Re: array_filter vs for/foreach usage cost

On Fri, Sep 8, 2017 at 9:06 AM, Johannes Schlüter <johannes@schlueters.de> wrote: > Hi, > > On Do, 2017-09-07 at 15:13 -0300, David Rodrigues wrote: >> I understand that array_filter() should costs more than for/foreach >> because >> it is a function call that call another function for each item, while >> the >> for/foreach is a language constructor that works on a way totally >> different >> and its optimized for this kind of job. > > The main cost in that is that array_filter has to create a copy of the > array. An alternative is using an FilterIterator or generator or such > which would make this a pipeline step. (with iterators there are > multiple function calls, while the function descriptor is cached, > making them relatively cheap) I'd focus on improving those. As far as I can tell from the source array_filter does not create a copy of the array. It initializes a new array and then appends to it. If we want to improve the performance of array_filter we need to examine output of common compilers to see if they hoist the have_callback check out of the loop; I suspect it may not given the complexity of ZEND_HASH_FOREACH_KEY_VAL_IND.