duke@435: /* duke@435: * Copyright 1997-2007 Sun Microsystems, Inc. All Rights Reserved. duke@435: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. duke@435: * duke@435: * This code is free software; you can redistribute it and/or modify it duke@435: * under the terms of the GNU General Public License version 2 only, as duke@435: * published by the Free Software Foundation. duke@435: * duke@435: * This code is distributed in the hope that it will be useful, but WITHOUT duke@435: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or duke@435: * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License duke@435: * version 2 for more details (a copy is included in the LICENSE file that duke@435: * accompanied this code). duke@435: * duke@435: * You should have received a copy of the GNU General Public License version duke@435: * 2 along with this work; if not, write to the Free Software Foundation, duke@435: * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. duke@435: * duke@435: * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, duke@435: * CA 95054 USA or visit www.sun.com if you need additional information or duke@435: * have any questions. duke@435: * duke@435: */ duke@435: duke@435: //------------------------------------------------------------------------------------------------------------------------ duke@435: // In order to preserve oops during garbage collection, they should be duke@435: // allocated and passed around via Handles within the VM. A handle is duke@435: // simply an extra indirection allocated in a thread local handle area. duke@435: // duke@435: // A handle is a ValueObj, so it can be passed around as a value, can duke@435: // be used as a parameter w/o using &-passing, and can be returned as a duke@435: // return value. duke@435: // duke@435: // oop parameters and return types should be Handles whenever feasible. duke@435: // duke@435: // Handles are declared in a straight-forward manner, e.g. duke@435: // duke@435: // oop obj = ...; duke@435: // Handle h1(obj); // allocate new handle duke@435: // Handle h2(thread, obj); // faster allocation when current thread is known duke@435: // Handle h3; // declare handle only, no allocation occurs duke@435: // ... duke@435: // h3 = h1; // make h3 refer to same indirection as h1 duke@435: // oop obj2 = h2(); // get handle value duke@435: // h1->print(); // invoking operation on oop duke@435: // duke@435: // Handles are specialized for different oop types to provide extra type duke@435: // information and avoid unnecessary casting. For each oop type xxxOop duke@435: // there is a corresponding handle called xxxHandle, e.g. duke@435: // duke@435: // oop Handle duke@435: // methodOop methodHandle duke@435: // instanceOop instanceHandle duke@435: // duke@435: // For klassOops, it is often useful to model the Klass hierarchy in order duke@435: // to get access to the klass_part without casting. For each xxxKlass there duke@435: // is a corresponding handle called xxxKlassHandle, e.g. duke@435: // duke@435: // klassOop Klass KlassHandle duke@435: // klassOop methodKlass methodKlassHandle duke@435: // klassOop instanceKlass instanceKlassHandle duke@435: // duke@435: duke@435: //------------------------------------------------------------------------------------------------------------------------ duke@435: // Base class for all handles. Provides overloading of frequently duke@435: // used operators for ease of use. duke@435: duke@435: class Handle VALUE_OBJ_CLASS_SPEC { duke@435: private: duke@435: oop* _handle; duke@435: duke@435: protected: duke@435: oop obj() const { return _handle == NULL ? (oop)NULL : *_handle; } duke@435: oop non_null_obj() const { assert(_handle != NULL, "resolving NULL handle"); return *_handle; } duke@435: duke@435: public: duke@435: // Constructors duke@435: Handle() { _handle = NULL; } duke@435: Handle(oop obj); duke@435: #ifndef ASSERT duke@435: Handle(Thread* thread, oop obj); duke@435: #else duke@435: // Don't inline body with assert for current thread duke@435: Handle(Thread* thread, oop obj); duke@435: #endif // ASSERT duke@435: duke@435: // General access duke@435: oop operator () () const { return obj(); } duke@435: oop operator -> () const { return non_null_obj(); } duke@435: bool operator == (oop o) const { return obj() == o; } duke@435: bool operator == (const Handle& h) const { return obj() == h.obj(); } duke@435: duke@435: // Null checks duke@435: bool is_null() const { return _handle == NULL; } duke@435: bool not_null() const { return _handle != NULL; } duke@435: duke@435: // Debugging duke@435: void print() { obj()->print(); } duke@435: duke@435: // Direct interface, use very sparingly. duke@435: // Used by JavaCalls to quickly convert handles and to create handles static data structures. duke@435: // Constructor takes a dummy argument to prevent unintentional type conversion in C++. duke@435: Handle(oop *handle, bool dummy) { _handle = handle; } duke@435: duke@435: // Raw handle access. Allows easy duplication of Handles. This can be very unsafe duke@435: // since duplicates is only valid as long as original handle is alive. duke@435: oop* raw_value() { return _handle; } duke@435: static oop raw_resolve(oop *handle) { return handle == NULL ? (oop)NULL : *handle; } duke@435: }; duke@435: duke@435: duke@435: //------------------------------------------------------------------------------------------------------------------------ duke@435: // Base class for Handles containing klassOops. Provides overloading of frequently duke@435: // used operators for ease of use and typed access to the Klass part. duke@435: class KlassHandle: public Handle { duke@435: protected: duke@435: klassOop obj() const { return (klassOop)Handle::obj(); } duke@435: klassOop non_null_obj() const { return (klassOop)Handle::non_null_obj(); } duke@435: Klass* as_klass() const { return non_null_obj()->klass_part(); } duke@435: duke@435: public: duke@435: // Constructors duke@435: KlassHandle () : Handle() {} duke@435: KlassHandle (oop obj) : Handle(obj) { duke@435: assert(SharedSkipVerify || is_null() || obj->is_klass(), "not a klassOop"); duke@435: } duke@435: KlassHandle (Klass* kl) : Handle(kl ? kl->as_klassOop() : (klassOop)NULL) { duke@435: assert(SharedSkipVerify || is_null() || obj()->is_klass(), "not a klassOop"); duke@435: } duke@435: duke@435: // Faster versions passing Thread duke@435: KlassHandle (Thread* thread, oop obj) : Handle(thread, obj) { duke@435: assert(SharedSkipVerify || is_null() || obj->is_klass(), "not a klassOop"); duke@435: } duke@435: KlassHandle (Thread *thread, Klass* kl) duke@435: : Handle(thread, kl ? kl->as_klassOop() : (klassOop)NULL) { duke@435: assert(is_null() || obj()->is_klass(), "not a klassOop"); duke@435: } duke@435: duke@435: // General access duke@435: klassOop operator () () const { return obj(); } duke@435: Klass* operator -> () const { return as_klass(); } duke@435: }; duke@435: duke@435: duke@435: //------------------------------------------------------------------------------------------------------------------------ duke@435: // Specific Handles for different oop types duke@435: #define DEF_HANDLE(type, is_a) \ duke@435: class type##Handle; \ duke@435: class type##Handle: public Handle { \ duke@435: protected: \ duke@435: type##Oop obj() const { return (type##Oop)Handle::obj(); } \ duke@435: type##Oop non_null_obj() const { return (type##Oop)Handle::non_null_obj(); } \ duke@435: \ duke@435: public: \ duke@435: /* Constructors */ \ duke@435: type##Handle () : Handle() {} \ duke@435: type##Handle (type##Oop obj) : Handle((oop)obj) { \ duke@435: assert(SharedSkipVerify || is_null() || ((oop)obj)->is_a(), \ duke@435: "illegal