3 static const cell free_list_count = 32;
4 static const cell allocation_page_size = 1024;
6 struct free_heap_block {
9 bool free_p() const { return (header & 1) == 1; }
12 cell size = header & ~7;
13 FACTOR_ASSERT(size > 0);
17 void make_free(cell size) {
18 FACTOR_ASSERT(size > 0);
23 struct block_size_compare {
24 bool operator()(free_heap_block* a, free_heap_block* b) const {
25 return a->size() < b->size();
29 typedef std::multiset<free_heap_block*, block_size_compare> large_block_set;
32 std::vector<free_heap_block*> small_blocks[free_list_count];
33 large_block_set large_blocks;
34 cell free_block_count;
37 void clear_free_list();
38 void initial_free_list(cell start, cell end, cell occupied);
39 void add_to_free_list(free_heap_block* block);
40 free_heap_block* find_free_block(cell size);
41 free_heap_block* split_free_block(free_heap_block* block, cell size);
42 bool can_allot_p(cell size);
43 cell largest_free_block();
46 struct allocator_room {
51 cell free_block_count;
54 template <typename Block> struct free_list_allocator {
58 free_list free_blocks;
61 free_list_allocator(cell size, cell start);
62 void initial_free_list(cell occupied);
63 bool contains_p(Block* block);
64 bool can_allot_p(cell size);
65 Block* allot(cell size);
66 void free(Block* block);
67 cell occupied_space();
69 cell largest_free_block();
70 cell free_block_count();
72 template <typename Iterator> void sweep(Iterator& iter);
73 template <typename Iterator, typename Fixup>
74 void compact(Iterator& iter, Fixup fixup, const Block** finger);
75 template <typename Iterator, typename Fixup>
76 void iterate(Iterator& iter, Fixup fixup);
77 template <typename Iterator> void iterate(Iterator& iter);
78 allocator_room as_allocator_room();
81 template <typename Block>
82 free_list_allocator<Block>::free_list_allocator(cell size, cell start)
86 state(mark_bits(size, start)) {
90 template <typename Block>
91 void free_list_allocator<Block>::initial_free_list(cell occupied) {
92 free_blocks.initial_free_list(start, end, occupied);
95 template <typename Block>
96 bool free_list_allocator<Block>::contains_p(Block* block) {
97 return ((cell)block - start) < size;
100 template <typename Block>
101 bool free_list_allocator<Block>::can_allot_p(cell size) {
102 return free_blocks.can_allot_p(size);
105 template <typename Block> Block* free_list_allocator<Block>::allot(cell size) {
106 size = align(size, data_alignment);
108 free_heap_block* block = free_blocks.find_free_block(size);
110 block = free_blocks.split_free_block(block, size);
111 return (Block*)block;
116 template <typename Block> void free_list_allocator<Block>::free(Block* block) {
117 free_heap_block* free_block = (free_heap_block*)block;
118 free_block->make_free(block->size());
119 free_blocks.add_to_free_list(free_block);
122 template <typename Block> cell free_list_allocator<Block>::free_space() {
123 return free_blocks.free_space;
126 template <typename Block> cell free_list_allocator<Block>::occupied_space() {
127 return size - free_blocks.free_space;
130 template <typename Block>
131 cell free_list_allocator<Block>::largest_free_block() {
132 return free_blocks.largest_free_block();
135 template <typename Block> cell free_list_allocator<Block>::free_block_count() {
136 return free_blocks.free_block_count;
139 template <typename Block>
140 template <typename Iterator>
141 void free_list_allocator<Block>::sweep(Iterator& iter) {
142 free_blocks.clear_free_list();
144 cell start = this->start;
145 cell end = this->end;
147 while (start != end) {
148 // find next unmarked block
149 start = state.next_unmarked_block_after(start);
153 cell size = state.unmarked_block_size(start);
154 FACTOR_ASSERT(size > 0);
156 free_heap_block* free_block = (free_heap_block*)start;
157 free_block->make_free(size);
158 free_blocks.add_to_free_list(free_block);
159 iter((Block*)start, size);
161 start = start + size;
166 template <typename Block> void free_list_allocator<Block>::sweep() {
167 auto null_sweep = [](Block* free_block, cell size) { };
171 // The forwarding map must be computed first by calling
172 // state.compute_forwarding().
173 template <typename Block>
174 template <typename Iterator, typename Fixup>
175 void free_list_allocator<Block>::compact(Iterator& iter, Fixup fixup,
176 const Block** finger) {
177 cell dest_addr = start;
178 auto compact_block_func = [&](Block* block, cell size) {
179 cell block_addr = (cell)block;
180 if (!state.marked_p(block_addr))
182 *finger = (Block*)(block_addr + size);
183 memmove((Block*)dest_addr, block, size);
184 iter(block, (Block*)dest_addr, size);
187 iterate(compact_block_func, fixup);
189 // Now update the free list; there will be a single free block at
191 free_blocks.initial_free_list(start, end, dest_addr - start);
194 // During compaction we have to be careful and measure object sizes
196 template <typename Block>
197 template <typename Iterator, typename Fixup>
198 void free_list_allocator<Block>::iterate(Iterator& iter, Fixup fixup) {
199 cell scan = this->start;
200 while (scan != this->end) {
201 Block* block = (Block*)scan;
202 cell size = fixup.size(block);
203 if (!block->free_p())
209 template <typename Block>
210 allocator_room free_list_allocator<Block>::as_allocator_room() {
213 room.occupied_space = occupied_space();
214 room.total_free = free_space();
215 room.contiguous_free = largest_free_block();
216 room.free_block_count = free_block_count();