浅谈PHP设计模式之对象池模式Pool

吾爱主题阅读：214 2021-11-15 15:59:00 评论：0

目的

在初始化实例成本高，实例化率高，可用实例不足的情况下，对象池可以极大地提升性能。在创建对象（尤其是通过网络）时间花销不确定的情况下，通过对象池在可期时间内就可以获得所需的对象。

无论如何，对象池模式在需要耗时创建对象方面，例如创建数据库连接，套接字连接，线程和大型图形对象（比方字体或位图等），使用起来都是大有裨益的。在某些情况下，简单的对象池（无外部资源，只占内存）可能效率不高，甚至会有损性能。

UML 类图

代码

WorkerPool.php

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 <?php namespace DesignPatterns\Creational\Pool; class WorkerPool implements \Countable { /** * @var StringReverseWorker[] */ private $occupiedWorkers = []; /** * @var StringReverseWorker[] */ private $freeWorkers = []; public function get(): StringReverseWorker { if ( count ( $this ->freeWorkers) == 0) { $worker = new StringReverseWorker(); } else { $worker = array_pop ( $this ->freeWorkers); } $this ->occupiedWorkers[spl_object_hash( $worker )] = $worker ; return $worker ; } public function dispose(StringReverseWorker $worker ) { $key = spl_object_hash( $worker ); if (isset( $this ->occupiedWorkers[ $key ])) { unset( $this ->occupiedWorkers[ $key ]); $this ->freeWorkers[ $key ] = $worker ; } } public function count (): int { return count ( $this ->occupiedWorkers) + count ( $this ->freeWorkers); } }

StringReverseWorker.php

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 <?php namespace DesignPatterns\Creational\Pool; class StringReverseWorker { /** * @var \DateTime */ private $createdAt ; public function __construct() { $this ->createdAt = new \DateTime(); } public function run(string $text ) { return strrev ( $text ); } }

测试

Tests/PoolTest.php

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 <?php namespace DesignPatterns\Creational\Pool\Tests; use DesignPatterns\Creational\Pool\WorkerPool; use PHPUnit\Framework\TestCase; class PoolTest extends TestCase { public function testCanGetNewInstancesWithGet() { $pool = new WorkerPool(); $worker1 = $pool ->get(); $worker2 = $pool ->get(); $this ->assertCount(2, $pool ); $this ->assertNotSame( $worker1 , $worker2 ); } public function testCanGetSameInstanceTwiceWhenDisposingItFirst() { $pool = new WorkerPool(); $worker1 = $pool ->get(); $pool ->dispose( $worker1 ); $worker2 = $pool ->get(); $this ->assertCount(1, $pool ); $this ->assertSame( $worker1 , $worker2 ); } }