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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * 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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#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1ALLOCATOR_HPP
#define SHARE_VM_GC_IMPLEMENTATION_G1_G1ALLOCATOR_HPP

#include "gc_implementation/g1/g1AllocationContext.hpp"
#include "gc_implementation/g1/g1AllocRegion.hpp"
#include "gc_implementation/g1/g1InCSetState.hpp"
#include "gc_implementation/shared/parGCAllocBuffer.hpp"

// Interface to keep track of which regions G1 is currently allocating into and
// allowing access to it (e.g. allocating into them, or getting their occupancy).
// Also keeps track of retained regions across GCs.
class G1Allocator : public CHeapObj<mtGC> {
  friend class VMStructs;
 protected:
  G1CollectedHeap* _g1h;

  virtual MutatorAllocRegion*    mutator_alloc_region(AllocationContext_t context) = 0;
  virtual SurvivorGCAllocRegion* survivor_gc_alloc_region(AllocationContext_t context) = 0;
  virtual OldGCAllocRegion*      old_gc_alloc_region(AllocationContext_t context) = 0;

  // Allocation attempt during GC for a survivor object / PLAB.
  inline HeapWord* survivor_attempt_allocation(size_t min_word_size,
                                               size_t& word_size,
                                               AllocationContext_t context);

  // Allocation attempt during GC for an old object / PLAB.
  inline HeapWord* old_attempt_allocation(size_t min_word_size,
                                          size_t& word_size,
                                          AllocationContext_t context);

  void reuse_retained_old_region(EvacuationInfo& evacuation_info,
                                 OldGCAllocRegion* old,
                                 HeapRegion** retained);

 public:
  G1Allocator(G1CollectedHeap* heap) : _g1h(heap) { }

  static G1Allocator* create_allocator(G1CollectedHeap* g1h);

  virtual void init_mutator_alloc_region() = 0;
  virtual void release_mutator_alloc_region() = 0;

  virtual void init_gc_alloc_regions(EvacuationInfo& evacuation_info) = 0;
  virtual void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) = 0;
  virtual void abandon_gc_alloc_regions() = 0;

  size_t desired_plab_size(InCSetState dest);
  virtual G1EvacStats* evac_stats(InCSetState dest) = 0;

  // Allocate blocks during garbage collection. Will ensure an allocation region
  // is available, either by picking one or getting a new one from the heap,
  // and then allocate a block of the given size. The block may not be a humongous -
  // it must fit into a single heap region.
  HeapWord* par_allocate_during_gc(InCSetState dest,
                                   size_t min_word_size,
                                   size_t& word_size,
                                   AllocationContext_t context);

  HeapWord* par_allocate_during_gc(InCSetState dest, size_t word_size, AllocationContext_t context) {
    return par_allocate_during_gc(dest, word_size, word_size, context);
  }

  HeapWord* par_allocate_during_mutator(size_t word_size, bool bot_updates, AllocationContext_t context) {
    return mutator_alloc_region(context)->attempt_allocation(word_size, bot_updates);
  }

  HeapWord* par_allocate_during_mutator_locked(size_t word_size, bool bot_updates, AllocationContext_t context) {
    return mutator_alloc_region(context)->attempt_allocation_locked(word_size, bot_updates);
  }

  HeapWord* par_allocate_during_mutator_force(size_t word_size, bool bot_updates, AllocationContext_t context) {
    return mutator_alloc_region(context)->attempt_allocation_force(word_size, bot_updates);
  }

  size_t unsafe_max_tlab_alloc();

  virtual bool is_retained_old_region(HeapRegion* hr) = 0;

  // Returns the amount of memory that is in use by the managed allocation regions.
  virtual size_t used_in_alloc_regions() const = 0;
};

// The default allocation region manager for G1. Provides a single mutator, survivor
// and old generation allocation region.
// Can retain the old generation allocation region across GCs.
class G1DefaultAllocator : public G1Allocator {
 private:
  // PLAB sizing policy for survivors.
  G1EvacStats _survivor_plab_stats;
  // PLAB sizing policy for tenured objects.
  G1EvacStats _old_plab_stats;

 protected:
  // Alloc region used to satisfy mutator allocation requests.
  MutatorAllocRegion _mutator_alloc_region;

  // Alloc region used to satisfy allocation requests by the GC for
  // survivor objects.
  SurvivorGCAllocRegion _survivor_gc_alloc_region;

  // Alloc region used to satisfy allocation requests by the GC for
  // old objects.
  OldGCAllocRegion _old_gc_alloc_region;

  HeapRegion* _retained_old_gc_alloc_region;

  G1EvacStats* evac_stats(InCSetState dest);

  virtual MutatorAllocRegion* mutator_alloc_region(AllocationContext_t context) {
    return &_mutator_alloc_region;
  }

  virtual SurvivorGCAllocRegion* survivor_gc_alloc_region(AllocationContext_t context) {
    return &_survivor_gc_alloc_region;
  }

  virtual OldGCAllocRegion* old_gc_alloc_region(AllocationContext_t context) {
    return &_old_gc_alloc_region;
  }

 public:
  G1DefaultAllocator(G1CollectedHeap* heap);

  virtual void init_mutator_alloc_region();
  virtual void release_mutator_alloc_region();

  virtual void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
  virtual void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info);
  virtual void abandon_gc_alloc_regions();

  virtual bool is_retained_old_region(HeapRegion* hr) {
    return _retained_old_gc_alloc_region == hr;
  }

  virtual size_t used_in_alloc_regions() const {
    assert(Heap_lock->owner() != NULL,
           "Should be owned on this thread's behalf.");
    size_t result = 0;

