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 G1HeapRegionTable _regions;
75
76 G1RegionToSpaceMapper* _heap_mapper;
77 G1RegionToSpaceMapper* _prev_bitmap_mapper;
78 G1RegionToSpaceMapper* _next_bitmap_mapper;
79 G1RegionToSpaceMapper* _bot_mapper;
80 G1RegionToSpaceMapper* _cardtable_mapper;
81 G1RegionToSpaceMapper* _card_counts_mapper;
82
83 FreeRegionList _free_list;
84
85 // Each bit in this bitmap indicates that the corresponding region is available
86 // for allocation.
87 CHeapBitMap _available_map;
88
89 // The number of regions committed in the heap.
90 uint _num_committed;
91
92 // Internal only. The highest heap region +1 we allocated a HeapRegion instance for.
93 uint _allocated_heapregions_length;
94
95 HeapWord* heap_bottom() const { return _regions.bottom_address_mapped(); }
96 HeapWord* heap_end() const {return _regions.end_address_mapped(); }
97
98 void make_regions_available(uint index, uint num_regions = 1, WorkGang* pretouch_gang = NULL);
99
100 // Pass down commit calls to the VirtualSpace.
101 void commit_regions(uint index, size_t num_regions = 1, WorkGang* pretouch_gang = NULL);
102 void uncommit_regions(uint index, size_t num_regions = 1);
103
104 // Notify other data structures about change in the heap layout.
105 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
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();
132
133 void initialize(G1RegionToSpaceMapper* heap_storage,
134 G1RegionToSpaceMapper* prev_bitmap,
135 G1RegionToSpaceMapper* next_bitmap,
136 G1RegionToSpaceMapper* bot,
137 G1RegionToSpaceMapper* cardtable,
138 G1RegionToSpaceMapper* card_counts);
139
140 // Return the "dummy" region used for G1AllocRegion. This is currently a hardwired
141 // new HeapRegion that owns HeapRegion at index 0. Since at the moment we commit
142 // the heap from the lowest address, this region (and its associated data
143 // structures) are available and we do not need to check further.
144 HeapRegion* get_dummy_region() { return new_heap_region(0); }
145
146 // Return the HeapRegion at the given index. Assume that the index
147 // is valid.
148 inline HeapRegion* at(uint index) const;
149
150 // Return the next region (by index) that is part of the same
151 // humongous object that hr is part of.
152 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) 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_free_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, WorkGang* pretouch_workers);
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, WorkGang* pretouch_workers);
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 // Find the highest free or uncommitted region in the reserved heap,
226 // and if uncommitted, commit it. If none are available, return G1_NO_HRM_INDEX.
227 // Set the 'expanded' boolean true if a new region was committed.
228 uint find_highest_free(bool* expanded);
229
230 // Allocate the regions that contain the address range specified, committing the
231 // regions if necessary. Return false if any of the regions is already committed
232 // and not free, and return the number of regions newly committed in commit_count.
233 bool allocate_containing_regions(MemRegion range, size_t* commit_count, WorkGang* pretouch_workers);
234
235 // Apply blk->do_heap_region() on all committed regions in address order,
236 // terminating the iteration early if do_heap_region() returns true.
237 void iterate(HeapRegionClosure* blk) const;
238
239 void par_iterate(HeapRegionClosure* blk, HeapRegionClaimer* hrclaimer, const uint start_index) const;
240
241 // Uncommit up to num_regions_to_remove regions that are completely free.
242 // Return the actual number of uncommitted regions.
243 uint shrink_by(uint num_regions_to_remove);
244
245 // Uncommit a number of regions starting at the specified index, which must be available,
246 // empty, and free.
247 void shrink_at(uint index, size_t num_regions);
248
249 void verify();
250
251 // Do some sanity checking.
252 void verify_optional() PRODUCT_RETURN;
253 };
254
255 // The HeapRegionClaimer is used during parallel iteration over heap regions,
256 // allowing workers to claim heap regions, gaining exclusive rights to these regions.
257 class HeapRegionClaimer : public StackObj {
258 uint _n_workers;
259 uint _n_regions;
260 volatile uint* _claims;
261
262 static const uint Unclaimed = 0;
263 static const uint Claimed = 1;
264
265 public:
266 HeapRegionClaimer(uint n_workers);
267 ~HeapRegionClaimer();
268
269 inline uint n_regions() const {
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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 bool is_available(uint region) const;
128 #else
129 // Returns whether the given region is available for allocation.
130 protected:
131 bool is_available(uint region) const;
132 #endif
133 // Allocate a new HeapRegion for the given index.
134 HeapRegion* new_heap_region(uint hrm_index);
135
136 public:
137 // Empty constructor, we'll initialize it with the initialize() method.
138 HeapRegionManager();
139
140 void initialize(G1RegionToSpaceMapper* heap_storage,
141 G1RegionToSpaceMapper* prev_bitmap,
142 G1RegionToSpaceMapper* next_bitmap,
143 G1RegionToSpaceMapper* bot,
144 G1RegionToSpaceMapper* cardtable,
145 G1RegionToSpaceMapper* card_counts);
146
147 // Return the "dummy" region used for G1AllocRegion. This is currently a hardwired
148 // new HeapRegion that owns HeapRegion at index 0. Since at the moment we commit
149 // the heap from the lowest address, this region (and its associated data
150 // structures) are available and we do not need to check further.
