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  * accompanied this code).

  *

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 #ifndef SHARE_VM_MEMORY_COLLECTORPOLICY_HPP

 #define SHARE_VM_MEMORY_COLLECTORPOLICY_HPP

 #include "memory/allocation.hpp"

 #include "memory/barrierSet.hpp"

 #include "memory/generationSpec.hpp"

 #include "memory/genRemSet.hpp"

 #include "utilities/macros.hpp"

 // This class (or more correctly, subtypes of this class)

 // are used to define global garbage collector attributes.

 // This includes initialization of generations and any other

 // shared resources they may need.

 //

 // In general, all flag adjustment and validation should be

 // done in initialize_flags(), which is called prior to

 // initialize_size_info().

 //

 // This class is not fully developed yet. As more collector(s)

 // are added, it is expected that we will come across further

 // behavior that requires global attention. The correct place

 // to deal with those issues is this class.

 // Forward declarations.

 class GenCollectorPolicy;

 class TwoGenerationCollectorPolicy;

 class AdaptiveSizePolicy;

 #if INCLUDE_ALL_GCS

 class ConcurrentMarkSweepPolicy;

 class G1CollectorPolicy;

 #endif // INCLUDE_ALL_GCS

 class GCPolicyCounters;

 class MarkSweepPolicy;

 class CollectorPolicy : public CHeapObj<mtGC> {

  protected:

   GCPolicyCounters* _gc_policy_counters;

   virtual void initialize_alignments() = 0;

   virtual void initialize_flags();

   virtual void initialize_size_info();

   DEBUG_ONLY(virtual void assert_flags();)

   DEBUG_ONLY(virtual void assert_size_info();)

   size_t _initial_heap_byte_size;

   size_t _max_heap_byte_size;

   size_t _min_heap_byte_size;

   size_t _space_alignment;

   size_t _heap_alignment;

   // Needed to keep information if MaxHeapSize was set on the command line

   // when the flag value is aligned etc by ergonomics

   bool _max_heap_size_cmdline;

   // The sizing of the heap are controlled by a sizing policy.

   AdaptiveSizePolicy* _size_policy;

   // Set to true when policy wants soft refs cleared.

   // Reset to false by gc after it clears all soft refs.

   bool _should_clear_all_soft_refs;

   // Set to true by the GC if the just-completed gc cleared all

   // softrefs.  This is set to true whenever a gc clears all softrefs, and

   // set to false each time gc returns to the mutator.  For example, in the

   // ParallelScavengeHeap case the latter would be done toward the end of

   // mem_allocate() where it returns op.result()

   bool _all_soft_refs_clear;

   CollectorPolicy();

  public:

   virtual void initialize_all() {

     initialize_alignments();

     initialize_flags();

     initialize_size_info();

   }

   // Return maximum heap alignment that may be imposed by the policy

   static size_t compute_heap_alignment();

   size_t space_alignment()        { return _space_alignment; }

   size_t heap_alignment()         { return _heap_alignment; }

   size_t initial_heap_byte_size() { return _initial_heap_byte_size; }

   size_t max_heap_byte_size()     { return _max_heap_byte_size; }

   size_t min_heap_byte_size()     { return _min_heap_byte_size; }

   enum Name {

     CollectorPolicyKind,

     TwoGenerationCollectorPolicyKind,

     ConcurrentMarkSweepPolicyKind,

     ASConcurrentMarkSweepPolicyKind,

     G1CollectorPolicyKind

   };

   AdaptiveSizePolicy* size_policy() { return _size_policy; }

   bool should_clear_all_soft_refs() { return _should_clear_all_soft_refs; }

   void set_should_clear_all_soft_refs(bool v) { _should_clear_all_soft_refs = v; }

   // Returns the current value of _should_clear_all_soft_refs.

