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