1 /*
2 * Copyright (c) 2001, 2010, 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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15 * You should have received a copy of the GNU General Public License version
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23 */
24
25 // This class (or more correctly, subtypes of this class)
26 // are used to define global garbage collector attributes.
27 // This includes initialization of generations and any other
28 // shared resources they may need.
29 //
30 // In general, all flag adjustment and validation should be
31 // done in initialize_flags(), which is called prior to
32 // initialize_size_info().
33 //
34 // This class is not fully developed yet. As more collector(s)
35 // are added, it is expected that we will come across further
36 // behavior that requires global attention. The correct place
37 // to deal with those issues is this class.
38
39 // Forward declarations.
40 class GenCollectorPolicy;
41 class TwoGenerationCollectorPolicy;
42 class AdaptiveSizePolicy;
43 #ifndef SERIALGC
44 class ConcurrentMarkSweepPolicy;
45 class G1CollectorPolicy;
46 #endif // SERIALGC
47
48 class GCPolicyCounters;
49 class PermanentGenerationSpec;
50 class MarkSweepPolicy;
51
52 class CollectorPolicy : public CHeapObj {
53 protected:
54 PermanentGenerationSpec *_permanent_generation;
55 GCPolicyCounters* _gc_policy_counters;
56
57 // Requires that the concrete subclass sets the alignment constraints
58 // before calling.
59 virtual void initialize_flags();
60 virtual void initialize_size_info();
61 // Initialize "_permanent_generation" to a spec for the given kind of
62 // Perm Gen.
63 void initialize_perm_generation(PermGen::Name pgnm);
64
65 size_t _initial_heap_byte_size;
66 size_t _max_heap_byte_size;
67 size_t _min_heap_byte_size;
68
69 size_t _min_alignment;
70 size_t _max_alignment;
71
72 // The sizing of the heap are controlled by a sizing policy.
73 AdaptiveSizePolicy* _size_policy;
74
75 // Set to true when policy wants soft refs cleared.
76 // Reset to false by gc after it clears all soft refs.
77 bool _should_clear_all_soft_refs;
78 // Set to true by the GC if the just-completed gc cleared all
79 // softrefs. This is set to true whenever a gc clears all softrefs, and
80 // set to false each time gc returns to the mutator. For example, in the
81 // ParallelScavengeHeap case the latter would be done toward the end of
82 // mem_allocate() where it returns op.result()
83 bool _all_soft_refs_clear;
84
85 CollectorPolicy() :
86 _min_alignment(1),
87 _max_alignment(1),
88 _initial_heap_byte_size(0),
89 _max_heap_byte_size(0),
90 _min_heap_byte_size(0),
91 _size_policy(NULL),
92 _should_clear_all_soft_refs(false),
93 _all_soft_refs_clear(false)
94 {}
95
96 public:
97 void set_min_alignment(size_t align) { _min_alignment = align; }
98 size_t min_alignment() { return _min_alignment; }
99 void set_max_alignment(size_t align) { _max_alignment = align; }
100 size_t max_alignment() { return _max_alignment; }
101
102 size_t initial_heap_byte_size() { return _initial_heap_byte_size; }
103 void set_initial_heap_byte_size(size_t v) { _initial_heap_byte_size = v; }
104 size_t max_heap_byte_size() { return _max_heap_byte_size; }
105 void set_max_heap_byte_size(size_t v) { _max_heap_byte_size = v; }
106 size_t min_heap_byte_size() { return _min_heap_byte_size; }
107 void set_min_heap_byte_size(size_t v) { _min_heap_byte_size = v; }
108
109 enum Name {
110 CollectorPolicyKind,
111 TwoGenerationCollectorPolicyKind,
112 ConcurrentMarkSweepPolicyKind,
113 ASConcurrentMarkSweepPolicyKind,
114 G1CollectorPolicyKind
115 };
116
117 AdaptiveSizePolicy* size_policy() { return _size_policy; }
118 bool should_clear_all_soft_refs() { return _should_clear_all_soft_refs; }
119 void set_should_clear_all_soft_refs(bool v) { _should_clear_all_soft_refs = v; }
120 // Returns the current value of _should_clear_all_soft_refs.
121 // _should_clear_all_soft_refs is set to false as a side effect.