   // _should_clear_all_soft_refs is set to false as a side effect.

   bool use_should_clear_all_soft_refs(bool v);

   bool all_soft_refs_clear() { return _all_soft_refs_clear; }

   void set_all_soft_refs_clear(bool v) { _all_soft_refs_clear = v; }

   // Called by the GC after Soft Refs have been cleared to indicate

   // that the request in _should_clear_all_soft_refs has been fulfilled.

   void cleared_all_soft_refs();

   // Identification methods.

   virtual GenCollectorPolicy*           as_generation_policy()            { return NULL; }

   virtual TwoGenerationCollectorPolicy* as_two_generation_policy()        { return NULL; }

   virtual MarkSweepPolicy*              as_mark_sweep_policy()            { return NULL; }

 #if INCLUDE_ALL_GCS

   virtual ConcurrentMarkSweepPolicy*    as_concurrent_mark_sweep_policy() { return NULL; }

   virtual G1CollectorPolicy*            as_g1_policy()                    { return NULL; }

 #endif // INCLUDE_ALL_GCS

   // Note that these are not virtual.

   bool is_generation_policy()            { return as_generation_policy() != NULL; }

   bool is_two_generation_policy()        { return as_two_generation_policy() != NULL; }

   bool is_mark_sweep_policy()            { return as_mark_sweep_policy() != NULL; }

 #if INCLUDE_ALL_GCS

   bool is_concurrent_mark_sweep_policy() { return as_concurrent_mark_sweep_policy() != NULL; }

   bool is_g1_policy()                    { return as_g1_policy() != NULL; }

 #else  // INCLUDE_ALL_GCS

   bool is_concurrent_mark_sweep_policy() { return false; }

   bool is_g1_policy()                    { return false; }

 #endif // INCLUDE_ALL_GCS

   virtual BarrierSet::Name barrier_set_name() = 0;

   // Create the remembered set (to cover the given reserved region,

   // allowing breaking up into at most "max_covered_regions").

   virtual GenRemSet* create_rem_set(MemRegion reserved,

                                     int max_covered_regions);

   // This method controls how a collector satisfies a request

   // for a block of memory.  "gc_time_limit_was_exceeded" will

   // be set to true if the adaptive size policy determine that

   // an excessive amount of time is being spent doing collections

   // and caused a NULL to be returned.  If a NULL is not returned,

   // "gc_time_limit_was_exceeded" has an undefined meaning.

   virtual HeapWord* mem_allocate_work(size_t size,

                                       bool is_tlab,

                                       bool* gc_overhead_limit_was_exceeded) = 0;

   // This method controls how a collector handles one or more

   // of its generations being fully allocated.

   virtual HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab) = 0;

   // This method controls how a collector handles a metadata allocation

   // failure.

   virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,

                                                        size_t size,

                                                        Metaspace::MetadataType mdtype);

   // Performace Counter support

   GCPolicyCounters* counters()     { return _gc_policy_counters; }

   // Create the jstat counters for the GC policy.  By default, policy's

   // don't have associated counters, and we complain if this is invoked.

   virtual void initialize_gc_policy_counters() {

     ShouldNotReachHere();

   }

   virtual CollectorPolicy::Name kind() {

     return CollectorPolicy::CollectorPolicyKind;

   }

   // Returns true if a collector has eden space with soft end.

   virtual bool has_soft_ended_eden() {

     return false;

   }

   // Do any updates required to global flags that are due to heap initialization

   // changes

   virtual void post_heap_initialize() = 0;

 };

 class ClearedAllSoftRefs : public StackObj {

   bool _clear_all_soft_refs;

   CollectorPolicy* _collector_policy;

  public:

   ClearedAllSoftRefs(bool clear_all_soft_refs,

                      CollectorPolicy* collector_policy) :

     _clear_all_soft_refs(clear_all_soft_refs),

     _collector_policy(collector_policy) {}

   ~ClearedAllSoftRefs() {

     if (_clear_all_soft_refs) {

       _collector_policy->cleared_all_soft_refs();

     }

   }

 };

 class GenCollectorPolicy : public CollectorPolicy {

 friend class TestGenCollectorPolicy;

  protected:

   size_t _min_gen0_size;

   size_t _initial_gen0_size;

   size_t _max_gen0_size;

   // _gen_alignment and _space_alignment will have the same value most of the

   // time. When using large pages they can differ.

