--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/runtime/handles.hpp Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,348 @@
+/*
+ * Copyright 1997-2007 Sun Microsystems, Inc. All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+//------------------------------------------------------------------------------------------------------------------------
+// In order to preserve oops during garbage collection, they should be
+// allocated and passed around via Handles within the VM. A handle is
+// simply an extra indirection allocated in a thread local handle area.
+//
+// A handle is a ValueObj, so it can be passed around as a value, can
+// be used as a parameter w/o using &-passing, and can be returned as a
+// return value.
+//
+// oop parameters and return types should be Handles whenever feasible.
+//
+// Handles are declared in a straight-forward manner, e.g.
+//
+// oop obj = ...;
+// Handle h1(obj); // allocate new handle
+// Handle h2(thread, obj); // faster allocation when current thread is known
+// Handle h3; // declare handle only, no allocation occurs
+// ...
+// h3 = h1; // make h3 refer to same indirection as h1
+// oop obj2 = h2(); // get handle value
+// h1->print(); // invoking operation on oop
+//
+// Handles are specialized for different oop types to provide extra type
+// information and avoid unnecessary casting. For each oop type xxxOop
+// there is a corresponding handle called xxxHandle, e.g.
+//
+// oop Handle
+// methodOop methodHandle
+// instanceOop instanceHandle
+//
+// For klassOops, it is often useful to model the Klass hierarchy in order
+// to get access to the klass_part without casting. For each xxxKlass there
+// is a corresponding handle called xxxKlassHandle, e.g.
+//
+// klassOop Klass KlassHandle
+// klassOop methodKlass methodKlassHandle
+// klassOop instanceKlass instanceKlassHandle
+//
+
+//------------------------------------------------------------------------------------------------------------------------
+// Base class for all handles. Provides overloading of frequently
+// used operators for ease of use.
+
+class Handle VALUE_OBJ_CLASS_SPEC {
+ private:
+ oop* _handle;
+
+ protected:
+ oop obj() const { return _handle == NULL ? (oop)NULL : *_handle; }
+ oop non_null_obj() const { assert(_handle != NULL, "resolving NULL handle"); return *_handle; }
+
+ public:
+ // Constructors
+ Handle() { _handle = NULL; }
+ Handle(oop obj);
+#ifndef ASSERT
+ Handle(Thread* thread, oop obj);
+#else
+ // Don't inline body with assert for current thread
+ Handle(Thread* thread, oop obj);
+#endif // ASSERT
+
+ // General access
+ oop operator () () const { return obj(); }
+ oop operator -> () const { return non_null_obj(); }
+ bool operator == (oop o) const { return obj() == o; }
+ bool operator == (const Handle& h) const { return obj() == h.obj(); }
+
+ // Null checks
+ bool is_null() const { return _handle == NULL; }
+ bool not_null() const { return _handle != NULL; }
+
+ // Debugging
+ void print() { obj()->print(); }
+
+ // Direct interface, use very sparingly.
+ // Used by JavaCalls to quickly convert handles and to create handles static data structures.
+ // Constructor takes a dummy argument to prevent unintentional type conversion in C++.
+ Handle(oop *handle, bool dummy) { _handle = handle; }
+
+ // Raw handle access. Allows easy duplication of Handles. This can be very unsafe
+ // since duplicates is only valid as long as original handle is alive.
+ oop* raw_value() { return _handle; }
+ static oop raw_resolve(oop *handle) { return handle == NULL ? (oop)NULL : *handle; }
+};
+
+
+//------------------------------------------------------------------------------------------------------------------------
+// Base class for Handles containing klassOops. Provides overloading of frequently
+// used operators for ease of use and typed access to the Klass part.
