1 /*
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   6  * under the terms of the GNU General Public License version 2 only, as
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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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  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   // compute (conservative) maximum heap alignment
 102   static size_t compute_max_alignment();
 103 
 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 #if INCLUDE_ALL_GCS
 142   virtual ConcurrentMarkSweepPolicy*    as_concurrent_mark_sweep_policy() { return NULL; }
 143   virtual G1CollectorPolicy*            as_g1_policy()                    { return NULL; }
 144 #endif // INCLUDE_ALL_GCS
 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 #if INCLUDE_ALL_GCS
 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  // INCLUDE_ALL_GCS
 153   bool is_concurrent_mark_sweep_policy() { return false; }
 154   bool is_g1_policy()                    { return false; }
 155 #endif // INCLUDE_ALL_GCS
 156 
 157 
 158   virtual BarrierSet::Name barrier_set_name() = 0;
 159   virtual GenRemSet::Name  rem_set_name() = 0;
 160 
 161   // Create the remembered set (to cover the given reserved region,
 162   // allowing breaking up into at most "max_covered_regions").
 163   virtual GenRemSet* create_rem_set(MemRegion reserved,
 164                                     int max_covered_regions);
 165 
 166   // This method controls how a collector satisfies a request
 167   // for a block of memory.  "gc_time_limit_was_exceeded" will
 168   // be set to true if the adaptive size policy determine that
 169   // an excessive amount of time is being spent doing collections
 170   // and caused a NULL to be returned.  If a NULL is not returned,
 171   // "gc_time_limit_was_exceeded" has an undefined meaning.
 172   virtual HeapWord* mem_allocate_work(size_t size,
 173                                       bool is_tlab,
 174                                       bool* gc_overhead_limit_was_exceeded) = 0;
 175 
 176   // This method controls how a collector handles one or more
 177   // of its generations being fully allocated.
 178   virtual HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab) = 0;
 179   // This method controls how a collector handles a metadata allocation
 180   // failure.
 181   virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
 182                                                        size_t size,
 183                                                        Metaspace::MetadataType mdtype);
 184 
 185   // Performace Counter support
 186   GCPolicyCounters* counters()     { return _gc_policy_counters; }
 187 
 188   // Create the jstat counters for the GC policy.  By default, policy's
 189   // don't have associated counters, and we complain if this is invoked.
 190   virtual void initialize_gc_policy_counters() {
 191     ShouldNotReachHere();
 192   }
 193 
 194   virtual CollectorPolicy::Name kind() {
 195     return CollectorPolicy::CollectorPolicyKind;
 196   }
 197 
 198   // Returns true if a collector has eden space with soft end.
 199   virtual bool has_soft_ended_eden() {
 200     return false;
 201   }
 202 
 203 };
 204 
 205 class ClearedAllSoftRefs : public StackObj {
 206   bool _clear_all_soft_refs;
 207   CollectorPolicy* _collector_policy;
 208  public:
 209   ClearedAllSoftRefs(bool clear_all_soft_refs,
 210                      CollectorPolicy* collector_policy) :
 211     _clear_all_soft_refs(clear_all_soft_refs),
 212     _collector_policy(collector_policy) {}
 213 
 214   ~ClearedAllSoftRefs() {
 215     if (_clear_all_soft_refs) {
 216       _collector_policy->cleared_all_soft_refs();
 217     }
 218   }
 219 };
 220 
 221 class GenCollectorPolicy : public CollectorPolicy {
 222  protected:
 223   size_t _min_gen0_size;
 224   size_t _initial_gen0_size;
 225   size_t _max_gen0_size;
 226 
 227   GenerationSpec **_generations;
 228 
 229   // Return true if an allocation should be attempted in the older
 230   // generation if it fails in the younger generation.  Return
 231   // false, otherwise.
 232   virtual bool should_try_older_generation_allocation(size_t word_size) const;
 233 
 234   void initialize_flags();
 235   void initialize_size_info();
 236 
 237   // Try to allocate space by expanding the heap.
