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src/share/vm/runtime/handles.hpp@a61af66fc99e (annotated)

src/share/vm/runtime/handles.hpp

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

author

duke

date

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

changeset 435

a61af66fc99e

child 1100

c89f86385056

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	//------------------------------------------------------------------------------------------------------------------------
duke@435	26	// In order to preserve oops during garbage collection, they should be
duke@435	27	// allocated and passed around via Handles within the VM. A handle is
duke@435	28	// simply an extra indirection allocated in a thread local handle area.
duke@435	29	//
duke@435	30	// A handle is a ValueObj, so it can be passed around as a value, can
duke@435	31	// be used as a parameter w/o using &-passing, and can be returned as a
duke@435	32	// return value.
duke@435	33	//
duke@435	34	// oop parameters and return types should be Handles whenever feasible.
duke@435	35	//
duke@435	36	// Handles are declared in a straight-forward manner, e.g.
duke@435	37	//
duke@435	38	// oop obj = ...;
duke@435	39	// Handle h1(obj); // allocate new handle
duke@435	40	// Handle h2(thread, obj); // faster allocation when current thread is known
duke@435	41	// Handle h3; // declare handle only, no allocation occurs
duke@435	42	// ...
duke@435	43	// h3 = h1; // make h3 refer to same indirection as h1
duke@435	44	// oop obj2 = h2(); // get handle value
duke@435	45	// h1->print(); // invoking operation on oop
duke@435	46	//
duke@435	47	// Handles are specialized for different oop types to provide extra type
duke@435	48	// information and avoid unnecessary casting. For each oop type xxxOop
duke@435	49	// there is a corresponding handle called xxxHandle, e.g.
duke@435	50	//
duke@435	51	// oop Handle
duke@435	52	// methodOop methodHandle
duke@435	53	// instanceOop instanceHandle
duke@435	54	//
duke@435	55	// For klassOops, it is often useful to model the Klass hierarchy in order
duke@435	56	// to get access to the klass_part without casting. For each xxxKlass there
duke@435	57	// is a corresponding handle called xxxKlassHandle, e.g.
duke@435	58	//
duke@435	59	// klassOop Klass KlassHandle
duke@435	60	// klassOop methodKlass methodKlassHandle
duke@435	61	// klassOop instanceKlass instanceKlassHandle
duke@435	62	//
duke@435	63
duke@435	64	//------------------------------------------------------------------------------------------------------------------------
duke@435	65	// Base class for all handles. Provides overloading of frequently
duke@435	66	// used operators for ease of use.
duke@435	67
duke@435	68	class Handle VALUE_OBJ_CLASS_SPEC {
duke@435	69	private:
duke@435	70	oop* _handle;
duke@435	71
duke@435	72	protected:
duke@435	73	oop obj() const { return _handle == NULL ? (oop)NULL : *_handle; }
duke@435	74	oop non_null_obj() const { assert(_handle != NULL, "resolving NULL handle"); return *_handle; }
duke@435	75
duke@435	76	public:
duke@435	77	// Constructors
duke@435	78	Handle() { _handle = NULL; }
duke@435	79	Handle(oop obj);
duke@435	80	#ifndef ASSERT
duke@435	81	Handle(Thread* thread, oop obj);
duke@435	82	#else
duke@435	83	// Don't inline body with assert for current thread
duke@435	84	Handle(Thread* thread, oop obj);
duke@435	85	#endif // ASSERT
duke@435	86
duke@435	87	// General access
duke@435	88	oop operator () () const { return obj(); }
duke@435	89	oop operator -> () const { return non_null_obj(); }
duke@435	90	bool operator == (oop o) const { return obj() == o; }
duke@435	91	bool operator == (const Handle& h) const { return obj() == h.obj(); }
duke@435	92
duke@435	93	// Null checks
duke@435	94	bool is_null() const { return _handle == NULL; }
duke@435	95	bool not_null() const { return _handle != NULL; }
duke@435	96
