PHP operates shared memory shmop class and simple usage test code

<?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&#39;ll check if the block we&#39;re going to manipulate
     * already exists or needs to be created. If it exists, let&#39;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&#39;t exist, warnings will be cast, therefore we
     * suppress those with the @ operator.
     *
     * @access public
     * @param string $id ID of the shared memory block you want to check
     * @return boolean True if the block exists, false if it doesn&#39;t
     */
    public function exists($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&#39;t, we&#39;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 $data The data that you wan&#39;t to write into the shared memory block
     */
    public function write($data)
    {
        $size = mb_strlen($data, &#39;UTF-8&#39;);

        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(&#39;Simple\\SHM\\Block&#39;, $memory);

        $memory->write(&#39;Sample&#39;);
        $data = $memory->read();
        $this->assertEquals(&#39;Sample&#39;, $data);
    }

    public function testIsCreatingNewBlockWithId()
    {
        $memory = new Block(897);
        $this->assertInstanceOf(&#39;Simple\\SHM\\Block&#39;, $memory);
        $this->assertEquals(897, $memory->getId());

        $memory->write(&#39;Sample 2&#39;);
        $data = $memory->read();
        $this->assertEquals(&#39;Sample 2&#39;, $data);
    }

    public function testIsMarkingBlockForDeletion()
    {
        $memory = new Block(897);
        $memory->delete();
        $data = $memory->read();
        $this->assertEquals(&#39;Sample 2&#39;, $data);
    }

    public function testIsPersistingNewBlockWithoutId()
    {
        $memory = new Block;
        $this->assertInstanceOf(&#39;Simple\\SHM\\Block&#39;, $memory);
        $memory->write(&#39;Sample 3&#39;);
        unset($memory);

        $memory = new Block;
        $data = $memory->read();
        $this->assertEquals(&#39;Sample 3&#39;, $data);
    }
}

<?php
 
$memory = new SimpleSHM;
$memory->write(&#39;Sample&#39;);
echo $memory->read();
 
?>

<?php
 
$new = new SimpleSHM(897);
$new->write(&#39;Sample&#39;);
echo $new->read();
 
?>

<?php
 
require(&#39;SimpleSHM.class.php&#39;);
 
$results = array(
    &#39;user&#39; => &#39;John&#39;,
    &#39;password&#39; => &#39;123456&#39;,
    &#39;posts&#39; => array(&#39;My name is John&#39;, &#39;My name is not John&#39;)
);
 
$data = json_encode($results);
 
$memory = new SimpleSHM;
$memory->write($data);
$storedarray = json_decode($memory->read());
 
print_r($storedarray);
 
?>