43 //      ========= <--- low_boundary for H, high_boundary for L
  44 //      |       |
  45 //      |       |
  46 //      |       |
  47 //      --------- <--- high for L
  48 //      |       |
  49 //      |   L   |
  50 //      |       |
  51 //      |       |
  52 //      |       |
  53 //      +-------+ <--- low_boundary for L
  54 //
  55 // Each virtual space in the AdjoiningVirtualSpaces grows and shrink
  56 // within its reserved region (between the low_boundary and the
  57 // boundary) independently.  If L want to grow above its high_boundary,
  58 // then the high_boundary of L and the low_boundary of H must be
  59 // moved up consistently.  AdjoiningVirtualSpaces provide the
  60 // interfaces for moving the this boundary.
  61 
  62 class AdjoiningVirtualSpaces : public CHeapObj<mtGC> {

  63   // space at the high end and the low end, respectively
  64   PSVirtualSpace*    _high;
  65   PSVirtualSpace*    _low;
  66 
  67 protected:
  68   // The reserved space spanned by the two spaces.
  69   ReservedSpace      _reserved_space;
  70 
  71   // The minimum byte size for the low space.  It will not
  72   // be shrunk below this value.
  73   size_t _min_low_byte_size;
  74   // Same for the high space
  75   size_t _min_high_byte_size;
  76 
  77   const size_t _alignment;
  78 
  79  public:
  80   // Allocates two virtual spaces that will be located at the
  81   // high and low ends.  Does no initialization.
  82   AdjoiningVirtualSpaces(ReservedSpace rs,
  83                          size_t min_low_byte_size,
  84                          size_t min_high_byte_size,
  85                          size_t alignment);
  86 
  87   // accessors

  91   size_t min_low_byte_size() { return _min_low_byte_size; }
  92   size_t min_high_byte_size() { return _min_high_byte_size; }
  93   size_t alignment() const { return _alignment; }
  94 
  95   // move boundary between the two spaces up
  96   virtual bool adjust_boundary_up(size_t size_in_bytes);
  97   // and down
  98   virtual bool adjust_boundary_down(size_t size_in_bytes);
  99 
 100   // Maximum byte size for the high space.
 101   size_t high_byte_size_limit() {
 102     return _reserved_space.size() - _min_low_byte_size;
 103   }
 104   // Maximum byte size for the low space.
 105   size_t low_byte_size_limit() {
 106     return _reserved_space.size() - _min_high_byte_size;
 107   }
 108 
 109   // Sets the boundaries for the virtual spaces and commits and
 110   // initial size;
 111   void initialize(size_t max_low_byte_size,
 112                   size_t init_low_byte_size,
 113                   size_t init_high_byte_size);
 114 };
 115 #endif // SHARE_VM_GC_PARALLEL_ADJOININGVIRTUALSPACES_HPP

  43 //      ========= <--- low_boundary for H, high_boundary for L
  44 //      |       |
  45 //      |       |
  46 //      |       |
  47 //      --------- <--- high for L
  48 //      |       |
  49 //      |   L   |
  50 //      |       |
  51 //      |       |
  52 //      |       |
  53 //      +-------+ <--- low_boundary for L
  54 //
  55 // Each virtual space in the AdjoiningVirtualSpaces grows and shrink
  56 // within its reserved region (between the low_boundary and the
  57 // boundary) independently.  If L want to grow above its high_boundary,
  58 // then the high_boundary of L and the low_boundary of H must be
  59 // moved up consistently.  AdjoiningVirtualSpaces provide the
  60 // interfaces for moving the this boundary.
  61 
  62 class AdjoiningVirtualSpaces : public CHeapObj<mtGC> {
  63 protected:
  64   // space at the high end and the low end, respectively
  65   PSVirtualSpace*    _high;
  66   PSVirtualSpace*    _low;
  67 

  68   // The reserved space spanned by the two spaces.
  69   ReservedSpace      _reserved_space;
  70 
  71   // The minimum byte size for the low space.  It will not
  72   // be shrunk below this value.
  73   size_t _min_low_byte_size;
  74   // Same for the high space
  75   size_t _min_high_byte_size;
  76 
  77   const size_t _alignment;
  78 
  79  public:
  80   // Allocates two virtual spaces that will be located at the
  81   // high and low ends.  Does no initialization.
  82   AdjoiningVirtualSpaces(ReservedSpace rs,
  83                          size_t min_low_byte_size,
  84                          size_t min_high_byte_size,
  85                          size_t alignment);
  86 
  87   // accessors

  91   size_t min_low_byte_size() { return _min_low_byte_size; }
  92   size_t min_high_byte_size() { return _min_high_byte_size; }
  93   size_t alignment() const { return _alignment; }
  94 
  95   // move boundary between the two spaces up
  96   virtual bool adjust_boundary_up(size_t size_in_bytes);
  97   // and down
  98   virtual bool adjust_boundary_down(size_t size_in_bytes);
  99 
 100   // Maximum byte size for the high space.
 101   size_t high_byte_size_limit() {
 102     return _reserved_space.size() - _min_low_byte_size;
 103   }
 104   // Maximum byte size for the low space.
 105   size_t low_byte_size_limit() {
 106     return _reserved_space.size() - _min_high_byte_size;
 107   }
 108 
 109   // Sets the boundaries for the virtual spaces and commits and
 110   // initial size;
 111   virtual void initialize(size_t max_low_byte_size,
 112                   size_t init_low_byte_size,
 113                   size_t init_high_byte_size);
 114 };
 115 #endif // SHARE_VM_GC_PARALLEL_ADJOININGVIRTUALSPACES_HPP