upb/internal/arena.h

/*
 * Copyright (c) 2009-2021, Google LLC
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
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 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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 */

#ifndef UPB_INTERNAL_ARENA_H_
#define UPB_INTERNAL_ARENA_H_

#include "upb/arena.h"

// Must be last.
#include "upb/port_def.inc"

#ifdef __cplusplus
extern "C" {
#endif

typedef struct mem_block mem_block;

struct upb_Arena {
  _upb_ArenaHead head;
  /* Stores cleanup metadata for this arena.
   * - a pointer to the current cleanup counter.
   * - a boolean indicating if there is an unowned initial block.  */
  uintptr_t cleanup_metadata;

  /* Allocator to allocate arena blocks.  We are responsible for freeing these
   * when we are destroyed. */
  upb_alloc* block_alloc;
  uint32_t last_size;

  /* When multiple arenas are fused together, each arena points to a parent
   * arena (root points to itself). The root tracks how many live arenas
   * reference it. */
  uint32_t refcount; /* Only used when a->parent == a */
  struct upb_Arena* parent;

  /* Linked list of blocks to free/cleanup. */
  mem_block *freelist, *freelist_tail;
};

#ifdef __cplusplus
} /* extern "C" */
#endif

#include "upb/port_undef.inc"

#endif /* UPB_INTERNAL_ARENA_H_ */