type"); \ duke@435: } \ duke@435: type##Handle (Thread* thread, type##Oop obj) : Handle(thread, (oop)obj) { \ duke@435: assert(SharedSkipVerify || is_null() || ((oop)obj)->is_a(), "illegal type"); \ duke@435: } \ duke@435: \ duke@435: /* Special constructor, use sparingly */ \ duke@435: type##Handle (type##Oop *handle, bool dummy) : Handle((oop*)handle, dummy) {} \ duke@435: \ duke@435: /* Operators for ease of use */ \ duke@435: type##Oop operator () () const { return obj(); } \ duke@435: type##Oop operator -> () const { return non_null_obj(); } \ duke@435: }; duke@435: duke@435: duke@435: DEF_HANDLE(instance , is_instance ) duke@435: DEF_HANDLE(method , is_method ) duke@435: DEF_HANDLE(constMethod , is_constMethod ) duke@435: DEF_HANDLE(methodData , is_methodData ) duke@435: DEF_HANDLE(array , is_array ) duke@435: DEF_HANDLE(constantPool , is_constantPool ) duke@435: DEF_HANDLE(constantPoolCache, is_constantPoolCache) duke@435: DEF_HANDLE(objArray , is_objArray ) duke@435: DEF_HANDLE(typeArray , is_typeArray ) duke@435: DEF_HANDLE(symbol , is_symbol ) duke@435: duke@435: //------------------------------------------------------------------------------------------------------------------------ duke@435: // Specific KlassHandles for different Klass types duke@435: duke@435: #define DEF_KLASS_HANDLE(type, is_a) \ duke@435: class type##Handle : public KlassHandle { \ duke@435: public: \ duke@435: /* Constructors */ \ duke@435: type##Handle () : KlassHandle() {} \ duke@435: type##Handle (klassOop obj) : KlassHandle(obj) { \ duke@435: assert(SharedSkipVerify || is_null() || obj->klass_part()->is_a(), \ duke@435: "illegal type"); \ duke@435: } \ duke@435: type##Handle (Thread* thread, klassOop obj) : KlassHandle(thread, obj) { \ duke@435: assert(SharedSkipVerify || is_null() || obj->klass_part()->is_a(), \ duke@435: "illegal type"); \ duke@435: } \ duke@435: \ duke@435: /* Access to klass part */ \ duke@435: type* operator -> () const { return (type*)obj()->klass_part(); } \ duke@435: \ duke@435: static type##Handle cast(KlassHandle h) { return type##Handle(h()); } \ duke@435: \ duke@435: }; duke@435: duke@435: duke@435: DEF_KLASS_HANDLE(instanceKlass , oop_is_instance_slow ) duke@435: DEF_KLASS_HANDLE(methodKlass , oop_is_method ) duke@435: DEF_KLASS_HANDLE(constMethodKlass , oop_is_constMethod ) duke@435: DEF_KLASS_HANDLE(klassKlass , oop_is_klass ) duke@435: DEF_KLASS_HANDLE(arrayKlassKlass , oop_is_arrayKlass ) duke@435: DEF_KLASS_HANDLE(objArrayKlassKlass , oop_is_objArrayKlass ) duke@435: DEF_KLASS_HANDLE(typeArrayKlassKlass , oop_is_typeArrayKlass) duke@435: DEF_KLASS_HANDLE(arrayKlass , oop_is_array ) duke@435: DEF_KLASS_HANDLE(typeArrayKlass , oop_is_typeArray_slow) duke@435: DEF_KLASS_HANDLE(objArrayKlass , oop_is_objArray_slow ) duke@435: DEF_KLASS_HANDLE(symbolKlass , oop_is_symbol ) duke@435: DEF_KLASS_HANDLE(constantPoolKlass , oop_is_constantPool ) duke@435: DEF_KLASS_HANDLE(constantPoolCacheKlass, oop_is_constantPool ) duke@435: duke@435: duke@435: //------------------------------------------------------------------------------------------------------------------------ duke@435: // Thread local handle area duke@435: duke@435: class HandleArea: public Arena { duke@435: friend class HandleMark; duke@435: friend class NoHandleMark; duke@435: friend class ResetNoHandleMark; duke@435: #ifdef ASSERT duke@435: int _handle_mark_nesting; duke@435: int _no_handle_mark_nesting; duke@435: #endif duke@435: HandleArea* _prev; // link to outer (older) area duke@435: public: duke@435: // Constructor duke@435: HandleArea(HandleArea* prev) { duke@435: debug_only(_handle_mark_nesting = 0); duke@435: debug_only(_no_handle_mark_nesting = 0); duke@435: _prev = prev; duke@435: } duke@435: duke@435: // Handle allocation duke@435: private: duke@435: oop* real_allocate_handle(oop obj) { duke@435: #ifdef