jdk8-mips64-public/hotspot: src/share/vm/runtime/handles.hpp@9f4457a14b58

     1 /*

     2  * Copyright 1997-2007 Sun Microsystems, Inc.  All Rights Reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    20  * CA 95054 USA or visit www.sun.com if you need additional information or

    21  * have any questions.

    22  *

    23  */

    25 //------------------------------------------------------------------------------------------------------------------------

    26 // In order to preserve oops during garbage collection, they should be

    27 // allocated and passed around via Handles within the VM. A handle is

    28 // simply an extra indirection allocated in a thread local handle area.

    29 //

    30 // A handle is a ValueObj, so it can be passed around as a value, can

    31 // be used as a parameter w/o using &-passing, and can be returned as a

    32 // return value.

    33 //

    34 // oop parameters and return types should be Handles whenever feasible.

    35 //

    36 // Handles are declared in a straight-forward manner, e.g.

    37 //

    38 //   oop obj = ...;

    39 //   Handle h1(obj);              // allocate new handle

    40 //   Handle h2(thread, obj);      // faster allocation when current thread is known

    41 //   Handle h3;                   // declare handle only, no allocation occurs

    42 //   ...

    43 //   h3 = h1;                     // make h3 refer to same indirection as h1

    44 //   oop obj2 = h2();             // get handle value

    45 //   h1->print();                 // invoking operation on oop

    46 //

    47 // Handles are specialized for different oop types to provide extra type

    48 // information and avoid unnecessary casting. For each oop type xxxOop

    49 // there is a corresponding handle called xxxHandle, e.g.

    50 //

    51 //   oop           Handle

    52 //   methodOop     methodHandle

    53 //   instanceOop   instanceHandle

    54 //

    55 // For klassOops, it is often useful to model the Klass hierarchy in order

    56 // to get access to the klass_part without casting. For each xxxKlass there

    57 // is a corresponding handle called xxxKlassHandle, e.g.

    58 //

    59 //   klassOop      Klass           KlassHandle

    60 //   klassOop      methodKlass     methodKlassHandle

    61 //   klassOop      instanceKlass   instanceKlassHandle

    62 //

    64 //------------------------------------------------------------------------------------------------------------------------

    65 // Base class for all handles. Provides overloading of frequently

    66 // used operators for ease of use.

    68 class Handle VALUE_OBJ_CLASS_SPEC {

    69  private:

    70   oop* _handle;

    72  protected:

    73   oop     obj() const                            { return _handle == NULL ? (oop)NULL : *_handle; }

    74   oop     non_null_obj() const                   { assert(_handle != NULL, "resolving NULL handle"); return *_handle; }

    76  public:

    77   // Constructors

    78   Handle()                                       { _handle = NULL; }

    79   Handle(oop obj);

    80 #ifndef ASSERT

    81   Handle(Thread* thread, oop obj);

    82 #else

    83   // Don't inline body with assert for current thread

    84   Handle(Thread* thread, oop obj);

    85 #endif // ASSERT

    87   // General access

    88   oop     operator () () const                   { return obj(); }

    89   oop     operator -> () const                   { return non_null_obj(); }

    90   bool    operator == (oop o) const              { return obj() == o; }

    91   bool    operator == (const Handle& h) const          { return obj() == h.obj(); }

    93   // Null checks

    94   bool    is_null() const                        { return _handle == NULL; }

    95   bool    not_null() const                       { return _handle != NULL; }

    97   // Debugging

    98   void    print()                                { obj()->print(); }

   100   // Direct interface, use very sparingly.

   101   // Used by JavaCalls to quickly convert handles and to create handles static data structures.

   102   // Constructor takes a dummy argument to prevent unintentional type conversion in C++.

   103   Handle(oop *handle, bool dummy)                { _handle = handle; }

   105   // Raw handle access. Allows easy duplication of Handles. This can be very unsafe

   106   // since duplicates is only valid as long as original handle is alive.

   107   oop* raw_value()                               { return _handle; }

   108   static oop raw_resolve(oop *handle)            { return handle == NULL ? (oop)NULL : *handle; }

   109 };

   112 //------------------------------------------------------------------------------------------------------------------------

   113 // Base class for Handles containing klassOops. Provides overloading of frequently

   114 // used operators for ease of use and typed access to the Klass part.

