BLI_mempool.c

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/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2008 by Blender Foundation.
 * All rights reserved.
 *
 * The Original Code is: all of this file.
 *
 * Contributor(s): Geoffery Bantle
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/*
 * Simple, fast memory allocator for allocating many elements of the same size.
 */

#include "BLI_utildefines.h"
#include "BLI_listbase.h"

#include "BLI_mempool.h" /* own include */

#include "DNA_listBase.h"

#include "MEM_guardedalloc.h"

#include <string.h>
#include <stdlib.h>

/* note: copied from BKE_utildefines.h, dont use here because we're in BLI */
#ifdef __BIG_ENDIAN__
/* Big Endian */
#  define MAKE_ID(a,b,c,d) ( (int)(a)<<24 | (int)(b)<<16 | (c)<<8 | (d) )
#else
/* Little Endian */
#  define MAKE_ID(a,b,c,d) ( (int)(d)<<24 | (int)(c)<<16 | (b)<<8 | (a) )
#endif

#define FREEWORD MAKE_ID('f', 'r', 'e', 'e')

typedef struct BLI_freenode {
    struct BLI_freenode *next;
    int freeword; /* used to identify this as a freed node */
} BLI_freenode;

typedef struct BLI_mempool_chunk {
    struct BLI_mempool_chunk *next, *prev;
    void *data;
} BLI_mempool_chunk;

struct BLI_mempool {
    struct ListBase chunks;
    int esize;         /* element size in bytes */
    int csize;         /* chunk size in bytes */
    int pchunk;        /* number of elements per chunk */
    short use_sysmalloc, allow_iter;
    /* keeps aligned to 16 bits */

    BLI_freenode *free;              /* free element list. Interleaved into chunk datas.*/
    int totalloc, totused;           /* total number of elements allocated in total,
                                      * and currently in use*/
};

#define MEMPOOL_ELEM_SIZE_MIN (sizeof(void *) * 2)

BLI_mempool *BLI_mempool_create(int esize, int tote, int pchunk,
                                short use_sysmalloc, short allow_iter)
{
    BLI_mempool  *pool = NULL;
    BLI_freenode *lasttail = NULL, *curnode = NULL;
    int i,j, maxchunks;
    char *addr;

    if (esize < MEMPOOL_ELEM_SIZE_MIN)
        esize = MEMPOOL_ELEM_SIZE_MIN;

    /*allocate the pool structure*/
    pool = use_sysmalloc ? malloc(sizeof(BLI_mempool)) : MEM_mallocN(sizeof(BLI_mempool), "memory pool");
    pool->esize = allow_iter ? MAX2(esize, sizeof(BLI_freenode)) : esize;
    pool->use_sysmalloc = use_sysmalloc;
    pool->pchunk = pchunk;
    pool->csize = esize * pchunk;
    pool->chunks.first = pool->chunks.last = NULL;
    pool->totused= 0;
    pool->allow_iter= allow_iter;
    
    maxchunks = tote / pchunk + 1;
    if (maxchunks==0) maxchunks = 1;

    /*allocate the actual chunks*/
    for (i=0; i < maxchunks; i++) {
        BLI_mempool_chunk *mpchunk = use_sysmalloc ? malloc(sizeof(BLI_mempool_chunk)) : MEM_mallocN(sizeof(BLI_mempool_chunk), "BLI_Mempool Chunk");
        mpchunk->next = mpchunk->prev = NULL;
        mpchunk->data = use_sysmalloc ? malloc(pool->csize) : MEM_mallocN(pool->csize, "BLI Mempool Chunk Data");
        BLI_addtail(&(pool->chunks), mpchunk);
        
        if (i==0) {
            pool->free = mpchunk->data; /*start of the list*/
            if (pool->allow_iter)
                pool->free->freeword = FREEWORD;
        }

        /*loop through the allocated data, building the pointer structures*/
        for (addr = mpchunk->data, j=0; j < pool->pchunk; j++) {
            curnode = ((BLI_freenode*)addr);
            addr += pool->esize;
            curnode->next = (BLI_freenode*)addr;
            if (pool->allow_iter) {
                if (j != pool->pchunk-1)
                    curnode->next->freeword = FREEWORD;
                curnode->freeword = FREEWORD;
            }
        }
        /*final pointer in the previously allocated chunk is wrong.*/
        if (lasttail) {
            lasttail->next = mpchunk->data;
            if (pool->allow_iter)
                lasttail->freeword = FREEWORD;
        }

        /*set the end of this chunks memoryy to the new tail for next iteration*/
        lasttail = curnode;

        pool->totalloc += pool->pchunk;
    }
    /*terminate the list*/
    curnode->next = NULL;
    return pool;
}

void *BLI_mempool_alloc(BLI_mempool *pool)
{
    void *retval=NULL;

    pool->totused++;

    if (!(pool->free)) {
        BLI_freenode *curnode=NULL;
        char *addr;
        int j;

