1 /*
2 * Copyright (c) 2001, 2015, 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
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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 #include "services/memoryUsage.hpp"
32
33 class HeapRegion;
34 class HeapRegionClosure;
35 class FreeRegionList;
36
37 class G1HeapRegionTable : public G1BiasedMappedArray<HeapRegion*> {
38 protected:
39 virtual HeapRegion* default_value() const { return NULL; }
40 };
41
42 // This class keeps track of the actual heap memory, auxiliary data
43 // and its metadata (i.e., HeapRegion instances) and the list of free regions.
44 //
45 // This allows maximum flexibility for deciding what to commit or uncommit given
46 // a request from outside.
47 //
48 // HeapRegions are kept in the _regions array in address order. A region's
49 // index in the array corresponds to its index in the heap (i.e., 0 is the
50 // region at the bottom of the heap, 1 is the one after it, etc.). Two
51 // regions that are consecutive in the array should also be adjacent in the
52 // address space (i.e., region(i).end() == region(i+1).bottom().
53 //
54 // We create a HeapRegion when we commit the region's address space
55 // for the first time. When we uncommit the address space of a
56 // region we retain the HeapRegion to be able to re-use it in the
57 // future (in case we recommit it).
58 //
59 // We keep track of three lengths:
60 //
61 // * _num_committed (returned by length()) is the number of currently
62 // committed regions. These may not be contiguous.
63 // * _allocated_heapregions_length (not exposed outside this class) is the
64 // number of regions+1 for which we have HeapRegions.
65 // * max_length() returns the maximum number of regions the heap can have.
66 //
67
68 class HeapRegionManager: public CHeapObj<mtGC> {
69 friend class VMStructs;
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 // Calculate the starting region for each worker during parallel iteration so
104 // that they do not all start from the same region.
105 uint start_region_for_worker(uint worker_i, uint num_workers, uint num_regions) const;
106
107 // Find a contiguous set of empty or uncommitted regions of length num and return
108 // the index of the first region or G1_NO_HRM_INDEX if the search was unsuccessful.
109 // If only_empty is true, only empty regions are considered.
110 // Searches from bottom to top of the heap, doing a first-fit.
111 uint find_contiguous(size_t num, bool only_empty);
112 // Finds the next sequence of unavailable regions starting from start_idx. Returns the
113 // length of the sequence found. If this result is zero, no such sequence could be found,
114 // otherwise res_idx indicates the start index of these regions.
115 uint find_unavailable_from_idx(uint start_idx, uint* res_idx) const;
116 // Finds the next sequence of empty regions starting from start_idx, going backwards in
117 // the heap. Returns the length of the sequence found. If this value is zero, no
118 // sequence could be found, otherwise res_idx contains the start index of this range.
119 uint find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const;
120 // Allocate a new HeapRegion for the given index.
121 HeapRegion* new_heap_region(uint hrm_index);
122 #ifdef ASSERT
123 public:
124 bool is_free(HeapRegion* hr) const;
125 #endif
126 // Returns whether the given region is available for allocation.
127 bool is_available(uint region) const;
128
129 public:
130 // Empty constructor, we'll initialize it with the initialize() method.
131 HeapRegionManager() : _regions(), _heap_mapper(NULL), _num_committed(0),
132 _next_bitmap_mapper(NULL), _prev_bitmap_mapper(NULL), _bot_mapper(NULL),
133 _allocated_heapregions_length(0), _available_map(),
134 _free_list("Free list", new MasterFreeRegionListMtSafeChecker())
135 { }
136
137 void initialize(G1RegionToSpaceMapper* heap_storage,
138 G1RegionToSpaceMapper* prev_bitmap,
139 G1RegionToSpaceMapper* next_bitmap,
140 G1RegionToSpaceMapper* bot,
141 G1RegionToSpaceMapper* cardtable,
142 G1RegionToSpaceMapper* card_counts);
143
144 // Return the "dummy" region used for G1AllocRegion. This is currently a hardwired
145 // new HeapRegion that owns HeapRegion at index 0. Since at the moment we commit
146 // the heap from the lowest address, this region (and its associated data
147 // structures) are available and we do not need to check further.
