jdk8-mips64-public/hotspot: src/share/vm/runtime/handles.hpp@833b0f92429a (annotated)

src/share/vm/runtime/handles.hpp@833b0f92429a (annotated)

src/share/vm/runtime/handles.hpp

Wed, 27 Aug 2014 08:19:12 -0400

author: zgu
date: Wed, 27 Aug 2014 08:19:12 -0400
changeset 7074: 833b0f92429a
parent 5749: 4f9a42c33738
child 7535: 7ae4e26cb1e0
permissions: -rw-r--r--

8046598: Scalable Native memory tracking development
Summary: Enhance scalability of native memory tracking
Reviewed-by: coleenp, ctornqvi, gtriantafill

 /*
  * Copyright (c) 1997, 2014, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #ifndef SHARE_VM_RUNTIME_HANDLES_HPP
 #define SHARE_VM_RUNTIME_HANDLES_HPP
 #include "oops/klass.hpp"
 //------------------------------------------------------------------------------------------------------------------------
 // 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
 //   Method*       methodHandle
 //   instanceOop   instanceHandle
 //------------------------------------------------------------------------------------------------------------------------
 // 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);
   Handle(Thread* thread, oop obj);
   // 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; }
 };
 // Specific Handles for different oop types
 #define DEF_HANDLE(type, is_a)                   \
   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(is_null() || ((oop)obj)->is_a(),                                 \
              "illegal type");                                                 \
     }                                                                         \
     type##Handle (Thread* thread, type##Oop obj) : Handle(thread, (oop)obj) { \
       assert(is_null() || ((oop)obj)->is_a(), "illegal type");                \
     }                                                                         \
     \
     /* 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(array            , is_array            )
 DEF_HANDLE(objArray         , is_objArray         )
 DEF_HANDLE(typeArray        , is_typeArray        )
 //------------------------------------------------------------------------------------------------------------------------
 // Metadata Handles.  Unlike oop Handles these are needed to prevent metadata
 // from being reclaimed by RedefineClasses.
 // Specific Handles for different oop types
 #define DEF_METADATA_HANDLE(name, type)          \
   class name##Handle;                            \
   class name##Handle : public StackObj {         \
     type*     _value;                            \
     Thread*   _thread;                           \
    protected:                                    \
     type*        obj() const                     { return _value; } \
     type*        non_null_obj() const            { assert(_value != NULL, "resolving NULL _value"); return _value; } \
                                                  \
    public:                                       \
     /* Constructors */                           \
     name##Handle () : _value(NULL), _thread(NULL) {}   \
     name##Handle (type* obj);                    \
     name##Handle (Thread* thread, type* obj);    \
                                                  \
     name##Handle (const name##Handle &h);        \
     name##Handle& operator=(const name##Handle &s); \
                                                  \
     /* Destructor */                             \
     ~name##Handle ();                            \
     void remove();                               \
                                                  \
     /* Operators for ease of use */              \
     type*        operator () () const            { return obj(); } \
     type*        operator -> () const            { return non_null_obj(); } \
                                                  \
     bool    operator == (type* o) const          { return obj() == o; } \
     bool    operator == (const name##Handle& h) const  { return obj() == h.obj(); } \
                                                  \
     /* Null checks */                            \
     bool    is_null() const                      { return _value == NULL; } \
     bool    not_null() const                     { return _value != NULL; } \
   };
 DEF_METADATA_HANDLE(method, Method)
 DEF_METADATA_HANDLE(constantPool, ConstantPool)
 // Writing this class explicitly, since DEF_METADATA_HANDLE(klass) doesn't
 // provide the necessary Klass* <-> Klass* conversions. This Klass
 // could be removed when we don't have the Klass* typedef anymore.
 class KlassHandle : public StackObj {
   Klass* _value;
  protected:
    Klass* obj() const          { return _value; }
    Klass* non_null_obj() const { assert(_value != NULL, "resolving NULL _value"); return _value; }
  public:
    KlassHandle()                                 : _value(NULL) {}
    KlassHandle(const Klass* obj)                 : _value(const_cast<Klass *>(obj)) {};
    KlassHandle(Thread* thread, const Klass* obj) : _value(const_cast<Klass *>(obj)) {};
    Klass* operator () () const { return obj(); }
    Klass* operator -> () const { return non_null_obj(); }
    bool operator == (Klass* o) const             { return obj() == o; }
    bool operator == (const KlassHandle& h) const { return obj() == h.obj(); }
     bool is_null() const  { return _value == NULL; }
     bool not_null() const { return _value != NULL; }
 };
 class instanceKlassHandle : public KlassHandle {
  public:
   /* Constructors */
   instanceKlassHandle () : KlassHandle() {}
   instanceKlassHandle (const Klass* k) : KlassHandle(k) {
     assert(k == NULL || k->oop_is_instance(),
            "illegal type");
   }
   instanceKlassHandle (Thread* thread, const Klass* k) : KlassHandle(thread, k) {
     assert(k == NULL || k->oop_is_instance(),
            "illegal type");
   }
   /* Access to klass part */
   InstanceKlass*       operator () () const { return (InstanceKlass*)obj(); }
   InstanceKlass*       operator -> () const { return (InstanceKlass*)obj(); }
 };
 //------------------------------------------------------------------------------------------------------------------------
 // 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) : Arena(mtThread, Chunk::tiny_size) {
     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. The operator new is for this special case.
 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
   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; }
   size_t size_in_bytes() const { return _size_in_bytes; }
  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();
   // overloaded operators
   void* operator new(size_t size) throw();
   void* operator new [](size_t size) throw();
   void operator delete(void* p);
   void operator delete[](void* p);
 };
 //------------------------------------------------------------------------------------------------------------------------
 // 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
 };
 #endif // SHARE_VM_RUNTIME_HANDLES_HPP

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/runtime/handles.hpp@833b0f92429a (annotated)

src/share/vm/runtime/handles.hpp