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Library and tools to measure execution speed of PHP code

Introduction

This package contain a library and tools to measure execution speed of PHP code. You can use it to measure alternative code when profiling and improving performance of your application.

Requirements

This package requires PHP 5.4 or above.

How to use

You should require src/Timer.php in your PHP script to use the object-oriented interface. A procedural interface is also available -- to use it, require src/functions.php.

Basic usage

To get timings of code runs, use the code below:

$timer = new \TimeIt\Timer('pow(2, 5)');
$res = $timer->timeit();

The returned $res variable contains a three-elements array with the following information:

• $res[0]: The number of rounds (iterations) used to calculate the timing. By default, the object figures out the number of iterations needed to give the most accurate results possible.

• $res[1]: The time spent on each run of your code, in seconds. In other words, this is the approximate time that it takes to run your code once.

• $res[2]: A human-readable, time-scaled string representation of the time needed to run your code (i.e., the value in $res[1]). For example, for a code that takes 2 seconds to run the function would return 2.00s. The string returned may represent time in seconds (s), milliseconds (ms), or microseconds (us).

As said above, the object will calculate the number of rounds to return appropriate values, depending on the speed of your code (starting at 10 iterations). However, you can force it to use any number of rounds. To do this, pass the desired number to the timeit() method:

 $res = $timer->timeit(500);

You can make the object run the code several times, and return an array of results. To do this, call the repeat() method:

 $multi_res = $timer->repeat(500, 5);

This will call timeit(500) five times. In the example above, the returned value will be a multi-dimensional five-elements array containing the result of each run. The array of results will be sorted by execution speed in ascending order (i.e., highest execution speed first). The number of repetitions is optional. The default is 3.

Reference

• $timer->__construct($code, $setup = NULL) - construct a TimeIt\Timer object for measuring execution speed of $code. Code can be a string containing PHP code, or any other callable (for example, anonymous functions, class/objects methods specified using arrays, etc.).

  $setup may contain setup code that should be run only once, before each speed evaluation of $code. It may be used to setup the environment needed by the code to run properly. If NULL, then no setup code will be run.

• $timer->timeit($rounds = NULL) - measure code execution speed, and return an array with results. See Basic usage above for details about the returned array structure. You can specify a number of rounds in the $rounds parameter, or let the object determine an appropriate number.

• $timer->repeat($rounds = NULL, $repeat = 3) - run the timeit() method $repeat times to get separate samples of execution speed. The return value is an array of array structures as returned by timeit(), ordered by execution speed (fastest first).

Procedural interface

The library also provide a convenient procedural interface:

• timeit($code, $setup = NULL, $rounds = NULL) - Measure the speed of code in $code. See the Reference section above for information about the other parameters.

• timeit_repeat($code, $setup = NULL, $rounds = NULL, $repeat = 3) - Take $repeat speed measurements of the code in $code. See the Reference section above for information about the other parameters.

• timeit_str($code, $setup = NULL, $rounds = NULL, $repeat = 3) - run timeit_repeat() using the provided parameters, and return a human-readable string with information about the best measurement found.

Command line script

The bin/timeit script provides a convenient interface to check execution speed of PHP code from the command line. Run the script passing PHP code as parameters. You can can pass many parameters in the same run, which make the script a very convenient way to help select which code perform best.

Example:

$ bin/timeit 'pow(5, 5)'
pow(5, 5): 100000 loops, best of 3: 9.21us per loop

$ bin/timeit 'pow(2, 5)' '2 * 2 * 2 * 2 * 2'
pow(2, 5): 100000 loops, best of 3: 8.51us per loop
2 * 2 * 2 * 2 * 2: 1000000 loops, best of 3: 4.10us per loop

Warning: you must be extra careful when passing PHP code in the command line to the timeit script, because single/double quotes -- very often used in PHP code -- may clash with the ones expected by your shell. The script expect that each separate shell parameter contains a single piece of code, but if you do not escape your quotes properly, the shell may divide the parameter in unexpected ways. You probably need to escape dollar signs as well, to prevent them to be interpreted by the shell.

Examples:

Wrong

$ bin/timeit '$a = 'foobar'; substr($a, 0, 1)'
PHP Notice:  Use of undefined constant foobar - assumed 'foobar' in /home/flaviovs/github/timeit/src/Timer.php(39) : eval()'d code on line 1
PHP Stack trace:
(...several errors...)

Right

$ bin/timeit '$a = "foobar"; substr($a, 0, 1)'

or

$ bin/timeit "\$a = 'foobar'; substr(\$a, 0, 1)" # We must escape the "$"

Caveat

This library measure the wall clock time needed to run code. This mean that different computers, different CPUs, or even different execution environments may affect measurements.

For instance, you should not expect to get the same numbers when measuring on two different computers, nor if you do measurements on the same computer at different times. For example, measuring the same code on a server under heavy I/O and in quiet times will probably not give you the same results.

Legal

Copyright 2015-2016 Flávio Veloso

This package is licensed under the Apache License version 2.0. See the file LICENSE for more details.

If you find bugs in this software, please open an issue on GitHub at https://github.com/flaviovs/timeit, or send it to me at flaviovs at magnux dot com.