1 /*
   2  * Copyright 2001-2008 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  */
  24 
  25 class PSMarkSweepDecorator;
  26 
  27 class PSOldGen : public CHeapObj {
  28   friend class VMStructs;
  29   friend class PSPromotionManager; // Uses the cas_allocate methods
  30   friend class ParallelScavengeHeap;
  31   friend class AdjoiningGenerations;
  32 
  33  protected:
  34   MemRegion                _reserved;          // Used for simple containment tests
  35   PSVirtualSpace*          _virtual_space;     // Controls mapping and unmapping of virtual mem
  36   ObjectStartArray         _start_array;       // Keeps track of where objects start in a 512b block
  37   MutableSpace*            _object_space;      // Where all the objects live
  38   PSMarkSweepDecorator*    _object_mark_sweep; // The mark sweep view of _object_space
  39   const char* const        _name;              // Name of this generation.
  40 
  41   // Performance Counters
  42   PSGenerationCounters*    _gen_counters;
  43   SpaceCounters*           _space_counters;
  44 
  45   // Sizing information, in bytes, set in constructor
  46   const size_t _init_gen_size;
  47   const size_t _min_gen_size;
  48   const size_t _max_gen_size;
  49 
  50   // Used when initializing the _name field.
  51   static inline const char* select_name();
  52 
  53   HeapWord* allocate_noexpand(size_t word_size, bool is_tlab) {
  54     // We assume the heap lock is held here.
  55     assert(!is_tlab, "Does not support TLAB allocation");
  56     assert_locked_or_safepoint(Heap_lock);
  57     HeapWord* res = object_space()->allocate(word_size);
  58     if (res != NULL) {
  59       _start_array.allocate_block(res);
  60     }
  61     return res;
  62   }
  63 
  64   // Support for MT garbage collection. CAS allocation is lower overhead than grabbing
  65   // and releasing the heap lock, which is held during gc's anyway. This method is not
  66   // safe for use at the same time as allocate_noexpand()!
  67   HeapWord* cas_allocate_noexpand(size_t word_size) {
  68     assert(SafepointSynchronize::is_at_safepoint(), "Must only be called at safepoint")
  69     HeapWord* res = object_space()->cas_allocate(word_size);
  70     if (res != NULL) {
  71       _start_array.allocate_block(res);
  72     }
  73     return res;
  74   }
  75 
  76   // Support for MT garbage collection. See above comment.
  77   HeapWord* cas_allocate(size_t word_size) {
  78     HeapWord* res = cas_allocate_noexpand(word_size);
  79     return (res == NULL) ? expand_and_cas_allocate(word_size) : res;
  80   }
  81 
  82   HeapWord* expand_and_allocate(size_t word_size, bool is_tlab);
  83   HeapWord* expand_and_cas_allocate(size_t word_size);
  84   void expand(size_t bytes);
  85   bool expand_by(size_t bytes);
  86   bool expand_to_reserved();
  87 
  88   void shrink(size_t bytes);
  89 
  90   void post_resize();
  91 
  92  public:
  93   // Initialize the generation.
  94   PSOldGen(ReservedSpace rs, size_t alignment,
  95            size_t initial_size, size_t min_size, size_t max_size,
  96            const char* perf_data_name, int level);
  97 
  98   PSOldGen(size_t initial_size, size_t min_size, size_t max_size,
  99            const char* perf_data_name, int level);
 100 
 101   void initialize(ReservedSpace rs, size_t alignment,
 102                   const char* perf_data_name, int level);
 103   void initialize_virtual_space(ReservedSpace rs, size_t alignment);
 104   void initialize_work(const char* perf_data_name, int level);
 105 
 106   MemRegion reserved() const                { return _reserved; }
 107   virtual size_t max_gen_size()             { return _max_gen_size; }
 108   size_t min_gen_size()                     { return _min_gen_size; }
 109 
 110   // Returns limit on the maximum size of the generation.  This
 111   // is the same as _max_gen_size for PSOldGen but need not be
 112   // for a derived class.
 113   virtual size_t gen_size_limit();
 114 
 115   bool is_in(const void* p) const           {
 116     return _virtual_space->contains((void *)p);
 117   }
 118 
 119   bool is_in_reserved(const void* p) const {
 120     return reserved().contains(p);
 121   }
 122 
 123   MutableSpace*         object_space() const      { return _object_space; }
 124   PSMarkSweepDecorator* object_mark_sweep() const { return _object_mark_sweep; }
 125   ObjectStartArray*     start_array()             { return &_start_array; }
 126   PSVirtualSpace*       virtual_space() const     { return _virtual_space;}
 127 
 128   // Has the generation been successfully allocated?
 129   bool is_allocated();
 130 
 131   // MarkSweep methods
 132   virtual void precompact();
 133   void adjust_pointers();
 134   void compact();
 135 
 136   // Parallel old
 137   virtual void move_and_update(ParCompactionManager* cm);
 138 
 139   // Size info
 140   size_t capacity_in_bytes() const        { return object_space()->capacity_in_bytes(); }
 141   size_t used_in_bytes() const            { return object_space()->used_in_bytes(); }
 142   size_t free_in_bytes() const            { return object_space()->free_in_bytes(); }
 143 
 144   size_t capacity_in_words() const        { return object_space()->capacity_in_words(); }
 145   size_t used_in_words() const            { return object_space()->used_in_words(); }
 146   size_t free_in_words() const            { return object_space()->free_in_words(); }
 147 
 148   // Includes uncommitted memory
 149   size_t contiguous_available() const;
 150 
 151   bool is_maximal_no_gc() const {
 152     return virtual_space()->uncommitted_size() == 0;
 153   }
 154 
 155   // Calculating new sizes
 156   void resize(size_t desired_free_space);
 157 
 158   // Allocation. We report all successful allocations to the size policy
 159   // Note that the perm gen does not use this method, and should not!
 160   HeapWord* allocate(size_t word_size, bool is_tlab);
 161 
 162   // Iteration.
 163   void oop_iterate(OopClosure* cl) { object_space()->oop_iterate(cl); }
 164   void object_iterate(ObjectClosure* cl) { object_space()->object_iterate(cl); }
 165 
 166   // Debugging - do not use for time critical operations
 167   virtual void print() const;
 168   virtual void print_on(outputStream* st) const;
 169   void print_used_change(size_t prev_used) const;
 170 
 171   void verify(bool allow_dirty);
 172   void verify_object_start_array();
 173 
 174   // These should not used
 175   virtual void reset_after_change();
 176 
 177   // These should not used
 178   virtual size_t available_for_expansion();
 179   virtual size_t available_for_contraction();
 180 
 181   void space_invariants() PRODUCT_RETURN;
 182 
 183   // Performace Counter support
 184   void update_counters();
 185 
 186   // Printing support
 187   virtual const char* name() const { return _name; }
 188 
 189   // Debugging support
 190   // Save the tops of all spaces for later use during mangling.
 191   void record_spaces_top() PRODUCT_RETURN;
 192 };