+class KlassHandle: public Handle {
+ protected:
+ klassOop obj() const { return (klassOop)Handle::obj(); }
+ klassOop non_null_obj() const { return (klassOop)Handle::non_null_obj(); }
+ Klass* as_klass() const { return non_null_obj()->klass_part(); }
+
+ public:
+ // Constructors
+ KlassHandle () : Handle() {}
+ KlassHandle (oop obj) : Handle(obj) {
+ assert(SharedSkipVerify || is_null() || obj->is_klass(), "not a klassOop");
+ }
+ KlassHandle (Klass* kl) : Handle(kl ? kl->as_klassOop() : (klassOop)NULL) {
+ assert(SharedSkipVerify || is_null() || obj()->is_klass(), "not a klassOop");
+ }
+
+ // Faster versions passing Thread
+ KlassHandle (Thread* thread, oop obj) : Handle(thread, obj) {
+ assert(SharedSkipVerify || is_null() || obj->is_klass(), "not a klassOop");
+ }
+ KlassHandle (Thread *thread, Klass* kl)
+ : Handle(thread, kl ? kl->as_klassOop() : (klassOop)NULL) {
+ assert(is_null() || obj()->is_klass(), "not a klassOop");
+ }
+
+ // General access
+ klassOop operator () () const { return obj(); }
+ Klass* operator -> () const { return as_klass(); }
+};
+
+
+//------------------------------------------------------------------------------------------------------------------------
+// Specific Handles for different oop types
+#define DEF_HANDLE(type, is_a) \
+ class type##Handle; \
+ class type##Handle: public Handle { \
+ protected: \
+ type##Oop obj() const { return (type##Oop)Handle::obj(); } \
+ type##Oop non_null_obj() const { return (type##Oop)Handle::non_null_obj(); } \
+ \
+ public: \
+ /* Constructors */ \
+ type##Handle () : Handle() {} \
+ type##Handle (type##Oop obj) : Handle((oop)obj) { \
+ assert(SharedSkipVerify || is_null() || ((oop)obj)->is_a(), \
+ "illegal type"); \
+ } \
+ type##Handle (Thread* thread, type##Oop obj) : Handle(thread, (oop)obj) { \
+ assert(SharedSkipVerify || is_null() || ((oop)obj)->is_a(), "illegal type"); \
+ } \
+ \
+ /* Special constructor, use sparingly */ \
+ type##Handle (type##Oop *handle, bool dummy) : Handle((oop*)handle, dummy) {} \
+ \
+ /* Operators for ease of use */ \
+ type##Oop operator () () const { return obj(); } \
+ type##Oop operator -> () const { return non_null_obj(); } \
+ };
+
+
+DEF_HANDLE(instance , is_instance )
+DEF_HANDLE(method , is_method )
+DEF_HANDLE(constMethod , is_constMethod )
+DEF_HANDLE(methodData , is_methodData )
+DEF_HANDLE(array , is_array )
+DEF_HANDLE(constantPool , is_constantPool )
+DEF_HANDLE(constantPoolCache, is_constantPoolCache)
+DEF_HANDLE(objArray , is_objArray )
+DEF_HANDLE(typeArray , is_typeArray )
+DEF_HANDLE(symbol , is_symbol )
+
+//------------------------------------------------------------------------------------------------------------------------
+// Specific KlassHandles for different Klass types
+
+#define DEF_KLASS_HANDLE(type, is_a) \
+ class type##Handle : public KlassHandle { \
+ public: \
+ /* Constructors */ \
+ type##Handle () : KlassHandle() {} \
+ type##Handle (klassOop obj) : KlassHandle(obj) { \
+ assert(SharedSkipVerify || is_null() || obj->klass_part()->is_a(), \
+ "illegal type"); \
+ } \
+ type##Handle (Thread* thread, klassOop obj) : KlassHandle(thread, obj) { \
+ assert(SharedSkipVerify || is_null() || obj->klass_part()->is_a(), \
+ "illegal type"); \
+ } \
+ \
+ /* Access to klass part */ \
+ type* operator -> () const { return (type*)obj()->klass_part(); } \
+ \
+ static type##Handle cast(KlassHandle h) { return type##Handle(h()); } \
+ \
+ };
+
+
+DEF_KLASS_HANDLE(instanceKlass , oop_is_instance_slow )
+DEF_KLASS_HANDLE(methodKlass , oop_is_method )
+DEF_KLASS_HANDLE(constMethodKlass , oop_is_constMethod )
+DEF_KLASS_HANDLE(klassKlass , oop_is_klass )
+DEF_KLASS_HANDLE(arrayKlassKlass , oop_is_arrayKlass )
+DEF_KLASS_HANDLE(objArrayKlassKlass , oop_is_objArrayKlass )
+DEF_KLASS_HANDLE(typeArrayKlassKlass , oop_is_typeArrayKlass)
+DEF_KLASS_HANDLE(arrayKlass , oop_is_array )
+DEF_KLASS_HANDLE(typeArrayKlass , oop_is_typeArray_slow)
