parallelScavengeHeap.hpp

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class AdjoiningGenerations;
class GCTaskManager;
class PSAdaptiveSizePolicy;
class GenerationSizer;
class CollectorPolicy;

class ParallelScavengeHeap : public CollectedHeap {
  friend class VMStructs;
 private:
  static PSYoungGen* _young_gen;
  static PSOldGen*   _old_gen;
  static PSPermGen*  _perm_gen;

  // Sizing policy for entire heap
  static PSAdaptiveSizePolicy* _size_policy;
  static PSGCAdaptivePolicyCounters*   _gc_policy_counters;

  static ParallelScavengeHeap* _psh;

  size_t _perm_gen_alignment;
  size_t _young_gen_alignment;
  size_t _old_gen_alignment;

  GenerationSizer* _collector_policy;

  inline size_t set_alignment(size_t& var, size_t val);

  // Collection of generations that are adjacent in the
  // space reserved for the heap.
  AdjoiningGenerations* _gens;

  static GCTaskManager*          _gc_task_manager;      // The task manager.

 protected:
  static inline size_t total_invocations();
  HeapWord* allocate_new_tlab(size_t size);

 public:
  ParallelScavengeHeap() : CollectedHeap() {
    set_alignment(_perm_gen_alignment, intra_heap_alignment());
    set_alignment(_young_gen_alignment, intra_heap_alignment());
    set_alignment(_old_gen_alignment, intra_heap_alignment());
  }

  // For use by VM operations
  enum CollectionType {
    Scavenge,
    MarkSweep
  };

  ParallelScavengeHeap::Name kind() const {
    return CollectedHeap::ParallelScavengeHeap;
  }

CollectorPolicy* collector_policy() const { return (CollectorPolicy*) _collector_policy; }
  // GenerationSizer* collector_policy() const { return _collector_policy; }

  static PSYoungGen* young_gen()     { return _young_gen; }
  static PSOldGen* old_gen()         { return _old_gen; }
  static PSPermGen* perm_gen()       { return _perm_gen; }

  virtual PSAdaptiveSizePolicy* size_policy() { return _size_policy; }

  static PSGCAdaptivePolicyCounters* gc_policy_counters() { return _gc_policy_counters; }

  static ParallelScavengeHeap* heap();

  static GCTaskManager* const gc_task_manager() { return _gc_task_manager; }

  AdjoiningGenerations* gens() { return _gens; }

  // Returns JNI_OK on success
  virtual jint initialize();

  void post_initialize();
  void update_counters();
  // The alignment used for the various generations.
  size_t perm_gen_alignment()  const { return _perm_gen_alignment; }
  size_t young_gen_alignment() const { return _young_gen_alignment; }
  size_t old_gen_alignment()  const { return _old_gen_alignment; }

  // The alignment used for eden and survivors within the young gen
  // and for boundary between young gen and old gen.
  size_t intra_heap_alignment() const { return 64 * K; }

  size_t capacity() const;
  size_t used() const;

  // Return "true" if all generations (but perm) have reached the
  // maximal committed limit that they can reach, without a garbage
  // collection.
  virtual bool is_maximal_no_gc() const;

  // Does this heap support heap inspection? (+PrintClassHistogram)
  bool supports_heap_inspection() const { return true; }

  size_t permanent_capacity() const;
  size_t permanent_used() const;

  size_t max_capacity() const;

  // Whether p is in the allocated part of the heap
  bool is_in(const void* p) const;

  bool is_in_reserved(const void* p) const;
  bool is_in_permanent(const void *p) const {    // reserved part
    return perm_gen()->reserved().contains(p);
  }

  bool is_permanent(const void *p) const {    // committed part
    return perm_gen()->is_in(p);
  }

  inline bool is_in_young(oop p);        // reserved part
  inline bool is_in_old_or_perm(oop p);  // reserved part

  // Memory allocation.   "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.

