1 /*
   2  * Copyright (c) 2001, 2013, 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/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   virtual void initialize_alignments() = 0;
  65   virtual void initialize_flags();
  66   virtual void initialize_size_info();
  67 
  68   DEBUG_ONLY(virtual void assert_flags();)
  69   DEBUG_ONLY(virtual void assert_size_info();)
  70 
  71   size_t _initial_heap_byte_size;
  72   size_t _max_heap_byte_size;
  73   size_t _min_heap_byte_size;
  74 
  75   size_t _space_alignment;
  76   size_t _heap_alignment;
  77 
  78   // Needed to keep information if MaxHeapSize was set on the command line
  79   // when the flag value is aligned etc by ergonomics.
  80   bool _max_heap_size_cmdline;
  81 
  82   // The sizing of the heap is controlled by a sizing policy.
  83   AdaptiveSizePolicy* _size_policy;
  84 
  85   // Set to true when policy wants soft refs cleared.
  86   // Reset to false by gc after it clears all soft refs.
  87   bool _should_clear_all_soft_refs;
  88 
  89   // Set to true by the GC if the just-completed gc cleared all
  90   // softrefs.  This is set to true whenever a gc clears all softrefs, and
  91   // set to false each time gc returns to the mutator.  For example, in the
  92   // ParallelScavengeHeap case the latter would be done toward the end of
  93   // mem_allocate() where it returns op.result()
  94   bool _all_soft_refs_clear;
  95 
  96   CollectorPolicy();
  97 
  98  public:
  99   virtual void initialize_all() {
 100     initialize_alignments();
 101     initialize_flags();
 102     initialize_size_info();
 103   }
 104 
 105   // Return maximum heap alignment that may be imposed by the policy.
 106   static size_t compute_heap_alignment();
 107 
 108   size_t space_alignment()        { return _space_alignment; }
 109   size_t heap_alignment()         { return _heap_alignment; }
 110 
 111   size_t initial_heap_byte_size() { return _initial_heap_byte_size; }
 112   size_t max_heap_byte_size()     { return _max_heap_byte_size; }
 113   size_t min_heap_byte_size()     { return _min_heap_byte_size; }
 114 
 115   enum Name {
 116     CollectorPolicyKind,
 117     TwoGenerationCollectorPolicyKind,
 118     ConcurrentMarkSweepPolicyKind,
 119     ASConcurrentMarkSweepPolicyKind,
 120     G1CollectorPolicyKind
 121   };
 122 
 123   AdaptiveSizePolicy* size_policy() { return _size_policy; }
 124   bool should_clear_all_soft_refs() { return _should_clear_all_soft_refs; }
 125   void set_should_clear_all_soft_refs(bool v) { _should_clear_all_soft_refs = v; }
 126   // Returns the current value of _should_clear_all_soft_refs.
 127   // _should_clear_all_soft_refs is set to false as a side effect.
 128   bool use_should_clear_all_soft_refs(bool v);
 129   bool all_soft_refs_clear() { return _all_soft_refs_clear; }
 130   void set_all_soft_refs_clear(bool v) { _all_soft_refs_clear = v; }
 131 
 132   // Called by the GC after Soft Refs have been cleared to indicate
 133   // that the request in _should_clear_all_soft_refs has been fulfilled.
 134   void cleared_all_soft_refs();
 135 
 136   // Identification methods.
 137   virtual GenCollectorPolicy*           as_generation_policy()            { return NULL; }
 138   virtual TwoGenerationCollectorPolicy* as_two_generation_policy()        { return NULL; }
 139   virtual MarkSweepPolicy*              as_mark_sweep_policy()            { return NULL; }
 140 #if INCLUDE_ALL_GCS
 141   virtual ConcurrentMarkSweepPolicy*    as_concurrent_mark_sweep_policy() { return NULL; }
 142   virtual G1CollectorPolicy*            as_g1_policy()                    { return NULL; }
 143 #endif // INCLUDE_ALL_GCS
 144   // Note that these are not virtual.
 145   bool is_generation_policy()            { return as_generation_policy() != NULL; }
 146   bool is_two_generation_policy()        { return as_two_generation_policy() != NULL; }
 147   bool is_mark_sweep_policy()            { return as_mark_sweep_policy() != NULL; }
 148 #if INCLUDE_ALL_GCS
 149   bool is_concurrent_mark_sweep_policy() { return as_concurrent_mark_sweep_policy() != NULL; }
 150   bool is_g1_policy()                    { return as_g1_policy() != NULL; }
 151 #else  // INCLUDE_ALL_GCS
 152   bool is_concurrent_mark_sweep_policy() { return false; }
 153   bool is_g1_policy()                    { return false; }
 154 #endif // INCLUDE_ALL_GCS
 155 
 156 
 157   virtual BarrierSet::Name barrier_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   // This method controls how a collector handles a metadata allocation
 178   // failure.
 179   virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
 180                                                        size_t size,
 181                                                        Metaspace::MetadataType mdtype);
 182 
 183   // Performance Counter support
 184   GCPolicyCounters* counters()     { return _gc_policy_counters; }
 185 
 186   // Create the jstat counters for the GC policy.  By default, policy's
 187   // don't have associated counters, and we complain if this is invoked.
 188   virtual void initialize_gc_policy_counters() {
 189     ShouldNotReachHere();
 190   }
 191 
 192   virtual CollectorPolicy::Name kind() {
 193     return CollectorPolicy::CollectorPolicyKind;
 194   }
 195 
 196   // Returns true if a collector has eden space with soft end.
