欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识!
您现在的位置是: 首页  >  后端开发

php操作共享内存shmop类及简单使用测试的代码

程序员文章站 2022-03-27 22:09:46
...
这篇文章主要介绍了关于php操作共享内存shmop类及简单使用测试的代码,有着一定的参考价值,现在分享给大家,有需要的朋友可以参考一下

SimpleSHM 是一个较小的抽象层,用于使用 PHP 操作共享内存,支持以一种面向对象的方式轻松操作内存段。在编写使用共享内存进行存储的小型应用程序时,这个库可帮助创建非常简洁的代码。可以使用 3 个方法进行处理:读、写和删除。从该类中简单地实例化一个对象,可以控制打开的共享内存段。

类对象和测试代码

<?php
//类对象
namespace Simple\SHM;

class Block
{
    /**
     * Holds the system id for the shared memory block
     *
     * @var int
     * @access protected
     */
    protected $id;

    /**
     * Holds the shared memory block id returned by shmop_open
     *
     * @var int
     * @access protected
     */
    protected $shmid;

    /**
     * Holds the default permission (octal) that will be used in created memory blocks
     *
     * @var int
     * @access protected
     */
    protected $perms = 0644;

    /**
     * Shared memory block instantiation
     *
     * In the constructor we'll check if the block we're going to manipulate
     * already exists or needs to be created. If it exists, let's open it.
     *
     * @access public
     * @param string $id (optional) ID of the shared memory block you want to manipulate
     */
    public function __construct($id = null)
    {
        if($id === null) {
            $this->id = $this->generateID();
        } else {
            $this->id = $id;
        }

        if($this->exists($this->id)) {
            $this->shmid = shmop_open($this->id, "w", 0, 0);
        }
    }

    /**
     * Generates a random ID for a shared memory block
     *
     * @access protected
     * @return int System V IPC key generated from pathname and a project identifier
     */
    protected function generateID()
    {
        $id = ftok(__FILE__, "b");
        return $id;
    }

    /**
     * Checks if a shared memory block with the provided id exists or not
     *
     * In order to check for shared memory existance, we have to open it with
     * reading access. If it doesn't exist, warnings will be cast, therefore we
     * suppress those with the @ operator.
     *
     * @access public
     * @param string $id ID of the shared memory block you want to check
     * @return boolean True if the block exists, false if it doesn't
     */
    public function exists($id)
    {
        $status = @shmop_open($id, "a", 0, 0);
        return $status;
    }

    /**
     * Writes on a shared memory block
     *
     * First we check for the block existance, and if it doesn't, we'll create it. Now, if the
     * block already exists, we need to delete it and create it again with a new byte allocation that
     * matches the size of the data that we want to write there. We mark for deletion,  close the semaphore
     * and create it again.
     *
     * @access public
     * @param string $data The data that you wan't to write into the shared memory block
     */
    public function write($data)
    {
        $size = mb_strlen($data, 'UTF-8');

        if($this->exists($this->id)) {
            shmop_delete($this->shmid);
            shmop_close($this->shmid);
            $this->shmid = shmop_open($this->id, "c", $this->perms, $size);
            shmop_write($this->shmid, $data, 0);
        } else {
            $this->shmid = shmop_open($this->id, "c", $this->perms, $size);
            shmop_write($this->shmid, $data, 0);
        }
    }

    /**
     * Reads from a shared memory block
     *
     * @access public
     * @return string The data read from the shared memory block
     */
    public function read()
    {
        $size = shmop_size($this->shmid);
        $data = shmop_read($this->shmid, 0, $size);

        return $data;
    }

    /**
     * Mark a shared memory block for deletion
     *
     * @access public
     */
    public function delete()
    {
        shmop_delete($this->shmid);
    }

    /**
     * Gets the current shared memory block id
     *
     * @access public
     */
    public function getId()
    {
        return $this->id;
    }

    /**
     * Gets the current shared memory block permissions
     *
     * @access public
     */
    public function getPermissions()
    {
        return $this->perms;
    }