122 bool use_should_clear_all_soft_refs(bool v);
123 bool all_soft_refs_clear() { return _all_soft_refs_clear; }
124 void set_all_soft_refs_clear(bool v) { _all_soft_refs_clear = v; }
125
126 // Called by the GC after Soft Refs have been cleared to indicate
127 // that the request in _should_clear_all_soft_refs has been fulfilled.
128 void cleared_all_soft_refs();
129
130 // Identification methods.
131 virtual GenCollectorPolicy* as_generation_policy() { return NULL; }
132 virtual TwoGenerationCollectorPolicy* as_two_generation_policy() { return NULL; }
133 virtual MarkSweepPolicy* as_mark_sweep_policy() { return NULL; }
134 #ifndef SERIALGC
135 virtual ConcurrentMarkSweepPolicy* as_concurrent_mark_sweep_policy() { return NULL; }
136 virtual G1CollectorPolicy* as_g1_policy() { return NULL; }
137 #endif // SERIALGC
138 // Note that these are not virtual.
139 bool is_generation_policy() { return as_generation_policy() != NULL; }
140 bool is_two_generation_policy() { return as_two_generation_policy() != NULL; }
141 bool is_mark_sweep_policy() { return as_mark_sweep_policy() != NULL; }
142 #ifndef SERIALGC
143 bool is_concurrent_mark_sweep_policy() { return as_concurrent_mark_sweep_policy() != NULL; }
144 bool is_g1_policy() { return as_g1_policy() != NULL; }
145 #else // SERIALGC
146 bool is_concurrent_mark_sweep_policy() { return false; }
147 bool is_g1_policy() { return false; }
148 #endif // SERIALGC
149
150
151 virtual PermanentGenerationSpec *permanent_generation() {
152 assert(_permanent_generation != NULL, "Sanity check");
153 return _permanent_generation;
154 }
155
156 virtual BarrierSet::Name barrier_set_name() = 0;
157 virtual GenRemSet::Name rem_set_name() = 0;
158
159 // Create the remembered set (to cover the given reserved region,
160 // allowing breaking up into at most "max_covered_regions").
161 virtual GenRemSet* create_rem_set(MemRegion reserved,
162 int max_covered_regions);
163
164 // This method controls how a collector satisfies a request
165 // for a block of memory. "gc_time_limit_was_exceeded" will
166 // be set to true if the adaptive size policy determine that
167 // an excessive amount of time is being spent doing collections
168 // and caused a NULL to be returned. If a NULL is not returned,
169 // "gc_time_limit_was_exceeded" has an undefined meaning.
170 virtual HeapWord* mem_allocate_work(size_t size,
171 bool is_tlab,
172 bool* gc_overhead_limit_was_exceeded) = 0;
173
174 // This method controls how a collector handles one or more
175 // of its generations being fully allocated.
176 virtual HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab) = 0;
177 // Performace Counter support
178 GCPolicyCounters* counters() { return _gc_policy_counters; }
179
180 // Create the jstat counters for the GC policy. By default, policy's
181 // don't have associated counters, and we complain if this is invoked.
182 virtual void initialize_gc_policy_counters() {
183 ShouldNotReachHere();
184 }
185
186 virtual CollectorPolicy::Name kind() {
187 return CollectorPolicy::CollectorPolicyKind;
188 }
189
190 // Returns true if a collector has eden space with soft end.
191 virtual bool has_soft_ended_eden() {
192 return false;
193 }
194
195 };
196
197 class ClearedAllSoftRefs : public StackObj {
198 bool _clear_all_soft_refs;
199 CollectorPolicy* _collector_policy;
200 public:
201 ClearedAllSoftRefs(bool clear_all_soft_refs,
202 CollectorPolicy* collector_policy) :
203 _clear_all_soft_refs(clear_all_soft_refs),
204 _collector_policy(collector_policy) {}
205
206 ~ClearedAllSoftRefs() {
207 if (_clear_all_soft_refs) {
208 _collector_policy->cleared_all_soft_refs();
209 }
210 }
211 };
212
213 class GenCollectorPolicy : public CollectorPolicy {
214 protected:
215 size_t _min_gen0_size;
216 size_t _initial_gen0_size;
217 size_t _max_gen0_size;
218
219 GenerationSpec **_generations;
220
221 // Return true if an allocation should be attempted in the older
222 // generation if it fails in the younger generation. Return
223 // false, otherwise.