   115 class KlassHandle: public Handle {

   116  protected:

   117   klassOop    obj() const                        { return (klassOop)Handle::obj(); }

   118   klassOop    non_null_obj() const               { return (klassOop)Handle::non_null_obj(); }

   119   Klass*      as_klass() const                   { return non_null_obj()->klass_part(); }

   121  public:

   122   // Constructors

   123   KlassHandle ()                                 : Handle()            {}

   124   KlassHandle (oop obj) : Handle(obj) {

   125     assert(SharedSkipVerify || is_null() || obj->is_klass(), "not a klassOop");

   126   }

   127   KlassHandle (Klass* kl) : Handle(kl ? kl->as_klassOop() : (klassOop)NULL) {

   128     assert(SharedSkipVerify || is_null() || obj()->is_klass(), "not a klassOop");

   129   }

   131   // Faster versions passing Thread

   132   KlassHandle (Thread* thread, oop obj) : Handle(thread, obj) {

   133     assert(SharedSkipVerify || is_null() || obj->is_klass(), "not a klassOop");

   134   }

   135   KlassHandle (Thread *thread, Klass* kl)

   136     : Handle(thread, kl ? kl->as_klassOop() : (klassOop)NULL) {

   137     assert(is_null() || obj()->is_klass(), "not a klassOop");

   138   }

   140   // General access

   141   klassOop    operator () () const               { return obj(); }

   142   Klass*      operator -> () const               { return as_klass(); }

   143 };

   146 //------------------------------------------------------------------------------------------------------------------------

   147 // Specific Handles for different oop types

   148 #define DEF_HANDLE(type, is_a)                   \

   149   class type##Handle;                            \

   150   class type##Handle: public Handle {            \

   151    protected:                                    \

   152     type##Oop    obj() const                     { return (type##Oop)Handle::obj(); } \

   153     type##Oop    non_null_obj() const            { return (type##Oop)Handle::non_null_obj(); } \

   154                                                  \

   155    public:                                       \

   156     /* Constructors */                           \

   157     type##Handle ()                              : Handle()                 {} \

   158     type##Handle (type##Oop obj) : Handle((oop)obj) {                         \

   159       assert(SharedSkipVerify || is_null() || ((oop)obj)->is_a(),             \

   160              "illegal type");                                                 \

   161     }                                                                         \

   162     type##Handle (Thread* thread, type##Oop obj) : Handle(thread, (oop)obj) { \

   163       assert(SharedSkipVerify || is_null() || ((oop)obj)->is_a(), "illegal type");  \

   164     }                                                                         \

   165     \

   166     /* Special constructor, use sparingly */ \

   167     type##Handle (type##Oop *handle, bool dummy) : Handle((oop*)handle, dummy) {} \

   168                                                  \

   169     /* Operators for ease of use */              \

   170     type##Oop    operator () () const            { return obj(); } \

   171     type##Oop    operator -> () const            { return non_null_obj(); } \

   172   };

   175 DEF_HANDLE(instance         , is_instance         )

   176 DEF_HANDLE(method           , is_method           )

   177 DEF_HANDLE(constMethod      , is_constMethod      )

   178 DEF_HANDLE(methodData       , is_methodData       )

   179 DEF_HANDLE(array            , is_array            )

   180 DEF_HANDLE(constantPool     , is_constantPool     )

   181 DEF_HANDLE(constantPoolCache, is_constantPoolCache)

   182 DEF_HANDLE(objArray         , is_objArray         )

   183 DEF_HANDLE(typeArray        , is_typeArray        )

   184 DEF_HANDLE(symbol           , is_symbol           )

   186 //------------------------------------------------------------------------------------------------------------------------

   187 // Specific KlassHandles for different Klass types

   189 #define DEF_KLASS_HANDLE(type, is_a)             \

   190   class type##Handle : public KlassHandle {      \

   191    public:                                       \

   192     /* Constructors */                           \

   193     type##Handle ()                              : KlassHandle()           {} \

   194     type##Handle (klassOop obj) : KlassHandle(obj) {                          \

   195       assert(SharedSkipVerify || is_null() || obj->klass_part()->is_a(),      \

   196              "illegal type");                                                 \

   197     }                                                                         \

   198     type##Handle (Thread* thread, klassOop obj) : KlassHandle(thread, obj) {  \

   199       assert(SharedSkipVerify || is_null() || obj->klass_part()->is_a(),      \

   200              "illegal type");                                                 \

   201     }                                                                         \

   202                                                  \

   203     /* Access to klass part */                   \

   204     type*        operator -> () const            { return (type*)obj()->klass_part(); } \

   205                                                  \

   206     static type##Handle cast(KlassHandle h)      { return type##Handle(h()); } \

   207                                                  \

   208   };

   211 DEF_KLASS_HANDLE(instanceKlass         , oop_is_instance_slow )

   212 DEF_KLASS_HANDLE(methodKlass           , oop_is_method        )

   213 DEF_KLASS_HANDLE(constMethodKlass      , oop_is_constMethod   )

   214 DEF_KLASS_HANDLE(klassKlass            , oop_is_klass         )

   215 DEF_KLASS_HANDLE(arrayKlassKlass       , oop_is_arrayKlass    )

   216 DEF_KLASS_HANDLE(objArrayKlassKlass    , oop_is_objArrayKlass )

   217 DEF_KLASS_HANDLE(typeArrayKlassKlass   , oop_is_typeArrayKlass)

   218 DEF_KLASS_HANDLE(arrayKlass            , oop_is_array         )

   219 DEF_KLASS_HANDLE(typeArrayKlass        , oop_is_typeArray_slow)

   220 DEF_KLASS_HANDLE(objArrayKlass         , oop_is_objArray_slow )

   221 DEF_KLASS_HANDLE(symbolKlass           , oop_is_symbol        )

   222 DEF_KLASS_HANDLE(constantPoolKlass     , oop_is_constantPool  )

   223 DEF_KLASS_HANDLE(constantPoolCacheKlass, oop_is_constantPool  )

   226 //------------------------------------------------------------------------------------------------------------------------

