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_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 are 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 // Set to true by the GC if the just-completed gc cleared all
83 // softrefs. This is set to true whenever a gc clears all softrefs, and
84 // set to false each time gc returns to the mutator. For example, in the
85 // ParallelScavengeHeap case the latter would be done toward the end of
86 // mem_allocate() where it returns op.result()
87 bool _all_soft_refs_clear;
88
89 CollectorPolicy() :
90 _min_alignment(1),
91 _max_alignment(1),
92 _initial_heap_byte_size(0),
93 _max_heap_byte_size(0),
94 _min_heap_byte_size(0),
95 _size_policy(NULL),
96 _should_clear_all_soft_refs(false),
97 _all_soft_refs_clear(false)
98 {}
99
100 public:
101 // Return maximum heap alignment that may be imposed by the policy
102 static size_t compute_max_alignment();
103
104 size_t min_alignment() { return _min_alignment; }
105 size_t max_alignment() { return _max_alignment; }
106
107 size_t initial_heap_byte_size() { return _initial_heap_byte_size; }
108 size_t max_heap_byte_size() { return _max_heap_byte_size; }
109 size_t min_heap_byte_size() { return _min_heap_byte_size; }
110
111 enum Name {
112 CollectorPolicyKind,
113 TwoGenerationCollectorPolicyKind,
114 ConcurrentMarkSweepPolicyKind,
115 ASConcurrentMarkSweepPolicyKind,
116 G1CollectorPolicyKind
117 };
118
119 AdaptiveSizePolicy* size_policy() { return _size_policy; }
120 bool should_clear_all_soft_refs() { return _should_clear_all_soft_refs; }
121 void set_should_clear_all_soft_refs(bool v) { _should_clear_all_soft_refs = v; }
122 // Returns the current value of _should_clear_all_soft_refs.
123 // _should_clear_all_soft_refs is set to false as a side effect.
124 bool use_should_clear_all_soft_refs(bool v);
125 bool all_soft_refs_clear() { return _all_soft_refs_clear; }
126 void set_all_soft_refs_clear(bool v) { _all_soft_refs_clear = v; }
127
128 // Called by the GC after Soft Refs have been cleared to indicate
129 // that the request in _should_clear_all_soft_refs has been fulfilled.
130 void cleared_all_soft_refs();
131
132 // Identification methods.
133 virtual GenCollectorPolicy* as_generation_policy() { return NULL; }
134 virtual TwoGenerationCollectorPolicy* as_two_generation_policy() { return NULL; }
135 virtual MarkSweepPolicy* as_mark_sweep_policy() { return NULL; }
136 #if INCLUDE_ALL_GCS
137 virtual ConcurrentMarkSweepPolicy* as_concurrent_mark_sweep_policy() { return NULL; }
138 virtual G1CollectorPolicy* as_g1_policy() { return NULL; }
139 #endif // INCLUDE_ALL_GCS
140 // Note that these are not virtual.
141 bool is_generation_policy() { return as_generation_policy() != NULL; }
142 bool is_two_generation_policy() { return as_two_generation_policy() != NULL; }
143 bool is_mark_sweep_policy() { return as_mark_sweep_policy() != NULL; }
144 #if INCLUDE_ALL_GCS
145 bool is_concurrent_mark_sweep_policy() { return as_concurrent_mark_sweep_policy() != NULL; }
146 bool is_g1_policy() { return as_g1_policy() != NULL; }
147 #else // INCLUDE_ALL_GCS
148 bool is_concurrent_mark_sweep_policy() { return false; }
149 bool is_g1_policy() { return false; }
150 #endif // INCLUDE_ALL_GCS
151
152
153 virtual BarrierSet::Name barrier_set_name() = 0;
154 virtual GenRemSet::Name rem_set_name() = 0;
155
156 // Create the remembered set (to cover the given reserved region,
157 // allowing breaking up into at most "max_covered_regions").
158 virtual GenRemSet* create_rem_set(MemRegion reserved,
159 int max_covered_regions);
160
161 // This method controls how a collector satisfies a request
162 // for a block of memory. "gc_time_limit_was_exceeded" will
163 // be set to true if the adaptive size policy determine that
164 // an excessive amount of time is being spent doing collections
165 // and caused a NULL to be returned. If a NULL is not returned,
166 // "gc_time_limit_was_exceeded" has an undefined meaning.
167 virtual HeapWord* mem_allocate_work(size_t size,
168 bool is_tlab,
169 bool* gc_overhead_limit_was_exceeded) = 0;
170
171 // This method controls how a collector handles one or more
172 // of its generations being fully allocated.
173 virtual HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab) = 0;
174 // This method controls how a collector handles a metadata allocation
175 // failure.
