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/heapRegionSet.hpp" 30 31 class HeapRegion; 32 class HeapRegionClosure; 33 class FreeRegionList; 34 35 class G1HeapRegionTable : public G1BiasedMappedArray<HeapRegion*> { 36 protected: 37 virtual HeapRegion* default_value() const { return NULL; } 38 }; 39 40 // This class keeps track of the region metadata (i.e., HeapRegion 41 // instances). They are kept in the _regions array in address 42 // order. A region's index in the array corresponds to its index in 43 // the heap (i.e., 0 is the region at the bottom of the heap, 1 is 44 // the one after it, etc.). Two regions that are consecutive in the 45 // array should also be adjacent in the address space (i.e., 46 // region(i).end() == region(i+1).bottom(). 47 // 48 // We create a HeapRegion when we commit the region's address space 49 // for the first time. When we uncommit the address space of a 50 // region we retain the HeapRegion to be able to re-use it in the 51 // future (in case we recommit it). 52 // 53 // We keep track of three lengths: 54 // 55 // * _committed_length (returned by length()) is the number of currently 56 // committed regions. 57 // * _allocated_length (not exposed outside this class) is the 58 // number of regions for which we have HeapRegions. 59 // * max_length() returns the maximum number of regions the heap can have. 60 // 61 // and maintain that: _committed_length <= _allocated_length <= max_length() 62 63 class HeapRegionSeq: public CHeapObj<mtGC> { 64 friend class VMStructs; 65 66 G1HeapRegionTable _regions; 67 68 ReservedSpace _reserved; 69 VirtualSpace _storage; 70 71 FreeRegionList _free_list; 72 73 // The number of regions committed in the heap. 74 uint _num_committed; 75 76 // Internal only. The highest heap region +1 we allocated a HeapRegion instance for. 77 uint _allocated_heapregions_length; 78 79 HeapWord* heap_bottom() const { return _regions.bottom_address_mapped(); } 80 HeapWord* heap_top() const { return heap_bottom() + _num_committed * HeapRegion::GrainWords; } 81 HeapWord* heap_end() const {return _regions.end_address_mapped(); } 82 83 void make_regions_available(uint index, uint num_regions = 1); 84 85 // Pass down commit calls to the VirtualSpace. 86 void commit_regions(uint index, size_t num_regions = 1); 87 void uncommit_regions(uint index, size_t num_regions = 1); 88 89 // Notify other data structures about change in the heap layout. 90 void update_committed_space(HeapWord* old_end, HeapWord* new_end); 91 // Calculate the starting region for each worker during parallel iteration so 92 // that they do not all start from the same region. 93 uint start_region_for_worker(uint worker_i, uint num_workers, uint num_regions) const; 94 95 // Finds the next sequence of unavailable regions starting from start_idx. Returns the 96 // length of the sequence found. If this result is zero, no such sequence could be found, 97 // otherwise res_idx indicates the start index of these regions. 98 uint find_unavailable_from_idx(uint start_idx, uint* res_idx) const; 99 // Finds the next sequence of empty regions starting from start_idx, going backwards in 100 // the heap. Returns the length of the sequence found. If this value is zero, no 101 // sequence could be found, otherwise res_idx contains the start index of this range. 102 uint find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const; 103 #ifdef ASSERT 104 public: 105 bool is_free(HeapRegion* hr) const; 106 #endif 107 // Returns whether the given region is available for allocation. 108 bool is_available(uint region) const; 109 110 // Allocate a new HeapRegion for the given index. 111 HeapRegion* new_heap_region(uint hrs_index); 112 public: 113 // Empty constructor, we'll initialize it with the initialize() method. 