1 /* 2 * Copyright (c) 2001, 2009, 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 class HeapRegion; 26 class HeapRegionClosure; 27 28 class HeapRegionSeq: public CHeapObj { 29 30 // _regions is kept sorted by start address order, and no two regions are 31 // overlapping. 32 GrowableArray<HeapRegion*> _regions; 33 34 // The index in "_regions" at which to start the next allocation search. 35 // (For efficiency only; private to obj_allocate after initialization.) 36 int _alloc_search_start; 37 38 // Attempts to allocate a block of the (assumed humongous) word_size, 39 // starting at the region "ind". 40 HeapWord* alloc_obj_from_region_index(int ind, size_t word_size); 41 42 // Currently, we're choosing collection sets in a round-robin fashion, 43 // starting here. 44 int _next_rr_candidate; 45 46 // The bottom address of the bottom-most region, or else NULL if there 47 // are no regions in the sequence. 48 char* _seq_bottom; 49 50 public: 51 // Initializes "this" to the empty sequence of regions. 52 HeapRegionSeq(const size_t max_size); 53 54 // Adds "hr" to "this" sequence. Requires "hr" not to overlap with 55 // any region already in "this". (Will perform better if regions are 56 // inserted in ascending address order.) 57 void insert(HeapRegion* hr); 58 59 // Given a HeapRegion*, returns its index within _regions, 60 // or returns -1 if not found. 61 int find(HeapRegion* hr); 62 63 // Requires the index to be valid, and return the region at the index. 64 HeapRegion* at(size_t i) { return _regions.at((int)i); } 65 66 // Return the number of regions in the sequence. 67 size_t length(); 68 69 // Returns the number of contiguous regions at the end of the sequence 70 // that are available for allocation. 71 size_t free_suffix(); 72 73 // Requires "word_size" to be humongous (in the technical sense). If 74 // possible, allocates a contiguous subsequence of the heap regions to 75 // satisfy the allocation, and returns the address of the beginning of 76 // that sequence, otherwise returns NULL. 77 HeapWord* obj_allocate(size_t word_size); 78 79 // Apply the "doHeapRegion" method of "blk" to all regions in "this", 80 // in address order, terminating the iteration early 81 // if the "doHeapRegion" method returns "true". 82 void iterate(HeapRegionClosure* blk); 83 84 // Apply the "doHeapRegion" method of "blk" to all regions in "this", 85 // starting at "r" (or first region, if "r" is NULL), in a circular 86 // manner, terminating the iteration early if the "doHeapRegion" method 87 // returns "true". 88 void iterate_from(HeapRegion* r, HeapRegionClosure* blk); 89 90 // As above, but start from a given index in the sequence 91 // instead of a given heap region. 92 void iterate_from(int idx, HeapRegionClosure* blk); 93 94 // Requires "shrink_bytes" to be a multiple of the page size and heap 95 // region granularity. Deletes as many "rightmost" completely free heap 96 // regions from the sequence as comprise shrink_bytes bytes. Returns the 97 // MemRegion indicating the region those regions comprised, and sets 98 // "num_regions_deleted" to the number of regions deleted. 99 MemRegion shrink_by(size_t shrink_bytes, size_t& num_regions_deleted); 100 101 // If "addr" falls within a region in the sequence, return that region, 102 // or else NULL. 103 HeapRegion* addr_to_region(const void* addr); 104 105 void print(); 106 107 // Prints out runs of empty regions. 108 void print_empty_runs(); 109 110 };