151 virtual HeapRegion* get_dummy_region() { return new_heap_region(0); }
152
153 // Return the HeapRegion at the given index. Assume that the index
154 // is valid.
155 inline HeapRegion* at(uint index) const;
156
157 // Return the next region (by index) that is part of the same
158 // humongous object that hr is part of.
159 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
160
161 // If addr is within the committed space return its corresponding
162 // HeapRegion, otherwise return NULL.
163 inline HeapRegion* addr_to_region(HeapWord* addr) const;
164
165 // Insert the given region into the free region list.
166 inline void insert_into_free_list(HeapRegion* hr);
167
168 // Insert the given region list into the global free region list.
169 void insert_list_into_free_list(FreeRegionList* list) {
170 _free_list.add_ordered(list);
171 }
172
173 virtual HeapRegion* allocate_free_region(bool is_old) {
174 HeapRegion* hr = _free_list.remove_region(is_old);
175
176 if (hr != NULL) {
177 assert(hr->next() == NULL, "Single region should not have next");
178 assert(is_available(hr->hrm_index()), "Must be committed");
179 }
180 return hr;
181 }
182
183 inline void allocate_free_regions_starting_at(uint first, uint num_regions);
184
185 // Remove all regions from the free list.
186 void remove_all_free_regions() {
187 _free_list.remove_all();
188 }
189
190 // Return the number of committed free regions in the heap.
191 uint num_free_regions() const {
192 return _free_list.length();
193 }
194
195 size_t total_free_bytes() const {
196 return num_free_regions() * HeapRegion::GrainBytes;
197 }
198
199 // Return the number of available (uncommitted) regions.
200 uint available() const { return max_length() - length(); }
201
202 // Return the number of regions that have been committed in the heap.
203 uint length() const { return _num_committed; }
204
205 // Return the maximum number of regions in the heap.
206 uint max_length() const { return (uint)_regions.length(); }
207
208 // Return maximum number of regions that heap can expand to.
209 virtual uint max_expandable_length() const { return (uint)_regions.length(); }
210
211 MemoryUsage get_auxiliary_data_memory_usage() const;
212
213 MemRegion reserved() const { return MemRegion(heap_bottom(), heap_end()); }
214
215 // Expand the sequence to reflect that the heap has grown. Either create new
216 // HeapRegions, or re-use existing ones. Returns the number of regions the
217 // sequence was expanded by. If a HeapRegion allocation fails, the resulting
218 // number of regions might be smaller than what's desired.
219 virtual uint expand_by(uint num_regions, WorkGang* pretouch_workers);
220
221 // Makes sure that the regions from start to start+num_regions-1 are available
222 // for allocation. Returns the number of regions that were committed to achieve
223 // this.
224 virtual uint expand_at(uint start, uint num_regions, WorkGang* pretouch_workers);
225
226 // Find a contiguous set of empty regions of length num. Returns the start index of
227 // that set, or G1_NO_HRM_INDEX.
228 virtual uint find_contiguous_only_empty(size_t num) { return find_contiguous(num, true); }
229 // Find a contiguous set of empty or unavailable regions of length num. Returns the
230 // start index of that set, or G1_NO_HRM_INDEX.
231 virtual uint find_contiguous_empty_or_unavailable(size_t num) { return find_contiguous(num, false); }
232
233 HeapRegion* next_region_in_heap(const HeapRegion* r) const;
234
235 // Find the highest free or uncommitted region in the reserved heap,
236 // and if uncommitted, commit it. If none are available, return G1_NO_HRM_INDEX.
237 // Set the 'expanded' boolean true if a new region was committed.
238 virtual uint find_highest_free(bool* expanded);
239
240 // Allocate the regions that contain the address range specified, committing the
241 // regions if necessary. Return false if any of the regions is already committed
242 // and not free, and return the number of regions newly committed in commit_count.
243 bool allocate_containing_regions(MemRegion range, size_t* commit_count, WorkGang* pretouch_workers);
244
245 // Apply blk->do_heap_region() on all committed regions in address order,
246 // terminating the iteration early if do_heap_region() returns true.
247 void iterate(HeapRegionClosure* blk) const;
248
249 void par_iterate(HeapRegionClosure* blk, HeapRegionClaimer* hrclaimer, const uint start_index) const;
250
251 // Uncommit up to num_regions_to_remove regions that are completely free.
252 // Return the actual number of uncommitted regions.
253 virtual uint shrink_by(uint num_regions_to_remove);
254
255 // Uncommit a number of regions starting at the specified index, which must be available,
256 // empty, and free.
257 void shrink_at(uint index, size_t num_regions);
258
259 virtual void verify();
260
261 // Do some sanity checking.
262 void verify_optional() PRODUCT_RETURN;
263 };
264
265 // The HeapRegionClaimer is used during parallel iteration over heap regions,
266 // allowing workers to claim heap regions, gaining exclusive rights to these regions.
267 class HeapRegionClaimer : public StackObj {
268 uint _n_workers;
269 uint _n_regions;
270 volatile uint* _claims;
271
272 static const uint Unclaimed = 0;
273 static const uint Claimed = 1;
274
275 public:
276 HeapRegionClaimer(uint n_workers);
277 ~HeapRegionClaimer();
278
279 inline uint n_regions() const {
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