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.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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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).
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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 HeapRegionClaimer;
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 friend class HeapRegionClaimer;
71
72 G1HeapRegionTable _regions;
73
74 G1RegionToSpaceMapper* _heap_mapper;
75 G1RegionToSpaceMapper* _prev_bitmap_mapper;
76 G1RegionToSpaceMapper* _next_bitmap_mapper;
77 G1RegionToSpaceMapper* _bot_mapper;
78 G1RegionToSpaceMapper* _cardtable_mapper;
79 G1RegionToSpaceMapper* _card_counts_mapper;
80
81 FreeRegionList _free_list;
82
83 // Each bit in this bitmap indicates that the corresponding region is available
84 // for allocation.
85 BitMap _available_map;
86
87 // The number of regions committed in the heap.
88 uint _num_committed;
89
90 // Internal only. The highest heap region +1 we allocated a HeapRegion instance for.
91 uint _allocated_heapregions_length;
92
93 HeapWord* heap_bottom() const { return _regions.bottom_address_mapped(); }
94 HeapWord* heap_end() const {return _regions.end_address_mapped(); }
95
96 void make_regions_available(uint index, uint num_regions = 1);
97
98 // Pass down commit calls to the VirtualSpace.
99 void commit_regions(uint index, size_t num_regions = 1);
100 void uncommit_regions(uint index, size_t num_regions = 1);
101
102 // Notify other data structures about change in the heap layout.
103 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
104
105 // Find a contiguous set of empty or uncommitted regions of length num and return
106 // the index of the first region or G1_NO_HRM_INDEX if the search was unsuccessful.
107 // If only_empty is true, only empty regions are considered.
108 // Searches from bottom to top of the heap, doing a first-fit.
109 uint find_contiguous(size_t num, bool only_empty);
110 // Finds the next sequence of unavailable regions starting from start_idx. Returns the
111 // length of the sequence found. If this result is zero, no such sequence could be found,
112 // otherwise res_idx indicates the start index of these regions.
113 uint find_unavailable_from_idx(uint start_idx, uint* res_idx) const;
114 // Finds the next sequence of empty regions starting from start_idx, going backwards in
115 // the heap. Returns the length of the sequence found. If this value is zero, no
116 // sequence could be found, otherwise res_idx contains the start index of this range.
117 uint find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const;
118 // Allocate a new HeapRegion for the given index.
119 HeapRegion* new_heap_region(uint hrm_index);
120 #ifdef ASSERT
121 public:
122 bool is_free(HeapRegion* hr) const;
123 #endif
124 // Returns whether the given region is available for allocation.
125 bool is_available(uint region) const;
126
127 void sum_memory_usage(size_t& used, size_t& committed, G1RegionToSpaceMapper* mapper) const {
128 used += mapper->committed_size();
129 committed += mapper->reserved_size();
130 }
131 public:
132 // Empty constructor, we'll initialize it with the initialize() method.
133 HeapRegionManager() : _regions(), _heap_mapper(NULL), _num_committed(0),
134 _next_bitmap_mapper(NULL), _prev_bitmap_mapper(NULL), _bot_mapper(NULL),
135 _allocated_heapregions_length(0), _available_map(),
136 _free_list("Free list", new MasterFreeRegionListMtSafeChecker())
137 { }
138
139 void initialize(G1RegionToSpaceMapper* heap_storage,
140 G1RegionToSpaceMapper* prev_bitmap,
141 G1RegionToSpaceMapper* next_bitmap,
142 G1RegionToSpaceMapper* bot,
143 G1RegionToSpaceMapper* cardtable,
144 G1RegionToSpaceMapper* card_counts);
145
146 // Return the "dummy" region used for G1AllocRegion. This is currently a hardwired
147 // new HeapRegion that owns HeapRegion at index 0. Since at the moment we commit
148 // the heap from the lowest address, this region (and its associated data
149 // structures) are available and we do not need to check further.
150 HeapRegion* get_dummy_region() { return new_heap_region(0); }
151
152 // Return the HeapRegion at the given index. Assume that the index
153 // is valid.
154 inline HeapRegion* at(uint index) const;
155
156 // If addr is within the committed space return its corresponding
157 // HeapRegion, otherwise return NULL.
