php操作共享内存shmop类及简单使用测试的代码

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html' target='_blank'>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-  * 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

 ?phprequire( 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。

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