PHP SPL标准库 SplFixedArray 介绍及和Array的性能测试

发布:smiling　来源: PHP粉丝网　添加日期：2015-05-09 09:58:20　浏览: 评论：0　

SPL - Standard PHP Library,标准PHP类库,本文我们来看看SPL标准库之数据结构SplFixedArray,及SplFixedArray和Array的性能测试对比.

SplFixedArray主要是处理数组相关的主要功能,与普通php array不同的是,它是固定长度的,且以数字为键名的数组,优势就是比普通的数组处理更快.

看看我本机的Benchmark测试:

ini_set('memory_limit','12800M');

for($size = 10000; $size < 10000000; $size *= 4) {

    echo PHP_EOL . "Testing size: $size" . PHP_EOL;

    for($s = microtime(true), $container = Array(), $i = 0; $i < $size; $i++) $container[$i] = NULL;

    echo "Array(): " . (microtime(true) - $s) . PHP_EOL;

    for($s = microtime(true), $container = new SplFixedArray($size), $i = 0; $i < $size; $i++) $container[$i] = NULL;

    echo "SplArray(): " . (microtime(true) - $s) . PHP_EOL;

}

//结果如下：

Testing size: 10000

Array(): 0.004000186920166

SplArray(): 0.0019998550415039

Testing size: 40000

Array(): 0.017001152038574

SplArray(): 0.0090007781982422

Testing size: 160000

Array(): 0.050002098083496

SplArray(): 0.046003103256226

Testing size: 640000

Array(): 0.19701099395752

SplArray(): 0.16700983047485

Testing size: 2560000

Array(): 0.75704312324524

SplArray(): 0.67303895950317

通常情况下SplFixedArray要比php array快上20%~30%,所以如果你是处理巨大数量的固定长度数组,还是强烈建议使用.

SplFixedArray类摘要如下:

SplFixedArray  implements Iterator   , ArrayAccess   , Countable   {

    /* 方法 */

    public __construct  ([ int $size  = 0  ] )

    public int count  ( void )

    public mixed current  ( void )

    public static SplFixedArray fromArray  ( array $array  [, bool $save_indexes  = true  ] )

    public int getSize  ( void )

    public int key  ( void )

    public void next  ( void )

    public bool offsetExists  ( int $index  )

    public mixed offsetGet  ( int $index  )

    public void offsetSet  ( int $index  , mixed  $newval  )

    public void offsetUnset  ( int $index  )

    public void rewind  ( void )

    public int setSize  ( int $size  )

    public array toArray  ( void )

    public bool valid  ( void )

    public void __wakeup  ( void )

}

使用SplFixedArray:

$arr = new SplFixedArray(4);

$arr[0] = 'php';

$arr[1] = 1;

$arr[3] = 'python';

//遍历， $arr[2] 为null

foreach($arr as $v) {

    echo $v . PHP_EOL;

}

//获取数组长度

echo $arr->getSize(); //4

//增加数组长度

$arr->setSize(5);

$arr[4] = 'new one';

//捕获异常

try{

    echo $arr[10];

} catch (RuntimeException $e) {

    echo $e->getMessage();

}

SplFixedArray和Array的性能测试

PHP文档专门说明:

The SplFixedArray class provides the main functionalities of array. The main differences between a SplFixedArray and a normal PHP array is that the SplFixedArray is of fixed length and allows only integers within the range as indexes. The advantage is that it allows a faster array implementation.

所以在处理大型的、以数字为索引的数组时,应该用SplFixedArray来代替普通Array,下面是测试代码:

<?php

function pr() {

    $params = func_get_args();

    $env = php_sapi_name();

    if ("cli" == $env) {

        foreach ($params as $key => $value) {

            echo $value;

        }

    } else {

        foreach ($params as $key => $value) {

            echo "<pre>";

            print_r($value);

            echo "</pre>";

        }

    }

} // 用来打印输出结果

<?php

require dirname(__FILE__)."/function.php";

for ($size=1000; $size<=50000000; $size*=2) {

    pr(PHP_EOL . "Testing size: $size" . PHP_EOL);

    for($s = microtime(true), $container = Array(), $i = 0; $i < $size; $i++) {

        $container[$i] = NULL;

    }  //phpfensi.com

    pr( "Array(): " . (microtime(true) - $s) . PHP_EOL);

    for($s = microtime(true), $container = new SplFixedArray($size), $i = 0; $i < $size; $i++) {

        $container[$i] = NULL;

    }

    pr("SplArray(): " . (microtime(true) - $s) . PHP_EOL);

}