1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
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  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).
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  24 
  25 #ifndef SHARE_VM_GC_PARALLEL_PSPROMOTIONLAB_HPP
  26 #define SHARE_VM_GC_PARALLEL_PSPROMOTIONLAB_HPP
  27 
  28 #include "gc/parallel/objectStartArray.hpp"
  29 #include "gc/shared/collectedHeap.hpp"
  30 #include "memory/allocation.hpp"
  31 
  32 //
  33 // PSPromotionLAB is a parallel scavenge promotion lab. This class acts very
  34 // much like a MutableSpace. We couldn't embed a MutableSpace, though, as
  35 // it has a considerable number of asserts and invariants that are violated.
  36 //
  37 
  38 class ObjectStartArray;
  39 
  40 class PSPromotionLAB : public CHeapObj<mtGC> {
  41  protected:
  42   static size_t filler_header_size;
  43 
  44   enum LabState {
  45     needs_flush,
  46     flushed,
  47     zero_size
  48   };
  49 
  50   HeapWord* _top;
  51   HeapWord* _bottom;
  52   HeapWord* _end;
  53   LabState _state;
  54 
  55   void set_top(HeapWord* value)    { _top = value; }
  56   void set_bottom(HeapWord* value) { _bottom = value; }
  57   void set_end(HeapWord* value)    { _end = value; }
  58 
  59   // The shared initialize code invokes this.
  60   debug_only(virtual bool lab_is_valid(MemRegion lab) { return false; });
  61 
  62   PSPromotionLAB() : _top(NULL), _bottom(NULL), _end(NULL), _state(zero_size) { }
  63 
  64  public:
  65   // Filling and flushing.
  66   void initialize(MemRegion lab);
  67 
  68   virtual void flush();
  69 
  70   // Accessors
  71   HeapWord* bottom() const           { return _bottom; }
  72   HeapWord* end() const              { return _end;    }
  73   HeapWord* top() const              { return _top;    }
  74 
  75   bool is_flushed()                  { return _state == flushed; }
  76 
  77   bool unallocate_object(HeapWord* obj, size_t obj_size);
  78 
  79   // Returns a subregion containing all objects in this space.
  80   MemRegion used_region()            { return MemRegion(bottom(), top()); }
  81 
  82   // Boolean queries.
  83   bool is_empty() const              { return used() == 0; }
  84   bool not_empty() const             { return used() > 0; }
  85   bool contains(const void* p) const { return _bottom <= p && p < _end; }
  86 
  87   // Size computations.  Sizes are in bytes.
  88   size_t capacity() const            { return byte_size(bottom(), end()); }
  89   size_t used() const                { return byte_size(bottom(), top()); }
  90   size_t free() const                { return byte_size(top(),    end()); }
  91 };
  92 
  93 class PSYoungPromotionLAB : public PSPromotionLAB {
  94  public:
  95   PSYoungPromotionLAB() { }
  96 
  97   // Not MT safe
  98   inline HeapWord* allocate(size_t size);
  99 
 100   debug_only(virtual bool lab_is_valid(MemRegion lab);)
 101 };
 102 
 103 class PSOldPromotionLAB : public PSPromotionLAB {
 104  private:
 105   ObjectStartArray* _start_array;
 106 
 107  public:
 108   PSOldPromotionLAB() : _start_array(NULL) { }
 109   PSOldPromotionLAB(ObjectStartArray* start_array) : _start_array(start_array) { }
 110 
 111   void set_start_array(ObjectStartArray* start_array) { _start_array = start_array; }
 112 
 113   void flush();
 114 
 115   // Not MT safe
 116   HeapWord* allocate(size_t size) {
 117     // Cannot test for this now that we're doing promotion failures
 118     // assert(_state != flushed, "Sanity");
 119     assert(_start_array != NULL, "Sanity");
 120     HeapWord* obj = top();
 121     HeapWord* new_top = obj + size;
 122     // The 'new_top>obj' check is needed to detect overflow of obj+size.
 123     if (new_top > obj && new_top <= end()) {
 124       set_top(new_top);
 125       assert(is_object_aligned((intptr_t)obj) && is_object_aligned((intptr_t)new_top),
 126              "checking alignment");
 127       _start_array->allocate_block(obj);
 128       return obj;
 129     }
 130 
 131     return NULL;
 132   }
 133 
 134   debug_only(virtual bool lab_is_valid(MemRegion lab));
 135 };
 136 
 137 #endif // SHARE_VM_GC_PARALLEL_PSPROMOTIONLAB_HPP
--- EOF ---