BLI_memblock.c

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/*
 * 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.
 */
 
#include <stdlib.h>
#include <string.h>
 
#include "atomic_ops.h"
 
#include "BLI_utildefines.h"
 
#include "BLI_memblock.h" /* own include */
 
#include "MEM_guardedalloc.h"
 
#include "BLI_strict_flags.h" /* keep last */
 
#define CHUNK_LIST_SIZE 16
 
struct BLI_memblock {
  void **chunk_list;
 
  int elem_size;
  int elem_next;
  int elem_last;
  int elem_next_ofs;
  int chunk_max_ofs;
  int chunk_next;
  int chunk_size;
  int chunk_len;
};
 
BLI_memblock *BLI_memblock_create_ex(uint elem_size, uint chunk_size)
{
  BLI_assert(elem_size < chunk_size);
 
  BLI_memblock *mblk = MEM_mallocN(sizeof(BLI_memblock), "BLI_memblock");
  mblk->elem_size = (int)elem_size;
  mblk->elem_next = 0;
  mblk->elem_last = -1;
  mblk->chunk_size = (int)chunk_size;
  mblk->chunk_len = CHUNK_LIST_SIZE;
  mblk->chunk_list = MEM_callocN(sizeof(void *) * (uint)mblk->chunk_len, "chunk list");
  mblk->chunk_list[0] = MEM_mallocN_aligned((uint)mblk->chunk_size, 32, "BLI_memblock chunk");
  memset(mblk->chunk_list[0], 0x0, (uint)mblk->chunk_size);
  mblk->chunk_max_ofs = (mblk->chunk_size / mblk->elem_size) * mblk->elem_size;
  mblk->elem_next_ofs = 0;
  mblk->chunk_next = 0;
  return mblk;
}
 
void BLI_memblock_destroy(BLI_memblock *mblk, MemblockValFreeFP free_callback)
{
  int elem_per_chunk = mblk->chunk_size / mblk->elem_size;
 
  if (free_callback) {
    for (int i = 0; i <= mblk->elem_last; i++) {
      int chunk_idx = i / elem_per_chunk;
      int elem_idx = i - elem_per_chunk * chunk_idx;
      void *val = (char *)(mblk->chunk_list[chunk_idx]) + mblk->elem_size * elem_idx;
      free_callback(val);
    }
  }
 
  for (int i = 0; i < mblk->chunk_len; i++) {
    MEM_SAFE_FREE(mblk->chunk_list[i]);
  }
  MEM_SAFE_FREE(mblk->chunk_list);
  MEM_freeN(mblk);
}
 
/* Reset elem count to 0 but keep as much memory allocated needed for at least the previous elem
 * count. */
void BLI_memblock_clear(BLI_memblock *mblk, MemblockValFreeFP free_callback)
{
  int elem_per_chunk = mblk->chunk_size / mblk->elem_size;
  int last_used_chunk = mblk->elem_next / elem_per_chunk;
 
  if (free_callback) {
    for (int i = mblk->elem_last; i >= mblk->elem_next; i--) {
      int chunk_idx = i / elem_per_chunk;
      int elem_idx = i - elem_per_chunk * chunk_idx;
      void *val = (char *)(mblk->chunk_list[chunk_idx]) + mblk->elem_size * elem_idx;
      free_callback(val);
    }
  }
 
  for (int i = last_used_chunk + 1; i < mblk->chunk_len; i++) {
    MEM_SAFE_FREE(mblk->chunk_list[i]);
  }
 
  if (UNLIKELY(last_used_chunk + 1 < mblk->chunk_len - CHUNK_LIST_SIZE)) {
    mblk->chunk_len -= CHUNK_LIST_SIZE;
    mblk->chunk_list = MEM_recallocN(mblk->chunk_list, sizeof(void *) * (uint)mblk->chunk_len);
  }
 
  mblk->elem_last = mblk->elem_next - 1;
  mblk->elem_next = 0;
  mblk->elem_next_ofs = 0;
  mblk->chunk_next = 0;
}
 
void *BLI_memblock_alloc(BLI_memblock *mblk)
{
  /* Bookkeeping. */
  if (mblk->elem_last < mblk->elem_next) {
    mblk->elem_last = mblk->elem_next;
  }
  mblk->elem_next++;
 
  void *ptr = (char *)(mblk->chunk_list[mblk->chunk_next]) + mblk->elem_next_ofs;
 
  mblk->elem_next_ofs += mblk->elem_size;
 
  if (mblk->elem_next_ofs == mblk->chunk_max_ofs) {
    mblk->elem_next_ofs = 0;
    mblk->chunk_next++;
 
    if (UNLIKELY(mblk->chunk_next >= mblk->chunk_len)) {
      mblk->chunk_len += CHUNK_LIST_SIZE;
      mblk->chunk_list = MEM_recallocN(mblk->chunk_list, sizeof(void *) * (uint)mblk->chunk_len);
    }
 
    if (UNLIKELY(mblk->chunk_list[mblk->chunk_next] == NULL)) {
      mblk->chunk_list[mblk->chunk_next] = MEM_mallocN_aligned(
          (uint)mblk->chunk_size, 32, "BLI_memblock chunk");
      memset(mblk->chunk_list[mblk->chunk_next], 0x0, (uint)mblk->chunk_size);
    }
  }
  return ptr;
}
 
void BLI_memblock_iternew(BLI_memblock *mblk, BLI_memblock_iter *iter)
{
  /* Small copy of the memblock used for better cache coherence. */
  iter->chunk_list = mblk->chunk_list;
  iter->end_index = mblk->elem_next;
  iter->cur_index = 0;
  iter->chunk_idx = 0;
  iter->elem_ofs = 0;
  iter->elem_size = mblk->elem_size;
  iter->chunk_max_ofs = mblk->chunk_max_ofs;
}
 
void *BLI_memblock_iterstep(BLI_memblock_iter *iter)
{
  if (iter->cur_index == iter->end_index) {
    return NULL;
  }
 
  iter->cur_index++;
 
  void *ptr = (char *)(iter->chunk_list[iter->chunk_idx]) + iter->elem_ofs;
 
  iter->elem_ofs += iter->elem_size;
 
  if (iter->elem_ofs == iter->chunk_max_ofs) {
    iter->elem_ofs = 0;
    iter->chunk_idx++;
  }
  return ptr;
}
 
/* Direct access. elem is element index inside the chosen chunk.
 * Double usage: You can set chunk to 0 and set the absolute elem index.
 * The correct chunk will be retrieve. */
void *BLI_memblock_elem_get(BLI_memblock *mblk, int chunk, int elem)
{
  BLI_assert(chunk < mblk->chunk_len);
  int elem_per_chunk = mblk->chunk_size / mblk->elem_size;
  chunk += elem / elem_per_chunk;
  elem = elem % elem_per_chunk;
  return (char *)(mblk->chunk_list[chunk]) + mblk->elem_size * elem;
}