src/hotspot/share/gc/parallel/parallelScavengeHeap.hpp

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
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#ifndef SHARE_VM_GC_PARALLEL_PARALLELSCAVENGEHEAP_HPP
#define SHARE_VM_GC_PARALLEL_PARALLELSCAVENGEHEAP_HPP

#include "gc/parallel/generationSizer.hpp"
#include "gc/parallel/objectStartArray.hpp"
#include "gc/parallel/psGCAdaptivePolicyCounters.hpp"
#include "gc/parallel/psOldGen.hpp"
#include "gc/parallel/psYoungGen.hpp"
#include "gc/shared/collectedHeap.hpp"
#include "gc/shared/collectorPolicy.hpp"
#include "gc/shared/gcPolicyCounters.hpp"
#include "gc/shared/gcWhen.hpp"
#include "gc/shared/strongRootsScope.hpp"
#include "memory/metaspace.hpp"
#include "utilities/ostream.hpp"

class AdjoiningGenerations;
class GCHeapSummary;
class GCTaskManager;
class PSAdaptiveSizePolicy;
class PSHeapSummary;

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

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

  GenerationSizer* _collector_policy;

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

  // The task manager
  static GCTaskManager* _gc_task_manager;

  void trace_heap(GCWhen::Type when, const GCTracer* tracer);

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

  inline bool should_alloc_in_eden(size_t size) const;
  inline void death_march_check(HeapWord* const result, size_t size);
  HeapWord* mem_allocate_old_gen(size_t size);

 public:
  ParallelScavengeHeap(GenerationSizer* policy) :
    CollectedHeap(), _collector_policy(policy), _death_march_count(0) { }

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

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

  virtual const char* name() const {
    return "Parallel";
  }

  virtual CollectorPolicy* collector_policy() const { return _collector_policy; }

  static PSYoungGen* young_gen() { return _young_gen; }
  static PSOldGen* old_gen()     { return _old_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 areas
  size_t space_alignment()      { return _collector_policy->space_alignment(); }
  size_t generation_alignment() { return _collector_policy->gen_alignment(); }

  // Return the (conservative) maximum heap alignment
  static size_t conservative_max_heap_alignment() {
    return CollectorPolicy::compute_heap_alignment();
  }

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

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

  // Return true if the reference points to an object that
  // can be moved in a partial collection.  For currently implemented
  // generational collectors that means during a collection of
  // the young gen.
  virtual bool is_scavengable(const void* addr);

  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_young(oop p);  // reserved part
  bool is_in_old(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* gc_overhead_limit_was_exceeded);

  // Allocation attempt(s) during a safepoint. It should never be called
  // to allocate a new TLAB as this allocation might be satisfied out
  // of the old generation.
  HeapWord* failed_mem_allocate(size_t size);

  // Support for System.gc()
  void collect(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();

  // Perform a full collection
  virtual void do_full_collection(bool clear_all_soft_refs);

  bool supports_inline_contig_alloc() const { return !UseNUMA; }

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

  bool supports_tlab_allocation() const { return true; }

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

  void object_iterate(ObjectClosure* cl);
  void safe_object_iterate(ObjectClosure* cl) { object_iterate(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();
  PSHeapSummary create_ps_heap_summary();
  virtual void print_on(outputStream* st) const;
  virtual void print_on_error(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(VerifyOption option /* ignored */);

  // 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 MarkScope {
   public:
    ParStrongRootsScope();
    ~ParStrongRootsScope();
  };
};

// Simple class for storing info about the heap at the start of GC, to be used
// after GC for comparison/printing.
class PreGCValues {
public:
  PreGCValues(ParallelScavengeHeap* heap) :
      _heap_used(heap->used()),
      _young_gen_used(heap->young_gen()->used_in_bytes()),
      _old_gen_used(heap->old_gen()->used_in_bytes()),
      _metadata_used(MetaspaceAux::used_bytes()) { };

  size_t heap_used() const      { return _heap_used; }
  size_t young_gen_used() const { return _young_gen_used; }
  size_t old_gen_used() const   { return _old_gen_used; }
  size_t metadata_used() const  { return _metadata_used; }

private:
  size_t _heap_used;
  size_t _young_gen_used;
  size_t _old_gen_used;
  size_t _metadata_used;
};

// Class that can be used to print information about the
// adaptive size policy at intervals specified by
// AdaptiveSizePolicyOutputInterval.  Only print information
// if an adaptive size policy is in use.
class AdaptiveSizePolicyOutput : AllStatic {
  static bool enabled() {
    return UseParallelGC &&
           UseAdaptiveSizePolicy &&
           log_is_enabled(Debug, gc, ergo);
  }
 public:
  static void print() {
    if (enabled()) {
      ParallelScavengeHeap::heap()->size_policy()->print();
    }
  }

  static void print(AdaptiveSizePolicy* size_policy, uint count) {
    bool do_print =
        enabled() &&
        (AdaptiveSizePolicyOutputInterval > 0) &&
        (count % AdaptiveSizePolicyOutputInterval) == 0;

    if (do_print) {
      size_policy->print();
    }
  }
};

#endif // SHARE_VM_GC_PARALLEL_PARALLELSCAVENGEHEAP_HPP