114 HeapRegionSeq() : _regions(), _reserved(), _storage(), _num_committed(0), 115 _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()), 116 _allocated_heapregions_length(0) 117 { } 118 119 void initialize(ReservedSpace reserved); 120 121 // Return the "dummy" region used for G1AllocRegion. This is currently a hardwired 122 // new HeapRegion that owns HeapRegion at index 0. Since at the moment we commit 123 // the heap from the lowest address, this region (and its associated data 124 // structures) are available and we do not need to check further. 125 HeapRegion* get_dummy_region() { return new_heap_region(0); } 126 127 // Return the HeapRegion at the given index. Assume that the index 128 // is valid. 129 inline HeapRegion* at(uint index) const; 130 131 // If addr is within the committed space return its corresponding 132 // HeapRegion, otherwise return NULL. 133 inline HeapRegion* addr_to_region(HeapWord* addr) const; 134 135 // Insert the given region into the free region list. 136 inline void insert_into_free_list(HeapRegion* hr); 137 138 // Insert the given region list into the global free region list. 139 void insert_list_into_free_list(FreeRegionList* list) { 140 _free_list.add_ordered(list); 141 } 142 143 HeapRegion* allocate_free_region(bool is_old) { 144 HeapRegion* hr = _free_list.remove_region(is_old); 145 146 if (hr != NULL) { 147 assert(hr->next() == NULL, "Single region should not have next"); 148 assert(is_available(hr->hrs_index()), "Must be committed"); 149 } 150 return hr; 151 } 152 153 inline void allocate_free_regions_starting_at(uint first, uint num_regions); 154 155 // Remove all regions from the free list. 156 void remove_all_free_regions() { 157 _free_list.remove_all(); 158 } 159 160 // Return the number of committed free regions in the heap. 161 uint num_free_regions() const { 162 return _free_list.length(); 163 } 164 165 size_t total_capacity_bytes() const { 166 return num_free_regions() * HeapRegion::GrainBytes; 167 } 168 169 // Return the number of available (uncommitted) regions. 170 uint available() const { return max_length() - length(); } 171 172 // Return the number of regions that have been committed in the heap. 173 uint length() const { return _num_committed; } 174 175 // Return the maximum number of regions in the heap. 176 uint max_length() const { return (uint)_regions.length(); } 177 178 MemRegion committed() const { MemRegion temp(heap_bottom(), heap_top()); return temp; } 179 180 MemRegion reserved() const { MemRegion temp(heap_bottom(), heap_end()); return temp; } 181 182 // Expand the sequence to reflect that the heap has grown. Either create new 183 // HeapRegions, or re-use existing ones. Returns the number of regions the 184 // sequence was expanded by. If a HeapRegion allocation fails, the resulting 185 // number of regions might be smaller than what's desired. 186 uint expand_by(uint num_regions); 187 188 // Makes sure that the regions from start to start+num_regions-1 are available 189 // for allocation. Returns the number of regions that were committed to achieve 190 // this. 191 uint expand_at(uint start, uint num_regions); 192 193 // Find a contiguous set of empty or uncommitted regions of length num and return 194 // the index of the first region or G1_NO_HRS_INDEX if the search was unsuccessful. 195 // If only_empty is true, only empty regions are considered. 196 // Searches from bottom to top of the heap, doing a first-fit. 197 uint find_contiguous(size_t num, bool only_empty); 198 199 HeapRegion* next_region_in_heap(const HeapRegion* r) const; 200 201 // Apply blk->doHeapRegion() on all committed regions in address order, 202 // terminating the iteration early if doHeapRegion() returns true. 203 void iterate(HeapRegionClosure* blk) const; 204 205 void par_iterate(HeapRegionClosure* blk, uint worker_id, uint no_of_par_workers, jint claim_value) const; 206 207 // Uncommit up to num_regions_to_remove regions that are completely free. 208 // Return the actual number of uncommitted regions. 209 uint shrink_by(uint num_regions_to_remove); 210 211 void verify(); 212 213 // Do some sanity checking. 214 void verify_optional() PRODUCT_RETURN; 215 }; 216 217 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSEQ_HPP