duke@435	97	// Debugging
duke@435	98	void print() { obj()->print(); }
duke@435	99
duke@435	100	// Direct interface, use very sparingly.
duke@435	101	// Used by JavaCalls to quickly convert handles and to create handles static data structures.
duke@435	102	// Constructor takes a dummy argument to prevent unintentional type conversion in C++.
duke@435	103	Handle(oop *handle, bool dummy) { _handle = handle; }
duke@435	104
duke@435	105	// Raw handle access. Allows easy duplication of Handles. This can be very unsafe
duke@435	106	// since duplicates is only valid as long as original handle is alive.
duke@435	107	oop* raw_value() { return _handle; }
duke@435	108	static oop raw_resolve(oop *handle) { return handle == NULL ? (oop)NULL : *handle; }
duke@435	109	};
duke@435	110
duke@435	111
duke@435	112	//------------------------------------------------------------------------------------------------------------------------
duke@435	113	// Base class for Handles containing klassOops. Provides overloading of frequently
duke@435	114	// used operators for ease of use and typed access to the Klass part.
duke@435	115	class KlassHandle: public Handle {
duke@435	116	protected:
duke@435	117	klassOop obj() const { return (klassOop)Handle::obj(); }
duke@435	118	klassOop non_null_obj() const { return (klassOop)Handle::non_null_obj(); }
duke@435	119	Klass* as_klass() const { return non_null_obj()->klass_part(); }
duke@435	120
duke@435	121	public:
duke@435	122	// Constructors
duke@435	123	KlassHandle () : Handle() {}
duke@435	124	KlassHandle (oop obj) : Handle(obj) {
duke@435	125	assert(SharedSkipVerify || is_null() || obj->is_klass(), "not a klassOop");
duke@435	126	}
duke@435	127	KlassHandle (Klass* kl) : Handle(kl ? kl->as_klassOop() : (klassOop)NULL) {
duke@435	128	assert(SharedSkipVerify || is_null() || obj()->is_klass(), "not a klassOop");
duke@435	129	}
duke@435	130
duke@435	131	// Faster versions passing Thread
duke@435	132	KlassHandle (Thread* thread, oop obj) : Handle(thread, obj) {
duke@435	133	assert(SharedSkipVerify || is_null() || obj->is_klass(), "not a klassOop");
duke@435	134	}
duke@435	135	KlassHandle (Thread *thread, Klass* kl)
duke@435	136	: Handle(thread, kl ? kl->as_klassOop() : (klassOop)NULL) {
duke@435	137	assert(is_null() || obj()->is_klass(), "not a klassOop");
duke@435	138	}
duke@435	139
duke@435	140	// General access
duke@435	141	klassOop operator () () const { return obj(); }
duke@435	142	Klass* operator -> () const { return as_klass(); }
duke@435	143	};
duke@435	144
duke@435	145
duke@435	146	//------------------------------------------------------------------------------------------------------------------------
duke@435	147	// Specific Handles for different oop types
duke@435	148	#define DEF_HANDLE(type, is_a) \
duke@435	149	class type##Handle; \
duke@435	150	class type##Handle: public Handle { \
duke@435	151	protected: \
duke@435	152	type##Oop obj() const { return (type##Oop)Handle::obj(); } \
duke@435	153	type##Oop non_null_obj() const { return (type##Oop)Handle::non_null_obj(); } \
duke@435	154	\
duke@435	155	public: \
duke@435	156	/* Constructors */ \
duke@435	157	type##Handle () : Handle() {} \
duke@435	158	type##Handle (type##Oop obj) : Handle((oop)obj) { \
duke@435	159	assert(SharedSkipVerify || is_null() || ((oop)obj)->is_a(), \
duke@435	160	"illegal type"); \
duke@435	161	} \
duke@435	162	type##Handle (Thread* thread, type##Oop obj) : Handle(thread, (oop)obj) { \
duke@435	163	assert(SharedSkipVerify || is_null() || ((oop)obj)->is_a(), "illegal type"); \
duke@435	164	} \
duke@435	165	\
duke@435	166	/* Special constructor, use sparingly */ \
duke@435	167	type##Handle (type##Oop *handle, bool dummy) : Handle((oop*)handle, dummy) {} \
duke@435	168	\
duke@435	169	/* Operators for ease of use */ \
duke@435	170	type##Oop operator () () const { return obj(); } \
