[wp-trac] [WordPress Trac] #10561: Improve do_action(): Make $wp_actions an assoc array.

[WordPress Trac]

#10561: Improve do_action(): Make $wp_actions an assoc array.
--------------------------+-------------------------------------------------
 Reporter:  koopersmith   |       Owner:                          
     Type:  enhancement   |      Status:  new                     
 Priority:  normal        |   Milestone:  Unassigned              
Component:  Optimization  |     Version:                          
 Severity:  normal        |    Keywords:  has-patch, needs-testing
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 I was benchmarking a few functions in wp-includes/plugin.php and came
 across some strange results: for 10000 blank hooks, do_action took 8.75
 seconds to run, while apply_filters took only 0.04 seconds. I found the
 bottleneck in do_action, and wrote a patch that brought the 8.75 seconds
 down to 0.05 seconds.

 Currently, $wp_actions is an unordered array of action $tags (strings).

 do_action, did_action, and do_action_ref_array all have a time complexity
 of O(n) (where n is the size of $wp_action), while their counterparts have
 a time complexity of O(1). While this doesn't affect performance for low
 values of n, as the size of $wp_action increases, the performance of the
 do_action family drastically decreases.

 This time complexity can be attributed to two things in do_action:
 is_array($wp_actions) and $wp_actions[] = $tag. Both calls traverse the
 entirety of $wp_actions—this is what bogs do_action down. In did_action,
 we run into the same problem by using array_keys.

 is_array can easily be changed to isset, since the $wp_actions global is
 only used by do_action, did_action, and do_action_ref_array. If $wp_action
 is converted to an associative array with $wp_action[$tag] =
 number_of_times_$tag_called, we'll no longer have to traverse the array to
 get or set values. The time complexity will drop to the ideal O(1). As a
 side effect, the array will also be smaller.




 Current Benchmark:
 {{{
 Benchmark take 1: do_action, 10000 blank actions.               Time
 elapsed: 8.75771
 Benchmark take 1: apply_filters, 10000 blank filters.           Time
 elapsed: 0.03978
 Benchmark take 1: has_action, 10000 blank actions.              Time
 elapsed: 0.02783
 Benchmark take 1: has_filter, 10000 blank filters.              Time
 elapsed: 0.01878
 Benchmark take 1: did_action, run 1000x, 10000 actions.         Time
 elapsed: 3.27091

 Benchmark take 2: do_action, 10000 blank actions.               Time
 elapsed: 29.29273
 Benchmark take 2: apply_filters, 10000 blank filters.           Time
 elapsed: 0.03888
 Benchmark take 2: has_action, 10000 blank actions.              Time
 elapsed: 0.02708
 Benchmark take 2: has_filter, 10000 blank filters.              Time
 elapsed: 0.01924
 Benchmark take 2: did_action, run 1000x, 20000 actions.         Time
 elapsed: 6.901
 }}}

 Patch Benchmark:
 {{{
 Benchmark take 1: do_action, 10000 blank actions.               Time
 elapsed: 0.0474
 Benchmark take 1: apply_filters, 10000 blank filters.           Time
 elapsed: 0.04281
 Benchmark take 1: has_action, 10000 blank actions.              Time
 elapsed: 0.03405
 Benchmark take 1: has_filter, 10000 blank filters.              Time
 elapsed: 0.02335
 Benchmark take 1: did_action, run 1000x, 10000 actions.         Time
 elapsed: 0.00214

 Benchmark take 2: do_action, 10000 blank actions.               Time
 elapsed: 0.04876
 Benchmark take 2: apply_filters, 10000 blank filters.           Time
 elapsed: 0.03999
 Benchmark take 2: has_action, 10000 blank actions.              Time
 elapsed: 0.0312
 Benchmark take 2: has_filter, 10000 blank filters.              Time
 elapsed: 0.02353
 Benchmark take 2: did_action, run 1000x, 20000 actions.         Time
 elapsed: 0.00213
 }}}

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Ticket URL: <http://core.trac.wordpress.org/ticket/10561>
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