1 /*
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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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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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24
25 #ifndef SHARE_VM_GC_G1_HEAPREGIONMANAGER_HPP
26 #define SHARE_VM_GC_G1_HEAPREGIONMANAGER_HPP
27
28 #include "gc/g1/g1BiasedArray.hpp"
29 #include "gc/g1/g1RegionToSpaceMapper.hpp"
30 #include "gc/g1/heapRegionSet.hpp"
31 #include "services/memoryUsage.hpp"
32
33 class HeapRegion;
34 class HeapRegionClosure;
35 class HeapRegionClaimer;
36 class FreeRegionList;
37 class WorkGang;
38
39 class G1HeapRegionTable : public G1BiasedMappedArray<HeapRegion*> {
40 protected:
41 virtual HeapRegion* default_value() const { return NULL; }
42 };
43
44 // This class keeps track of the actual heap memory, auxiliary data
45 // and its metadata (i.e., HeapRegion instances) and the list of free regions.
46 //
47 // This allows maximum flexibility for deciding what to commit or uncommit given
48 // a request from outside.
49 //
50 // HeapRegions are kept in the _regions array in address order. A region's
51 // index in the array corresponds to its index in the heap (i.e., 0 is the
52 // region at the bottom of the heap, 1 is the one after it, etc.). Two
53 // regions that are consecutive in the array should also be adjacent in the
54 // address space (i.e., region(i).end() == region(i+1).bottom().
55 //
56 // We create a HeapRegion when we commit the region's address space
57 // for the first time. When we uncommit the address space of a
58 // region we retain the HeapRegion to be able to re-use it in the
59 // future (in case we recommit it).
60 //
61 // We keep track of three lengths:
62 //
63 // * _num_committed (returned by length()) is the number of currently
64 // committed regions. These may not be contiguous.
65 // * _allocated_heapregions_length (not exposed outside this class) is the
66 // number of regions+1 for which we have HeapRegions.
67 // * max_length() returns the maximum number of regions the heap can have.
68 //
69
70 class HeapRegionManager: public CHeapObj<mtGC> {
71 friend class VMStructs;
72 friend class HeapRegionClaimer;
73
74 protected:
75 G1HeapRegionTable _regions;
76 G1RegionToSpaceMapper* _heap_mapper;
77 private:
78 G1RegionToSpaceMapper* _prev_bitmap_mapper;
79 G1RegionToSpaceMapper* _next_bitmap_mapper;
80 G1RegionToSpaceMapper* _bot_mapper;
81 G1RegionToSpaceMapper* _cardtable_mapper;
82 G1RegionToSpaceMapper* _card_counts_mapper;
83
84 protected:
85 FreeRegionList _free_list;
86 private:
87
88 // Each bit in this bitmap indicates that the corresponding region is available
89 // for allocation.
90 CHeapBitMap _available_map;
91
92 // The number of regions committed in the heap.
93 uint _num_committed;
94
95 // Internal only. The highest heap region +1 we allocated a HeapRegion instance for.
96 uint _allocated_heapregions_length;
97
98 HeapWord* heap_bottom() const { return _regions.bottom_address_mapped(); }
99 HeapWord* heap_end() const {return _regions.end_address_mapped(); }
100
101 protected:
102 void make_regions_available(uint index, uint num_regions = 1, WorkGang* pretouch_gang = NULL);
103 void uncommit_regions(uint index, size_t num_regions = 1);
104 private:
105 // Pass down commit calls to the VirtualSpace.
106 void commit_regions(uint index, size_t num_regions = 1, WorkGang* pretouch_gang = NULL);
107
108 // Notify other data structures about change in the heap layout.
109 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
110
111 // Find a contiguous set of empty or uncommitted regions of length num and return
112 // the index of the first region or G1_NO_HRM_INDEX if the search was unsuccessful.
113 // If only_empty is true, only empty regions are considered.
114 // Searches from bottom to top of the heap, doing a first-fit.
115 uint find_contiguous(size_t num, bool only_empty);
116 // Finds the next sequence of unavailable regions starting from start_idx. Returns the
117 // length of the sequence found. If this result is zero, no such sequence could be found,
118 // otherwise res_idx indicates the start index of these regions.
119 uint find_unavailable_from_idx(uint start_idx, uint* res_idx) const;
120 // Finds the next sequence of empty regions starting from start_idx, going backwards in
121 // the heap. Returns the length of the sequence found. If this value is zero, no
122 // sequence could be found, otherwise res_idx contains the start index of this range.
123 uint find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const;
124 #ifdef ASSERT
125 public:
126 bool is_free(HeapRegion* hr) const;
127 #endif
128 protected:
129 // Allocate a new HeapRegion for the given index.
130 HeapRegion* new_heap_region(uint hrm_index);
131 public:
132 // Empty constructor, we'll initialize it with the initialize() method.
133 HeapRegionManager();
134
135 void initialize(G1RegionToSpaceMapper* heap_storage,
136 G1RegionToSpaceMapper* prev_bitmap,
137 G1RegionToSpaceMapper* next_bitmap,
138 G1RegionToSpaceMapper* bot,
139 G1RegionToSpaceMapper* cardtable,
140 G1RegionToSpaceMapper* card_counts);
141
142 // Return the "dummy" region used for G1AllocRegion. This is currently a hardwired
143 // new HeapRegion that owns HeapRegion at index 0. Since at the moment we commit
144 // the heap from the lowest address, this region (and its associated data
145 // structures) are available and we do not need to check further.
146 virtual HeapRegion* get_dummy_region() { return new_heap_region(0); }
147
148 // Return the HeapRegion at the given index. Assume that the index
149 // is valid.
