Re: INDRECT in arrays causes count() to become unpredictable

Hey: On Sun, Nov 22, 2015 at 6:47 AM, Anthony Ferrara <ircmaxell@gmail.com> wrote: > All, > > It appears that in our efforts to optimize PHP 7 we've introduced an > inconsistency into array handling. This is demonstrated by this > script: https://3v4l.org/hVcAB > > $a = 1; > unset($a); > var_dump(count($GLOBALS), $GLOBALS); > > The result is that the count doesn't match the contents of the array. > > It also affects objects casted to arrays in certain cases. > > Here, the array has 1 element, but should have 0. Trying to access the > "1" element "a" results in a notice. > > This means that the count is incorrect. This is due to the fact that > the "a" element follows an IS_INDIRECT type pointing to the other > symbol table. > > A potential solution would be to make count() an O(n) operation in the > case that the hashtable is a symbol table or if it has INDIRECT > elements. Meaning that we'd compute the real count at runtime. > > This obviously has performance ramifications, but we shouldn't > sacrifice consistency and behavior for performance IMHO. Especially > when it comes to core data structures. > > I think this is significant enough to be a blocker to gold and that we > should fix it prior to release. > I don't think so, it's only affects symbol tables. means, it won't affects normal arrays. like: <?php $array = range(1, 10); unset($array[2]); var_dump(count($array)); $array = array("foo" => 1, "bar" => 2, "dummy" => 3); unset($array["bar"]); var_dump(count($array)); ?> anyway, I've fixed this here: https://github.com/php/php-src/commit/eada2aa91add2de69bc5783b840a21243a7b0678 and, we maybe move this new functions into zend_hash(as a ZEND_API), anyway I am not sure whether it's okey for PHP-7.0. will discuss with welting and Dmitry on Monday. thanks > > Thoughts? > Anthony > > -- > PHP Internals - PHP Runtime Development Mailing List > To unsubscribe, visit: http://www.php.net/unsub.php > -- Xinchen Hui @Laruence http://www.laruence.com/