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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  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  *
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 19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 24 
 25 #ifndef SHARE_GC_PARALLEL_MUTABLESPACE_HPP
 26 #define SHARE_GC_PARALLEL_MUTABLESPACE_HPP
 27 
 28 #include "memory/allocation.hpp"
 29 #include "memory/iterator.hpp"
 30 #include "memory/memRegion.hpp"
 31 #include "utilities/copy.hpp"
 32 #include "utilities/globalDefinitions.hpp"
 33 #include "utilities/macros.hpp"
 34 
 35 class WorkGang;
 36 
 37 // A MutableSpace supports the concept of allocation. This includes the
 38 // concepts that a space may be only partially full, and the query methods
 39 // that go with such an assumption.
 40 //
 41 // MutableSpace is also responsible for minimizing the
 42 // page allocation time by having the memory pretouched (with
 43 // AlwaysPretouch) and for optimizing page placement on NUMA systems
 44 // by make the underlying region interleaved (with UseNUMA).
 45 //
 46 // Invariant: bottom() <= top() <= end()
 47 // top() and end() are exclusive.
 48 
 49 class MutableSpaceMangler;
 50 
 51 class MutableSpace: public CHeapObj<mtGC> {
 52   friend class VMStructs;
 53 
 54   // Helper for mangling unused space in debug builds
 55   MutableSpaceMangler* _mangler;
 56   // The last region which page had been setup to be interleaved.
 57   MemRegion _last_setup_region;
 58   size_t _alignment;
 59   HeapWord* _bottom;
 60   HeapWord* volatile _top;
 61   HeapWord* _end;
 62 
 63   MutableSpaceMangler* mangler() { return _mangler; }
 64 
 65   void numa_setup_pages(MemRegion mr, bool clear_space);
 66 
 67   void set_last_setup_region(MemRegion mr) { _last_setup_region = mr;   }
 68   MemRegion last_setup_region() const      { return _last_setup_region; }
 69 
 70   template<bool COMPACT_HEADERS>
 71   void object_iterate_impl(ObjectClosure* cl);
 72 
 73  public:
 74   virtual ~MutableSpace();
 75   MutableSpace(size_t page_size);
 76 
 77   // Accessors
 78   HeapWord* bottom() const                 { return _bottom; }
 79   HeapWord* top() const                    { return _top;    }
 80   HeapWord* end() const                    { return _end; }
 81 
 82   void set_bottom(HeapWord* value)         { _bottom = value; }
 83   virtual void set_top(HeapWord* value)    { _top = value;   }
 84   void set_end(HeapWord* value)            { _end = value; }
 85 
 86   HeapWord* volatile* top_addr()           { return &_top; }
 87   HeapWord** end_addr()                    { return &_end; }
 88 
 89   size_t alignment()                       { return _alignment; }
 90 
 91   MemRegion region() const { return MemRegion(bottom(), end()); }
 92 
 93   size_t capacity_in_bytes() const { return capacity_in_words() * HeapWordSize; }
 94   size_t capacity_in_words() const { return pointer_delta(end(), bottom()); }
 95   virtual size_t capacity_in_words(Thread*) const { return capacity_in_words(); }
 96 
 97   // Returns a subregion containing all objects in this space.
 98   MemRegion used_region() { return MemRegion(bottom(), top()); }
 99 
100   static const bool SetupPages = true;
101   static const bool DontSetupPages = false;
102 
103   // Initialization
104   virtual void initialize(MemRegion mr,
105                           bool clear_space,
106                           bool mangle_space,
107                           bool setup_pages = SetupPages,
108                           WorkGang* pretouch_gang = NULL);
109 
110   virtual void clear(bool mangle_space);
111   virtual void update() { }
112   virtual void accumulate_statistics() { }
113 
114   // Methods used in mangling.  See descriptions under SpaceMangler.
115   virtual void mangle_unused_area() PRODUCT_RETURN;
116   virtual void mangle_unused_area_complete() PRODUCT_RETURN;
117   virtual void check_mangled_unused_area(HeapWord* limit) PRODUCT_RETURN;
118   virtual void check_mangled_unused_area_complete() PRODUCT_RETURN;
119   virtual void set_top_for_allocations(HeapWord* v) PRODUCT_RETURN;
120 
121   // Used to save the space's current top for later use during mangling.
122   virtual void set_top_for_allocations() PRODUCT_RETURN;
123 
124   virtual void ensure_parsability() { }
125 
126   virtual void mangle_region(MemRegion mr) PRODUCT_RETURN;
127 
128   // Boolean queries.
129   bool is_empty() const              { return used_in_words() == 0; }
130   bool not_empty() const             { return used_in_words() > 0; }
131   bool contains(const void* p) const { return _bottom <= p && p < _end; }
132 
133   // Size computations.  Sizes are in bytes.
134   size_t used_in_bytes() const                { return used_in_words() * HeapWordSize; }
135   size_t free_in_bytes() const                { return free_in_words() * HeapWordSize; }
136 
137   // Size computations.  Sizes are in heapwords.
138   virtual size_t used_in_words() const                    { return pointer_delta(top(), bottom()); }
139   virtual size_t free_in_words() const                    { return pointer_delta(end(),    top()); }
140   virtual size_t tlab_capacity(Thread* thr) const         { return capacity_in_bytes();            }
141   virtual size_t tlab_used(Thread* thr) const             { return used_in_bytes();                }
142   virtual size_t unsafe_max_tlab_alloc(Thread* thr) const { return free_in_bytes();                }
143 
144   // Allocation (return NULL if full)
145   virtual HeapWord* cas_allocate(size_t word_size);
146   // Optional deallocation. Used in NUMA-allocator.
147   bool cas_deallocate(HeapWord *obj, size_t size);
148   // Return true if this space needs to be expanded in order to satisfy an
149   // allocation request of the indicated size.  Concurrent allocations and
150   // resizes may change the result of a later call.  Used by oldgen allocator.
151   // precondition: holding ExpandHeap_lock
152   bool needs_expand(size_t word_size) const;
153 
154   // Iteration.
155   void oop_iterate(OopIterateClosure* cl);
156   void object_iterate(ObjectClosure* cl);
157 
158   // Debugging
159   virtual void print() const;
160   virtual void print_on(outputStream* st) const;
161   virtual void print_short() const;
162   virtual void print_short_on(outputStream* st) const;
163   virtual void verify();
164 };
165 
166 #endif // SHARE_GC_PARALLEL_MUTABLESPACE_HPP