   227 // Thread local handle area

   229 class HandleArea: public Arena {

   230   friend class HandleMark;

   231   friend class NoHandleMark;

   232   friend class ResetNoHandleMark;

   233 #ifdef ASSERT

   234   int _handle_mark_nesting;

   235   int _no_handle_mark_nesting;

   236 #endif

   237   HandleArea* _prev;          // link to outer (older) area

   238  public:

   239   // Constructor

   240   HandleArea(HandleArea* prev) {

   241     debug_only(_handle_mark_nesting    = 0);

   242     debug_only(_no_handle_mark_nesting = 0);

   243     _prev = prev;

   244   }

   246   // Handle allocation

   247  private:

   248   oop* real_allocate_handle(oop obj) {

   249 #ifdef ASSERT

   250     oop* handle = (oop*) (UseMallocOnly ? internal_malloc_4(oopSize) : Amalloc_4(oopSize));

   251 #else

   252     oop* handle = (oop*) Amalloc_4(oopSize);

   253 #endif

   254     *handle = obj;

   255     return handle;

   256   }

   257  public:

   258 #ifdef ASSERT

   259   oop* allocate_handle(oop obj);

   260 #else

   261   oop* allocate_handle(oop obj) { return real_allocate_handle(obj); }

   262 #endif

   264   // Garbage collection support

   265   void oops_do(OopClosure* f);

   267   // Number of handles in use

   268   size_t used() const     { return Arena::used() / oopSize; }

   270   debug_only(bool no_handle_mark_active() { return _no_handle_mark_nesting > 0; })

   271 };

   274 //------------------------------------------------------------------------------------------------------------------------

   275 // Handles are allocated in a (growable) thread local handle area. Deallocation

   276 // is managed using a HandleMark. It should normally not be necessary to use

   277 // HandleMarks manually.

   278 //

   279 // A HandleMark constructor will record the current handle area top, and the

   280 // desctructor will reset the top, destroying all handles allocated in between.

   281 // The following code will therefore NOT work:

   282 //

   283 //   Handle h;

   284 //   {

   285 //     HandleMark hm;

   286 //     h = Handle(obj);

   287 //   }

   288 //   h()->print();       // WRONG, h destroyed by HandleMark destructor.

   289 //

   290 // If h has to be preserved, it can be converted to an oop or a local JNI handle

   291 // across the HandleMark boundary.

   293 // The base class of HandleMark should have been StackObj but we also heap allocate

   294 // a HandleMark when a thread is created.

   296 class HandleMark {

   297  private:

   298   Thread *_thread;              // thread that owns this mark

   299   HandleArea *_area;            // saved handle area

   300   Chunk *_chunk;                // saved arena chunk

   301   char *_hwm, *_max;            // saved arena info

   302   NOT_PRODUCT(size_t _size_in_bytes;) // size of handle area

   303   // Link to previous active HandleMark in thread

   304   HandleMark* _previous_handle_mark;

   306   void initialize(Thread* thread);                // common code for constructors

   307   void set_previous_handle_mark(HandleMark* mark) { _previous_handle_mark = mark; }

   308   HandleMark* previous_handle_mark() const        { return _previous_handle_mark; }

   310  public:

   311   HandleMark();                            // see handles_inline.hpp

   312   HandleMark(Thread* thread)                      { initialize(thread); }

   313   ~HandleMark();

   315   // Functions used by HandleMarkCleaner

   316   // called in the constructor of HandleMarkCleaner

   317   void push();

   318   // called in the destructor of HandleMarkCleaner

   319   void pop_and_restore();

   320 };

   322 //------------------------------------------------------------------------------------------------------------------------

   323 // A NoHandleMark stack object will verify that no handles are allocated

   324 // in its scope. Enabled in debug mode only.

   326 class NoHandleMark: public StackObj {

   327  public:

   328 #ifdef ASSERT

   329   NoHandleMark();

   330   ~NoHandleMark();

   331 #else

   332   NoHandleMark()  {}

   333   ~NoHandleMark() {}

   334 #endif

   335 };

   338 class ResetNoHandleMark: public StackObj {

   339   int _no_handle_mark_nesting;

   340  public:

   341 #ifdef ASSERT

   342   ResetNoHandleMark();

   343   ~ResetNoHandleMark();

   344 #else

   345   ResetNoHandleMark()  {}

   346   ~ResetNoHandleMark() {}

   347 #endif

   348 };

Mercurial > jdk8-mips64-public > hotspot / file revision

src/share/vm/runtime/handles.hpp@9f4457a14b58

src/share/vm/runtime/handles.hpp