jobject handle);
duke@435	50
duke@435	51	// Local handles
duke@435	52	static jobject make_local(oop obj);
duke@435	53	static jobject make_local(JNIEnv* env, oop obj); // Fast version when env is known
duke@435	54	static jobject make_local(Thread* thread, oop obj); // Even faster version when current thread is known
duke@435	55	inline static void destroy_local(jobject handle);
duke@435	56
duke@435	57	// Global handles
duke@435	58	static jobject make_global(Handle obj);
duke@435	59	static void destroy_global(jobject handle);
duke@435	60
duke@435	61	// Weak global handles
duke@435	62	static jobject make_weak_global(Handle obj);
duke@435	63	static void destroy_weak_global(jobject handle);
duke@435	64
duke@435	65	// Sentinel marking deleted handles in block. Note that we cannot store NULL as
duke@435	66	// the sentinel, since clearing weak global JNI refs are done by storing NULL in
duke@435	67	// the handle. The handle may not be reused before destroy_weak_global is called.
duke@435	68	static oop deleted_handle() { return _deleted_handle; }
duke@435	69
duke@435	70	// Initialization
duke@435	71	static void initialize();
duke@435	72
duke@435	73	// Debugging
duke@435	74	static void print_on(outputStream* st);
duke@435	75	static void print() { print_on(tty); }
duke@435	76	static void verify();
duke@435	77	static bool is_local_handle(Thread* thread, jobject handle);
duke@435	78	static bool is_frame_handle(JavaThread* thr, jobject obj);
duke@435	79	static bool is_global_handle(jobject handle);
duke@435	80	static bool is_weak_global_handle(jobject handle);
duke@435	81	static long global_handle_memory_usage();
duke@435	82	static long weak_global_handle_memory_usage();
duke@435	83
duke@435	84	// Garbage collection support(global handles only, local handles are traversed from thread)
duke@435	85	// Traversal of regular global handles
duke@435	86	static void oops_do(OopClosure* f);
duke@435	87	// Traversal of weak global handles. Unreachable oops are cleared.
duke@435	88	static void weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f);
duke@435	89	};
duke@435	90
duke@435	91
duke@435	92
duke@435	93	// JNI handle blocks holding local/global JNI handles
duke@435	94
zgu@3900	95	class JNIHandleBlock : public CHeapObj<mtInternal> {
duke@435	96	friend class VMStructs;
never@1445	97	friend class CppInterpreter;
never@1445	98
duke@435	99	private:
duke@435	100	enum SomeConstants {
duke@435	101	block_size_in_oops = 32 // Number of handles per handle block
duke@435	102	};
duke@435	103
duke@435	104	oop _handles[block_size_in_oops]; // The handles
duke@435	105	int _top; // Index of next unused handle
duke@435	106	JNIHandleBlock* _next; // Link to next block
duke@435	107
duke@435	108	// The following instance variables are only used by the first block in a chain.
duke@435	109	// Having two types of blocks complicates the code and the space overhead in negligble.
duke@435	110	JNIHandleBlock* _last; // Last block in use
duke@435	111	JNIHandleBlock* _pop_frame_link; // Block to restore on PopLocalFrame call
duke@435	112	oop* _free_list; // Handle free list
duke@435	113	int _allocate_before_rebuild; // Number of blocks to allocate before rebuilding free list
duke@435	114
duke@435	115	#ifndef PRODUCT
duke@435	116	JNIHandleBlock* _block_list_link; // Link for list below
duke@435	117	static JNIHandleBlock* _block_list; // List of all allocated blocks (for debugging only)
duke@435	118	#endif
duke@435	119
duke@435	120	static JNIHandleBlock* _block_free_list; // Free list of currently unused blocks
duke@435	121	static int _blocks_allocated; // For debugging/printing
duke@435	122
duke@435	123	// Fill block with bad_handle values
duke@435	124	void zap();
duke@435	125
never@1445	126	protected:
duke@435	127	// No more handles in the both the current and following blocks
duke@435	128	void clear() { _top = 0; }
duke@435	129
never@1445	130	private:
duke@435	131	// Free list computation
duke@435	132	void rebuild_free_list();
duke@435	133
duke@435	134	public:
duke@435	135	// Handle allocation
duke@435	136	jobject allocate_handle(oop obj);
duke@435	137
duke@435	138	// Block allocation and block free list management
duke@435	139	static JNIHandleBlock* allocate_block(Thread* thread = NULL);
duke@435	140	static void release_block(JNIHandleBlock* block, Thread* thread = NULL);
duke@435	141
duke@435	142	// JNI PushLocalFrame/PopLocalFrame support
duke@435	143	JNIHandleBlock* pop_frame_link() const { return _pop_frame_link; }
duke@435	144	void set_pop_frame_link(JNIHandleBlock* block) { _pop_frame_link = block; }
duke@435	145
duke@435	146	// Stub generator support
duke@435	147	static int top_offset_in_bytes() { return offset_of(JNIHandleBlock, _top); }
duke@435	148
duke@435	149	// Garbage collection support
duke@435	150	// Traversal of regular handles
duke@435	151	void oops_do(OopClosure* f);
duke@435	152	// Traversal of weak handles. Unreachable oops are cleared.
duke@435	153	void weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f);
duke@435	154
duke@435	155	// Debugging
duke@435	156	bool chain_contains(jobject handle) const; // Does this block or following blocks contain handle
duke@435	157	bool contains(jobject handle) const; // Does this block contain handle
duke@435	158	int length() const; // Length of chain starting with this block
duke@435	159	long memory_usage() const;
duke@435	160	#ifndef PRODUCT
duke@435	161	static bool any_contains(jobject handle); // Does any block currently in use contain handle
duke@435	162	static void print_statistics();
duke@435	163	#endif
duke@435	164	};
duke@435	165
duke@435	166
duke@435	167	inline oop JNIHandles::resolve(jobject handle) {
duke@435	168	oop result = (handle == NULL ? (oop)NULL : *(oop*)handle);
duke@435	169	assert(result != NULL || (handle == NULL || !CheckJNICalls || is_weak_global_handle(handle)), "Invalid value read from jni handle");
duke@435	170	assert(result != badJNIHandle, "Pointing to zapped jni handle area");
duke@435	171	return result;
duke@435	172	};
duke@435	173
duke@435	174
duke@435	175	inline oop JNIHandles::resolve_external_guard(jobject handle) {
duke@435	176	if (handle == NULL) return NULL;
duke@435	177	oop result = *(oop*)handle;
duke@435	178	if (result == NULL || result == badJNIHandle) return NULL;
duke@435	179	return result;
duke@435	180	};
duke@435	181
duke@435	182
duke@435	183	inline oop JNIHandles::resolve_non_null(jobject handle) {
duke@435	184	assert(handle != NULL, "JNI handle should not be null");
duke@435	185	oop result = *(oop*)handle;
duke@435	186	assert(result != NULL, "Invalid value read from jni handle");
duke@435	187	assert(result != badJNIHandle, "Pointing to zapped jni handle area");
duke@435	188	// Don't let that private _deleted_handle object escape into the wild.
duke@435	189	assert(result != deleted_handle(), "Used a deleted global handle.");
duke@435	190	return result;
duke@435	191	};
duke@435	192
duke@435	193	inline void JNIHandles::destroy_local(jobject handle) {
duke@435	194	if (handle != NULL) {
duke@435	195	*((oop*)handle) = deleted_handle(); // Mark the handle as deleted, allocate will reuse it
duke@435	196	}
duke@435	197	}
stefank@2314	198
stefank@2314	199	#endif // SHARE_VM_RUNTIME_JNIHANDLES_HPP