    /**
     * Sets the default permission (octal) that will be used in created memory blocks
     *
     * @access public
     * @param string $perms Permissions, in octal form
     */
    public function setPermissions($perms)
    {
        $this->perms = $perms;
    }

    /**
     * Closes the shared memory block and stops manipulation
     *
     * @access public
     */
    public function __destruct()
    {
        shmop_close($this->shmid);
    }
}
<?php
//测试使用代码
namespace Simple\SHM\Test;

use Simple\SHM\Block;

class BlockTest extends \PHPUnit_Framework_TestCase
{
    public function testIsCreatingNewBlock()
    {
        $memory = new Block;
        $this->assertInstanceOf('Simple\\SHM\\Block', $memory);

        $memory->write('Sample');
        $data = $memory->read();
        $this->assertEquals('Sample', $data);
    }

    public function testIsCreatingNewBlockWithId()
    {
        $memory = new Block(897);
        $this->assertInstanceOf('Simple\\SHM\\Block', $memory);
        $this->assertEquals(897, $memory->getId());

        $memory->write('Sample 2');
        $data = $memory->read();
        $this->assertEquals('Sample 2', $data);
    }

    public function testIsMarkingBlockForDeletion()
    {
        $memory = new Block(897);
        $memory->delete();
        $data = $memory->read();
        $this->assertEquals('Sample 2', $data);
    }

    public function testIsPersistingNewBlockWithoutId()
    {
        $memory = new Block;
        $this->assertInstanceOf('Simple\\SHM\\Block', $memory);
        $memory->write('Sample 3');
        unset($memory);

        $memory = new Block;
        $data = $memory->read();
        $this->assertEquals('Sample 3', $data);
    }
}

额外说明

<?php
 
$memory = new SimpleSHM;
$memory->write('Sample');
echo $memory->read();
 
?>

请注意,上面代码里没有为该类传递一个 ID。如果没有传递 ID,它将随机选择一个编号并打开该编号的新内存段。我们可以以参数的形式传递一个编号,供构造函数打开现有的内存段,或者创建一个具有特定 ID 的内存段,如下

<?php
 
$new = new SimpleSHM(897);
$new->write('Sample');
echo $new->read();
 
?>

神奇的方法 __destructor 负责在该内存段上调用 shmop_close 来取消设置对象,以与该内存段分离。我们将这称为 “SimpleSHM 101”。现在让我们将此方法用于更高级的用途:使用共享内存作为存储。存储数据集需要序列化,因为数组或对象无法存储在内存中。尽管这里使用了 JSON 来序列化,但任何其他方法(比如 XML 或内置的 PHP 序列化功能)也已足够。如下

<?php
 
require('SimpleSHM.class.php');
 
$results = array(
    'user' => 'John',
    'password' => '123456',
    'posts' => array('My name is John', 'My name is not John')
);
 
$data = json_encode($results);
 
$memory = new SimpleSHM;
$memory->write($data);
$storedarray = json_decode($memory->read());
 
print_r($storedarray);
 
?>

我们成功地将一个数组序列化为一个 JSON 字符串,将它存储在共享内存块中,从中读取数据,去序列化 JSON 字符串,并显示存储的数组。这看起来很简单,但请想象一下这个代码片段带来的可能性。您可以使用它存储 Web 服务请求、数据库查询或者甚至模板引擎缓存的结果。在内存中读取和写入将带来比在磁盘中读取和写入更高的性能。

使用此存储技术不仅对缓存有用,也对应用程序之间的数据交换也有用,只要数据以两端都可读的格式存储。不要低估共享内存在 Web 应用程序中的力量。可采用许多不同的方式来巧妙地实现这种存储,惟一的限制是开发人员的创造力和技能。

以上就是本文的全部内容,希望对大家的学习有所帮助,更多相关内容请关注PHP中文网!

相关推荐:

php实现共享内存进程通信函数(_shm)

以上就是php操作共享内存shmop类及简单使用测试的代码的详细内容,更多请关注其它相关文章!

相关标签: linux 缓存 php