 197   virtual bool has_soft_ended_eden() {
 198     return false;
 199   }
 200 
 201   // Do any updates required to global flags that are due to heap initialization
 202   // changes
 203   virtual void post_heap_initialize() = 0;
 204 };
 205 
 206 class ClearedAllSoftRefs : public StackObj {
 207   bool _clear_all_soft_refs;
 208   CollectorPolicy* _collector_policy;
 209  public:
 210   ClearedAllSoftRefs(bool clear_all_soft_refs,
 211                      CollectorPolicy* collector_policy) :
 212     _clear_all_soft_refs(clear_all_soft_refs),
 213     _collector_policy(collector_policy) {}
 214 
 215   ~ClearedAllSoftRefs() {
 216     if (_clear_all_soft_refs) {
 217       _collector_policy->cleared_all_soft_refs();
 218     }
 219   }
 220 };
 221 
 222 class GenCollectorPolicy : public CollectorPolicy {
 223  protected:
 224   size_t _min_gen0_size;
 225   size_t _initial_gen0_size;
 226   size_t _max_gen0_size;
 227 
 228   // _gen_alignment and _space_alignment will have the same value most of the
 229   // time. When using large pages they can differ.
 230   size_t _gen_alignment;
 231 
 232   GenerationSpec **_generations;
 233 
 234   // Return true if an allocation should be attempted in the older generation
 235   // if it fails in the younger generation.  Return false, otherwise.
 236   virtual bool should_try_older_generation_allocation(size_t word_size) const;
 237 
 238   void initialize_flags();
 239   void initialize_size_info();
 240 
 241   DEBUG_ONLY(void assert_flags();)
 242   DEBUG_ONLY(void assert_size_info();)
 243 
 244   // Try to allocate space by expanding the heap.
 245   virtual HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab);
 246 
 247   // Compute max heap alignment.
 248   size_t compute_max_alignment();
 249 
 250  // Scale the base_size by NewRatio according to
 251  //     result = base_size / (NewRatio + 1)
 252  // and align by min_alignment()
 253  size_t scale_by_NewRatio_aligned(size_t base_size);
 254 
 255  // Bound the value by the given maximum minus the min_alignment.
 256  size_t bound_minus_alignment(size_t desired_size, size_t maximum_size);
 257 
 258  public:
 259   GenCollectorPolicy();
 260 
 261   // Accessors
 262   size_t min_gen0_size()     { return _min_gen0_size; }
 263   size_t initial_gen0_size() { return _initial_gen0_size; }
 264   size_t max_gen0_size()     { return _max_gen0_size; }
 265   size_t gen_alignment()     { return _gen_alignment; }
 266 
 267   virtual int number_of_generations() = 0;
 268 
 269   virtual GenerationSpec **generations() {
 270     assert(_generations != NULL, "Sanity check");
 271     return _generations;
 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_gen0_size == MaxNewSize, "Should be taken care of by initialize_size_info");
 298   }
 299 };
 300 
 301 // All of hotspot's current collectors are subtypes of this
 302 // class. Currently, these collectors all use the same gen[0],
 303 // but have different gen[1] types. If we add another subtype
 304 // of CollectorPolicy, this class should be broken out into
 305 // its own file.
 306 
 307 class TwoGenerationCollectorPolicy : public GenCollectorPolicy {
 308  protected:
 309   size_t _min_gen1_size;
 310   size_t _initial_gen1_size;
 311   size_t _max_gen1_size;
 312 
 313   void initialize_flags();
 314   void initialize_size_info();
 315 
 316   DEBUG_ONLY(void assert_flags();)
 317   DEBUG_ONLY(void assert_size_info();)
 318 
 319  public:
 320   TwoGenerationCollectorPolicy() : GenCollectorPolicy(), _min_gen1_size(0),
 321     _initial_gen1_size(0), _max_gen1_size(0) {}
 322 
 323   // Accessors
 324   size_t min_gen1_size()     { return _min_gen1_size; }
 325   size_t initial_gen1_size() { return _initial_gen1_size; }
 326   size_t max_gen1_size()     { return _max_gen1_size; }
 327 
 328   // Inherited methods
 329   TwoGenerationCollectorPolicy* as_two_generation_policy() { return this; }
 330 
 331   int number_of_generations()          { return 2; }
 332   BarrierSet::Name barrier_set_name()  { return BarrierSet::CardTableModRef; }
 333 
 334   virtual CollectorPolicy::Name kind() {
 335     return CollectorPolicy::TwoGenerationCollectorPolicyKind;
 336   }
 337 
 338   // Returns true if gen0 sizes were adjusted
 339   bool adjust_gen0_sizes(size_t* gen0_size_ptr, size_t* gen1_size_ptr,
 340                          const size_t heap_size);
 341 };
 342 
 343 class MarkSweepPolicy : public TwoGenerationCollectorPolicy {
 344  protected:
 345   void initialize_alignments();
 346   void initialize_generations();
 347 
 348  public:
 349   MarkSweepPolicy() {}
 350 
 351   MarkSweepPolicy* as_mark_sweep_policy() { return this; }
 352 
 353   void initialize_gc_policy_counters();
 354 };
 355 
 356 #endif // SHARE_VM_MEMORY_COLLECTORPOLICY_HPP