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_HEAPREGIONSEQ_HPP 26 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSEQ_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 HeapRegionSeq: public CHeapObj<mtGC> { 68 friend class VMStructs; 69 70 G1HeapRegionTable _regions; 71 72 G1RegionToSpaceMapper* _heap_mapper; 73 G1RegionToSpaceMapper* _prev_bitmap_mapper; 74 G1RegionToSpaceMapper* _next_bitmap_mapper; 75 G1RegionToSpaceMapper* _bot_mapper; 76 G1RegionToSpaceMapper* _cardtable_mapper; 77 G1RegionToSpaceMapper* _card_counts_mapper; 78 79 FreeRegionList _free_list; 80 81 // Each bit in this bitmap indicates that the corresponding region is available 82 // for allocation. 83 BitMap _available_map; 84 85 // The number of regions committed in the heap. 86 uint _num_committed; 87 88 // Internal only. The highest heap region +1 we allocated a HeapRegion instance for. 89 uint _allocated_heapregions_length; 90 91 HeapWord* heap_bottom() const { return _regions.bottom_address_mapped(); } 92 HeapWord* heap_end() const {return _regions.end_address_mapped(); } 93 94 void make_regions_available(uint index, uint num_regions = 1); 95 96 // Pass down commit calls to the VirtualSpace. 97 void commit_regions(uint index, size_t num_regions = 1); 98 void uncommit_regions(uint index, size_t num_regions = 1); 99 100 // Notify other data structures about change in the heap layout. 101 void update_committed_space(HeapWord* old_end, HeapWord* new_end); 102 // Calculate the starting region for each worker during parallel iteration so 103 // that they do not all start from the same region. 104 uint start_region_for_worker(uint worker_i, uint num_workers, uint num_regions) const; 105 106 // Find a contiguous set of empty or uncommitted regions of length num and return 107 // the index of the first region or G1_NO_HRS_INDEX if the search was unsuccessful. 108 // If only_empty is true, only empty regions are considered. 109 // Searches from bottom to top of the heap, doing a first-fit. 110 uint find_contiguous(size_t num, bool only_empty); 111 // Finds the next sequence of unavailable regions starting from start_idx. Returns the 112 // length of the sequence found. If this result is zero, no such sequence could be found, 113 // otherwise res_idx indicates the start index of these regions. 114 uint find_unavailable_from_idx(uint start_idx, uint* res_idx) const; 115 // Finds the next sequence of empty regions starting from start_idx, going backwards in 116 // the heap. Returns the length of the sequence found. If this value is zero, no 117 // sequence could be found, otherwise res_idx contains the start index of this range. 118 uint find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const; 119 // Allocate a new HeapRegion for the given index. 120 HeapRegion* new_heap_region(uint hrs_index); 121 #ifdef ASSERT 122 public: 123 bool is_free(HeapRegion* hr) const; 124 #endif 125 // Returns whether the given region is available for allocation. 126 bool is_available(uint region) const; 127 128 public: 129 // Empty constructor, we'll initialize it with the initialize() method. 130 HeapRegionSeq() : _regions(), _heap_mapper(NULL), _num_committed(0), 131 _next_bitmap_mapper(NULL), _prev_bitmap_mapper(NULL), _bot_mapper(NULL), 132 _allocated_heapregions_length(0), _available_map(), 133 _free_list("Free list", new MasterFreeRegionListMtSafeChecker()) 134 { } 135 136 void initialize(G1RegionToSpaceMapper* heap_storage, 137 G1RegionToSpaceMapper* prev_bitmap, 138 G1RegionToSpaceMapper* next_bitmap, 139 G1RegionToSpaceMapper* bot, 140 G1RegionToSpaceMapper* cardtable, 141 G1RegionToSpaceMapper* card_counts); 142 143 // Return the "dummy" region used for G1AllocRegion. This is currently a hardwired 144 // new HeapRegion that owns HeapRegion at index 0. Since at the moment we commit 145 // the heap from the lowest address, this region (and its associated data 146 // structures) are available and we do not need to check further. 147 HeapRegion* get_dummy_region() { return new_heap_region(0); } 148 149 // Return the HeapRegion at the given index. Assume that the index 150 // is valid. 151 inline HeapRegion* at(uint index) const; 152 153 // If addr is within the committed space return its corresponding 154 // HeapRegion, otherwise return NULL. 155 inline HeapRegion* addr_to_region(HeapWord* addr) const; 156 157 // Insert the given region into the free region list. 158 inline void insert_into_free_list(HeapRegion* hr); 159 160 // Insert the given region list into the global free region list. 161 void insert_list_into_free_list(FreeRegionList* list) { 162 _free_list.add_ordered(list); 163 } 164 165 HeapRegion* allocate_free_region(bool is_old) { 166 HeapRegion* hr = _free_list.remove_region(is_old); 167 168 if (hr != NULL) { 169 assert(hr->next() == NULL, "Single region should not have next"); 170 assert(is_available(hr->hrs_index()), "Must be committed"); 171 } 172 return hr; 173 } 174 175 inline void allocate_free_regions_starting_at(uint first, uint num_regions); 176 177 // Remove all regions from the free list. 178 void remove_all_free_regions() { 179 _free_list.remove_all(); 180 } 181 182 // Return the number of committed free regions in the heap. 183 uint num_free_regions() const { 184 return _free_list.length(); 185 } 186 187 size_t total_capacity_bytes() const { 188 return num_free_regions() * HeapRegion::GrainBytes; 189 } 190 191 // Return the number of available (uncommitted) regions. 192 uint available() const { return max_length() - length(); } 193 194 // Return the number of regions that have been committed in the heap. 195 uint length() const { return _num_committed; } 196 197 // Return the maximum number of regions in the heap. 198 uint max_length() const { return (uint)_regions.length(); } 199 200 MemRegion reserved() const { return MemRegion(heap_bottom(), heap_end()); } 201 202 // Expand the sequence to reflect that the heap has grown. Either create new 203 // HeapRegions, or re-use existing ones. Returns the number of regions the 204 // sequence was expanded by. If a HeapRegion allocation fails, the resulting 205 // number of regions might be smaller than what's desired. 206 uint expand_by(uint num_regions); 207 208 // Makes sure that the regions from start to start+num_regions-1 are available 209 // for allocation. Returns the number of regions that were committed to achieve 210 // this. 211 uint expand_at(uint start, uint num_regions); 212 213 // Find a contiguous set of empty regions of length num. Returns the start index of 214 // that set, or G1_NO_HRS_INDEX. 215 uint find_contiguous_only_empty(size_t num) { return find_contiguous(num, true); } 216 // Find a contiguous set of empty or unavailable regions of length num. Returns the 217 // start index of that set, or G1_NO_HRS_INDEX. 218 uint find_contiguous_empty_or_unavailable(size_t num) { return find_contiguous(num, false); } 219 220 HeapRegion* next_region_in_heap(const HeapRegion* r) const; 221 222 // Apply blk->doHeapRegion() on all committed regions in address order, 223 // terminating the iteration early if doHeapRegion() returns true. 224 void iterate(HeapRegionClosure* blk) const; 225 226 void par_iterate(HeapRegionClosure* blk, uint worker_id, uint no_of_par_workers, jint claim_value) const; 227 228 // Uncommit up to num_regions_to_remove regions that are completely free. 229 // Return the actual number of uncommitted regions. 230 uint shrink_by(uint num_regions_to_remove); 231 232 void verify(); 233 234 // Do some sanity checking. 235 void verify_optional() PRODUCT_RETURN; 236 }; 237 238 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSEQ_HPP 239