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 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

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 */

// 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;

#ifndef SERIALGC

class ConcurrentMarkSweepPolicy;

class G1CollectorPolicy;

#endif // SERIALGC

class GCPolicyCounters;

class PermanentGenerationSpec;

class MarkSweepPolicy;

class CollectorPolicy : public CHeapObj {

 protected:

  PermanentGenerationSpec *_permanent_generation;

  GCPolicyCounters* _gc_policy_counters;

  // Requires that the concrete subclass sets the alignment constraints

  // before calling.

  virtual void initialize_flags();

  virtual void initialize_size_info();

  // Initialize "_permanent_generation" to a spec for the given kind of

  // Perm Gen.

  void initialize_perm_generation(PermGen::Name pgnm);

  size_t _initial_heap_byte_size;

  size_t _max_heap_byte_size;

  size_t _min_heap_byte_size;

  size_t _min_alignment;

  size_t _max_alignment;

  // 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() :

    _min_alignment(1),

    _max_alignment(1),

    _initial_heap_byte_size(0),

    _max_heap_byte_size(0),

    _min_heap_byte_size(0),

    _size_policy(NULL),

    _should_clear_all_soft_refs(false),

    _all_soft_refs_clear(false)

  {}

 public:

  void set_min_alignment(size_t align)         { _min_alignment = align; }

  size_t min_alignment()                       { return _min_alignment; }

  void set_max_alignment(size_t align)         { _max_alignment = align; }

  size_t max_alignment()                       { return _max_alignment; }

  size_t initial_heap_byte_size() { return _initial_heap_byte_size; }

  void set_initial_heap_byte_size(size_t v) { _initial_heap_byte_size = v; }

  size_t max_heap_byte_size()     { return _max_heap_byte_size; }

  void set_max_heap_byte_size(size_t v) { _max_heap_byte_size = v; }

  size_t min_heap_byte_size()     { return _min_heap_byte_size; }

  void set_min_heap_byte_size(size_t v) { _min_heap_byte_size = v; }

  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; }

#ifndef SERIALGC

  virtual ConcurrentMarkSweepPolicy*    as_concurrent_mark_sweep_policy() { return NULL; }

  virtual G1CollectorPolicy*            as_g1_policy()                    { return NULL; }

#endif // SERIALGC

  // 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; }

#ifndef SERIALGC

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

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

#else  // SERIALGC

  bool is_concurrent_mark_sweep_policy() { return false; }

  bool is_g1_policy()                    { return false; }

#endif // SERIALGC

  virtual PermanentGenerationSpec *permanent_generation() {

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

    return _permanent_generation;

  }

  virtual BarrierSet::Name barrier_set_name() = 0;

  virtual GenRemSet::Name  rem_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;

  // 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;

  }

};

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 {

 protected:

  size_t _min_gen0_size;

  size_t _initial_gen0_size;

  size_t _max_gen0_size;

  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();

  // 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 NewRation 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:

  // Accessors

  size_t min_gen0_size() { return _min_gen0_size; }

  void set_min_gen0_size(size_t v) { _min_gen0_size = v; }

  size_t initial_gen0_size() { return _initial_gen0_size; }

  void set_initial_gen0_size(size_t v) { _initial_gen0_size = v; }

  size_t max_gen0_size() { return _max_gen0_size; }

  void set_max_gen0_size(size_t v) { _max_gen0_size = v; }

  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() = 0;

  virtual void initialize_all() {

    initialize_flags();

    initialize_size_info();

    initialize_generations();

  }

  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);

  // The size that defines a "large array".

  virtual size_t large_typearray_limit();

  // Adaptive size policy

  virtual void initialize_size_policy(size_t init_eden_size,

                                      size_t init_promo_size,

                                      size_t init_survivor_size);

};

// 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();

  void initialize_generations()                { ShouldNotReachHere(); }

 public:

  // Accessors

  size_t min_gen1_size() { return _min_gen1_size; }

  void set_min_gen1_size(size_t v) { _min_gen1_size = v; }

  size_t initial_gen1_size() { return _initial_gen1_size; }

  void set_initial_gen1_size(size_t v) { _initial_gen1_size = v; }

  size_t max_gen1_size() { return _max_gen1_size; }

  void set_max_gen1_size(size_t v) { _max_gen1_size = v; }

  // Inherited methods

  TwoGenerationCollectorPolicy* as_two_generation_policy() { return this; }

  int number_of_generations()                  { return 2; }

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

  GenRemSet::Name rem_set_name()               { return GenRemSet::CardTable; }

  virtual CollectorPolicy::Name kind() {

    return CollectorPolicy::TwoGenerationCollectorPolicyKind;

  }

  // Returns true is gen0 sizes were adjusted

  bool adjust_gen0_sizes(size_t* gen0_size_ptr, size_t* gen1_size_ptr,

                               size_t heap_size, size_t min_gen1_size);

};

class MarkSweepPolicy : public TwoGenerationCollectorPolicy {

 protected:

  void initialize_generations();

 public:

  MarkSweepPolicy();

  MarkSweepPolicy* as_mark_sweep_policy() { return this; }

  void initialize_gc_policy_counters();

};