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	/*
	* Memory Pool implementation logic.
	*/

	#include "cache.h"
	#include "mem-pool.h"

	#define BLOCK_GROWTH_SIZE (1024 * 1024 - sizeof(struct mp_block))

	/*
	* Allocate a new mp_block and insert it after the block specified in
	* `insert_after`. If `insert_after` is NULL, then insert block at the
	* head of the linked list.
	*/
	static struct mp_block mem_pool_alloc_block(struct mem_pool pool,
	size_t block_alloc,
	struct mp_block *insert_after)
	{
	struct mp_block *p;

	pool->pool_alloc += sizeof(struct mp_block) + block_alloc;
	p = xmalloc(st_add(sizeof(struct mp_block), block_alloc));

	p->next_free = (char *)p->space;
	p->end = p->next_free + block_alloc;

	if (insert_after) {
	p->next_block = insert_after->next_block;
	insert_after->next_block = p;
	} else {
	p->next_block = pool->mp_block;
	pool->mp_block = p;
	}

	return p;
	}

	void mem_pool_init(struct mem_pool *pool, size_t initial_size)
	{
	memset(pool, 0, sizeof(*pool));
	pool->block_alloc = BLOCK_GROWTH_SIZE;

	if (initial_size > 0)
	mem_pool_alloc_block(pool, initial_size, NULL);
	}

	void mem_pool_discard(struct mem_pool *pool, int invalidate_memory)
	{
	struct mp_block block, block_to_free;

	block = pool->mp_block;
	while (block)
	{
	block_to_free = block;
	block = block->next_block;

	if (invalidate_memory)
	memset(block_to_free->space, 0xDD, ((char )block_to_free->end) - ((char )block_to_free->space));

	free(block_to_free);
	}

	pool->mp_block = NULL;
	pool->pool_alloc = 0;
	}

	void mem_pool_alloc(struct mem_pool pool, size_t len)
	{
	struct mp_block *p = NULL;
	void *r;

	/* round up to a 'uintmax_t' alignment */
	if (len & (sizeof(uintmax_t) - 1))
	len += sizeof(uintmax_t) - (len & (sizeof(uintmax_t) - 1));

	if (pool->mp_block &&
	pool->mp_block->end - pool->mp_block->next_free >= len)
	p = pool->mp_block;

	if (!p) {
	if (len >= (pool->block_alloc / 2))
	return mem_pool_alloc_block(pool, len, pool->mp_block);

	p = mem_pool_alloc_block(pool, pool->block_alloc, NULL);
	}

	r = p->next_free;
	p->next_free += len;
	return r;
	}

	void mem_pool_calloc(struct mem_pool pool, size_t count, size_t size)
	{
	size_t len = st_mult(count, size);
	void *r = mem_pool_alloc(pool, len);
	memset(r, 0, len);
	return r;
	}

	char mem_pool_strdup(struct mem_pool pool, const char *str)
	{
	size_t len = strlen(str) + 1;
	char *ret = mem_pool_alloc(pool, len);

	return memcpy(ret, str, len);
	}

	char mem_pool_strndup(struct mem_pool pool, const char *str, size_t len)
	{
	char *p = memchr(str, '\0', len);
	size_t actual_len = (p ? p - str : len);
	char *ret = mem_pool_alloc(pool, actual_len+1);

	ret[actual_len] = '\0';
	return memcpy(ret, str, actual_len);
	}

	int mem_pool_contains(struct mem_pool pool, void mem)
	{
	struct mp_block *p;

	/* Check if memory is allocated in a block */
	for (p = pool->mp_block; p; p = p->next_block)
	if ((mem >= ((void *)p->space)) &&
	(mem < ((void *)p->end)))
	return 1;

	return 0;
	}

	void mem_pool_combine(struct mem_pool dst, struct mem_pool src)
	{
	struct mp_block *p;

	/* Append the blocks from src to dst */
	if (dst->mp_block && src->mp_block) {
	/*
	* src and dst have blocks, append
	* blocks from src to dst.
	*/
	p = dst->mp_block;
	while (p->next_block)
	p = p->next_block;

	p->next_block = src->mp_block;
	} else if (src->mp_block) {
	/*
	* src has blocks, dst is empty.
	*/
	dst->mp_block = src->mp_block;
	} else {
	/* src is empty, nothing to do. */
	}

	dst->pool_alloc += src->pool_alloc;
	src->pool_alloc = 0;
	src->mp_block = NULL;
	}

git / git

git/mem-pool.c