224 virtual bool should_try_older_generation_allocation(size_t word_size) const;
225
226 void initialize_flags();
227 void initialize_size_info();
228
229 // Try to allocate space by expanding the heap.
230 virtual HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab);
231
232 // compute max heap alignment
233 size_t compute_max_alignment();
234
235 // Scale the base_size by NewRation according to
236 // result = base_size / (NewRatio + 1)
237 // and align by min_alignment()
238 size_t scale_by_NewRatio_aligned(size_t base_size);
239
240 // Bound the value by the given maximum minus the
241 // min_alignment.
242 size_t bound_minus_alignment(size_t desired_size, size_t maximum_size);
243
244 public:
245 // Accessors
246 size_t min_gen0_size() { return _min_gen0_size; }
247 void set_min_gen0_size(size_t v) { _min_gen0_size = v; }
248 size_t initial_gen0_size() { return _initial_gen0_size; }
249 void set_initial_gen0_size(size_t v) { _initial_gen0_size = v; }
250 size_t max_gen0_size() { return _max_gen0_size; }
251 void set_max_gen0_size(size_t v) { _max_gen0_size = v; }
252
253 virtual int number_of_generations() = 0;
254
255 virtual GenerationSpec **generations() {
256 assert(_generations != NULL, "Sanity check");
257 return _generations;
258 }
259
260 virtual GenCollectorPolicy* as_generation_policy() { return this; }
261
262 virtual void initialize_generations() = 0;
263
264 virtual void initialize_all() {
265 initialize_flags();
266 initialize_size_info();
267 initialize_generations();
268 }
269
270 HeapWord* mem_allocate_work(size_t size,
271 bool is_tlab,
272 bool* gc_overhead_limit_was_exceeded);
273
274 HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab);
275
276 // The size that defines a "large array".
277 virtual size_t large_typearray_limit();
278
279 // Adaptive size policy
280 virtual void initialize_size_policy(size_t init_eden_size,
281 size_t init_promo_size,
282 size_t init_survivor_size);
283 };
284
285 // All of hotspot's current collectors are subtypes of this
286 // class. Currently, these collectors all use the same gen[0],
287 // but have different gen[1] types. If we add another subtype
288 // of CollectorPolicy, this class should be broken out into
289 // its own file.
290
291 class TwoGenerationCollectorPolicy : public GenCollectorPolicy {
292 protected:
293 size_t _min_gen1_size;
294 size_t _initial_gen1_size;
295 size_t _max_gen1_size;
296
297 void initialize_flags();
298 void initialize_size_info();
299 void initialize_generations() { ShouldNotReachHere(); }
300
301 public:
302 // Accessors
303 size_t min_gen1_size() { return _min_gen1_size; }
304 void set_min_gen1_size(size_t v) { _min_gen1_size = v; }
305 size_t initial_gen1_size() { return _initial_gen1_size; }
306 void set_initial_gen1_size(size_t v) { _initial_gen1_size = v; }
307 size_t max_gen1_size() { return _max_gen1_size; }
308 void set_max_gen1_size(size_t v) { _max_gen1_size = v; }
309
310 // Inherited methods
311 TwoGenerationCollectorPolicy* as_two_generation_policy() { return this; }
312
313 int number_of_generations() { return 2; }
314 BarrierSet::Name barrier_set_name() { return BarrierSet::CardTableModRef; }
315 GenRemSet::Name rem_set_name() { return GenRemSet::CardTable; }
316
317 virtual CollectorPolicy::Name kind() {
318 return CollectorPolicy::TwoGenerationCollectorPolicyKind;
319 }
320
321 // Returns true is gen0 sizes were adjusted
322 bool adjust_gen0_sizes(size_t* gen0_size_ptr, size_t* gen1_size_ptr,
323 size_t heap_size, size_t min_gen1_size);
324 };
325
326 class MarkSweepPolicy : public TwoGenerationCollectorPolicy {
327 protected:
328 void initialize_generations();
329
330 public:
331 MarkSweepPolicy();
332
333 MarkSweepPolicy* as_mark_sweep_policy() { return this; }
334
335 void initialize_gc_policy_counters();
336 };