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.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
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).
14 *
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,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_VM_MEMORY_COLLECTORPOLICY_HPP
26 #define SHARE_VM_MEMORY_COLLECTORPOLICY_HPP
27
28 #include "memory/barrierSet.hpp"
29 #include "memory/genRemSet.hpp"
30 #include "memory/permGen.hpp"
31
32 // This class (or more correctly, subtypes of this class)
33 // are used to define global garbage collector attributes.
34 // This includes initialization of generations and any other
35 // shared resources they may need.
36 //
37 // In general, all flag adjustment and validation should be
38 // done in initialize_flags(), which is called prior to
39 // initialize_size_info().
40 //
41 // This class is not fully developed yet. As more collector(s)
42 // are added, it is expected that we will come across further
43 // behavior that requires global attention. The correct place
44 // to deal with those issues is this class.
45
46 // Forward declarations.
47 class GenCollectorPolicy;
48 class TwoGenerationCollectorPolicy;
49 class AdaptiveSizePolicy;
50 #ifndef SERIALGC
51 class ConcurrentMarkSweepPolicy;
52 class G1CollectorPolicy;
53 #endif // SERIALGC
54
55 class GCPolicyCounters;
56 class PermanentGenerationSpec;
57 class MarkSweepPolicy;
58
59 class CollectorPolicy : public CHeapObj {
60 protected:
61 PermanentGenerationSpec *_permanent_generation;
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 // Initialize "_permanent_generation" to a spec for the given kind of
69 // Perm Gen.
70 void initialize_perm_generation(PermGen::Name pgnm);
71
72 size_t _initial_heap_byte_size;
73 size_t _max_heap_byte_size;
74 size_t _min_heap_byte_size;
75
76 size_t _min_alignment;
77 size_t _max_alignment;
78
79 // The sizing of the heap are controlled by a sizing policy.
80 AdaptiveSizePolicy* _size_policy;
81
82 // Set to true when policy wants soft refs cleared.
83 // Reset to false by gc after it clears all soft refs.
84 bool _should_clear_all_soft_refs;
85 // Set to true by the GC if the just-completed gc cleared all
86 // softrefs. This is set to true whenever a gc clears all softrefs, and
87 // set to false each time gc returns to the mutator. For example, in the
88 // ParallelScavengeHeap case the latter would be done toward the end of
89 // mem_allocate() where it returns op.result()
90 bool _all_soft_refs_clear;
91
92 CollectorPolicy() :
93 _min_alignment(1),
94 _max_alignment(1),
95 _initial_heap_byte_size(0),
96 _max_heap_byte_size(0),
97 _min_heap_byte_size(0),
98 _size_policy(NULL),
99 _should_clear_all_soft_refs(false),
100 _all_soft_refs_clear(false)
101 {}
102
103 public:
104 void set_min_alignment(size_t align) { _min_alignment = align; }
105 size_t min_alignment() { return _min_alignment; }
106 void set_max_alignment(size_t align) { _max_alignment = align; }
107 size_t max_alignment() { return _max_alignment; }
108
109 size_t initial_heap_byte_size() { return _initial_heap_byte_size; }
110 void set_initial_heap_byte_size(size_t v) { _initial_heap_byte_size = v; }
111 size_t max_heap_byte_size() { return _max_heap_byte_size; }
112 void set_max_heap_byte_size(size_t v) { _max_heap_byte_size = v; }
113 size_t min_heap_byte_size() { return _min_heap_byte_size; }
114 void set_min_heap_byte_size(size_t v) { _min_heap_byte_size = v; }
115
116 enum Name {
117 CollectorPolicyKind,
118 TwoGenerationCollectorPolicyKind,
119 ConcurrentMarkSweepPolicyKind,
120 ASConcurrentMarkSweepPolicyKind,
121 G1CollectorPolicyKind
122 };
123
124 AdaptiveSizePolicy* size_policy() { return _size_policy; }
125 bool should_clear_all_soft_refs() { return _should_clear_all_soft_refs; }
126 void set_should_clear_all_soft_refs(bool v) { _should_clear_all_soft_refs = v; }
127 // Returns the current value of _should_clear_all_soft_refs.
128 // _should_clear_all_soft_refs is set to false as a side effect.