    // Read only once in case it is set to NULL concurrently
    HeapRegion* hr = _mutator_alloc_region.get();
    if (hr != NULL) {
      result += hr->used();
    }
    return result;
  }
};

// A PLAB used during garbage collection that is specific to G1.
class G1PLAB: public ParGCAllocBuffer {
 private:
  bool _retired;

 public:
  G1PLAB(size_t gclab_word_size);
  virtual ~G1PLAB() {
    guarantee(_retired, "Allocation buffer has not been retired");
  }

  // The amount of space in words wasted within the PLAB including
  // waste due to refills and alignment.
  size_t wasted() const { return _wasted; }

  virtual void set_buf(HeapWord* buf) {
    ParGCAllocBuffer::set_buf(buf);
    _retired = false;
  }

  virtual void retire() {
    if (_retired) {
      return;
    }
    ParGCAllocBuffer::retire();
    _retired = true;
  }
};

// Manages the PLABs used during garbage collection. Interface for allocation from PLABs.
// Needs to handle multiple contexts, extra alignment in any "survivor" area and some
// statistics.
class PLABAllocator : public CHeapObj<mtGC> {
  friend class G1ParScanThreadState;
 protected:
  G1Allocator* _allocator;

  // The survivor alignment in effect in bytes.
  // == 0 : don't align survivors
  // != 0 : align survivors to that alignment
  // These values were chosen to favor the non-alignment case since some
  // architectures have a special compare against zero instructions.
  const uint _survivor_alignment_bytes;

  size_t _undo_waste[InCSetState::Num];
  size_t _inline_allocated[InCSetState::Num];

  virtual void flush_stats_and_retire() = 0;
  virtual G1PLAB* alloc_buffer(InCSetState dest, AllocationContext_t context) = 0;

  // Calculate the survivor space object alignment in bytes. Returns that or 0 if
  // there are no restrictions on survivor alignment.
  static uint calc_survivor_alignment_bytes() {
    assert(SurvivorAlignmentInBytes >= ObjectAlignmentInBytes, "sanity");
    if (SurvivorAlignmentInBytes == ObjectAlignmentInBytes) {
      // No need to align objects in the survivors differently, return 0
      // which means "survivor alignment is not used".
      return 0;
    } else {
      assert(SurvivorAlignmentInBytes > 0, "sanity");
      return SurvivorAlignmentInBytes;
    }
  }

 public:
  PLABAllocator(G1Allocator* heap_manager) :
    _allocator(heap_manager), _survivor_alignment_bytes(calc_survivor_alignment_bytes()) {
    for (size_t i = 0; i < ARRAY_SIZE(_inline_allocated); i++) {
      _inline_allocated[i] = 0;
    }
    for (size_t i = 0; i < ARRAY_SIZE(_undo_waste); i++) {
      _undo_waste[i] = 0;
    }
  }

  static PLABAllocator* create_allocator(G1Allocator* allocator);

  // Returns the number of words allocated inline for the given state so far.
  size_t inline_allocated(InCSetState value) const { return _inline_allocated[value.value()]; }
  // Returns the number of words wasted due to und for the given state so far.
  size_t lab_undo_waste(InCSetState value) const { return _undo_waste[value.value()]; }
  // Returns the number of words wasted due to alignment or LAB refills.
  virtual size_t lab_waste(InCSetState value) const = 0;

  // Allocate word_sz words in dest, either directly into the regions or by
  // allocating a new PLAB. Returns the address of the allocated memory, NULL if
  // not successful.
  HeapWord* allocate_direct_or_new_plab(InCSetState dest,
                                        size_t word_sz,
                                        AllocationContext_t context);

  // Allocate word_sz words in the PLAB of dest.  Returns the address of the
  // allocated memory, NULL if not successful.
  HeapWord* plab_allocate(InCSetState dest,
                          size_t word_sz,
                          AllocationContext_t context) {
    G1PLAB* buffer = alloc_buffer(dest, context);
    if (_survivor_alignment_bytes == 0) {
      return buffer->allocate(word_sz);
    } else {
      return buffer->allocate_aligned(word_sz, _survivor_alignment_bytes);
    }
  }

  HeapWord* allocate(InCSetState dest, size_t word_sz,
                     AllocationContext_t context) {
    HeapWord* const obj = plab_allocate(dest, word_sz, context);
    if (obj != NULL) {
      return obj;
    }
    return allocate_direct_or_new_plab(dest, word_sz, context);
  }

  void undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz, AllocationContext_t context);
};

// The default PLAB allocator for G1. Keeps the current (single) PLAB for survivor
// and old generation allocation.
class DefaultPLABAllocator : public PLABAllocator {
  G1PLAB  _surviving_alloc_buffer;
  G1PLAB  _tenured_alloc_buffer;
  G1PLAB* _alloc_buffers[InCSetState::Num];

 public:
  DefaultPLABAllocator(G1Allocator* allocator);

  virtual G1PLAB* alloc_buffer(InCSetState dest, AllocationContext_t context) {
    assert(dest.is_valid(),
           err_msg("Allocation buffer index out-of-bounds: " CSETSTATE_FORMAT, dest.value()));
    assert(_alloc_buffers[dest.value()] != NULL,
           err_msg("Allocation buffer is NULL: " CSETSTATE_FORMAT, dest.value()));
    return _alloc_buffers[dest.value()];
  }

  virtual size_t lab_waste(InCSetState value) const;

  virtual void flush_stats_and_retire() ;
};

#endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1ALLOCATOR_HPP