+DEF_KLASS_HANDLE(objArrayKlass , oop_is_objArray_slow )
+DEF_KLASS_HANDLE(symbolKlass , oop_is_symbol )
+DEF_KLASS_HANDLE(constantPoolKlass , oop_is_constantPool )
+DEF_KLASS_HANDLE(constantPoolCacheKlass, oop_is_constantPool )
+
+
+//------------------------------------------------------------------------------------------------------------------------
+// Thread local handle area
+
+class HandleArea: public Arena {
+ friend class HandleMark;
+ friend class NoHandleMark;
+ friend class ResetNoHandleMark;
+#ifdef ASSERT
+ int _handle_mark_nesting;
+ int _no_handle_mark_nesting;
+#endif
+ HandleArea* _prev; // link to outer (older) area
+ public:
+ // Constructor
+ HandleArea(HandleArea* prev) {
+ debug_only(_handle_mark_nesting = 0);
+ debug_only(_no_handle_mark_nesting = 0);
+ _prev = prev;
+ }
+
+ // Handle allocation
+ private:
+ oop* real_allocate_handle(oop obj) {
+#ifdef ASSERT
+ oop* handle = (oop*) (UseMallocOnly ? internal_malloc_4(oopSize) : Amalloc_4(oopSize));
+#else
+ oop* handle = (oop*) Amalloc_4(oopSize);
+#endif
+ *handle = obj;
+ return handle;
+ }
+ public:
+#ifdef ASSERT
+ oop* allocate_handle(oop obj);
+#else
+ oop* allocate_handle(oop obj) { return real_allocate_handle(obj); }
+#endif
+
+ // Garbage collection support
+ void oops_do(OopClosure* f);
+
+ // Number of handles in use
+ size_t used() const { return Arena::used() / oopSize; }
+
+ debug_only(bool no_handle_mark_active() { return _no_handle_mark_nesting > 0; })
+};
+
+
+//------------------------------------------------------------------------------------------------------------------------
+// Handles are allocated in a (growable) thread local handle area. Deallocation
+// is managed using a HandleMark. It should normally not be necessary to use
+// HandleMarks manually.
+//
+// A HandleMark constructor will record the current handle area top, and the
+// desctructor will reset the top, destroying all handles allocated in between.
+// The following code will therefore NOT work:
+//
+// Handle h;
+// {
+// HandleMark hm;
+// h = Handle(obj);
+// }
+// h()->print(); // WRONG, h destroyed by HandleMark destructor.
+//
+// If h has to be preserved, it can be converted to an oop or a local JNI handle
+// across the HandleMark boundary.
+
+// The base class of HandleMark should have been StackObj but we also heap allocate
+// a HandleMark when a thread is created.
+
+class HandleMark {
+ private:
+ Thread *_thread; // thread that owns this mark
+ HandleArea *_area; // saved handle area
+ Chunk *_chunk; // saved arena chunk
+ char *_hwm, *_max; // saved arena info
+ NOT_PRODUCT(size_t _size_in_bytes;) // size of handle area
+ // Link to previous active HandleMark in thread
+ HandleMark* _previous_handle_mark;
+
+ void initialize(Thread* thread); // common code for constructors
+ void set_previous_handle_mark(HandleMark* mark) { _previous_handle_mark = mark; }
+ HandleMark* previous_handle_mark() const { return _previous_handle_mark; }
+
+ public:
+ HandleMark(); // see handles_inline.hpp
+ HandleMark(Thread* thread) { initialize(thread); }
+ ~HandleMark();
+
+ // Functions used by HandleMarkCleaner
+ // called in the constructor of HandleMarkCleaner
+ void push();
+ // called in the destructor of HandleMarkCleaner
+ void pop_and_restore();
+};
+
+//------------------------------------------------------------------------------------------------------------------------
+// A NoHandleMark stack object will verify that no handles are allocated
+// in its scope. Enabled in debug mode only.
+
+class NoHandleMark: public StackObj {
+ public:
+#ifdef ASSERT
+ NoHandleMark();
+ ~NoHandleMark();
+#else
+ NoHandleMark() {}
+ ~NoHandleMark() {}
+#endif
+};
+
+
+class ResetNoHandleMark: public StackObj {
+ int _no_handle_mark_nesting;
+ public:
+#ifdef ASSERT
+ ResetNoHandleMark();
+ ~ResetNoHandleMark();
+#else
+ ResetNoHandleMark() {}
+ ~ResetNoHandleMark() {}
+#endif
+};