[cairo] deleting hash objects while iterating

[Carl Worth]

On Sun, 09 Apr 2006 00:59:52 -0700, Keith Packard wrote:
> 
> It was also easy to fix; just prevent the table from being resized while
> iterating and clean it up after the iteration is completed.
> 
> Is this a reasonable thing to do?

Looks good. Thanks for the fix.

Existing code for deleting all entries was rather painful[*]. So it
will be nice to replace that with something more straightforward and
more efficient now.

Since this is just used internally and only for iterating, I might
switch to a name of "iterating" rather than the less descriptive
"locked".

-Carl

[*] For example:

        /* This is rather inefficient, but destroying the hash table
         * is something we only do during debugging, (during
         * cairo_debug_reset_static_data), when efficiency is not
         * relevant. */
        while (1) {
            unscaled = _cairo_hash_table_random_entry (font_map->hash_table,
                                                       NULL);
            if (unscaled == NULL)
                break;
            _cairo_hash_table_remove (font_map->hash_table,
                                      &unscaled->base.hash_entry);

            _font_map_release_face_lock_held (font_map, unscaled);
            _cairo_ft_unscaled_font_fini (unscaled);
            free (unscaled);
        }
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