   size_t _gen_alignment;

   GenerationSpec **_generations;

   // Return true if an allocation should be attempted in the older

   // generation if it fails in the younger generation.  Return

   // false, otherwise.

   virtual bool should_try_older_generation_allocation(size_t word_size) const;

   void initialize_flags();

   void initialize_size_info();

   DEBUG_ONLY(void assert_flags();)

   DEBUG_ONLY(void assert_size_info();)

   // Try to allocate space by expanding the heap.

   virtual HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab);

   // Compute max heap alignment

   size_t compute_max_alignment();

  // Scale the base_size by NewRatio according to

  //     result = base_size / (NewRatio + 1)

  // and align by min_alignment()

  size_t scale_by_NewRatio_aligned(size_t base_size);

  // Bound the value by the given maximum minus the min_alignment

  size_t bound_minus_alignment(size_t desired_size, size_t maximum_size);

  public:

   GenCollectorPolicy();

   // Accessors

   size_t min_gen0_size()     { return _min_gen0_size; }

   size_t initial_gen0_size() { return _initial_gen0_size; }

   size_t max_gen0_size()     { return _max_gen0_size; }

   size_t gen_alignment()     { return _gen_alignment; }

   virtual int number_of_generations() = 0;

   virtual GenerationSpec **generations() {

     assert(_generations != NULL, "Sanity check");

     return _generations;

   }

   virtual GenCollectorPolicy* as_generation_policy() { return this; }

   virtual void initialize_generations() { };

   virtual void initialize_all() {

     CollectorPolicy::initialize_all();

     initialize_generations();

   }

   size_t young_gen_size_lower_bound();

   HeapWord* mem_allocate_work(size_t size,

                               bool is_tlab,

                               bool* gc_overhead_limit_was_exceeded);

   HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab);

   // Adaptive size policy

   virtual void initialize_size_policy(size_t init_eden_size,

                                       size_t init_promo_size,

                                       size_t init_survivor_size);

   virtual void post_heap_initialize() {

     assert(_max_gen0_size == MaxNewSize, "Should be taken care of by initialize_size_info");

   }

 };

 // All of hotspot's current collectors are subtypes of this

 // class. Currently, these collectors all use the same gen[0],

 // but have different gen[1] types. If we add another subtype

 // of CollectorPolicy, this class should be broken out into

 // its own file.

 class TwoGenerationCollectorPolicy : public GenCollectorPolicy {

  protected:

   size_t _min_gen1_size;

   size_t _initial_gen1_size;

   size_t _max_gen1_size;

   void initialize_flags();

   void initialize_size_info();

   DEBUG_ONLY(void assert_flags();)

   DEBUG_ONLY(void assert_size_info();)

  public:

   TwoGenerationCollectorPolicy() : GenCollectorPolicy(), _min_gen1_size(0),

     _initial_gen1_size(0), _max_gen1_size(0) {}

   // Accessors

   size_t min_gen1_size()     { return _min_gen1_size; }

   size_t initial_gen1_size() { return _initial_gen1_size; }

   size_t max_gen1_size()     { return _max_gen1_size; }

   // Inherited methods

   TwoGenerationCollectorPolicy* as_two_generation_policy() { return this; }

   int number_of_generations()          { return 2; }

   BarrierSet::Name barrier_set_name()  { return BarrierSet::CardTableModRef; }

   virtual CollectorPolicy::Name kind() {

     return CollectorPolicy::TwoGenerationCollectorPolicyKind;

   }

   // Returns true if gen0 sizes were adjusted

   bool adjust_gen0_sizes(size_t* gen0_size_ptr, size_t* gen1_size_ptr,

                          const size_t heap_size);

 };

 class MarkSweepPolicy : public TwoGenerationCollectorPolicy {

  protected:

   void initialize_alignments();

   void initialize_generations();

  public:

   MarkSweepPolicy() {}

   MarkSweepPolicy* as_mark_sweep_policy() { return this; }

   void initialize_gc_policy_counters();

 };

 #endif // SHARE_VM_MEMORY_COLLECTORPOLICY_HPP