129 bool use_should_clear_all_soft_refs(bool v);
130 bool all_soft_refs_clear() { return _all_soft_refs_clear; }
131 void set_all_soft_refs_clear(bool v) { _all_soft_refs_clear = v; }
132
133 // Called by the GC after Soft Refs have been cleared to indicate
134 // that the request in _should_clear_all_soft_refs has been fulfilled.
135 void cleared_all_soft_refs();
136
137 // Identification methods.
138 virtual GenCollectorPolicy* as_generation_policy() { return NULL; }
139 virtual TwoGenerationCollectorPolicy* as_two_generation_policy() { return NULL; }
140 virtual MarkSweepPolicy* as_mark_sweep_policy() { return NULL; }
141 #ifndef SERIALGC
142 virtual ConcurrentMarkSweepPolicy* as_concurrent_mark_sweep_policy() { return NULL; }
143 virtual G1CollectorPolicy* as_g1_policy() { return NULL; }
144 #endif // SERIALGC
145 // Note that these are not virtual.
146 bool is_generation_policy() { return as_generation_policy() != NULL; }
147 bool is_two_generation_policy() { return as_two_generation_policy() != NULL; }
148 bool is_mark_sweep_policy() { return as_mark_sweep_policy() != NULL; }
149 #ifndef SERIALGC
150 bool is_concurrent_mark_sweep_policy() { return as_concurrent_mark_sweep_policy() != NULL; }
151 bool is_g1_policy() { return as_g1_policy() != NULL; }
152 #else // SERIALGC
153 bool is_concurrent_mark_sweep_policy() { return false; }
154 bool is_g1_policy() { return false; }
155 #endif // SERIALGC
156
157
158 virtual PermanentGenerationSpec *permanent_generation() {
159 assert(_permanent_generation != NULL, "Sanity check");
160 return _permanent_generation;
161 }
162
163 virtual BarrierSet::Name barrier_set_name() = 0;
164 virtual GenRemSet::Name rem_set_name() = 0;
165
166 // Create the remembered set (to cover the given reserved region,
167 // allowing breaking up into at most "max_covered_regions").
168 virtual GenRemSet* create_rem_set(MemRegion reserved,
169 int max_covered_regions);
170
171 // This method controls how a collector satisfies a request
172 // for a block of memory. "gc_time_limit_was_exceeded" will
173 // be set to true if the adaptive size policy determine that
174 // an excessive amount of time is being spent doing collections
175 // and caused a NULL to be returned. If a NULL is not returned,
176 // "gc_time_limit_was_exceeded" has an undefined meaning.
177 virtual HeapWord* mem_allocate_work(size_t size,
178 bool is_tlab,
179 bool* gc_overhead_limit_was_exceeded) = 0;
180
181 // This method controls how a collector handles one or more
182 // of its generations being fully allocated.
183 virtual HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab) = 0;
184 // Performace Counter support
185 GCPolicyCounters* counters() { return _gc_policy_counters; }
186
187 // Create the jstat counters for the GC policy. By default, policy's
188 // don't have associated counters, and we complain if this is invoked.
189 virtual void initialize_gc_policy_counters() {
190 ShouldNotReachHere();
191 }
192
193 virtual CollectorPolicy::Name kind() {
194 return CollectorPolicy::CollectorPolicyKind;
195 }
196
197 // Returns true if a collector has eden space with soft end.
198 virtual bool has_soft_ended_eden() {
199 return false;
200 }
201
202 };
203
204 class ClearedAllSoftRefs : public StackObj {
205 bool _clear_all_soft_refs;
206 CollectorPolicy* _collector_policy;
207 public:
208 ClearedAllSoftRefs(bool clear_all_soft_refs,
209 CollectorPolicy* collector_policy) :
210 _clear_all_soft_refs(clear_all_soft_refs),
211 _collector_policy(collector_policy) {}
212
213 ~ClearedAllSoftRefs() {
214 if (_clear_all_soft_refs) {
215 _collector_policy->cleared_all_soft_refs();
216 }
217 }
218 };
219
220 class GenCollectorPolicy : public CollectorPolicy {
221 protected:
222 size_t _min_gen0_size;
223 size_t _initial_gen0_size;
224 size_t _max_gen0_size;
225
226 GenerationSpec **_generations;
227
228 // Return true if an allocation should be attempted in the older
229 // generation if it fails in the younger generation. Return
230 // false, otherwise.
