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158dfeff3d
Add initialization and discard functions to mem_pool type. As the memory allocated by mem_pool can now be freed, we also track the large allocations. If the there are existing mp_blocks in the mem_poo's linked list of mp_blocksl, then the mp_block for a large allocation is inserted behind the head block. This is because only the head mp_block is considered when searching for availble space. This results in the following desirable properties: 1) The mp_block allocated for the large request will not be included not included in the search for available in future requests, the large mp_block is sized for the specific request and does not contain any spare space. 2) The head mp_block will not bumped from considation for future memory requests just because a request for a large chunk of memory came in. These changes are in preparation for a future commit that will utilize creating and discarding memory pool. Signed-off-by: Jameson Miller <jamill@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
99 lines
2.1 KiB
C
99 lines
2.1 KiB
C
/*
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* Memory Pool implementation logic.
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*/
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#include "cache.h"
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#include "mem-pool.h"
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#define BLOCK_GROWTH_SIZE 1024*1024 - sizeof(struct mp_block);
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/*
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* Allocate a new mp_block and insert it after the block specified in
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* `insert_after`. If `insert_after` is NULL, then insert block at the
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* head of the linked list.
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*/
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static struct mp_block *mem_pool_alloc_block(struct mem_pool *mem_pool, size_t block_alloc, struct mp_block *insert_after)
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{
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struct mp_block *p;
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mem_pool->pool_alloc += sizeof(struct mp_block) + block_alloc;
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p = xmalloc(st_add(sizeof(struct mp_block), block_alloc));
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p->next_free = (char *)p->space;
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p->end = p->next_free + block_alloc;
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if (insert_after) {
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p->next_block = insert_after->next_block;
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insert_after->next_block = p;
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} else {
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p->next_block = mem_pool->mp_block;
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mem_pool->mp_block = p;
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}
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return p;
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}
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void mem_pool_init(struct mem_pool **mem_pool, size_t initial_size)
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{
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struct mem_pool *pool;
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if (*mem_pool)
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return;
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pool = xcalloc(1, sizeof(*pool));
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pool->block_alloc = BLOCK_GROWTH_SIZE;
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if (initial_size > 0)
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mem_pool_alloc_block(pool, initial_size, NULL);
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*mem_pool = pool;
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}
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void mem_pool_discard(struct mem_pool *mem_pool)
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{
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struct mp_block *block, *block_to_free;
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while ((block = mem_pool->mp_block))
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{
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block_to_free = block;
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block = block->next_block;
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free(block_to_free);
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}
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free(mem_pool);
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}
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void *mem_pool_alloc(struct mem_pool *mem_pool, size_t len)
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{
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struct mp_block *p = NULL;
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void *r;
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/* round up to a 'uintmax_t' alignment */
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if (len & (sizeof(uintmax_t) - 1))
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len += sizeof(uintmax_t) - (len & (sizeof(uintmax_t) - 1));
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if (mem_pool->mp_block &&
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mem_pool->mp_block->end - mem_pool->mp_block->next_free >= len)
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p = mem_pool->mp_block;
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if (!p) {
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if (len >= (mem_pool->block_alloc / 2))
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return mem_pool_alloc_block(mem_pool, len, mem_pool->mp_block);
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p = mem_pool_alloc_block(mem_pool, mem_pool->block_alloc, NULL);
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}
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r = p->next_free;
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p->next_free += len;
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return r;
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}
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void *mem_pool_calloc(struct mem_pool *mem_pool, size_t count, size_t size)
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{
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size_t len = st_mult(count, size);
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void *r = mem_pool_alloc(mem_pool, len);
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memset(r, 0, len);
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return r;
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}
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