BLI_memblock: New memory allocator

This is really close to BLI_mempool but uses an array to keep track of the
chunks of memory. There is no tagging necessary to clear the whole
structure so reuse is fast.

Naturally supports iteration but does not support freeing.

source/blender/blenlib/BLI_memblock.h

@@ -0,0 +1,55 @@
+/*
+ * 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 Blender Foundation.
+ * All rights reserved.
+ */
+
+#ifndef __BLI_MEMBLOCK_H__
+#define __BLI_MEMBLOCK_H__
+
+/** \file
+ * \ingroup bli
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "BLI_compiler_attrs.h"
+
+struct BLI_memblock;
+
+typedef struct BLI_memblock BLI_memblock;
+
+BLI_memblock *BLI_memblock_create(uint elem_size) ATTR_MALLOC ATTR_WARN_UNUSED_RESULT;
+void *BLI_memblock_alloc(BLI_memblock *mblk) ATTR_MALLOC ATTR_WARN_UNUSED_RESULT ATTR_NONNULL(1);
+void BLI_memblock_clear(BLI_memblock *mblk) ATTR_NONNULL(1);
+void BLI_memblock_destroy(BLI_memblock *mblk) ATTR_NONNULL(1);
+
+typedef struct BLI_memblock_iter {
+  BLI_memblock *mblk;
+  uint current_index;
+  uint elem_per_chunk;
+} BLI_memblock_iter;
+
+void BLI_memblock_iternew(BLI_memblock *pool, BLI_memblock_iter *iter) ATTR_NONNULL();
+void *BLI_memblock_iterstep(BLI_memblock_iter *iter) ATTR_WARN_UNUSED_RESULT ATTR_NONNULL();
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __BLI_MEMBLOCK_H__ */

source/blender/blenlib/CMakeLists.txt

@@ -48,6 +48,7 @@ set(SRC
   intern/BLI_linklist.c
   intern/BLI_linklist_lockfree.c
   intern/BLI_memarena.c
+  intern/BLI_memblock.c
   intern/BLI_memiter.c
   intern/BLI_mempool.c
   intern/BLI_timer.c
@@ -194,6 +195,7 @@ set(SRC
   BLI_math_statistics.h
   BLI_math_vector.h
   BLI_memarena.h
+  BLI_memblock.h
   BLI_memiter.h
   BLI_memory_utils.h
   BLI_mempool.h

source/blender/blenlib/intern/BLI_memblock.c

@@ -0,0 +1,134 @@
+/*
+ * 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.
+ */
+
+/** \file
+ * \ingroup bli
+ *
+ * Dead simple, fast memory allocator for allocating many elements of the same size.
+ *
+ */
+
+#include <string.h>
+#include <stdlib.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 BLI_MEM_BLOCK_CHUNK_SIZE (1 << 15) /* 32KiB */
+#define CHUNK_LIST_SIZE 16
+
+struct BLI_memblock {
+  void **chunk_list;
+
+  /** Element size in bytes. */
+  uint elem_size;
+  /** First unused element index. */
+  uint elem_next;
+  /** Chunck size in bytes. */
+  uint chunk_size;
+  /** Number of allocated chunck. */
+  uint chunk_len;
+};
+
+BLI_memblock *BLI_memblock_create(uint elem_size)
+{
+  BLI_assert(elem_size < BLI_MEM_BLOCK_CHUNK_SIZE);
+
+  BLI_memblock *mblk = MEM_mallocN(sizeof(BLI_memblock), "BLI_memblock");
+  mblk->elem_size = elem_size;
+  mblk->elem_next = 0;
+  mblk->chunk_size = BLI_MEM_BLOCK_CHUNK_SIZE;
+  mblk->chunk_len = CHUNK_LIST_SIZE;
+  mblk->chunk_list = MEM_callocN(sizeof(void *) * mblk->chunk_len, "BLI_memblock chunk list");
+  return mblk;
+}
+
+void BLI_memblock_destroy(BLI_memblock *mblk)
+{
+  for (uint 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)
+{
+  uint elem_per_chunk = mblk->chunk_size / mblk->elem_size;
+  uint last_used_chunk = (mblk->elem_next - 1) / elem_per_chunk;
+
+  for (uint 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 *) * mblk->chunk_len);
+  }
+
+  mblk->elem_next = 0;
+}
+
+void *BLI_memblock_alloc(BLI_memblock *mblk)
+{
+  uint elem_per_chunk = mblk->chunk_size / mblk->elem_size;
+  uint chunk_idx = mblk->elem_next / elem_per_chunk;
+  uint elem_idx = mblk->elem_next - elem_per_chunk * chunk_idx;
+  mblk->elem_next++;
+
+  if (UNLIKELY(chunk_idx >= mblk->chunk_len)) {
+    mblk->chunk_len += CHUNK_LIST_SIZE;
+    mblk->chunk_list = MEM_recallocN(mblk->chunk_list, sizeof(void *) * mblk->chunk_len);
+  }
+
+  if (UNLIKELY(mblk->chunk_list[chunk_idx] == NULL)) {
+    mblk->chunk_list[chunk_idx] = MEM_mallocN(mblk->chunk_size, "BLI_memblock chunk");
+  }
+
+  return (char *)(mblk->chunk_list[chunk_idx]) + mblk->elem_size * elem_idx;
+}
+
+void BLI_memblock_iternew(BLI_memblock *mblk, BLI_memblock_iter *iter)
+{
+  iter->mblk = mblk;
+  iter->current_index = 0;
+  iter->elem_per_chunk = mblk->chunk_size / mblk->elem_size;
+}
+
+void *BLI_memblock_iterstep(BLI_memblock_iter *iter)
+{
+  if (iter->current_index >= iter->mblk->elem_next) {
+    return NULL;
+  }
+
+  uint chunk_idx = iter->current_index / iter->elem_per_chunk;
+  uint elem_idx = iter->current_index - iter->elem_per_chunk * chunk_idx;
+  iter->current_index++;
+
+  return (char *)(iter->mblk->chunk_list[chunk_idx]) + iter->mblk->elem_size * elem_idx;
+}