1 /*
   2  * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_GC_SHARED_MEM_ALLOCATOR_HPP
  26 #define SHARE_GC_SHARED_MEM_ALLOCATOR_HPP
  27 
  28 #include "gc/shared/collectedHeap.hpp"
  29 #include "memory/memRegion.hpp"
  30 #include "oops/oopsHierarchy.hpp"
  31 #include "utilities/exceptions.hpp"
  32 #include "utilities/macros.hpp"
  33 
  34 // These fascilities are used for allocating, and initializing newly allocated objects.
  35 
  36 class MemAllocator: StackObj {
  37 protected:
  38   class Allocation;
  39 
  40   CollectedHeap* const _heap;
  41   Thread* const        _thread;
  42   Klass* const         _klass;
  43   const size_t         _word_size;
  44 
  45 private:
  46   // Allocate from the current thread's TLAB, with broken-out slow path.
  47   HeapWord* allocate_inside_tlab(Allocation& allocation) const;
  48   HeapWord* allocate_inside_tlab_slow(Allocation& allocation) const;
  49   HeapWord* allocate_outside_tlab(Allocation& allocation) const;
  50 
  51 protected:
  52   MemAllocator(Klass* klass, size_t word_size, Thread* thread)
  53     : _heap(Universe::heap()),
  54       _thread(thread),
  55       _klass(klass),
  56       _word_size(word_size)
  57   { }
  58 
  59   // This function clears the memory of the object
  60   void mem_clear(HeapWord* mem) const;
  61   // This finish constructing an oop by installing the mark word and the Klass* pointer
  62   // last. At the point when the Klass pointer is initialized, this is a constructed object
  63   // that must be parseable as an oop by concurrent collectors.
  64   oop finish(HeapWord* mem) const;
  65 
  66   // Raw memory allocation. This may or may not use TLAB allocations to satisfy the
  67   // allocation. A GC implementation may override this function to satisfy the allocation
  68   // in any way. But the default is to try a TLAB allocation, and otherwise perform
  69   // mem_allocate.
  70   virtual HeapWord* mem_allocate(Allocation& allocation) const;
  71 
  72   virtual MemRegion obj_memory_range(oop obj) const {
  73     return MemRegion((HeapWord*)obj, _word_size);
  74   }
  75 
  76 public:
  77   oop allocate() const;
  78   virtual oop initialize(HeapWord* mem) const = 0;
  79 };
  80 
  81 class ObjAllocator: public MemAllocator {
  82 public:
  83   ObjAllocator(Klass* klass, size_t word_size, Thread* thread = Thread::current())
  84     : MemAllocator(klass, word_size, thread) {}
  85   virtual oop initialize(HeapWord* mem) const;
  86 };
  87 
  88 class ObjArrayAllocator: public MemAllocator {
  89   const int  _length;
  90   const bool _do_zero;
  91 protected:
  92   virtual MemRegion obj_memory_range(oop obj) const;
  93 
  94 public:
  95   ObjArrayAllocator(Klass* klass, size_t word_size, int length, bool do_zero,
  96                     Thread* thread = Thread::current())
  97     : MemAllocator(klass, word_size, thread),
  98       _length(length),
  99       _do_zero(do_zero) {}
 100   virtual oop initialize(HeapWord* mem) const;
 101 };
 102 
 103 class ClassAllocator: public MemAllocator {
 104 public:
 105   ClassAllocator(Klass* klass, size_t word_size, Thread* thread = Thread::current())
 106     : MemAllocator(klass, word_size, thread) {}
 107   virtual oop initialize(HeapWord* mem) const;
 108 };
 109 
 110 #endif // SHARE_GC_SHARED_MEM_ALLOCATOR_HPP