176 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
177 size_t size,
178 Metaspace::MetadataType mdtype);
179
180 // Performace Counter support
181 GCPolicyCounters* counters() { return _gc_policy_counters; }
182
183 // Create the jstat counters for the GC policy. By default, policy's
184 // don't have associated counters, and we complain if this is invoked.
185 virtual void initialize_gc_policy_counters() {
186 ShouldNotReachHere();
187 }
188
189 virtual CollectorPolicy::Name kind() {
190 return CollectorPolicy::CollectorPolicyKind;
191 }
192
193 // Returns true if a collector has eden space with soft end.
194 virtual bool has_soft_ended_eden() {
195 return false;
196 }
197
198 };
199
200 class ClearedAllSoftRefs : public StackObj {
201 bool _clear_all_soft_refs;
202 CollectorPolicy* _collector_policy;
203 public:
204 ClearedAllSoftRefs(bool clear_all_soft_refs,
205 CollectorPolicy* collector_policy) :
206 _clear_all_soft_refs(clear_all_soft_refs),
207 _collector_policy(collector_policy) {}
208
209 ~ClearedAllSoftRefs() {
210 if (_clear_all_soft_refs) {
211 _collector_policy->cleared_all_soft_refs();
212 }
213 }
214 };
215
216 class GenCollectorPolicy : public CollectorPolicy {
217 protected:
218 size_t _min_gen0_size;
219 size_t _initial_gen0_size;
220 size_t _max_gen0_size;
221
222 GenerationSpec **_generations;
223
224 // Return true if an allocation should be attempted in the older
225 // generation if it fails in the younger generation. Return
226 // false, otherwise.
227 virtual bool should_try_older_generation_allocation(size_t word_size) const;
228
229 void initialize_flags();
230 void initialize_size_info();
231
232 // Try to allocate space by expanding the heap.
233 virtual HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab);
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 size_t initial_gen0_size() { return _initial_gen0_size; }
248 size_t max_gen0_size() { return _max_gen0_size; }
249
250 virtual int number_of_generations() = 0;
251
252 virtual GenerationSpec **generations() {
253 assert(_generations != NULL, "Sanity check");
254 return _generations;
255 }
256
257 virtual GenCollectorPolicy* as_generation_policy() { return this; }
258
259 virtual void initialize_generations() = 0;
260
261 virtual void initialize_all() {
262 initialize_flags();
263 initialize_size_info();
264 initialize_generations();
265 }
266
267 HeapWord* mem_allocate_work(size_t size,
268 bool is_tlab,
269 bool* gc_overhead_limit_was_exceeded);
270
271 HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab);
272
273 // Adaptive size policy
274 virtual void initialize_size_policy(size_t init_eden_size,
275 size_t init_promo_size,
276 size_t init_survivor_size);
277 };
278
279 // All of hotspot's current collectors are subtypes of this
280 // class. Currently, these collectors all use the same gen[0],
281 // but have different gen[1] types. If we add another subtype
282 // of CollectorPolicy, this class should be broken out into
283 // its own file.
284
285 class TwoGenerationCollectorPolicy : public GenCollectorPolicy {
286 protected:
287 size_t _min_gen1_size;
288 size_t _initial_gen1_size;
289 size_t _max_gen1_size;
290
291 void initialize_flags();
292 void initialize_size_info();
293 void initialize_generations() { ShouldNotReachHere(); }
294
295 public:
296 // Accessors
297 size_t min_gen1_size() { return _min_gen1_size; }
298 size_t initial_gen1_size() { return _initial_gen1_size; }
299 size_t max_gen1_size() { return _max_gen1_size; }
300
301 // Inherited methods
302 TwoGenerationCollectorPolicy* as_two_generation_policy() { return this; }
303
304 int number_of_generations() { return 2; }
305 BarrierSet::Name barrier_set_name() { return BarrierSet::CardTableModRef; }
306 GenRemSet::Name rem_set_name() { return GenRemSet::CardTable; }
307
308 virtual CollectorPolicy::Name kind() {
309 return CollectorPolicy::TwoGenerationCollectorPolicyKind;
310 }
311
312 // Returns true is gen0 sizes were adjusted
313 bool adjust_gen0_sizes(size_t* gen0_size_ptr, size_t* gen1_size_ptr,
314 const size_t heap_size, const size_t min_gen1_size);
315 };
316
317 class MarkSweepPolicy : public TwoGenerationCollectorPolicy {
318 protected:
319 void initialize_generations();
320
321 public:
322 MarkSweepPolicy();
323
324 MarkSweepPolicy* as_mark_sweep_policy() { return this; }
325
326 void initialize_gc_policy_counters();
327 };
328
329 #endif // SHARE_VM_MEMORY_COLLECTORPOLICY_HPP