microbenchmark for lookup performance in arrays and objects in PHP

array_lookup.php

<?php
# vim: sw=2 ts=2

echo 'PHP version: ' . phpversion() . PHP_EOL;

function lookup_ake(array $a, $key, $default = null)
{
	if (array_key_exists($key, $a))
	{
		return $a[$key];
	}
	return $default;
}

function lookup_isset(array $a, $key, $default = null)
{
	if (isset($a[$key]))
	{
		return $a[$key];
	}
	return $default;
}

class AA implements ArrayAccess
{
	private $keys = array('existing_key' => 1, 'unset_key' => 1);

	public $existing_key = 1;
	public $unset_key    = null;

	public function offsetExists($offset)
	{
		return isset($this->keys[$offset]);
	}

	public function offsetGet($offset)
	{
		return isset($this->$offset) ? $this->$offset : null;
	}

	public function offsetSet($offset, $value)
	{
		$this->$offset = $value;
		$this->keys[$offset] = 1;
	}

	public function offsetUnset($offset)
	{
		$this->$offset = null;
		unset($this->keys[$offset]);
	}
}

class ArrayBackedAA implements ArrayAccess
{
	private $array = array('existing_key' => 1, 'unset_key' => null);

	public function offsetExists($offset)
	{
		return isset($this->array[$offset]);
	}

	public function offsetGet($offset)
	{
		return isset($this->array[$offset]) ? $this->array[$offset] : null;
	}

	public function offsetSet($offset, $value)
	{
		$this->array[$offset] = $value;
	}

	public function offsetUnset($offset)
	{
		unset($this->array[$offset]);
	}
}

// array keys
$existing_key     = 'existing_key';
$unset_key        = 'unset_key';
$non_existing_key = 'non_existing_key';
$keys             = array($existing_key, $unset_key, $non_existing_key);

// Arrays to lookup in
$array               = array($existing_key => 1, $unset_key => null);
$array_access_obj    = new AA();
$array_backed_aa_obj = new ArrayBackedAA();

$default = null;

define('ITERATIONS', 1000000);

/////////////////////
// Raw array lookup
error_reporting(E_ALL & ~E_STRICT & ~E_NOTICE);
foreach ($keys as $key)
{
	$start = microtime(true);
	for ($i = 0; $i < ITERATIONS; ++$i)
	{
		$value = $array[$key];
	}
	$stop = microtime(true);
	echo "Unsafe and non-E_STRICT-compliant lookup for key $key:\n\t" . number_format($stop - $start, 8) . PHP_EOL;
}

error_reporting(E_ALL | E_STRICT | E_NOTICE);

//////////////////
// inlined tests
foreach ($keys as $key)
{
	$start = microtime(true);
	for ($i = 0; $i < ITERATIONS; ++$i)
	{
		$value = $default;
		if (isset($array[$key]))
		{
			$value = $array[$key];
		}
	}
	$stop = microtime(true);
	echo "Inlined lookup using isset and key $key:\n\t" . number_format($stop - $start, 8) . PHP_EOL;
}

foreach ($keys as $key)
{
	$start = microtime(true);
	for ($i = 0; $i < ITERATIONS; ++$i)
	{
		$value = $default;
		if (array_key_exists($key, $array))
		{
			$value = $array[$key];
		}
	}
	$stop = microtime(true);
	echo "Inlined lookup using array_key_exists and key $key:\n\t" . number_format($stop - $start, 8) . PHP_EOL;
}

//////////////////////
// Lookup functions
foreach (array('lookup_isset', 'lookup_ake') as $function)
{
	foreach ($keys as $key)
	{
		$start = microtime(true);
		for ($i = 0; $i < ITERATIONS; ++$i)
		{
			$value = $function($array, $key);
		}
		$stop = microtime(true);
		echo "Lookup function '$function' and key $key:\n\t" .
			number_format($stop - $start, 8) . PHP_EOL;
	}
}

////////////////////////
// Array access objects
foreach (array($array_access_obj, $array_backed_aa_obj) as $array_access)
{
	foreach ($keys as $key)
	{
		$start = microtime(true);
		for ($i = 0; $i < ITERATIONS; ++$i)
		{
			$value = $array_access[$key];
		}
		$stop = microtime(true);
		echo "ArrayAccess " . get_class($array_access) . " and key $key:\n\t" .
			number_format($stop - $start, 8) . PHP_EOL;
	}
}

////////////////////
// Property access
foreach ($keys as $key)
{
	if ($key === $non_existing_key) continue;
	$start = microtime(true);
	for ($i = 0; $i < ITERATIONS; ++$i)
	{
		$value = $array_access_obj->$key;
	}
	$stop = microtime(true);
	echo "Class property get " . get_class($array_access_obj) . " and key $key:\n\t" .
		number_format($stop - $start, 8) . PHP_EOL;
}

output.txt

PHP version: 5.4.16
Unsafe and non-E_STRICT-compliant lookup for key existing_key:
	0.06961894
Unsafe and non-E_STRICT-compliant lookup for key unset_key:
	0.06871915
Unsafe and non-E_STRICT-compliant lookup for key non_existing_key:
	0.55242419
Inlined lookup using isset and key existing_key:
	0.10207295
Inlined lookup using isset and key unset_key:
	0.06304383
Inlined lookup using isset and key non_existing_key:
	0.06005597
Inlined lookup using array_key_exists and key existing_key:
	0.24598002
Inlined lookup using array_key_exists and key unset_key:
	0.24059892
Inlined lookup using array_key_exists and key non_existing_key:
	0.20083094
Lookup function 'lookup_isset' and key existing_key:
	0.41206813
Lookup function 'lookup_isset' and key unset_key:
	0.38659596
Lookup function 'lookup_isset' and key non_existing_key:
	0.40835810
Lookup function 'lookup_ake' and key existing_key:
	0.53824496
Lookup function 'lookup_ake' and key unset_key:
	0.53453398
Lookup function 'lookup_ake' and key non_existing_key:
	0.52240610
ArrayAccess AA and key existing_key:
	0.31920791
ArrayAccess AA and key unset_key:
	0.29070306
ArrayAccess AA and key non_existing_key:
	0.28701401
ArrayAccess ArrayBackedAA and key existing_key:
	0.35205817
ArrayAccess ArrayBackedAA and key unset_key:
	0.29902601
ArrayAccess ArrayBackedAA and key non_existing_key:
	0.28959703
Class property get AA and key existing_key:
	0.07733297
Class property get AA and key unset_key:
	0.07042480