示例 8.5 有效的池使用

/* Recursively crawl over DIRECTORY, adding the paths of all its file
   children to the FILES array, and doing some task to each path
   encountered.  Use POOL for the all temporary allocations, and store
   the hash paths in the same pool as the hash itself is allocated in.  */
static apr_status_t 
crawl_dir (apr_array_header_t *files,
           const char *directory,
           apr_pool_t *pool)
{
  apr_pool_t *hash_pool = files->pool;  /* array pool */
  apr_pool_t *subpool = svn_pool_create (pool);  /* iteration pool */
  apr_dir_t *dir;
  apr_finfo_t finfo;
  apr_status_t apr_err;
  apr_int32_t flags = APR_FINFO_TYPE | APR_FINFO_NAME;

  apr_err = apr_dir_open (&dir, directory, pool);
  if (apr_err)
    return apr_err;

  /* Loop over the directory entries, clearing the subpool at the top of
     each iteration.  */
  for (apr_err = apr_dir_read (&finfo, flags, dir);
       apr_err == APR_SUCCESS;
       apr_err = apr_dir_read (&finfo, flags, dir))
    {
      const char *child_path;

      /* Clear the per-iteration SUBPOOL.  */
      svn_pool_clear (subpool);

      /* Skip entries for "this dir" ('.') and its parent ('..').  */
      if (finfo.filetype == APR_DIR)
        {
          if (finfo.name[0] == '.'
              && (finfo.name[1] == '\0'
                  || (finfo.name[1] == '.' && finfo.name[2] == '\0')))
            continue;
        }

      /* Build CHILD_PATH from DIRECTORY and FINFO.name.  */
      child_path = svn_path_join (directory, finfo.name, subpool);

      /* Do some task to this encountered path. */
      do_some_task (child_path, subpool);

      /* Handle subdirectories by recursing into them, passing SUBPOOL
         as the pool for temporary allocations.  */
      if (finfo.filetype == APR_DIR)
        {
          apr_err = crawl_dir (files, child_path, subpool);
          if (apr_err)
            return apr_err;
        }

      /* Handle files by adding their paths to the FILES array.  */
      else if (finfo.filetype == APR_REG)
        {
          /* Copy the file's path into the FILES array's pool.  */
          child_path = apr_pstrdup (hash_pool, child_path);

          /* Add the path to the array.  */
          (*((const char **) apr_array_push (files))) = child_path;
        }
    }

  /* Destroy SUBPOOL.  */
  svn_pool_destroy (subpool);

  /* Check that the loop exited cleanly. */
  if (apr_err)
    return apr_err;

  /* Yes, it exited cleanly, so close the dir. */
  apr_err = apr_dir_close (dir);
  if (apr_err)
    return apr_err;

  return APR_SUCCESS;
}