2024 日本 PHP 研討會

    基本用法

    範例 #1 共享記憶體操作概觀

    <?php

    // 建立一個 100 位元組的共享記憶體區塊，系統 ID 為 0xff3
    $shm_id = shmop_open(0xff3, "c", 0644, 100);
    if (!    $shm_id) {
    echo     "無法建立共享記憶體區段\n";
    }

    // 取得共享記憶體區塊的大小
    $shm_size = shmop_size($shm_id);
    echo     "已建立共享記憶體區塊大小： " . $shm_size . " 位元組\n";

    // 將測試字串寫入共享記憶體
    $shm_bytes_written = shmop_write($shm_id, "my shared memory block", 0);
    if (    $shm_bytes_written != strlen("my shared memory block")) {
    echo     "無法寫入完整資料長度\n";
    }

    // 讀取字串
    $my_string = shmop_read($shm_id, 0, $shm_size);
    if (!    $my_string) {
    echo     "無法從共享記憶體區塊讀取資料\n";
    }
    echo     "共享記憶體中的資料為： " . $my_string . "\n";

    // 刪除區塊並關閉共享記憶體區段
    if (!shmop_delete($shm_id)) {
    echo     "無法標記共享記憶體區塊以進行刪除。";
    }
    shmop_close($shm_id);

    ?>

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    3
    匿名
    6 年前
    用於 SHMOP 實作的簡單類別。

    # 警告 #

    您只能單向讀寫。如果您嘗試同時讀寫，您將會得到損毀的資料。(它的運作方式類似標準輸入/輸出)
    如果您需要雙向通訊，請建立兩個 shmop 類別的實例。
    對於同一個 shmid，請勿嘗試附加多個讀取器或寫入器，否則會造成資料損毀。此類別使用了一些權宜的 spinlocks 來提升速度，並未使用真正的原子操作。您可以使用 flock 加入信號量，但速度會非常慢（約為原本的 1/3）。

    效能基準測試

    每秒讀取次數：6316 每秒資料大小：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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