duke@435	171	type##Oop operator -> () const { return non_null_obj(); } \
duke@435	172	};
duke@435	173
duke@435	174
duke@435	175	DEF_HANDLE(instance , is_instance )
duke@435	176	DEF_HANDLE(method , is_method )
duke@435	177	DEF_HANDLE(constMethod , is_constMethod )
duke@435	178	DEF_HANDLE(methodData , is_methodData )
duke@435	179	DEF_HANDLE(array , is_array )
duke@435	180	DEF_HANDLE(constantPool , is_constantPool )
duke@435	181	DEF_HANDLE(constantPoolCache, is_constantPoolCache)
duke@435	182	DEF_HANDLE(objArray , is_objArray )
duke@435	183	DEF_HANDLE(typeArray , is_typeArray )
duke@435	184	DEF_HANDLE(symbol , is_symbol )
duke@435	185
duke@435	186	//------------------------------------------------------------------------------------------------------------------------
duke@435	187	// Specific KlassHandles for different Klass types
duke@435	188
duke@435	189	#define DEF_KLASS_HANDLE(type, is_a) \
duke@435	190	class type##Handle : public KlassHandle { \
duke@435	191	public: \
duke@435	192	/* Constructors */ \
duke@435	193	type##Handle () : KlassHandle() {} \
duke@435	194	type##Handle (klassOop obj) : KlassHandle(obj) { \
duke@435	195	assert(SharedSkipVerify || is_null() || obj->klass_part()->is_a(), \
duke@435	196	"illegal type"); \
duke@435	197	} \
duke@435	198	type##Handle (Thread* thread, klassOop obj) : KlassHandle(thread, obj) { \
duke@435	199	assert(SharedSkipVerify || is_null() || obj->klass_part()->is_a(), \
duke@435	200	"illegal type"); \
duke@435	201	} \
duke@435	202	\
duke@435	203	/* Access to klass part */ \
duke@435	204	type* operator -> () const { return (type*)obj()->klass_part(); } \
duke@435	205	\
duke@435	206	static type##Handle cast(KlassHandle h) { return type##Handle(h()); } \
duke@435	207	\
duke@435	208	};
duke@435	209
duke@435	210
duke@435	211	DEF_KLASS_HANDLE(instanceKlass , oop_is_instance_slow )
duke@435	212	DEF_KLASS_HANDLE(methodKlass , oop_is_method )
duke@435	213	DEF_KLASS_HANDLE(constMethodKlass , oop_is_constMethod )
duke@435	214	DEF_KLASS_HANDLE(klassKlass , oop_is_klass )
duke@435	215	DEF_KLASS_HANDLE(arrayKlassKlass , oop_is_arrayKlass )
duke@435	216	DEF_KLASS_HANDLE(objArrayKlassKlass , oop_is_objArrayKlass )
duke@435	217	DEF_KLASS_HANDLE(typeArrayKlassKlass , oop_is_typeArrayKlass)
duke@435	218	DEF_KLASS_HANDLE(arrayKlass , oop_is_array )
duke@435	219	DEF_KLASS_HANDLE(typeArrayKlass , oop_is_typeArray_slow)
duke@435	220	DEF_KLASS_HANDLE(objArrayKlass , oop_is_objArray_slow )
duke@435	221	DEF_KLASS_HANDLE(symbolKlass , oop_is_symbol )
duke@435	222	DEF_KLASS_HANDLE(constantPoolKlass , oop_is_constantPool )
duke@435	223	DEF_KLASS_HANDLE(constantPoolCacheKlass, oop_is_constantPool )
duke@435	224
duke@435	225
duke@435	226	//------------------------------------------------------------------------------------------------------------------------
duke@435	227	// Thread local handle area
duke@435	228
duke@435	229	class HandleArea: public Arena {
duke@435	230	friend class HandleMark;
duke@435	231	friend class NoHandleMark;
duke@435	232	friend class ResetNoHandleMark;
duke@435	233	#ifdef ASSERT
duke@435	234	int _handle_mark_nesting;
duke@435	235	int _no_handle_mark_nesting;
duke@435	236	#endif
duke@435	237	HandleArea* _prev; // link to outer (older) area
duke@435	238	public:
duke@435	239	// Constructor
duke@435	240	HandleArea(HandleArea* prev) {
duke@435	241	debug_only(_handle_mark_nesting = 0);
duke@435	242	debug_only(_no_handle_mark_nesting = 0);
duke@435	243	_prev = prev;
duke@435	244	}
duke@435	245
duke@435	246	// Handle allocation
duke@435	247	private:
duke@435	248	oop* real_allocate_handle(oop obj) {
duke@435	249	#ifdef ASSERT
duke@435	250	oop* handle = (oop*) (UseMallocOnly ? internal_malloc_4(oopSize) : Amalloc_4(oopSize));
duke@435	251	#else
duke@435	252	oop* handle = (oop*) Amalloc_4(oopSize);
duke@435	253	#endif
duke@435	254	*handle = obj;
duke@435	255	return handle;
duke@435	256	}
