1 /*
   2  * Copyright (c) 2001, 2020, Oracle and/or its affiliates. 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.
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   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
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
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  24 
  25 #ifndef SHARE_GC_PARALLEL_PSOLDGEN_HPP
  26 #define SHARE_GC_PARALLEL_PSOLDGEN_HPP
  27 
  28 #include "gc/parallel/mutableSpace.hpp"
  29 #include "gc/parallel/objectStartArray.hpp"
  30 #include "gc/parallel/psGenerationCounters.hpp"
  31 #include "gc/parallel/psVirtualspace.hpp"
  32 #include "gc/parallel/spaceCounters.hpp"
  33 #include "runtime/safepoint.hpp"
  34 
  35 class PSOldGen : public CHeapObj<mtGC> {
  36   friend class VMStructs;
  37   friend class PSPromotionManager; // Uses the cas_allocate methods
  38   friend class ParallelScavengeHeap;
  39   friend class AdjoiningGenerations;
  40 
  41  private:
  42   MemRegion                _reserved;          // Used for simple containment tests
  43   PSVirtualSpace*          _virtual_space;     // Controls mapping and unmapping of virtual mem
  44   ObjectStartArray         _start_array;       // Keeps track of where objects start in a 512b block
  45   MutableSpace*            _object_space;      // Where all the objects live
  46 
  47   // Performance Counters
  48   PSGenerationCounters*    _gen_counters;
  49   SpaceCounters*           _space_counters;
  50 
  51   // Sizing information, in bytes, set in constructor
  52   const size_t _init_gen_size;
  53   const size_t _min_gen_size;
  54   const size_t _max_gen_size;
  55 
  56 #ifdef ASSERT
  57   void assert_block_in_covered_region(MemRegion new_memregion) {
  58     // Explictly capture current covered_region in a local
  59     MemRegion covered_region = this->start_array()->covered_region();
  60     assert(covered_region.contains(new_memregion),
  61            "new region is not in covered_region [ " PTR_FORMAT ", " PTR_FORMAT " ], "
  62            "new region [ " PTR_FORMAT ", " PTR_FORMAT " ], "
  63            "object space [ " PTR_FORMAT ", " PTR_FORMAT " ]",
  64            p2i(covered_region.start()),
  65            p2i(covered_region.end()),
  66            p2i(new_memregion.start()),
  67            p2i(new_memregion.end()),
  68            p2i(this->object_space()->used_region().start()),
  69            p2i(this->object_space()->used_region().end()));
  70   }
  71 #endif
  72 
  73   HeapWord* allocate_noexpand(size_t word_size) {
  74     // We assume the heap lock is held here.
  75     assert_locked_or_safepoint(Heap_lock);
  76     HeapWord* res = object_space()->allocate(word_size);
  77     if (res != NULL) {
  78       DEBUG_ONLY(assert_block_in_covered_region(MemRegion(res, word_size)));
  79       _start_array.allocate_block(res);
  80     }
  81     return res;
  82   }
  83 
  84   // Support for MT garbage collection. CAS allocation is lower overhead than grabbing
  85   // and releasing the heap lock, which is held during gc's anyway. This method is not
  86   // safe for use at the same time as allocate_noexpand()!
  87   HeapWord* cas_allocate_noexpand(size_t word_size) {
  88     assert(SafepointSynchronize::is_at_safepoint(), "Must only be called at safepoint");
  89     HeapWord* res = object_space()->cas_allocate(word_size);
  90     if (res != NULL) {
  91       DEBUG_ONLY(assert_block_in_covered_region(MemRegion(res, word_size)));
  92       _start_array.allocate_block(res);
  93     }
  94     return res;
  95   }
  96 
  97   // Support for MT garbage collection. See above comment.
  98   HeapWord* cas_allocate(size_t word_size) {
  99     HeapWord* res = cas_allocate_noexpand(word_size);
 100     return (res == NULL) ? expand_and_cas_allocate(word_size) : res;
 101   }
 102 
 103   HeapWord* expand_and_allocate(size_t word_size);
 104   HeapWord* expand_and_cas_allocate(size_t word_size);
 105   void expand(size_t bytes);
 106   bool expand_by(size_t bytes);
 107   bool expand_to_reserved();
 108 
 109   void shrink(size_t bytes);
 110 
 111   void post_resize();
 112 
 113   void initialize(ReservedSpace rs, size_t alignment,
 114                   const char* perf_data_name, int level);
 115   void initialize_virtual_space(ReservedSpace rs, size_t alignment);
 116   void initialize_work(const char* perf_data_name, int level);
 117   void initialize_performance_counters(const char* perf_data_name, int level);
 118 
 119  public:
 120   // Initialize the generation.
 121   PSOldGen(ReservedSpace rs, size_t initial_size, size_t min_size,
 122            size_t max_size, const char* perf_data_name, int level);
 123 
 124   MemRegion reserved() const    { return _reserved; }
 125   virtual size_t max_gen_size() { return _max_gen_size; }
 126   size_t min_gen_size()         { return _min_gen_size; }
 127 
 128   // Returns limit on the maximum size of the generation.  This
 129   // is the same as _max_gen_size for PSOldGen but need not be
 130   // for a derived class.
 131   virtual size_t gen_size_limit();
 132 
 133   bool is_in(const void* p) const           {
 134     return _virtual_space->contains((void *)p);
 135   }
 136 
 137   bool is_in_reserved(const void* p) const {
 138     return reserved().contains(p);
 139   }
 140 
 141   MutableSpace*         object_space() const      { return _object_space; }
 142   ObjectStartArray*     start_array()             { return &_start_array; }
 143   PSVirtualSpace*       virtual_space() const     { return _virtual_space;}
 144 
 145   // Has the generation been successfully allocated?
 146   bool is_allocated();
 147 
 148   // Size info
 149   size_t capacity_in_bytes() const        { return object_space()->capacity_in_bytes(); }
 150   size_t used_in_bytes() const            { return object_space()->used_in_bytes(); }
 151   size_t free_in_bytes() const            { return object_space()->free_in_bytes(); }
 152 
 153   size_t capacity_in_words() const        { return object_space()->capacity_in_words(); }
 154   size_t used_in_words() const            { return object_space()->used_in_words(); }
 155   size_t free_in_words() const            { return object_space()->free_in_words(); }
 156 
 157   bool is_maximal_no_gc() const {
 158     return virtual_space()->uncommitted_size() == 0;
 159   }
 160 
 161   // Calculating new sizes
 162   void resize(size_t desired_free_space);
 163 
 164   // Allocation. We report all successful allocations to the size policy
 165   // Note that the perm gen does not use this method, and should not!
 166   HeapWord* allocate(size_t word_size);
 167 
 168   // Iteration.
 169   void oop_iterate(OopIterateClosure* cl) { object_space()->oop_iterate(cl); }
 170   void object_iterate(ObjectClosure* cl) { object_space()->object_iterate(cl); }
 171 
 172   // Debugging - do not use for time critical operations
 173   void print() const;
 174   virtual void print_on(outputStream* st) const;
 175 
 176   void verify();
 177   void verify_object_start_array();
 178 
 179   // Performance Counter support
 180   void update_counters();
 181 
 182   // Printing support
 183   const char* name() const { return "ParOldGen"; }
 184 
 185   // Debugging support
 186   // Save the tops of all spaces for later use during mangling.
 187   void record_spaces_top() PRODUCT_RETURN;
 188 };
 189 
 190 #endif // SHARE_GC_PARALLEL_PSOLDGEN_HPP