[wp-trac] [WordPress Trac] #34525: Use wp_parse_id_list() in the WP_Query class

[WordPress Trac]

#34525: Use wp_parse_id_list() in the WP_Query class
-------------------------+------------------------------
 Reporter:  birgire      |       Owner:
     Type:  enhancement  |      Status:  new
 Priority:  normal       |   Milestone:  Awaiting Review
Component:  Query        |     Version:  4.3.1
 Severity:  normal       |  Resolution:
 Keywords:  close        |     Focuses:
-------------------------+------------------------------

Comment (by birgire):

 Thanks @DrewAPicture for these informative tests.

 Yes it's a constant battle between ''maintainable'' vs ''optimization''
 ;-)

 It's funny to see the {{{array_map}}} and {{{array_unique}}} swap
 difference ;-)

 Are you maybe suggesting to swap it within the  {{{wp_parse_id_list()}}}
 function?

 It's probably too much to allow comma separated values as well (even
 though it would add more consistancy), so we should add the {{{(array)}}}
 casting part, as suggested by @dd32



 === ps: here's a little detour regarding microoptimizations ===

 There are some interesting replacements out there for:

 1. {{{is_array()}}} with {{{(array) $var === $var}}}, but the former is
 more readable. Here's an in-depth discussion by ircmaxell:
 http://stackoverflow.com/a/3471356/2078474.

 2. {{{array_unique()}}} that seems to be slower than some suggested semi-
 replacements out there, where some preserve the key order and other don't.

 Here are some of these suggested semi-replacements for part 2)

 {{{
 <?php

 //----------------------------------
 // array_unique() semi-replacements
 //----------------------------------

 // @link http://php.net/manual/en/function.array-unique.php#98453
 function wp_array_unique1( $arr = array() )
 {
     $tmp = array();
     foreach( $arr as $key => $val ) {
         $tmp[$val] = true;
     }
     return array_keys( $tmp );
 }

 // @link http://www.puremango.co.uk/2010/06/fast-php-array_unique-for-
 removing-duplicates/#comment-202704
 function wp_array_unique2( $arr = array() )
 {
         $tempArray = array();
         foreach($arr as $key => $val ) {
                 if( isset( $tempArray[$val] ) ) continue;
                 $tempArray[$val] = $key;
         }
         return array_flip($tempArray);
 }

 // @link http://stackoverflow.com/questions/8321620/array-unique-vs-array-
 flip
 function wp_array_unique3( $arr = array() )
 {
         // Code documented at: http://www.puremango.co.uk/?p=1039
         return array_flip(array_flip(array_reverse($arr,true)));
 }

 // @link http://stackoverflow.com/questions/8321620/array-unique-vs-array-
 flip
 function wp_array_unique4( $arr = array() )
 {
         return array_keys( array_flip( $arr ) );
 }

 // @link http://stackoverflow.com/questions/8321620/array-unique-vs-array-
 flip
 function wp_array_unique5( $arr = array() )
 {
         return array_flip( array_flip( $arr ) );
 }

 //----------
 // Input
 //----------
 $input = array(
     0 => 1,
     1 => 2,
     2 => 2,
     3 => 0,
     4 => -1,
     5 => '1',
     'a' => 'c',
     'b' => 'a',
     'c' => 'c'
 );

 //-------------------
 // Test comparisions
 //-------------------
 echo 'Input:';
 print_r( $input );
 echo 'array_unique: ';
 print_r( array_unique( $input ) );
 echo 'Replacement #1: ';
 print_r( wp_array_unique1( $input ) );
 echo 'Replacement #2: ';
 print_r( wp_array_unique2( $input ) );
 echo 'Replacement #3: ';
 print_r( wp_array_unique3( $input ) );
 echo 'Replacement #4: ';
 print_r( wp_array_unique4( $input ) );
 echo 'Replacement #5: ';
 print_r( wp_array_unique5( $input ) );
 }}}

 I added this test here: https://3v4l.org/AaU1X

 The output is:

 {{{
 Input:Array
 (
     [0] => 1
     [1] => 2
     [2] => 2
     [3] => 0
     [4] => -1
     [5] => 1
     [a] => c
     [b] => a
     [c] => c
 )
 array_unique: Array
 (
     [0] => 1
     [1] => 2
     [3] => 0
     [4] => -1
     [a] => c
     [b] => a
 )
 Replacement #1: Array
 (
     [0] => 1
     [1] => 2
     [2] => 0
     [3] => -1
     [4] => c
     [5] => a
 )
 Replacement #2: Array
 (
     [0] => 1
     [1] => 2
     [3] => 0
     [4] => -1
     [a] => c
     [b] => a
 )
 Replacement #3: Array
 (
     [a] => c
     [b] => a
     [0] => 1
     [4] => -1
     [3] => 0
     [1] => 2
 )
 Replacement #4: Array
 (
     [0] => 1
     [1] => 2
     [2] => 0
     [3] => -1
     [4] => c
     [5] => a
 )
 Replacement #5: Array
 (
     [5] => 1
     [2] => 2
     [3] => 0
     [4] => -1
     [c] => c
     [b] => a
 )
 }}}

 Here's the input extended further, to better understand what happens for
 non-string/integer input values: https://3v4l.org/ZeLCf

 Let's play with the test by @DrewAPicture:

 {{{
 $ids = range( 1000, 2000 );

 $start      = microtime( true );
 $iterations = 5000;

 for ( $i = 0; $i < $iterations; $i++ )
 {

         // test #0
         $list = array_map( 'absint', array_unique( $ids ) );

         // test #1
         // $list = array_map( 'absint', wp_array_unique1( $ids ) );

         // test #2
         // $list = array_map( 'absint', wp_array_unique2( $ids ) );

         // test #3
         // $list = array_map( 'absint', wp_array_unique3( $ids ) );

         // test #4
         // $list = array_map( 'absint', wp_array_unique4( $ids ) );

         // test #5
         // $list = array_map( 'absint', wp_array_unique5( $ids ) );

 }

 $end = microtime( true ) - $start;
 print( $average = $end / $iterations );
 }}}

 The results on my server are:

 {{{
 test #0
         0.0094432024002075
         0.0093391174316406
         0.0093821507930756

 test #1
         0.0069236095905304
         0.0069987013816833
         0.0068500112056732

 test #2
         0.0071335470199585
         0.0070521537780762
         0.0069442203998566

 test #3
         0.0066374749660492
         0.0065019884109497
         0.0065506939888

 test #4
         0.0062625207901001
         0.0062665887832642
         0.0063331448078156

 test #5
         0.0063409204006195
         0.0063279666423798
         0.0063581778049469
 }}}

 So {{{array_unique()}}} is indeed the slowest one here.

--
Ticket URL: <https://core.trac.wordpress.org/ticket/34525#comment:3>
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