基本用法

    示例 #1 共享内存操作概述

    <?php

    // 创建一个系统 ID 为 0xff3 的 100 字节共享内存块
    $shm_id = shmop_open(0xff3, "c", 0644, 100);
    if (!    $shm_id) {
    echo     "无法创建共享内存段\n";
    }

    // 获取共享内存块的大小
    $shm_size = shmop_size($shm_id);
    echo     "SHM 块大小: " . $shm_size . " 已创建。\n";

    // 让我们将测试字符串写入共享内存
    $shm_bytes_written = shmop_write($shm_id, "my shared memory block", 0);
    if (    $shm_bytes_written != strlen("my shared memory block")) {
    echo     "无法写入整个长度的数据\n";
    }

    // 现在让我们读回字符串
    $my_string = shmop_read($shm_id, 0, $shm_size);
    if (!    $my_string) {
    echo     "无法从共享内存块读取\n";
    }
    echo     "共享内存中的数据为: " . $my_string . "\n";

    // 现在让我们删除块并关闭共享内存段
    if (!shmop_delete($shm_id)) {
    echo     "无法标记共享内存块以供删除。";
    }
    shmop_close($shm_id);

    ?>

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    用户贡献笔记 1 条笔记

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    匿名
    6 年前
    SHMOP 实现的简单类。

    # 警告 #

    您只能写/读一个方向。如果您尝试同时读写，您将获得损坏的数据。 (它像 STD 输入/输出一样工作)
    如果您需要双向通信，请创建 2 个 shmop 类实例。
    不要尝试为某个 shmid 附加多个阅读器或写入器，您将获得损坏的数据。此类使用笨拙的自旋锁来提高速度，而不是真正的原子操作。您可以使用 flock 添加信号量，但它非常慢。 (~x3)

    基准测试

    每秒读取次数：6316 每秒数据量：6.17 gb

    <?php
    ########################
    # shmopwriter.php
    ########################

    $blockSize = 1024 * 1024 * 100;
    $data = random_bytes($blockSize);

    try
    {
    $shm = new SHMOP('shmopwriter.php', 'c', 644, $blockSize);

    while(    1)
    {
    if(!    $shm->canWrite())
    continue;

    $shm->write($data);
    }

    $shm->close();

    } catch (    Exception $e) {
    echo     'Error: ', $e->getMessage(), PHP_EOL;
    exit;
    }

    ########################

    ########################
    # shmopreader.php
    ########################

    $blockSize = 1024 * 1024 * 100;
    $shm = new SHMOP('shmopwriter.php', 'c', 644, $blockSize);
    $readsMT = 0;
    $readsPS = 0;

    while(!    $shm->eof())
    {
    $times = microtime(true);

    if((    $data = $shm->read()) === false)
    continue;

    $readsPS++;
    $readsMT += round(((microtime(true) - $times ) * 1000), 3);

    if(    $readsMT > 1000)
    {
    echo     'Reads per sec: ', $readsPS, ' Data size per sec: ', convert($blockSize * $readsPS), PHP_EOL;
    $readsPS = 0;
    $readsMT = 0;
    }
    }

    function     convert($size)
    {
    $unit=array('b','kb','mb','gb','tb','pb');
    return @    round($size/pow(1024,($i=floor(log($size,1024)))),2).' '.$unit[$i];
    }
    ########################

    ########################
    # shmop.class.php
    ########################

    class SHMOP
    {
    private     $shmId;
    private     $shmHeaderSize;
    private     $shmHeaderOffset;
    private     $shmBlockSize;
    private     $shmMaxBlockSize;

    function     __construct(string $pathname, string $flags, int $mode, int $size)
    {
    $this->shmHeaderSize = strlen($size);
    $this->shmHeaderOffset = $this->shmHeaderSize + 1;
    $this->shmMaxBlockSize = $size;
    $this->shmBlockSize = $size + $this->shmHeaderOffset + 1;

    $this->shmId = shmop_open(ftok($pathname, 's'), $flags, $mode, $this->shmBlockSize);

    if(!    $this->shmId)
    throw new     Exception('shmop_open error');
    }

    function     __destruct()
    {
    if(!    $this->shmId)
    return;

    $this->close();
    }

    public function     read()
    {
    // Check SpinLock
    if(shmop_read($this->shmId, 0, 1) === "\0")
    return     false;

    // Get Header
    $dataSize = (int)shmop_read($this->shmId, 1, $this->shmHeaderSize);

    $data = shmop_read($this->shmId, $this->shmHeaderOffset, $dataSize);
    // release spinlock
    shmop_write($this->shmId, "\0", 0);
    return     $data;
    }

    public function     write(string $data)
    {
    // Check SpinLock
    if(shmop_read($this->shmId, 0, 1) !== "\0")
    return     false;

    $dataSize = strlen($data);

    if(    $dataSize < 1)
    throw new     Exception('dataSize < 1');

    if(    $dataSize > $this->shmMaxBlockSize)
    throw new     Exception('dataSize > shmMaxBlockSize: '. $this->shmMaxBlockSize);

    // pack very slow use kludge
    $dataSize .= "\0";

    // Write Header
    shmop_write($this->shmId, $dataSize, 1);
    // Write Data
    shmop_write($this->shmId, $data, $this->shmHeaderOffset);
    // Write spinlock
    shmop_write($this->shmId, "\1", 0);
    return     true;
    }

    public function     eof()
    {
    return (    shmop_read($this->shmId, 0, 1) === "\2") ? true : false;
    }

    public function     sendeof()
    {
    // Check SpinLock
    if(shmop_read($this->shmId, 0, 1) !== "\0")
    return     false;

    shmop_write($this->shmId, "\2", 0);
    return     true;
    }

    public function     canWrite()
    {
    // Check SpinLock
    return (shmop_read($this->shmId, 0, 1) === "\0") ? true : false;
    }

    public function     close()
    {
    return @    shmop_close($this->shmId);
    }

    private function     delete()
    {
    $del = @shmop_delete($this->shmId);

    if(    $del === false)
    return     false;

    return @    shmop_close($this->shmId);
    }
    }

    ?>
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