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