231 virtual bool should_try_older_generation_allocation(size_t word_size) const;
232
233 void initialize_flags();
234 void initialize_size_info();
235
236 // Try to allocate space by expanding the heap.
237 virtual HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab);
238
239 // compute max heap alignment
240 size_t compute_max_alignment();
241
242 // Scale the base_size by NewRation according to
243 // result = base_size / (NewRatio + 1)
244 // and align by min_alignment()
245 size_t scale_by_NewRatio_aligned(size_t base_size);
246
247 // Bound the value by the given maximum minus the
248 // min_alignment.
249 size_t bound_minus_alignment(size_t desired_size, size_t maximum_size);
250
251 public:
252 // Accessors
253 size_t min_gen0_size() { return _min_gen0_size; }
254 void set_min_gen0_size(size_t v) { _min_gen0_size = v; }
255 size_t initial_gen0_size() { return _initial_gen0_size; }
256 void set_initial_gen0_size(size_t v) { _initial_gen0_size = v; }
257 size_t max_gen0_size() { return _max_gen0_size; }
258 void set_max_gen0_size(size_t v) { _max_gen0_size = v; }
259
260 virtual int number_of_generations() = 0;
261
262 virtual GenerationSpec **generations() {
263 assert(_generations != NULL, "Sanity check");
264 return _generations;
265 }
266
267 virtual GenCollectorPolicy* as_generation_policy() { return this; }
268
269 virtual void initialize_generations() = 0;
270
271 virtual void initialize_all() {
272 initialize_flags();
273 initialize_size_info();
274 initialize_generations();
275 }
276
277 HeapWord* mem_allocate_work(size_t size,
278 bool is_tlab,
279 bool* gc_overhead_limit_was_exceeded);
280
281 HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab);
282
283 // The size that defines a "large array".
284 virtual size_t large_typearray_limit();
285
286 // Adaptive size policy
287 virtual void initialize_size_policy(size_t init_eden_size,
288 size_t init_promo_size,
289 size_t init_survivor_size);
290 };
291
292 // All of hotspot's current collectors are subtypes of this
293 // class. Currently, these collectors all use the same gen[0],
294 // but have different gen[1] types. If we add another subtype
295 // of CollectorPolicy, this class should be broken out into
296 // its own file.
297
298 class TwoGenerationCollectorPolicy : public GenCollectorPolicy {
299 protected:
300 size_t _min_gen1_size;
301 size_t _initial_gen1_size;
302 size_t _max_gen1_size;
303
304 void initialize_flags();
305 void initialize_size_info();
306 void initialize_generations() { ShouldNotReachHere(); }
307
308 public:
309 // Accessors
310 size_t min_gen1_size() { return _min_gen1_size; }
311 void set_min_gen1_size(size_t v) { _min_gen1_size = v; }
312 size_t initial_gen1_size() { return _initial_gen1_size; }
313 void set_initial_gen1_size(size_t v) { _initial_gen1_size = v; }
314 size_t max_gen1_size() { return _max_gen1_size; }
315 void set_max_gen1_size(size_t v) { _max_gen1_size = v; }
316
317 // Inherited methods
318 TwoGenerationCollectorPolicy* as_two_generation_policy() { return this; }
319
320 int number_of_generations() { return 2; }
321 BarrierSet::Name barrier_set_name() { return BarrierSet::CardTableModRef; }
322 GenRemSet::Name rem_set_name() { return GenRemSet::CardTable; }
323
324 virtual CollectorPolicy::Name kind() {
325 return CollectorPolicy::TwoGenerationCollectorPolicyKind;
326 }
327
328 // Returns true is gen0 sizes were adjusted
329 bool adjust_gen0_sizes(size_t* gen0_size_ptr, size_t* gen1_size_ptr,
330 size_t heap_size, size_t min_gen1_size);
331 };
332
333 class MarkSweepPolicy : public TwoGenerationCollectorPolicy {
334 protected:
335 void initialize_generations();
336
337 public:
338 MarkSweepPolicy();
339
340 MarkSweepPolicy* as_mark_sweep_policy() { return this; }
341
342 void initialize_gc_policy_counters();
343 };
344
345 #endif // SHARE_VM_MEMORY_COLLECTORPOLICY_HPP