1 /*
2 * Copyright (c) 2001, 2015, 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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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
16 * 2 along with this work; if not, write to the Free Software Foundation,
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23 */
24
25 #ifndef SHARE_VM_GC_SHARED_COLLECTORPOLICY_HPP
26 #define SHARE_VM_GC_SHARED_COLLECTORPOLICY_HPP
27
28 #include "gc/shared/barrierSet.hpp"
29 #include "gc/shared/genRemSet.hpp"
30 #include "gc/shared/generationSpec.hpp"
31 #include "memory/allocation.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 AdaptiveSizePolicy;
51 #if INCLUDE_ALL_GCS
52 class ConcurrentMarkSweepPolicy;
53 class G1CollectorPolicy;
54 #endif // INCLUDE_ALL_GCS
55
56 class GCPolicyCounters;
57 class MarkSweepPolicy;
58
59 class CollectorPolicy : public CHeapObj<mtGC> {
60 protected:
61 GCPolicyCounters* _gc_policy_counters;
62
63 virtual void initialize_alignments() = 0;
64 virtual void initialize_flags();
65 virtual void initialize_size_info();
66
67 DEBUG_ONLY(virtual void assert_flags();)
68 DEBUG_ONLY(virtual void assert_size_info();)
69
70 size_t _initial_heap_byte_size;
71 size_t _max_heap_byte_size;
72 size_t _min_heap_byte_size;
73
74 size_t _space_alignment;
75 size_t _heap_alignment;
76
77 // Needed to keep information if MaxHeapSize was set on the command line
78 // when the flag value is aligned etc by ergonomics.
79 bool _max_heap_size_cmdline;
80
81 // The sizing of the heap is controlled by a sizing policy.
82 AdaptiveSizePolicy* _size_policy;
83
84 // Set to true when policy wants soft refs cleared.
85 // Reset to false by gc after it clears all soft refs.
86 bool _should_clear_all_soft_refs;
87
88 // Set to true by the GC if the just-completed gc cleared all
89 // softrefs. This is set to true whenever a gc clears all softrefs, and
90 // set to false each time gc returns to the mutator. For example, in the
91 // ParallelScavengeHeap case the latter would be done toward the end of
92 // mem_allocate() where it returns op.result()
93 bool _all_soft_refs_clear;
94
95 CollectorPolicy();
96
97 public:
98 virtual void initialize_all() {
99 initialize_alignments();
100 initialize_flags();
101 initialize_size_info();
102 }
103
104 // Return maximum heap alignment that may be imposed by the policy.
105 static size_t compute_heap_alignment();
106
107 size_t space_alignment() { return _space_alignment; }
108 size_t heap_alignment() { return _heap_alignment; }
109
110 size_t initial_heap_byte_size() { return _initial_heap_byte_size; }
111 size_t max_heap_byte_size() { return _max_heap_byte_size; }
112 size_t min_heap_byte_size() { return _min_heap_byte_size; }
113
114 enum Name {
115 CollectorPolicyKind,
116 GenCollectorPolicyKind,
117 ConcurrentMarkSweepPolicyKind,
118 G1CollectorPolicyKind
119 };
120
121 AdaptiveSizePolicy* size_policy() { return _size_policy; }
122 bool should_clear_all_soft_refs() { return _should_clear_all_soft_refs; }
123 void set_should_clear_all_soft_refs(bool v) { _should_clear_all_soft_refs = v; }
124 // Returns the current value of _should_clear_all_soft_refs.
125 // _should_clear_all_soft_refs is set to false as a side effect.
126 bool use_should_clear_all_soft_refs(bool v);
127 bool all_soft_refs_clear() { return _all_soft_refs_clear; }
128 void set_all_soft_refs_clear(bool v) { _all_soft_refs_clear = v; }
129
130 // Called by the GC after Soft Refs have been cleared to indicate
131 // that the request in _should_clear_all_soft_refs has been fulfilled.
132 void cleared_all_soft_refs();
133
134 // Identification methods.
135 virtual GenCollectorPolicy* as_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_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
155 virtual GenRemSet* create_rem_set(MemRegion reserved);
156
157 // This method controls how a collector satisfies a request
158 // for a block of memory. "gc_time_limit_was_exceeded" will
159 // be set to true if the adaptive size policy determine that
160 // an excessive amount of time is being spent doing collections
161 // and caused a NULL to be returned. If a NULL is not returned,
162 // "gc_time_limit_was_exceeded" has an undefined meaning.
163 virtual HeapWord* mem_allocate_work(size_t size,
164 bool is_tlab,
165 bool* gc_overhead_limit_was_exceeded) = 0;
166
167 // This method controls how a collector handles one or more
168 // of its generations being fully allocated.
169 virtual HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab) = 0;
170 // This method controls how a collector handles a metadata allocation
171 // failure.
