1 /* 2 * Copyright (c) 2001, 2013, 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_GC_IMPLEMENTATION_G1_HEAPREGIONMANAGER_HPP 26 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONMANAGER_HPP 27 28 #include "gc_implementation/g1/g1BiasedArray.hpp" 29 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp" 30 #include "gc_implementation/g1/heapRegionSet.hpp" 31 32 class HeapRegion; 33 class HeapRegionClosure; 34 class FreeRegionList; 35 36 class G1HeapRegionTable : public G1BiasedMappedArray<HeapRegion*> { 37 protected: 38 virtual HeapRegion* default_value() const { return NULL; } 39 }; 40 41 // This class keeps track of the actual heap memory, auxiliary data 42 // and its metadata (i.e., HeapRegion instances) and the list of free regions. 43 // 44 // This allows maximum flexibility for deciding what to commit or uncommit given 45 // a request from outside. 46 // 47 // HeapRegions are kept in the _regions array in address order. A region's 48 // index in the array corresponds to its index in the heap (i.e., 0 is the 49 // region at the bottom of the heap, 1 is the one after it, etc.). Two 50 // regions that are consecutive in the array should also be adjacent in the 51 // address space (i.e., region(i).end() == region(i+1).bottom(). 52 // 53 // We create a HeapRegion when we commit the region's address space 54 // for the first time. When we uncommit the address space of a 55 // region we retain the HeapRegion to be able to re-use it in the 56 // future (in case we recommit it). 57 // 58 // We keep track of three lengths: 59 // 60 // * _num_committed (returned by length()) is the number of currently 61 // committed regions. These may not be contiguous. 62 // * _allocated_heapregions_length (not exposed outside this class) is the 63 // number of regions+1 for which we have HeapRegions. 64 // * max_length() returns the maximum number of regions the heap can have. 65 // 66 67 class HeapRegionManager: public CHeapObj<mtGC> { 68 friend class VMStructs; 69 friend class HeapRegionClaimer; 70 71 G1HeapRegionTable _regions; 72 73 G1RegionToSpaceMapper* _heap_mapper; 74 G1RegionToSpaceMapper* _prev_bitmap_mapper; 75 G1RegionToSpaceMapper* _next_bitmap_mapper; 76 G1RegionToSpaceMapper* _bot_mapper; 77 G1RegionToSpaceMapper* _cardtable_mapper; 78 G1RegionToSpaceMapper* _card_counts_mapper; 79 80 FreeRegionList _free_list; 81 82 // Each bit in this bitmap indicates that the corresponding region is available 83 // for allocation. 84 BitMap _available_map; 85 86 // The number of regions committed in the heap. 87 uint _num_committed; 88 89 // Internal only. The highest heap region +1 we allocated a HeapRegion instance for. 90 uint _allocated_heapregions_length; 91 92 HeapWord* heap_bottom() const { return _regions.bottom_address_mapped(); } 93 HeapWord* heap_end() const {return _regions.end_address_mapped(); } 94 95 void make_regions_available(uint index, uint num_regions = 1); 96 97 // Pass down commit calls to the VirtualSpace. 98 void commit_regions(uint index, size_t num_regions = 1); 99 void uncommit_regions(uint index, size_t num_regions = 1); 100 101 // Notify other data structures about change in the heap layout. 102 void update_committed_space(HeapWord* old_end, HeapWord* new_end); 103 104 // Find a contiguous set of empty or uncommitted regions of length num and return 105 // the index of the first region or G1_NO_HRM_INDEX if the search was unsuccessful. 106 // If only_empty is true, only empty regions are considered. 107 // Searches from bottom to top of the heap, doing a first-fit. 108 uint find_contiguous(size_t num, bool only_empty); 109 // Finds the next sequence of unavailable regions starting from start_idx. Returns the 110 // length of the sequence found. If this result is zero, no such sequence could be found, 111 // otherwise res_idx indicates the start index of these regions. 112 uint find_unavailable_from_idx(uint start_idx, uint* res_idx) const; 113 // Finds the next sequence of empty regions starting from start_idx, going backwards in 114 // the heap. Returns the length of the sequence found. If this value is zero, no 115 // sequence could be found, otherwise res_idx contains the start index of this range. 116 uint find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const; 117 // Allocate a new HeapRegion for the given index. 118 HeapRegion* new_heap_region(uint hrm_index); 119 #ifdef ASSERT 120 public: 121 bool is_free(HeapRegion* hr) const; 122 #endif 123 // Returns whether the given region is available for allocation. 124 bool is_available(uint region) const; 125 126 public: 127 // Empty constructor, we'll initialize it with the initialize() method. 