162 lines
6.0 KiB
C++
162 lines
6.0 KiB
C++
/*
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* Copyright 1997-2006 Sun Microsystems, Inc. All Rights Reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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* CA 95054 USA or visit www.sun.com if you need additional information or
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* have any questions.
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*
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*/
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// Blocks
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class HeapBlock VALUE_OBJ_CLASS_SPEC {
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friend class VMStructs;
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public:
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struct Header {
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size_t _length; // the length in segments
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bool _used; // Used bit
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};
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protected:
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union {
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Header _header;
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int64_t _padding[ (sizeof(Header) + sizeof(int64_t)-1) / sizeof(int64_t) ];
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// pad to 0 mod 8
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};
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public:
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// Initialization
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void initialize(size_t length) { _header._length = length; set_used(); }
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// Accessors
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void* allocated_space() const { return (void*)(this + 1); }
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size_t length() const { return _header._length; }
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// Used/free
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void set_used() { _header._used = true; }
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void set_free() { _header._used = false; }
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bool free() { return !_header._used; }
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};
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class FreeBlock: public HeapBlock {
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friend class VMStructs;
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protected:
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FreeBlock* _link;
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public:
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// Initialization
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void initialize(size_t length) { HeapBlock::initialize(length); _link= NULL; }
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// Merging
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void set_length(size_t l) { _header._length = l; }
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// Accessors
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FreeBlock* link() const { return _link; }
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void set_link(FreeBlock* link) { _link = link; }
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};
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class CodeHeap : public CHeapObj {
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friend class VMStructs;
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private:
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VirtualSpace _memory; // the memory holding the blocks
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VirtualSpace _segmap; // the memory holding the segment map
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size_t _number_of_committed_segments;
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size_t _number_of_reserved_segments;
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size_t _segment_size;
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int _log2_segment_size;
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size_t _next_segment;
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FreeBlock* _freelist;
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size_t _free_segments; // No. of segments in freelist
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// Helper functions
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size_t number_of_segments(size_t size) const { return (size + _segment_size - 1) >> _log2_segment_size; }
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size_t size(size_t number_of_segments) const { return number_of_segments << _log2_segment_size; }
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size_t segment_for(void* p) const { return ((char*)p - _memory.low()) >> _log2_segment_size; }
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HeapBlock* block_at(size_t i) const { return (HeapBlock*)(_memory.low() + (i << _log2_segment_size)); }
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void mark_segmap_as_free(size_t beg, size_t end);
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void mark_segmap_as_used(size_t beg, size_t end);
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// Freelist management helpers
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FreeBlock* following_block(FreeBlock *b);
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void insert_after(FreeBlock* a, FreeBlock* b);
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void merge_right (FreeBlock* a);
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// Toplevel freelist management
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void add_to_freelist(HeapBlock *b);
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FreeBlock* search_freelist(size_t length);
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// Iteration helpers
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void* next_free(HeapBlock* b) const;
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HeapBlock* first_block() const;
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HeapBlock* next_block(HeapBlock* b) const;
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HeapBlock* block_start(void* p) const;
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// to perform additional actions on creation of executable code
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void on_code_mapping(char* base, size_t size);
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public:
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CodeHeap();
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// Heap extents
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bool reserve(size_t reserved_size, size_t committed_size, size_t segment_size);
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void release(); // releases all allocated memory
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bool expand_by(size_t size); // expands commited memory by size
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void shrink_by(size_t size); // shrinks commited memory by size
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void clear(); // clears all heap contents
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// Memory allocation
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void* allocate (size_t size); // allocates a block of size or returns NULL
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void deallocate(void* p); // deallocates a block
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// Attributes
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void* begin() const { return _memory.low (); }
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void* end() const { return _memory.high(); }
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bool contains(void* p) const { return begin() <= p && p < end(); }
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void* find_start(void* p) const; // returns the block containing p or NULL
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size_t alignment_unit() const; // alignment of any block
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size_t alignment_offset() const; // offset of first byte of any block, within the enclosing alignment unit
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static size_t header_size(); // returns the header size for each heap block
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// Returns reserved area high and low addresses
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char *low_boundary() const { return _memory.low_boundary (); }
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char *high_boundary() const { return _memory.high_boundary(); }
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// Iteration
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// returns the first block or NULL
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void* first() const { return next_free(first_block()); }
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// returns the next block given a block p or NULL
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void* next(void* p) const { return next_free(next_block(block_start(p))); }
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// Statistics
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size_t capacity() const;
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size_t max_capacity() const;
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size_t allocated_capacity() const;
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size_t unallocated_capacity() const { return max_capacity() - allocated_capacity(); }
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// Debugging
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void verify();
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void print() PRODUCT_RETURN;
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};
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