dev/c/malloc_speed_test/mpool.c

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#include "mpool.h"
/*
* инициализация пула
*/
void mpool_init(struct mpool_s *bp, size_t nblocks, size_t mpool_block_size)
{
size_t i;
bp->nblocks = nblocks;
mpool_block_size += 2 * sizeof(struct mpool_block_s *);
bp->pool = (struct mpool_block_s *)malloc(nblocks * mpool_block_size);
if (!bp->pool)
fatal("virtual memory exhaused");
void *p = bp->pool + mpool_block_size,
*pmax = p + (nblocks - 2) * mpool_block_size;
for ( ; p < pmax; p += mpool_block_size) {
((struct mpool_block_s *)p)->prev = (struct mpool_block_s *)(p - mpool_block_size);
((struct mpool_block_s *)p)->next = (struct mpool_block_s *)(p + mpool_block_size);
}
((struct mpool_block_s *)bp->pool)->prev = NULL;
((struct mpool_block_s *)bp->pool)->next = (struct mpool_block_s *)(bp->pool + mpool_block_size);
((struct mpool_block_s *)(bp->pool + (nblocks - 1) * mpool_block_size))->prev =
(struct mpool_block_s *)(bp->pool + (nblocks - 2) * mpool_block_size);
((struct mpool_block_s *)(bp->pool + (nblocks - 1) * mpool_block_size))->next = NULL;
bp->free_pool = (struct mpool_block_s *)bp->pool;
bp->busy_pool = NULL;
}
/*
* уничтожение пула
*/
void mpool_destroy(struct mpool_s *bp)
{
free(bp->pool);
bp->nblocks = 0;
bp->pool = bp->free_pool = bp->busy_pool = NULL;
}
/*
* выдача блока из пула
*/
void *mpool_alloc(struct mpool_s *bp)
{
if (!bp->free_pool)
return NULL;
bp->free_pool->prev = bp->free_pool->next; // save free_pool->next in free_pool->prev
bp->free_pool->next = bp->busy_pool;
if (bp->busy_pool)
bp->busy_pool->prev = bp->free_pool;
bp->busy_pool = bp->free_pool;
bp->free_pool = bp->free_pool->prev;
bp->busy_pool->prev = NULL; // saved in free_pool->prev to NULL
return &bp->busy_pool->obj;
}
/*
* возвращение блока в пул
*/
void mpool_free(struct mpool_s *bp, void *p)
{
if (!p)
return;
struct mpool_block_s *b1 = (struct mpool_block_s *)(p - 2 * sizeof(struct mpool_block_s *)),
*b2 = b1->next;
if (b1->prev)
b1->prev->next = b2;
if (b2)
b2->prev = b1->prev;
if (bp->free_pool) {
b1->next = bp->free_pool;
bp->free_pool->prev = b1;
}
else
b1->next = NULL;
bp->free_pool = b2;
if (bp->busy_pool == b1)
bp->busy_pool = b2;
}