/*

 * Copyright (c) 2014, 2015, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * 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.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * 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_G1_G1ALLOCATOR_HPP

#define SHARE_VM_GC_G1_G1ALLOCATOR_HPP

#include "gc/g1/g1AllocRegion.hpp"

#include "gc/g1/g1AllocationContext.hpp"

#include "gc/g1/g1InCSetState.hpp"

#include "gc/shared/collectedHeap.hpp"

#include "gc/shared/plab.hpp"

class EvacuationInfo;

// Interface to keep track of which regions G1 is currently allocating into. Provides

// some accessors (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;

  // Accessors to the allocation regions.

  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 desired_word_size,

                                               size_t* actual_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 desired_word_size,

                                          size_t* actual_word_size,

                                          AllocationContext_t context);

public:

  virtual ~G1Allocator() { }

  static G1Allocator* create_allocator(G1CollectedHeap* g1h);

#ifdef ASSERT

  // Do we currently have an active mutator region to allocate into?

  bool has_mutator_alloc_region(AllocationContext_t context) { return mutator_alloc_region(context)->get() != NULL; }

#endif

  virtual void init_mutator_alloc_region() = 0;

  virtual void release_mutator_alloc_region() = 0;

  virtual void release_gc_alloc_regions(EvacuationInfo& evacuation_info) = 0;

  virtual void abandon_gc_alloc_regions() = 0;

  // Management of retained regions.

  virtual bool is_retained_old_region(HeapRegion* hr) = 0;

  void reuse_retained_old_region(EvacuationInfo& evacuation_info,

                                 OldGCAllocRegion* old,

                                 HeapRegion** retained);

  // Allocate blocks of memory during mutator time.

  inline HeapWord* attempt_allocation(size_t word_size, AllocationContext_t context);

  inline HeapWord* attempt_allocation_locked(size_t word_size, AllocationContext_t context);

  inline HeapWord* attempt_allocation_force(size_t word_size, AllocationContext_t context);

  size_t unsafe_max_tlab_alloc(AllocationContext_t context);

  // Allocate blocks of memory during garbage collection. Will ensure an

  // allocation region, either by picking one or expanding 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 word_size,

                                   AllocationContext_t context);

  HeapWord* par_allocate_during_gc(InCSetState dest,

                                   size_t min_word_size,

                                   size_t desired_word_size,

                                   size_t* actual_word_size,

                                   AllocationContext_t context);

  virtual size_t used_in_alloc_regions() = 0;

};

// The default allocation region manager for G1. Provides a single mutator, survivor

// and old generation allocation region.

// Can retain the (single) old generation allocation region across GCs.

class G1DefaultAllocator : public G1Allocator {

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;

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(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 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;

  }

  virtual size_t used_in_alloc_regions() {

    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(AllocationContext::current())->get();

    if (hr != NULL) {

      result += hr->used();

    }

    return result;

  }

};

class G1PLAB: public PLAB {

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, size_t word_size) {

    PLAB::set_buf(buf, word_size);

    _retired = false;

  }

  virtual void retire() {

    if (_retired) {

      return;

    }

    PLAB::retire();

    _retired = true;

  }

  virtual void flush_and_retire_stats(PLABStats* stats) {

    PLAB::flush_and_retire_stats(stats);

    _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 G1PLABAllocator : public CHeapObj<mtGC> {

  friend class G1ParScanThreadState;

protected:

  G1CollectedHeap* _g1h;

  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;

  // Number of words allocated directly (not counting PLAB allocation).

  size_t _direct_allocated[InCSetState::Num];

  virtual void flush_and_retire_stats() = 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;

    }

  }

  HeapWord* allocate_new_plab(InCSetState dest,

                              size_t word_sz,

                              AllocationContext_t context);

  bool may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const;

public:

  G1PLABAllocator(G1Allocator* allocator);

  virtual ~G1PLABAllocator() { }

  static G1PLABAllocator* create_allocator(G1Allocator* allocator);

  virtual void waste(size_t& wasted, size_t& undo_wasted) = 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. Plab_refill_failed indicates whether an attempt to refill the

  // PLAB failed or not.

