SimpleSHM 是一個較小的抽象層，用于使用 PHP 操作共享內存，支持以一種html' target='_blank'>面向對象的方式輕松操作內存段。在編寫使用共享內存進行存儲的小型應用程序時，這個庫可幫助創建非常簡潔的代碼。可以使用 3 個方法進行處理：讀、寫和刪除。從該類中簡單地實例化一個對象，可以控制打開的共享內存段。

類對象和測試代碼

 ?php//類對象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//測試使用代碼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);}

額外說明

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

請注意，上面代碼里沒有為該類傳遞一個 ID。如果沒有傳遞 ID，它將隨機選擇一個編號并打開該編號的新內存段。我們可以以參數的形式傳遞一個編號，供構造函數打開現有的內存段，或者創建一個具有特定 ID 的內存段，如下

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

神奇的方法 __destructor 負責在該內存段上調用 shmop_close 來取消設置對象，以與該內存段分離。我們將這稱為 “SimpleSHM 101”。現在讓我們將此方法用于更高級的用途：使用共享內存作為存儲。存儲數據集需要序列化，因為數組或對象無法存儲在內存中。盡管這里使用了 JSON 來序列化，但任何其他方法（比如 XML 或內置的 PHP 序列化功能）也已足夠。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);? 

我們成功地將一個數組序列化為一個 JSON 字符串，將它存儲在共享內存塊中，從中讀取數據，去序列化 JSON 字符串，并顯示存儲的數組。這看起來很簡單，但請想象一下這個代碼片段帶來的可能性。您可以使用它存儲 Web 服務請求、數據庫查詢或者甚至模板引擎緩存的結果。在內存中讀取和寫入將帶來比在磁盤中讀取和寫入更高的性能。

使用此存儲技術不僅對緩存有用，也對應用程序之間的數據交換也有用，只要數據以兩端都可讀的格式存儲。不要低估共享內存在 Web 應用程序中的力量。可采用許多不同的方式來巧妙地實現這種存儲，惟一的限制是開發人員的創造力和技能。

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