jdk8-mips64-public/hotspot: src/share/vm/utilities/stack.hpp@3582bf76420e (annotated)

src/share/vm/utilities/stack.hpp@3582bf76420e (annotated)

src/share/vm/utilities/stack.hpp

Thu, 27 Jan 2011 16:11:27 -0800

author: coleenp
date: Thu, 27 Jan 2011 16:11:27 -0800
changeset 2497: 3582bf76420e
parent 2314: f95d63e2154a
child 3900: d2a62e0f25eb
permissions: -rw-r--r--

6990754: Use native memory and reference counting to implement SymbolTable
Summary: move symbols from permgen into C heap and reference count them
Reviewed-by: never, acorn, jmasa, stefank

 /*
  * Copyright (c) 2009, 2010, 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_UTILITIES_STACK_HPP
 #define SHARE_VM_UTILITIES_STACK_HPP
 #include "memory/allocation.inline.hpp"
 // Class Stack (below) grows and shrinks by linking together "segments" which
 // are allocated on demand.  Segments are arrays of the element type (E) plus an
 // extra pointer-sized field to store the segment link.  Recently emptied
 // segments are kept in a cache and reused.
 //
 // Notes/caveats:
 //
 // The size of an element must either evenly divide the size of a pointer or be
 // a multiple of the size of a pointer.
 //
 // Destructors are not called for elements popped off the stack, so element
 // types which rely on destructors for things like reference counting will not
 // work properly.
 //
 // Class Stack allocates segments from the C heap.  However, two protected
 // virtual methods are used to alloc/free memory which subclasses can override:
 //
 //      virtual void* alloc(size_t bytes);
 //      virtual void  free(void* addr, size_t bytes);
 //
 // The alloc() method must return storage aligned for any use.  The
 // implementation in class Stack assumes that alloc() will terminate the process
 // if the allocation fails.
 template <class E> class StackIterator;
 // StackBase holds common data/methods that don't depend on the element type,
 // factored out to reduce template code duplication.
 class StackBase
 {
 public:
   size_t segment_size()   const { return _seg_size; } // Elements per segment.
   size_t max_size()       const { return _max_size; } // Max elements allowed.
   size_t max_cache_size() const { return _max_cache_size; } // Max segments
                                                             // allowed in cache.
   size_t cache_size() const { return _cache_size; }   // Segments in the cache.
 protected:
   // The ctor arguments correspond to the like-named functions above.
   // segment_size:    number of items per segment
   // max_cache_size:  maxmium number of *segments* to cache
   // max_size:        maximum number of items allowed, rounded to a multiple of
   //                  the segment size (0 == unlimited)
   inline StackBase(size_t segment_size, size_t max_cache_size, size_t max_size);
   // Round max_size to a multiple of the segment size.  Treat 0 as unlimited.
   static inline size_t adjust_max_size(size_t max_size, size_t seg_size);
 protected:
   const size_t _seg_size;       // Number of items per segment.
   const size_t _max_size;       // Maximum number of items allowed in the stack.
   const size_t _max_cache_size; // Maximum number of segments to cache.
   size_t       _cur_seg_size;   // Number of items in the current segment.
   size_t       _full_seg_size;  // Number of items in already-filled segments.
   size_t       _cache_size;     // Number of segments in the cache.
 };
 #ifdef __GNUC__
 #define inline
 #endif // __GNUC__
 template <class E>
 class Stack:  public StackBase
 {
 public:
   friend class StackIterator<E>;
   // segment_size:    number of items per segment
   // max_cache_size:  maxmium number of *segments* to cache
   // max_size:        maximum number of items allowed, rounded to a multiple of
   //                  the segment size (0 == unlimited)
   inline Stack(size_t segment_size = default_segment_size(),
                size_t max_cache_size = 4, size_t max_size = 0);
   inline ~Stack() { clear(true); }
   inline bool is_empty() const { return _cur_seg == NULL; }
   inline bool is_full()  const { return _full_seg_size >= max_size(); }
   // Performance sensitive code should use is_empty() instead of size() == 0 and
   // is_full() instead of size() == max_size().  Using a conditional here allows
   // just one var to be updated when pushing/popping elements instead of two;
   // _full_seg_size is updated only when pushing/popping segments.
   inline size_t size() const {
     return is_empty() ? 0 : _full_seg_size + _cur_seg_size;
   }
   inline void push(E elem);
   inline E    pop();
   // Clear everything from the stack, releasing the associated memory.  If
   // clear_cache is true, also release any cached segments.
   void clear(bool clear_cache = false);
   static inline size_t default_segment_size();
 protected:
   // Each segment includes space for _seg_size elements followed by a link
   // (pointer) to the previous segment; the space is allocated as a single block
   // of size segment_bytes().  _seg_size is rounded up if necessary so the link
   // is properly aligned.  The C struct for the layout would be:
   //
   // struct segment {
   //   E     elements[_seg_size];
   //   E*    link;
   // };
   // Round up seg_size to keep the link field aligned.
   static inline size_t adjust_segment_size(size_t seg_size);
   // Methods for allocation size and getting/setting the link.
   inline size_t link_offset() const;              // Byte offset of link field.
   inline size_t segment_bytes() const;            // Segment size in bytes.
   inline E**    link_addr(E* seg) const;          // Address of the link field.
   inline E*     get_link(E* seg) const;           // Extract the link from seg.
   inline E*     set_link(E* new_seg, E* old_seg); // new_seg.link = old_seg.
   virtual E*    alloc(size_t bytes);
   virtual void  free(E* addr, size_t bytes);
   void push_segment();
   void pop_segment();
   void free_segments(E* seg);          // Free all segments in the list.
   inline void reset(bool reset_cache); // Reset all data fields.
   DEBUG_ONLY(void verify(bool at_empty_transition) const;)
   DEBUG_ONLY(void zap_segment(E* seg, bool zap_link_field) const;)
 private:
   E* _cur_seg;    // Current segment.
   E* _cache;      // Segment cache to avoid ping-ponging.
 };
 template <class E> class ResourceStack:  public Stack<E>, public ResourceObj
 {
 public:
   // If this class becomes widely used, it may make sense to save the Thread
   // and use it when allocating segments.
   ResourceStack(size_t segment_size = Stack<E>::default_segment_size()):
     Stack<E>(segment_size, max_uintx)
     { }
   // Set the segment pointers to NULL so the parent dtor does not free them;
   // that must be done by the ResourceMark code.
   ~ResourceStack() { Stack<E>::reset(true); }
 protected:
   virtual E*   alloc(size_t bytes);
   virtual void free(E* addr, size_t bytes);
 private:
   void clear(bool clear_cache = false);
 };
 template <class E>
 class StackIterator: public StackObj
 {
 public:
   StackIterator(Stack<E>& stack): _stack(stack) { sync(); }
   Stack<E>& stack() const { return _stack; }
   bool is_empty() const { return _cur_seg == NULL; }
   E  next() { return *next_addr(); }
   E* next_addr();
   void sync(); // Sync the iterator's state to the stack's current state.
 private:
   Stack<E>& _stack;
   size_t    _cur_seg_size;
   E*        _cur_seg;
   size_t    _full_seg_size;
 };
 #ifdef __GNUC__
 #undef inline
 #endif // __GNUC__
 #endif // SHARE_VM_UTILITIES_STACK_HPP

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/utilities/stack.hpp@3582bf76420e (annotated)

src/share/vm/utilities/stack.hpp