150 inline HeapRegion* at(uint index) const;
151
152 // Return the HeapRegion at the given index, NULL if the index
153 // is for an unavailable region.
154 inline HeapRegion* at_or_null(uint index) const;
155
156 // Returns whether the given region is available for allocation.
157 bool is_available(uint region) const;
158
159 // Return the next region (by index) that is part of the same
160 // humongous object that hr is part of.
161 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
162
163 // If addr is within the committed space return its corresponding
164 // HeapRegion, otherwise return NULL.
165 inline HeapRegion* addr_to_region(HeapWord* addr) const;
166
167 // Insert the given region into the free region list.
168 inline void insert_into_free_list(HeapRegion* hr);
169
170 // Insert the given region list into the global free region list.
171 void insert_list_into_free_list(FreeRegionList* list) {
172 _free_list.add_ordered(list);
173 }
174
175 virtual HeapRegion* allocate_free_region(bool is_old) {
176 HeapRegion* hr = _free_list.remove_region(is_old);
177
178 if (hr != NULL) {
179 assert(hr->next() == NULL, "Single region should not have next");
180 assert(is_available(hr->hrm_index()), "Must be committed");
181 }
182 return hr;
183 }
184
185 inline void allocate_free_regions_starting_at(uint first, uint num_regions);
186
187 // Remove all regions from the free list.
188 void remove_all_free_regions() {
189 _free_list.remove_all();
190 }
191
192 // Return the number of committed free regions in the heap.
193 uint num_free_regions() const {
194 return _free_list.length();
195 }
196
197 size_t total_free_bytes() const {
198 return num_free_regions() * HeapRegion::GrainBytes;
199 }
200
201 // Return the number of available (uncommitted) regions.
202 uint available() const { return max_length() - length(); }
203
204 // Return the number of regions that have been committed in the heap.
205 uint length() const { return _num_committed; }
206
207 // Return the maximum number of regions in the heap.
208 uint max_length() const { return (uint)_regions.length(); }
209
210 // Return maximum number of regions that heap can expand to.
211 virtual uint max_expandable_length() const { return (uint)_regions.length(); }
212
213 MemoryUsage get_auxiliary_data_memory_usage() const;
214
215 MemRegion reserved() const { return MemRegion(heap_bottom(), heap_end()); }
216
217 // Expand the sequence to reflect that the heap has grown. Either create new
218 // HeapRegions, or re-use existing ones. Returns the number of regions the
219 // sequence was expanded by. If a HeapRegion allocation fails, the resulting
220 // number of regions might be smaller than what's desired.
221 virtual uint expand_by(uint num_regions, WorkGang* pretouch_workers);
222
223 // Makes sure that the regions from start to start+num_regions-1 are available
224 // for allocation. Returns the number of regions that were committed to achieve
225 // this.
226 virtual uint expand_at(uint start, uint num_regions, WorkGang* pretouch_workers);
227
228 // Find a contiguous set of empty regions of length num. Returns the start index of
229 // that set, or G1_NO_HRM_INDEX.
230 virtual uint find_contiguous_only_empty(size_t num) { return find_contiguous(num, true); }
231 // Find a contiguous set of empty or unavailable regions of length num. Returns the
232 // start index of that set, or G1_NO_HRM_INDEX.
233 virtual uint find_contiguous_empty_or_unavailable(size_t num) { return find_contiguous(num, false); }
234
235 HeapRegion* next_region_in_heap(const HeapRegion* r) const;
236
237 // Find the highest free or uncommitted region in the reserved heap,
238 // and if uncommitted, commit it. If none are available, return G1_NO_HRM_INDEX.
239 // Set the 'expanded' boolean true if a new region was committed.
240 virtual uint find_highest_free(bool* expanded);
241
242 // Allocate the regions that contain the address range specified, committing the
243 // regions if necessary. Return false if any of the regions is already committed
244 // and not free, and return the number of regions newly committed in commit_count.
245 bool allocate_containing_regions(MemRegion range, size_t* commit_count, WorkGang* pretouch_workers);
246
247 // Apply blk->do_heap_region() on all committed regions in address order,
248 // terminating the iteration early if do_heap_region() returns true.
249 void iterate(HeapRegionClosure* blk) const;
250
251 void par_iterate(HeapRegionClosure* blk, HeapRegionClaimer* hrclaimer, const uint start_index) const;
252
253 // Uncommit up to num_regions_to_remove regions that are completely free.
254 // Return the actual number of uncommitted regions.
255 virtual uint shrink_by(uint num_regions_to_remove);
256
257 // Uncommit a number of regions starting at the specified index, which must be available,
258 // empty, and free.
259 void shrink_at(uint index, size_t num_regions);
260
261 virtual void verify();
262
263 // Do some sanity checking.
264 void verify_optional() PRODUCT_RETURN;
265 };
266
267 // The HeapRegionClaimer is used during parallel iteration over heap regions,
268 // allowing workers to claim heap regions, gaining exclusive rights to these regions.
269 class HeapRegionClaimer : public StackObj {
270 uint _n_workers;
271 uint _n_regions;
272 volatile uint* _claims;
273
274 static const uint Unclaimed = 0;
275 static const uint Claimed = 1;
276
277 public:
278 HeapRegionClaimer(uint n_workers);
279 ~HeapRegionClaimer();
280
281 inline uint n_regions() const {
282 return _n_regions;
283 }
284
285 // Return a start offset given a worker id.
286 uint offset_for_worker(uint worker_id) const;
287
288 // Check if region has been claimed with this HRClaimer.
289 bool is_region_claimed(uint region_index) const;
290
291 // Claim the given region, returns true if successfully claimed.
292 bool claim_region(uint region_index);
293 };
294 #endif // SHARE_VM_GC_G1_HEAPREGIONMANAGER_HPP