ASSERT duke@435: oop* handle = (oop*) (UseMallocOnly ? internal_malloc_4(oopSize) : Amalloc_4(oopSize)); duke@435: #else duke@435: oop* handle = (oop*) Amalloc_4(oopSize); duke@435: #endif duke@435: *handle = obj; duke@435: return handle; duke@435: } duke@435: public: duke@435: #ifdef ASSERT duke@435: oop* allocate_handle(oop obj); duke@435: #else duke@435: oop* allocate_handle(oop obj) { return real_allocate_handle(obj); } duke@435: #endif duke@435: duke@435: // Garbage collection support duke@435: void oops_do(OopClosure* f); duke@435: duke@435: // Number of handles in use duke@435: size_t used() const { return Arena::used() / oopSize; } duke@435: duke@435: debug_only(bool no_handle_mark_active() { return _no_handle_mark_nesting > 0; }) duke@435: }; duke@435: duke@435: duke@435: //------------------------------------------------------------------------------------------------------------------------ duke@435: // Handles are allocated in a (growable) thread local handle area. Deallocation duke@435: // is managed using a HandleMark. It should normally not be necessary to use duke@435: // HandleMarks manually. duke@435: // duke@435: // A HandleMark constructor will record the current handle area top, and the duke@435: // desctructor will reset the top, destroying all handles allocated in between. duke@435: // The following code will therefore NOT work: duke@435: // duke@435: // Handle h; duke@435: // { duke@435: // HandleMark hm; duke@435: // h = Handle(obj); duke@435: // } duke@435: // h()->print(); // WRONG, h destroyed by HandleMark destructor. duke@435: // duke@435: // If h has to be preserved, it can be converted to an oop or a local JNI handle duke@435: // across the HandleMark boundary. duke@435: duke@435: // The base class of HandleMark should have been StackObj but we also heap allocate duke@435: // a HandleMark when a thread is created. duke@435: duke@435: class HandleMark { duke@435: private: duke@435: Thread *_thread; // thread that owns this mark duke@435: HandleArea *_area; // saved handle area duke@435: Chunk *_chunk; // saved arena chunk duke@435: char *_hwm, *_max; // saved arena info duke@435: NOT_PRODUCT(size_t _size_in_bytes;) // size of handle area duke@435: // Link to previous active HandleMark in thread duke@435: HandleMark* _previous_handle_mark; duke@435: duke@435: void initialize(Thread* thread); // common code for constructors duke@435: void set_previous_handle_mark(HandleMark* mark) { _previous_handle_mark = mark; } duke@435: HandleMark* previous_handle_mark() const { return _previous_handle_mark; } duke@435: duke@435: public: duke@435: HandleMark(); // see handles_inline.hpp duke@435: HandleMark(Thread* thread) { initialize(thread); } duke@435: ~HandleMark(); duke@435: duke@435: // Functions used by HandleMarkCleaner duke@435: // called in the constructor of HandleMarkCleaner duke@435: void push(); duke@435: // called in the destructor of HandleMarkCleaner duke@435: void pop_and_restore(); duke@435: }; duke@435: duke@435: //------------------------------------------------------------------------------------------------------------------------ duke@435: // A NoHandleMark stack object will verify that no handles are allocated duke@435: // in its scope. Enabled in debug mode only. duke@435: duke@435: class NoHandleMark: public StackObj { duke@435: public: duke@435: #ifdef ASSERT duke@435: NoHandleMark(); duke@435: ~NoHandleMark(); duke@435: #else duke@435: NoHandleMark() {} duke@435: ~NoHandleMark() {} duke@435: #endif duke@435: }; duke@435: duke@435: duke@435: class ResetNoHandleMark: public StackObj { duke@435: int _no_handle_mark_nesting; duke@435: public: duke@435: #ifdef ASSERT duke@435: ResetNoHandleMark(); duke@435: ~ResetNoHandleMark(); duke@435: #else duke@435: ResetNoHandleMark() {} duke@435: ~ResetNoHandleMark() {} duke@435: #endif duke@435: };