158 inline HeapRegion* addr_to_region(HeapWord* addr) const;
159
160 // Insert the given region into the free region list.
161 inline void insert_into_free_list(HeapRegion* hr);
162
163 // Insert the given region list into the global free region list.
164 void insert_list_into_free_list(FreeRegionList* list) {
165 _free_list.add_ordered(list);
166 }
167
168 HeapRegion* allocate_free_region(bool is_old) {
169 HeapRegion* hr = _free_list.remove_region(is_old);
170
171 if (hr != NULL) {
172 assert(hr->next() == NULL, "Single region should not have next");
173 assert(is_available(hr->hrm_index()), "Must be committed");
174 }
175 return hr;
176 }
177
178 inline void allocate_free_regions_starting_at(uint first, uint num_regions);
179
180 // Remove all regions from the free list.
181 void remove_all_free_regions() {
182 _free_list.remove_all();
183 }
184
185 // Return the number of committed free regions in the heap.
186 uint num_free_regions() const {
187 return _free_list.length();
188 }
189
190 size_t total_capacity_bytes() const {
191 return num_free_regions() * HeapRegion::GrainBytes;
192 }
193
194 // Return the number of available (uncommitted) regions.
195 uint available() const { return max_length() - length(); }
196
197 // Return the number of regions that have been committed in the heap.
198 uint length() const { return _num_committed; }
199
200 // Return the maximum number of regions in the heap.
201 uint max_length() const { return (uint)_regions.length(); }
202
203 MemoryUsage get_auxiliary_data_memory_usage() const;
204
205 MemRegion reserved() const { return MemRegion(heap_bottom(), heap_end()); }
206
207 // Expand the sequence to reflect that the heap has grown. Either create new
208 // HeapRegions, or re-use existing ones. Returns the number of regions the
209 // sequence was expanded by. If a HeapRegion allocation fails, the resulting
210 // number of regions might be smaller than what's desired.
211 uint expand_by(uint num_regions);
212
213 // Makes sure that the regions from start to start+num_regions-1 are available
214 // for allocation. Returns the number of regions that were committed to achieve
215 // this.
216 uint expand_at(uint start, uint num_regions);
217
218 // Find a contiguous set of empty regions of length num. Returns the start index of
219 // that set, or G1_NO_HRM_INDEX.
220 uint find_contiguous_only_empty(size_t num) { return find_contiguous(num, true); }
221 // Find a contiguous set of empty or unavailable regions of length num. Returns the
222 // start index of that set, or G1_NO_HRM_INDEX.
223 uint find_contiguous_empty_or_unavailable(size_t num) { return find_contiguous(num, false); }
224
225 HeapRegion* next_region_in_heap(const HeapRegion* r) const;
226
227 // Apply blk->doHeapRegion() on all committed regions in address order,
228 // terminating the iteration early if doHeapRegion() returns true.
229 void iterate(HeapRegionClosure* blk) const;
230
231 void par_iterate(HeapRegionClosure* blk, uint worker_id, HeapRegionClaimer* hrclaimer, bool concurrent) const;
232
233 // Uncommit up to num_regions_to_remove regions that are completely free.
234 // Return the actual number of uncommitted regions.
235 uint shrink_by(uint num_regions_to_remove);
236
237 void verify();
238
239 // Do some sanity checking.
240 void verify_optional() PRODUCT_RETURN;
241 };
242
243 // The HeapRegionClaimer is used during parallel iteration over heap regions,
244 // allowing workers to claim heap regions, gaining exclusive rights to these regions.
245 class HeapRegionClaimer : public StackObj {
246 uint _n_workers;
247 uint _n_regions;
248 uint* _claims;
249
250 static const uint Unclaimed = 0;
251 static const uint Claimed = 1;
252
253 public:
254 HeapRegionClaimer(uint n_workers);
255 ~HeapRegionClaimer();
256
257 inline uint n_regions() const {
258 return _n_regions;
259 }
260
261 // Calculate the starting region for given worker so
262 // that they do not all start from the same region.
263 uint start_region_for_worker(uint worker_id) const;
264
265 // Check if region has been claimed with this HRClaimer.
266 bool is_region_claimed(uint region_index) const;
267
268 // Claim the given region, returns true if successfully claimed.
269 bool claim_region(uint region_index);
270 };
271 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONMANAGER_HPP
272