 238   virtual HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab);
 239 
 240  // Scale the base_size by NewRation according to
 241  //     result = base_size / (NewRatio + 1)
 242  // and align by min_alignment()
 243  size_t scale_by_NewRatio_aligned(size_t base_size);
 244 
 245  // Bound the value by the given maximum minus the
 246  // min_alignment.
 247  size_t bound_minus_alignment(size_t desired_size, size_t maximum_size);
 248 
 249  public:
 250   // Accessors
 251   size_t min_gen0_size() { return _min_gen0_size; }
 252   void set_min_gen0_size(size_t v) { _min_gen0_size = v; }
 253   size_t initial_gen0_size() { return _initial_gen0_size; }
 254   void set_initial_gen0_size(size_t v) { _initial_gen0_size = v; }
 255   size_t max_gen0_size() { return _max_gen0_size; }
 256   void set_max_gen0_size(size_t v) { _max_gen0_size = v; }
 257 
 258   virtual int number_of_generations() = 0;
 259 
 260   virtual GenerationSpec **generations()       {
 261     assert(_generations != NULL, "Sanity check");
 262     return _generations;
 263   }
 264 
 265   virtual GenCollectorPolicy* as_generation_policy() { return this; }
 266 
 267   virtual void initialize_generations() = 0;
 268 
 269   virtual void initialize_all() {
 270     initialize_flags();
 271     initialize_size_info();
 272     initialize_generations();
 273   }
 274 
 275   HeapWord* mem_allocate_work(size_t size,
 276                               bool is_tlab,
 277                               bool* gc_overhead_limit_was_exceeded);
 278 
 279   HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab);
 280 
 281   // Adaptive size policy
 282   virtual void initialize_size_policy(size_t init_eden_size,
 283                                       size_t init_promo_size,
 284                                       size_t init_survivor_size);
 285 };
 286 
 287 // All of hotspot's current collectors are subtypes of this
 288 // class. Currently, these collectors all use the same gen[0],
 289 // but have different gen[1] types. If we add another subtype
 290 // of CollectorPolicy, this class should be broken out into
 291 // its own file.
 292 
 293 class TwoGenerationCollectorPolicy : public GenCollectorPolicy {
 294  protected:
 295   size_t _min_gen1_size;
 296   size_t _initial_gen1_size;
 297   size_t _max_gen1_size;
 298 
 299   void initialize_flags();
 300   void initialize_size_info();
 301   void initialize_generations()                { ShouldNotReachHere(); }
 302 
 303  public:
 304   // Accessors
 305   size_t min_gen1_size() { return _min_gen1_size; }
 306   void set_min_gen1_size(size_t v) { _min_gen1_size = v; }
 307   size_t initial_gen1_size() { return _initial_gen1_size; }
 308   void set_initial_gen1_size(size_t v) { _initial_gen1_size = v; }
 309   size_t max_gen1_size() { return _max_gen1_size; }
 310   void set_max_gen1_size(size_t v) { _max_gen1_size = v; }
 311 
 312   // Inherited methods
 313   TwoGenerationCollectorPolicy* as_two_generation_policy() { return this; }
 314 
 315   int number_of_generations()                  { return 2; }
 316   BarrierSet::Name barrier_set_name()          { return BarrierSet::CardTableModRef; }
 317   GenRemSet::Name rem_set_name()               { return GenRemSet::CardTable; }
 318 
 319   virtual CollectorPolicy::Name kind() {
 320     return CollectorPolicy::TwoGenerationCollectorPolicyKind;
 321   }
 322 
 323   // Returns true is gen0 sizes were adjusted
 324   bool adjust_gen0_sizes(size_t* gen0_size_ptr, size_t* gen1_size_ptr,
 325                          const size_t heap_size, const size_t min_gen1_size);
 326 };
 327 
 328 class MarkSweepPolicy : public TwoGenerationCollectorPolicy {
 329  protected:
 330   void initialize_generations();
 331 
 332  public:
 333   MarkSweepPolicy();
 334 
 335   MarkSweepPolicy* as_mark_sweep_policy() { return this; }
 336 
 337   void initialize_gc_policy_counters();
 338 };
 339 
 340 #endif // SHARE_VM_MEMORY_COLLECTORPOLICY_HPP