heap.hpp revision 7081:39231c6e51fe 
1/*
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24
25#ifndef SHARE_VM_MEMORY_HEAP_HPP
26#define SHARE_VM_MEMORY_HEAP_HPP
27
28#include "code/codeBlob.hpp"
29#include "memory/allocation.hpp"
30#include "runtime/virtualspace.hpp"
31
32// Blocks
33
34class HeapBlock VALUE_OBJ_CLASS_SPEC {
35  friend class VMStructs;
36
37 public:
38  struct Header {
39    size_t  _length;                             // the length in segments
40    bool    _used;                               // Used bit
41  };
42
43 protected:
44  union {
45    Header _header;
46    int64_t _padding[ (sizeof(Header) + sizeof(int64_t)-1) / sizeof(int64_t) ];
47                        // pad to 0 mod 8
48  };
49
50 public:
51  // Initialization
52  void initialize(size_t length)                 { _header._length = length; set_used(); }
53
54  // Accessors
55  void* allocated_space() const                  { return (void*)(this + 1); }
56  size_t length() const                          { return _header._length; }
57
58  // Used/free
59  void set_used()                                { _header._used = true; }
60  void set_free()                                { _header._used = false; }
61  bool free()                                    { return !_header._used; }
62};
63
64class FreeBlock: public HeapBlock {
65  friend class VMStructs;
66 protected:
67  FreeBlock* _link;
68
69 public:
70  // Initialization
71  void initialize(size_t length)             { HeapBlock::initialize(length); _link= NULL; }
72
73  // Merging
74  void set_length(size_t l)                  { _header._length = l; }
75
76  // Accessors
77  FreeBlock* link() const                    { return _link; }
78  void set_link(FreeBlock* link)             { _link = link; }
79};
80
81class CodeHeap : public CHeapObj<mtCode> {
82  friend class VMStructs;
83 private:
84  VirtualSpace _memory;                          // the memory holding the blocks
85  VirtualSpace _segmap;                          // the memory holding the segment map
86
87  size_t       _number_of_committed_segments;
88  size_t       _number_of_reserved_segments;
89  size_t       _segment_size;
90  int          _log2_segment_size;
91
92  size_t       _next_segment;
93
94  FreeBlock*   _freelist;
95  size_t       _freelist_segments;               // No. of segments in freelist
96  int          _freelist_length;
97  size_t       _max_allocated_capacity;          // Peak capacity that was allocated during lifetime of the heap
98
99  const char*  _name;                            // Name of the CodeHeap
100  const int    _code_blob_type;                  // CodeBlobType it contains
101  bool         _was_full;                        // True if the code heap was full
102
103  enum { free_sentinel = 0xFF };
104
105  // Helper functions
106  size_t   size_to_segments(size_t size) const { return (size + _segment_size - 1) >> _log2_segment_size; }
107  size_t   segments_to_size(size_t number_of_segments) const { return number_of_segments << _log2_segment_size; }
108
109  size_t   segment_for(void* p) const            { return ((char*)p - _memory.low()) >> _log2_segment_size; }
110  bool     is_segment_unused(int val) const      { return val == free_sentinel; }
111  HeapBlock* block_at(size_t i) const            { return (HeapBlock*)(_memory.low() + (i << _log2_segment_size)); }
112
113  void  mark_segmap_as_free(size_t beg, size_t end);
114  void  mark_segmap_as_used(size_t beg, size_t end);
115
116  // Freelist management helpers
117  FreeBlock* following_block(FreeBlock* b);
118  void insert_after(FreeBlock* a, FreeBlock* b);
119  bool merge_right (FreeBlock* a);
120
121  // Toplevel freelist management
122  void add_to_freelist(HeapBlock* b);
123  FreeBlock* search_freelist(size_t length, bool is_critical);
124
125  // Iteration helpers
126  void*      next_free(HeapBlock* b) const;
127  HeapBlock* first_block() const;
128  HeapBlock* next_block(HeapBlock* b) const;
129  HeapBlock* block_start(void* p) const;
130
131  // to perform additional actions on creation of executable code
132  void on_code_mapping(char* base, size_t size);
133  void clear();                                 // clears all heap contents
134
135 public:
136  CodeHeap(const char* name, const int code_blob_type);
137
138  // Heap extents
139  bool  reserve(ReservedSpace rs, size_t committed_size, size_t segment_size);
140  bool  expand_by(size_t size);                  // expands committed memory by size
141
142  // Memory allocation
143  void* allocate  (size_t size, bool is_critical);  // allocates a block of size or returns NULL
144  void  deallocate(void* p);                        // deallocates a block
145
146  // Attributes
147  char* low_boundary() const                     { return _memory.low_boundary (); }
148  char* high() const                             { return _memory.high(); }
149  char* high_boundary() const                    { return _memory.high_boundary(); }
150
151  bool  contains(const void* p) const            { return low_boundary() <= p && p < high(); }
152  void* find_start(void* p)     const;           // returns the block containing p or NULL
153  size_t alignment_unit()       const;           // alignment of any block
154  size_t alignment_offset()     const;           // offset of first byte of any block, within the enclosing alignment unit
155  static size_t header_size();                   // returns the header size for each heap block
156
157  size_t allocated_in_freelist() const           { return _freelist_segments * CodeCacheSegmentSize; }
158  int    freelist_length()       const           { return _freelist_length; } // number of elements in the freelist
159
160  // returns the first block or NULL
161  void* first() const       { return next_free(first_block()); }
162  // returns the next block given a block p or NULL
163  void* next(void* p) const { return next_free(next_block(block_start(p))); }
164
165  // Statistics
166  size_t capacity() const;
167  size_t max_capacity() const;
168  int    allocated_segments() const;
169  size_t allocated_capacity() const;
170  size_t max_allocated_capacity() const          { return _max_allocated_capacity; }
171  size_t unallocated_capacity() const            { return max_capacity() - allocated_capacity(); }
172
173  // Returns true if the CodeHeap contains CodeBlobs of the given type
174  bool accepts(int code_blob_type) const         { return (_code_blob_type == code_blob_type); }
175  int code_blob_type() const                     { return _code_blob_type; }
176
177  // Debugging / Profiling
178  const char* name() const                       { return _name; }
179  bool was_full()                                { return _was_full; }
180  void report_full()                             { _was_full = true; }
181
182private:
183  size_t heap_unallocated_capacity() const;
184
185public:
186  // Debugging
187  void verify() PRODUCT_RETURN;
188  void print()  PRODUCT_RETURN;
189};
190
191#endif // SHARE_VM_MEMORY_HEAP_HPP
192