148 HeapRegion* get_dummy_region() { return new_heap_region(0); }
149
150 // Return the HeapRegion at the given index. Assume that the index
151 // is valid.
152 inline HeapRegion* at(uint index) const;
153
154 // If addr is within the committed space return its corresponding
155 // HeapRegion, otherwise return NULL.
156 inline HeapRegion* addr_to_region(HeapWord* addr) const;
157
158 // Insert the given region into the free region list.
159 inline void insert_into_free_list(HeapRegion* hr);
160
161 // Insert the given region list into the global free region list.
162 void insert_list_into_free_list(FreeRegionList* list) {
163 _free_list.add_ordered(list);
164 }
165
166 HeapRegion* allocate_free_region(bool is_old) {
167 HeapRegion* hr = _free_list.remove_region(is_old);
168
169 if (hr != NULL) {
170 assert(hr->next() == NULL, "Single region should not have next");
171 assert(is_available(hr->hrm_index()), "Must be committed");
172 }
173 return hr;
174 }
175
176 inline void allocate_free_regions_starting_at(uint first, uint num_regions);
177
178 // Remove all regions from the free list.
179 void remove_all_free_regions() {
180 _free_list.remove_all();
181 }
182
183 // Return the number of committed free regions in the heap.
184 uint num_free_regions() const {
185 return _free_list.length();
186 }
187
188 size_t total_capacity_bytes() const {
189 return num_free_regions() * HeapRegion::GrainBytes;
190 }
191
192 // Return the number of available (uncommitted) regions.
193 uint available() const { return max_length() - length(); }
194
195 // Return the number of regions that have been committed in the heap.
196 uint length() const { return _num_committed; }
197
198 // Return the maximum number of regions in the heap.
199 uint max_length() const { return (uint)_regions.length(); }
200
201 MemoryUsage get_auxiliary_data_memory_usage() const;
202
203 MemRegion reserved() const { return MemRegion(heap_bottom(), heap_end()); }
204
205 // Expand the sequence to reflect that the heap has grown. Either create new
206 // HeapRegions, or re-use existing ones. Returns the number of regions the
207 // sequence was expanded by. If a HeapRegion allocation fails, the resulting
208 // number of regions might be smaller than what's desired.
209 uint expand_by(uint num_regions);
210
211 // Makes sure that the regions from start to start+num_regions-1 are available
212 // for allocation. Returns the number of regions that were committed to achieve
213 // this.
214 uint expand_at(uint start, uint num_regions);
215
216 // Find a contiguous set of empty regions of length num. Returns the start index of
217 // that set, or G1_NO_HRM_INDEX.
218 uint find_contiguous_only_empty(size_t num) { return find_contiguous(num, true); }
219 // Find a contiguous set of empty or unavailable regions of length num. Returns the
220 // start index of that set, or G1_NO_HRM_INDEX.
221 uint find_contiguous_empty_or_unavailable(size_t num) { return find_contiguous(num, false); }
222
223 HeapRegion* next_region_in_heap(const HeapRegion* r) const;
224
225 // Apply blk->doHeapRegion() on all committed regions in address order,
226 // terminating the iteration early if doHeapRegion() returns true.
227 void iterate(HeapRegionClosure* blk) const;
228
229 void par_iterate(HeapRegionClosure* blk, uint worker_id, uint no_of_par_workers, jint claim_value) const;
230
231 // Uncommit up to num_regions_to_remove regions that are completely free.
232 // Return the actual number of uncommitted regions.
233 uint shrink_by(uint num_regions_to_remove);
234
235 void verify();
236
237 // Do some sanity checking.
238 void verify_optional() PRODUCT_RETURN;
239 };
240
241 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONMANAGER_HPP