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 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     ASConcurrentMarkSweepPolicyKind,
 119     G1CollectorPolicyKind
 120   };
 121 
 122   AdaptiveSizePolicy* size_policy() { return _size_policy; }
 123   bool should_clear_all_soft_refs() { return _should_clear_all_soft_refs; }
 124   void set_should_clear_all_soft_refs(bool v) { _should_clear_all_soft_refs = v; }
 125   // Returns the current value of _should_clear_all_soft_refs.
 126   // _should_clear_all_soft_refs is set to false as a side effect.
 127   bool use_should_clear_all_soft_refs(bool v);
 128   bool all_soft_refs_clear() { return _all_soft_refs_clear; }
 129   void set_all_soft_refs_clear(bool v) { _all_soft_refs_clear = v; }
 130 
 131   // Called by the GC after Soft Refs have been cleared to indicate
 132   // that the request in _should_clear_all_soft_refs has been fulfilled.
 133   void cleared_all_soft_refs();
 134 
 135   // Identification methods.
 136   virtual GenCollectorPolicy*           as_generation_policy()            { return NULL; }
 137   virtual MarkSweepPolicy*              as_mark_sweep_policy()            { return NULL; }
 138 #if INCLUDE_ALL_GCS
 139   virtual ConcurrentMarkSweepPolicy*    as_concurrent_mark_sweep_policy() { return NULL; }
 140   virtual G1CollectorPolicy*            as_g1_policy()                    { return NULL; }
 141 #endif // INCLUDE_ALL_GCS
 142   // Note that these are not virtual.
 143   bool is_generation_policy()            { return as_generation_policy() != NULL; }
 144   bool is_mark_sweep_policy()            { return as_mark_sweep_policy() != NULL; }
 145 #if INCLUDE_ALL_GCS
 146   bool is_concurrent_mark_sweep_policy() { return as_concurrent_mark_sweep_policy() != NULL; }
 147   bool is_g1_policy()                    { return as_g1_policy() != NULL; }
 148 #else  // INCLUDE_ALL_GCS
 149   bool is_concurrent_mark_sweep_policy() { return false; }
 150   bool is_g1_policy()                    { return false; }
 151 #endif // INCLUDE_ALL_GCS
 152 
 153 
 154   virtual BarrierSet::Name barrier_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   // Performance 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   // Do any updates required to global flags that are due to heap initialization
 199   // changes
 200   virtual void post_heap_initialize() = 0;
 201 };
 202 
 203 class ClearedAllSoftRefs : public StackObj {
 204   bool _clear_all_soft_refs;
 205   CollectorPolicy* _collector_policy;
 206  public:
 207   ClearedAllSoftRefs(bool clear_all_soft_refs,
 208                      CollectorPolicy* collector_policy) :
 209     _clear_all_soft_refs(clear_all_soft_refs),
 210     _collector_policy(collector_policy) {}
 211 
 212   ~ClearedAllSoftRefs() {
 213     if (_clear_all_soft_refs) {
 214       _collector_policy->cleared_all_soft_refs();
 215     }
 216   }
 217 };
 218 
 219 class GenCollectorPolicy : public CollectorPolicy {
 220 friend class TestGenCollectorPolicy;
 221  protected:
 222   size_t _min_gen0_size;
 223   size_t _initial_gen0_size;
 224   size_t _max_gen0_size;
 225   size_t _min_gen1_size;
 226   size_t _initial_gen1_size;
 227   size_t _max_gen1_size;
 228 
 229   // _gen_alignment and _space_alignment will have the same value most of the
 230   // time. When using large pages they can differ.
 231   size_t _gen_alignment;
 232 
 233   GenerationSpec **_generations;
 234 
 235   // Return true if an allocation should be attempted in the older generation
 236   // if it fails in the younger generation.  Return false, otherwise.
 237   virtual bool should_try_older_generation_allocation(size_t word_size) const;
 238 
 239   void initialize_flags();
 240   void initialize_size_info();
 241 
 242   DEBUG_ONLY(void assert_flags();)
 243   DEBUG_ONLY(void assert_size_info();)
 244 
 245   // Try to allocate space by expanding the heap.
 246   virtual HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab);
 247 
 248   // Compute max heap alignment.
 249   size_t compute_max_alignment();
 250 
 251   // Scale the base_size by NewRatio according to
 252   //     result = base_size / (NewRatio + 1)
 253   // and align by min_alignment()
 254   size_t scale_by_NewRatio_aligned(size_t base_size);
 255 
 256   // Bound the value by the given maximum minus the min_alignment.
 257   size_t bound_minus_alignment(size_t desired_size, size_t maximum_size);
 258 
 259  public:
 260   GenCollectorPolicy();
 261 
 262   // Accessors
 263   size_t min_gen0_size()     { return _min_gen0_size; }
 264   size_t initial_gen0_size() { return _initial_gen0_size; }
 265   size_t max_gen0_size()     { return _max_gen0_size; }
 266   size_t gen_alignment()     { return _gen_alignment; }
 267   size_t min_gen1_size()     { return _min_gen1_size; }
 268   size_t initial_gen1_size() { return _initial_gen1_size; }
 269   size_t max_gen1_size()     { return _max_gen1_size; }
 270 
 271   int number_of_generations() { return 2; }
 272 
 273   virtual GenerationSpec **generations() {
 274     assert(_generations != NULL, "Sanity check");
 275     return _generations;
 276   }
 277 
 278   virtual GenCollectorPolicy* as_generation_policy() { return this; }
 279 
 280   virtual void initialize_generations() { };
 281 
 282   virtual void initialize_all() {
 283     CollectorPolicy::initialize_all();
 284     initialize_generations();
 285   }
 286 
 287   size_t young_gen_size_lower_bound();
 288 
 289   HeapWord* mem_allocate_work(size_t size,
 290                               bool is_tlab,
 291                               bool* gc_overhead_limit_was_exceeded);
 292 
 293   HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab);
 294 
 295   // Adaptive size policy
 296   virtual void initialize_size_policy(size_t init_eden_size,
 297                                       size_t init_promo_size,
 298                                       size_t init_survivor_size);
 299 
 300   virtual void post_heap_initialize() {
 301     assert(_max_gen0_size == MaxNewSize, "Should be taken care of by initialize_size_info");
 302   }
 303 
 304   BarrierSet::Name barrier_set_name()  { return BarrierSet::CardTableModRef; }
 305 
 306   virtual CollectorPolicy::Name kind() {
 307     return CollectorPolicy::GenCollectorPolicyKind;
 308   }
 309 };
 310 
 311 class MarkSweepPolicy : public GenCollectorPolicy {
 312  protected:
 313   void initialize_alignments();
 314   void initialize_generations();
 315 
 316  public:
 317   MarkSweepPolicy() {}
 318 
 319   MarkSweepPolicy* as_mark_sweep_policy() { return this; }
 320 
 321   void initialize_gc_policy_counters();
 322 };
 323 
 324 #endif // SHARE_VM_MEMORY_COLLECTORPOLICY_HPP