        /*need to allocate a new chunk*/
        BLI_mempool_chunk *mpchunk = pool->use_sysmalloc ? malloc(sizeof(BLI_mempool_chunk)) :  MEM_mallocN(sizeof(BLI_mempool_chunk), "BLI_Mempool Chunk");
        mpchunk->next = mpchunk->prev = NULL;
        mpchunk->data = pool->use_sysmalloc ? malloc(pool->csize) : MEM_mallocN(pool->csize, "BLI_Mempool Chunk Data");
        BLI_addtail(&(pool->chunks), mpchunk);

        pool->free = mpchunk->data; /*start of the list*/
        if (pool->allow_iter)
            pool->free->freeword = FREEWORD;
        for(addr = mpchunk->data, j=0; j < pool->pchunk; j++){
            curnode = ((BLI_freenode*)addr);
            addr += pool->esize;
            curnode->next = (BLI_freenode*)addr;

            if (pool->allow_iter) {
                curnode->freeword = FREEWORD;
                if (j != pool->pchunk-1)
                    curnode->next->freeword = FREEWORD;
            }
        }
        curnode->next = NULL; /*terminate the list*/

        pool->totalloc += pool->pchunk;
    }

    retval = pool->free;
    if (pool->allow_iter)
        pool->free->freeword = 0x7FFFFFFF;

    pool->free = pool->free->next;
    //memset(retval, 0, pool->esize);
    return retval;
}

void *BLI_mempool_calloc(BLI_mempool *pool)
{
    void *retval= BLI_mempool_alloc(pool);
    memset(retval, 0, pool->esize);
    return retval;
}

/* doesnt protect against double frees, dont be stupid! */
void BLI_mempool_free(BLI_mempool *pool, void *addr)
{
    BLI_freenode *newhead = addr;

    if (pool->allow_iter)
        newhead->freeword = FREEWORD;
    newhead->next = pool->free;
    pool->free = newhead;

    pool->totused--;

    /*nothing is in use; free all the chunks except the first*/
    if (pool->totused == 0) {
        BLI_freenode *curnode=NULL;
        char *tmpaddr=NULL;
        int i;

        BLI_mempool_chunk *mpchunk=NULL;
        BLI_mempool_chunk *first= pool->chunks.first;

        BLI_remlink(&pool->chunks, first);

        for (mpchunk = pool->chunks.first; mpchunk; mpchunk = mpchunk->next) {
            if (pool->use_sysmalloc) free(mpchunk->data);
            else                     MEM_freeN(mpchunk->data);
        }

        pool->use_sysmalloc ? BLI_freelist(&(pool->chunks)) : BLI_freelistN(&(pool->chunks));
        
        BLI_addtail(&pool->chunks, first);
        pool->totalloc = pool->pchunk;

        pool->free = first->data; /*start of the list*/
        for (tmpaddr = first->data, i=0; i < pool->pchunk; i++) {
            curnode = ((BLI_freenode*)tmpaddr);
            tmpaddr += pool->esize;
            curnode->next = (BLI_freenode*)tmpaddr;
        }
        curnode->next = NULL; /*terminate the list*/
    }
}

void *BLI_mempool_findelem(BLI_mempool *pool, int index)
{
    if (!pool->allow_iter) {
        fprintf(stderr, "%s: Error! you can't iterate over this mempool!\n", __func__);
        return NULL;
    }
    else if ((index >= 0) && (index < pool->totused)) {
        /* we could have some faster mem chunk stepping code inline */
        BLI_mempool_iter iter;
        void *elem;
        BLI_mempool_iternew(pool, &iter);
        for (elem= BLI_mempool_iterstep(&iter); index-- != 0; elem= BLI_mempool_iterstep(&iter)) { };
        return elem;
    }

    return NULL;
}

void BLI_mempool_iternew(BLI_mempool *pool, BLI_mempool_iter *iter)
{
    if (!pool->allow_iter) {
        fprintf(stderr, "%s: Error! you can't iterate over this mempool!\n", __func__);
        iter->curchunk = NULL;
        iter->curindex = 0;
        
        return;
    }
    
    iter->pool = pool;
    iter->curchunk = pool->chunks.first;
    iter->curindex = 0;
}

#if 0
/* unoptimized, more readable */

static void *bli_mempool_iternext(BLI_mempool_iter *iter)
{
    void *ret = NULL;
    
    if (!iter->curchunk || !iter->pool->totused) return NULL;
    
    ret = ((char*)iter->curchunk->data) + iter->pool->esize*iter->curindex;
    
    iter->curindex++;
    
    if (iter->curindex >= iter->pool->pchunk) {
        iter->curchunk = iter->curchunk->next;
        iter->curindex = 0;
    }
    
    return ret;
}

void *BLI_mempool_iterstep(BLI_mempool_iter *iter)
{
    BLI_freenode *ret;
    
    do {
        ret = bli_mempool_iternext(iter);
    } while (ret && ret->freeword == FREEWORD);
    
    return ret;
}

#else

/* optimized version of code above */

void *BLI_mempool_iterstep(BLI_mempool_iter *iter)
{
    BLI_freenode *ret;

    if (UNLIKELY(iter->pool->totused == 0)) {
        return NULL;
    }

    do {
        if (LIKELY(iter->curchunk)) {
            ret = (BLI_freenode *)(((char*)iter->curchunk->data) + iter->pool->esize*iter->curindex);
        }
        else {
            return NULL;
        }

        if (UNLIKELY(++iter->curindex >= iter->pool->pchunk)) {
            iter->curindex = 0;
            iter->curchunk = iter->curchunk->next;
        }
    } while (ret->freeword == FREEWORD);
    
    return ret;
}

#endif

void BLI_mempool_destroy(BLI_mempool *pool)
{
    BLI_mempool_chunk *mpchunk=NULL;

    if (pool->use_sysmalloc) {
        for (mpchunk = pool->chunks.first; mpchunk; mpchunk = mpchunk->next) {
            free(mpchunk->data);
        }
        BLI_freelist(&(pool->chunks));
        free(pool);
    }
    else {
        for (mpchunk = pool->chunks.first; mpchunk; mpchunk = mpchunk->next) {
            MEM_freeN(mpchunk->data);
        }
        BLI_freelistN(&(pool->chunks));
        MEM_freeN(pool);
    }
}