1 /* 2 * Copyright (c) 2014, 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. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #ifndef SHARE_VM_MEMORY_CARDGENERATION_HPP 26 #define SHARE_VM_MEMORY_CARDGENERATION_HPP 27 28 // Class CardGeneration is a generation that is covered by a card table, 29 // and uses a card-size block-offset array to implement block_start. 30 31 #include "memory/generation.hpp" 32 33 class BlockOffsetSharedArray; 34 class CompactibleSpace; 35 36 class CardGeneration: public Generation { 37 friend class VMStructs; 38 protected: 39 // This is shared with other generations. 40 GenRemSet* _rs; 41 // This is local to this generation. 42 BlockOffsetSharedArray* _bts; 43 44 // Current shrinking effect: this damps shrinking when the heap gets empty. 45 size_t _shrink_factor; 46 47 size_t _min_heap_delta_bytes; // Minimum amount to expand. 48 49 // Some statistics from before gc started. 50 // These are gathered in the gc_prologue (and should_collect) 51 // to control growing/shrinking policy in spite of promotions. 52 size_t _capacity_at_prologue; 53 size_t _used_at_prologue; 54 55 CardGeneration(ReservedSpace rs, size_t initial_byte_size, int level, 56 GenRemSet* remset); 57 58 virtual void assert_correct_size_change_locking() = 0; 59 60 virtual CompactibleSpace* space() const = 0; 61 62 public: 63 64 // Attempt to expand the generation by "bytes". Expand by at a 65 // minimum "expand_bytes". Return true if some amount (not 66 // necessarily the full "bytes") was done. 67 virtual bool expand(size_t bytes, size_t expand_bytes); 68 69 // Shrink generation with specified size 70 virtual void shrink(size_t bytes); 71 72 virtual void compute_new_size(); 73 74 virtual void clear_remembered_set(); 75 76 virtual void invalidate_remembered_set(); 77 78 virtual void prepare_for_verify(); 79 80 // Grow generation with specified size (returns false if unable to grow) 81 bool grow_by(size_t bytes); 82 // Grow generation to reserved size. 83 bool grow_to_reserved(); 84 85 size_t capacity() const; 86 size_t used() const; 87 size_t free() const; 88 MemRegion used_region() const; 89 90 void space_iterate(SpaceClosure* blk, bool usedOnly = false); 91 92 void younger_refs_iterate(OopsInGenClosure* blk, uint n_threads); 93 94 bool is_in(const void* p) const; 95 96 CompactibleSpace* first_compaction_space() const; 97 }; 98 99 #endif // SHARE_VM_MEMORY_CARDGENERATION_HPP