  HeapWord* mem_allocate(size_t size,
                         bool is_noref,
                         bool is_tlab,
                         bool* gc_overhead_limit_was_exceeded);
  HeapWord* failed_mem_allocate(size_t size, bool is_tlab);

  HeapWord* permanent_mem_allocate(size_t size);
  HeapWord* failed_permanent_mem_allocate(size_t size);

  // Support for System.gc()
  void collect(GCCause::Cause cause);

  // This interface assumes that it's being called by the
  // vm thread. It collects the heap assuming that the
  // heap lock is already held and that we are executing in
  // the context of the vm thread.
  void collect_as_vm_thread(GCCause::Cause cause);

  // These also should be called by the vm thread at a safepoint (e.g., from a
  // VM operation).
  //
  // The first collects the young generation only, unless the scavenge fails; it
  // will then attempt a full gc.  The second collects the entire heap; if
  // maximum_compaction is true, it will compact everything and clear all soft
  // references.
  inline void invoke_scavenge();
  inline void invoke_full_gc(bool maximum_compaction);

  size_t large_typearray_limit() { return FastAllocateSizeLimit; }

  bool supports_inline_contig_alloc() const { return !UseNUMA; }

  HeapWord** top_addr() const { return !UseNUMA ? young_gen()->top_addr() : (HeapWord**)-1; }
  HeapWord** end_addr() const { return !UseNUMA ? young_gen()->end_addr() : (HeapWord**)-1; }

  void ensure_parsability(bool retire_tlabs);
  void accumulate_statistics_all_tlabs();
  void resize_all_tlabs();

  size_t unsafe_max_alloc();

  bool supports_tlab_allocation() const { return true; }

  size_t tlab_capacity(Thread* thr) const;
  size_t unsafe_max_tlab_alloc(Thread* thr) const;

  // Can a compiler initialize a new object without store barriers?
  // This permission only extends from the creation of a new object
  // via a TLAB up to the first subsequent safepoint.
  virtual bool can_elide_tlab_store_barriers() const {
    return true;
  }

  virtual bool card_mark_must_follow_store() const {
    return false;
  }

  // Return true if we don't we need a store barrier for
  // initializing stores to an object at this address.
  virtual bool can_elide_initializing_store_barrier(oop new_obj);

  // Can a compiler elide a store barrier when it writes
  // a permanent oop into the heap?  Applies when the compiler
  // is storing x to the heap, where x->is_perm() is true.
  virtual bool can_elide_permanent_oop_store_barriers() const {
    return true;
  }

  void oop_iterate(OopClosure* cl);
  void object_iterate(ObjectClosure* cl);
  void safe_object_iterate(ObjectClosure* cl) { object_iterate(cl); }
  void permanent_oop_iterate(OopClosure* cl);
  void permanent_object_iterate(ObjectClosure* cl);

  HeapWord* block_start(const void* addr) const;
  size_t block_size(const HeapWord* addr) const;
  bool block_is_obj(const HeapWord* addr) const;

  jlong millis_since_last_gc();

  void prepare_for_verify();
  void print() const;
  void print_on(outputStream* st) const;
  virtual void print_gc_threads_on(outputStream* st) const;
  virtual void gc_threads_do(ThreadClosure* tc) const;
  virtual void print_tracing_info() const;

  void verify(bool allow_dirty, bool silent, bool /* option */);

  void print_heap_change(size_t prev_used);

  // Resize the young generation.  The reserved space for the
  // generation may be expanded in preparation for the resize.
  void resize_young_gen(size_t eden_size, size_t survivor_size);

  // Resize the old generation.  The reserved space for the
  // generation may be expanded in preparation for the resize.
  void resize_old_gen(size_t desired_free_space);

  // Save the tops of the spaces in all generations
  void record_gen_tops_before_GC() PRODUCT_RETURN;

  // Mangle the unused parts of all spaces in the heap
  void gen_mangle_unused_area() PRODUCT_RETURN;

  // Call these in sequential code around the processing of strong roots.
  class ParStrongRootsScope : public MarkingCodeBlobClosure::MarkScope {
  public:
    ParStrongRootsScope();
    ~ParStrongRootsScope();
  };
};

inline size_t ParallelScavengeHeap::set_alignment(size_t& var, size_t val)
{
  assert(is_power_of_2((intptr_t)val), "must be a power of 2");
  var = round_to(val, intra_heap_alignment());
  return var;
}