  HeapWord* allocate_direct_or_new_plab(InCSetState dest,

                                        size_t word_sz,

                                        AllocationContext_t context,

                                        bool* plab_refill_failed);

  // Allocate word_sz words in the PLAB of dest.  Returns the address of the

  // allocated memory, NULL if not successful.

  inline HeapWord* plab_allocate(InCSetState dest,

                                 size_t word_sz,

                                 AllocationContext_t context);

  HeapWord* allocate(InCSetState dest,

                     size_t word_sz,

                     AllocationContext_t context,

                     bool* refill_failed) {

    HeapWord* const obj = plab_allocate(dest, word_sz, context);

    if (obj != NULL) {

      return obj;

    }

    return allocate_direct_or_new_plab(dest, word_sz, context, refill_failed);

  }

  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 G1DefaultPLABAllocator : public G1PLABAllocator {

  G1PLAB  _surviving_alloc_buffer;

  G1PLAB  _tenured_alloc_buffer;

  G1PLAB* _alloc_buffers[InCSetState::Num];

public:

  G1DefaultPLABAllocator(G1Allocator* _allocator);

  virtual G1PLAB* alloc_buffer(InCSetState dest, AllocationContext_t context) {

    assert(dest.is_valid(),

           "Allocation buffer index out-of-bounds: " CSETSTATE_FORMAT, dest.value());

    assert(_alloc_buffers[dest.value()] != NULL,

           "Allocation buffer is NULL: " CSETSTATE_FORMAT, dest.value());

    return _alloc_buffers[dest.value()];

  }

  virtual void flush_and_retire_stats();

  virtual void waste(size_t& wasted, size_t& undo_wasted);

};

// G1ArchiveAllocator is used to allocate memory in archive

// regions. Such regions are not modifiable by GC, being neither

// scavenged nor compacted, or even marked in the object header.

// They can contain no pointers to non-archive heap regions,

class G1ArchiveAllocator : public CHeapObj<mtGC> {

protected:

  G1CollectedHeap* _g1h;

  // The current allocation region

  HeapRegion* _allocation_region;

  // Regions allocated for the current archive range.

  GrowableArray<HeapRegion*> _allocated_regions;

  // The number of bytes used in the current range.

  size_t _summary_bytes_used;

  // Current allocation window within the current region.

  HeapWord* _bottom;

  HeapWord* _top;

  HeapWord* _max;

  // Allocate a new region for this archive allocator.

  // Allocation is from the top of the reserved heap downward.

  bool alloc_new_region();

public:

  G1ArchiveAllocator(G1CollectedHeap* g1h) :

    _g1h(g1h),

    _allocation_region(NULL),

    _allocated_regions((ResourceObj::set_allocation_type((address) &_allocated_regions,

                                                         ResourceObj::C_HEAP),

                        2), true /* C_Heap */),

    _summary_bytes_used(0),

    _bottom(NULL),

    _top(NULL),

    _max(NULL) { }

  virtual ~G1ArchiveAllocator() {

    assert(_allocation_region == NULL, "_allocation_region not NULL");

  }

  static G1ArchiveAllocator* create_allocator(G1CollectedHeap* g1h);

  // Allocate memory for an individual object.

  HeapWord* archive_mem_allocate(size_t word_size);

  // Return the memory ranges used in the current archive, after

  // aligning to the requested alignment.

  void complete_archive(GrowableArray<MemRegion>* ranges,

                        size_t end_alignment_in_bytes);

  // The number of bytes allocated by this allocator.

  size_t used() {

    return _summary_bytes_used;

  }

  // Clear the count of bytes allocated in prior G1 regions. This

  // must be done when recalculate_use is used to reset the counter

  // for the generic allocator, since it counts bytes in all G1

  // regions, including those still associated with this allocator.

  void clear_used() {

    _summary_bytes_used = 0;

  }

};

#endif // SHARE_VM_GC_G1_G1ALLOCATOR_HPP