duke@435	257	public:
duke@435	258	#ifdef ASSERT
duke@435	259	oop* allocate_handle(oop obj);
duke@435	260	#else
duke@435	261	oop* allocate_handle(oop obj) { return real_allocate_handle(obj); }
duke@435	262	#endif
duke@435	263
duke@435	264	// Garbage collection support
duke@435	265	void oops_do(OopClosure* f);
duke@435	266
duke@435	267	// Number of handles in use
duke@435	268	size_t used() const { return Arena::used() / oopSize; }
duke@435	269
duke@435	270	debug_only(bool no_handle_mark_active() { return _no_handle_mark_nesting > 0; })
duke@435	271	};
duke@435	272
duke@435	273
duke@435	274	//------------------------------------------------------------------------------------------------------------------------
duke@435	275	// Handles are allocated in a (growable) thread local handle area. Deallocation
duke@435	276	// is managed using a HandleMark. It should normally not be necessary to use
duke@435	277	// HandleMarks manually.
duke@435	278	//
duke@435	279	// A HandleMark constructor will record the current handle area top, and the
duke@435	280	// desctructor will reset the top, destroying all handles allocated in between.
duke@435	281	// The following code will therefore NOT work:
duke@435	282	//
duke@435	283	// Handle h;
duke@435	284	// {
duke@435	285	// HandleMark hm;
duke@435	286	// h = Handle(obj);
duke@435	287	// }
duke@435	288	// h()->print(); // WRONG, h destroyed by HandleMark destructor.
duke@435	289	//
duke@435	290	// If h has to be preserved, it can be converted to an oop or a local JNI handle
duke@435	291	// across the HandleMark boundary.
duke@435	292
duke@435	293	// The base class of HandleMark should have been StackObj but we also heap allocate
duke@435	294	// a HandleMark when a thread is created.
duke@435	295
duke@435	296	class HandleMark {
duke@435	297	private:
duke@435	298	Thread *_thread; // thread that owns this mark
duke@435	299	HandleArea *_area; // saved handle area
duke@435	300	Chunk *_chunk; // saved arena chunk
duke@435	301	char *_hwm, *_max; // saved arena info
duke@435	302	NOT_PRODUCT(size_t _size_in_bytes;) // size of handle area
duke@435	303	// Link to previous active HandleMark in thread
duke@435	304	HandleMark* _previous_handle_mark;
duke@435	305
duke@435	306	void initialize(Thread* thread); // common code for constructors
duke@435	307	void set_previous_handle_mark(HandleMark* mark) { _previous_handle_mark = mark; }
duke@435	308	HandleMark* previous_handle_mark() const { return _previous_handle_mark; }
duke@435	309
duke@435	310	public:
duke@435	311	HandleMark(); // see handles_inline.hpp
duke@435	312	HandleMark(Thread* thread) { initialize(thread); }
duke@435	313	~HandleMark();
duke@435	314
duke@435	315	// Functions used by HandleMarkCleaner
duke@435	316	// called in the constructor of HandleMarkCleaner
duke@435	317	void push();
duke@435	318	// called in the destructor of HandleMarkCleaner
duke@435	319	void pop_and_restore();
duke@435	320	};
duke@435	321
duke@435	322	//------------------------------------------------------------------------------------------------------------------------
duke@435	323	// A NoHandleMark stack object will verify that no handles are allocated
duke@435	324	// in its scope. Enabled in debug mode only.
duke@435	325
duke@435	326	class NoHandleMark: public StackObj {
duke@435	327	public:
duke@435	328	#ifdef ASSERT
duke@435	329	NoHandleMark();
duke@435	330	~NoHandleMark();
duke@435	331	#else
duke@435	332	NoHandleMark() {}
duke@435	333	~NoHandleMark() {}
duke@435	334	#endif
duke@435	335	};
duke@435	336
duke@435	337
duke@435	338	class ResetNoHandleMark: public StackObj {
duke@435	339	int _no_handle_mark_nesting;
duke@435	340	public:
duke@435	341	#ifdef ASSERT
duke@435	342	ResetNoHandleMark();
duke@435	343	~ResetNoHandleMark();
duke@435	344	#else
duke@435	345	ResetNoHandleMark() {}
duke@435	346	~ResetNoHandleMark() {}
duke@435	347	#endif
duke@435	348	};