172 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
173 size_t size,
174 Metaspace::MetadataType mdtype);
175
176 // Performance Counter support
177 GCPolicyCounters* counters() { return _gc_policy_counters; }
178
179 // Create the jstat counters for the GC policy. By default, policy's
180 // don't have associated counters, and we complain if this is invoked.
181 virtual void initialize_gc_policy_counters() {
182 ShouldNotReachHere();
183 }
184
185 virtual CollectorPolicy::Name kind() {
186 return CollectorPolicy::CollectorPolicyKind;
187 }
188
189 // Do any updates required to global flags that are due to heap initialization
190 // changes
191 virtual void post_heap_initialize() = 0;
192 };
193
194 class ClearedAllSoftRefs : public StackObj {
195 bool _clear_all_soft_refs;
196 CollectorPolicy* _collector_policy;
197 public:
198 ClearedAllSoftRefs(bool clear_all_soft_refs,
199 CollectorPolicy* collector_policy) :
200 _clear_all_soft_refs(clear_all_soft_refs),
201 _collector_policy(collector_policy) {}
202
203 ~ClearedAllSoftRefs() {
204 if (_clear_all_soft_refs) {
205 _collector_policy->cleared_all_soft_refs();
206 }
207 }
208 };
209
210 class GenCollectorPolicy : public CollectorPolicy {
211 friend class TestGenCollectorPolicy;
212 friend class VMStructs;
213 protected:
214 size_t _min_young_size;
215 size_t _initial_young_size;
216 size_t _max_young_size;
217 size_t _min_old_size;
218 size_t _initial_old_size;
219 size_t _max_old_size;
220
221 // _gen_alignment and _space_alignment will have the same value most of the
222 // time. When using large pages they can differ.
223 size_t _gen_alignment;
224
225 GenerationSpec* _young_gen_spec;
226 GenerationSpec* _old_gen_spec;
227
228 // Return true if an allocation should be attempted in the older generation
229 // if it fails in the younger generation. Return false, otherwise.
230 virtual bool should_try_older_generation_allocation(size_t word_size) const;
231
232 void initialize_flags();
233 void initialize_size_info();
234
235 DEBUG_ONLY(void assert_flags();)
236 DEBUG_ONLY(void assert_size_info();)
237
238 // Try to allocate space by expanding the heap.
239 virtual HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab);
240
241 // Compute max heap alignment.
242 size_t compute_max_alignment();
243
244 // Scale the base_size by NewRatio according to
245 // result = base_size / (NewRatio + 1)
246 // and align by min_alignment()
247 size_t scale_by_NewRatio_aligned(size_t base_size);
248
249 // Bound the value by the given maximum minus the min_alignment.
250 size_t bound_minus_alignment(size_t desired_size, size_t maximum_size);
251
252 public:
253 GenCollectorPolicy();
254
255 // Accessors
256 size_t min_young_size() { return _min_young_size; }
257 size_t initial_young_size() { return _initial_young_size; }
258 size_t max_young_size() { return _max_young_size; }
259 size_t gen_alignment() { return _gen_alignment; }
260 size_t min_old_size() { return _min_old_size; }
261 size_t initial_old_size() { return _initial_old_size; }
262 size_t max_old_size() { return _max_old_size; }
263
264 GenerationSpec* young_gen_spec() const {
265 assert(_young_gen_spec != NULL, "_young_gen_spec should have been initialized");
266 return _young_gen_spec;
267 }
268
269 GenerationSpec* old_gen_spec() const {
270 assert(_old_gen_spec != NULL, "_old_gen_spec should have been initialized");
271 return _old_gen_spec;
272 }
273
274 virtual GenCollectorPolicy* as_generation_policy() { return this; }
275
276 virtual void initialize_generations() { };
277
278 virtual void initialize_all() {
279 CollectorPolicy::initialize_all();
280 initialize_generations();
281 }
282
283 size_t young_gen_size_lower_bound();
284
285 HeapWord* mem_allocate_work(size_t size,
286 bool is_tlab,
287 bool* gc_overhead_limit_was_exceeded);
288
289 HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab);
290
291 // Adaptive size policy
292 virtual void initialize_size_policy(size_t init_eden_size,
293 size_t init_promo_size,
294 size_t init_survivor_size);
295
296 virtual void post_heap_initialize() {
297 assert(_max_young_size == MaxNewSize, "Should be taken care of by initialize_size_info");
298 }
299
300 BarrierSet::Name barrier_set_name() { return BarrierSet::CardTableModRef; }
301
302 virtual CollectorPolicy::Name kind() {
303 return CollectorPolicy::GenCollectorPolicyKind;
304 }
305 };
306
307 class MarkSweepPolicy : public GenCollectorPolicy {
308 protected:
309 void initialize_alignments();
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_GC_SHARED_COLLECTORPOLICY_HPP