128 HeapRegionManager() : _regions(), _heap_mapper(NULL), _num_committed(0), 129 _next_bitmap_mapper(NULL), _prev_bitmap_mapper(NULL), _bot_mapper(NULL), 130 _allocated_heapregions_length(0), _available_map(), 131 _free_list("Free list", new MasterFreeRegionListMtSafeChecker()) 132 { } 133 134 void initialize(G1RegionToSpaceMapper* heap_storage, 135 G1RegionToSpaceMapper* prev_bitmap, 136 G1RegionToSpaceMapper* next_bitmap, 137 G1RegionToSpaceMapper* bot, 138 G1RegionToSpaceMapper* cardtable, 139 G1RegionToSpaceMapper* card_counts); 140 141 // Return the "dummy" region used for G1AllocRegion. This is currently a hardwired 142 // new HeapRegion that owns HeapRegion at index 0. Since at the moment we commit 143 // the heap from the lowest address, this region (and its associated data 144 // structures) are available and we do not need to check further. 145 HeapRegion* get_dummy_region() { return new_heap_region(0); } 146 147 // Return the HeapRegion at the given index. Assume that the index 148 // is valid. 149 inline HeapRegion* at(uint index) const; 150 151 // If addr is within the committed space return its corresponding 152 // HeapRegion, otherwise return NULL. 153 inline HeapRegion* addr_to_region(HeapWord* addr) const; 154 155 // Insert the given region into the free region list. 156 inline void insert_into_free_list(HeapRegion* hr); 157 158 // Insert the given region list into the global free region list. 159 void insert_list_into_free_list(FreeRegionList* list) { 160 _free_list.add_ordered(list); 161 } 162 163 HeapRegion* allocate_free_region(bool is_old) { 164 HeapRegion* hr = _free_list.remove_region(is_old); 165 166 if (hr != NULL) { 167 assert(hr->next() == NULL, "Single region should not have next"); 168 assert(is_available(hr->hrm_index()), "Must be committed"); 169 } 170 return hr; 171 } 172 173 inline void allocate_free_regions_starting_at(uint first, uint num_regions); 174 175 // Remove all regions from the free list. 176 void remove_all_free_regions() { 177 _free_list.remove_all(); 178 } 179 180 // Return the number of committed free regions in the heap. 181 uint num_free_regions() const { 182 return _free_list.length(); 183 } 184 185 size_t total_capacity_bytes() const { 186 return num_free_regions() * HeapRegion::GrainBytes; 187 } 188 189 // Return the number of available (uncommitted) regions. 190 uint available() const { return max_length() - length(); } 191 192 // Return the number of regions that have been committed in the heap. 193 uint length() const { return _num_committed; } 194 195 // Return the maximum number of regions in the heap. 196 uint max_length() const { return (uint)_regions.length(); } 197 198 MemRegion reserved() const { return MemRegion(heap_bottom(), heap_end()); } 199 200 // Expand the sequence to reflect that the heap has grown. Either create new 201 // HeapRegions, or re-use existing ones. Returns the number of regions the 202 // sequence was expanded by. If a HeapRegion allocation fails, the resulting 203 // number of regions might be smaller than what's desired. 204 uint expand_by(uint num_regions); 205 206 // Makes sure that the regions from start to start+num_regions-1 are available 207 // for allocation. Returns the number of regions that were committed to achieve 208 // this. 209 uint expand_at(uint start, uint num_regions); 210 211 // Find a contiguous set of empty regions of length num. Returns the start index of 212 // that set, or G1_NO_HRM_INDEX. 213 uint find_contiguous_only_empty(size_t num) { return find_contiguous(num, true); } 214 // Find a contiguous set of empty or unavailable regions of length num. Returns the 215 // start index of that set, or G1_NO_HRM_INDEX. 216 uint find_contiguous_empty_or_unavailable(size_t num) { return find_contiguous(num, false); } 217 218 HeapRegion* next_region_in_heap(const HeapRegion* r) const; 219 220 // Apply blk->doHeapRegion() on all committed regions in address order, 221 // terminating the iteration early if doHeapRegion() returns true. 222 void iterate(HeapRegionClosure* blk) const; 223 224 void par_iterate(HeapRegionClosure* blk, uint worker_id, HeapRegionClaimer* hrclaimer) const; 225 226 // Uncommit up to num_regions_to_remove regions that are completely free. 227 // Return the actual number of uncommitted regions. 228 uint shrink_by(uint num_regions_to_remove); 229 230 void verify(); 231 232 // Do some sanity checking. 233 void verify_optional() PRODUCT_RETURN; 234 }; 235 236 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONMANAGER_HPP 237