一致性哈希的替代算法 shard 可反解vsid php版

/**
 * Linux 系统 根据共享内存块获取一个增长的整型
 */
function getNxtValFromSharedMemory()
{
    $string_seed = 'global_sharedmemory_' . $_SERVER['SERVER_ADDR'] . '_key';

    $sem = $shm = null;
    $retry_times = 1;
    do
    {
        //获取一个系统共享内存生成的id resource资源
        $sem = sem_get($string_seed, 1, 0777);
        $shm = shm_attach($string_seed, 128, 0777);

        if (is_resource($sem) && is_resource($shm)) {
            break;
        }

        $cmd = "ipcrm -M 0x00000000; ipcrm -S 0x00000000; ipcrm -M {$string_seed} ; ipcrm -S {$string_seed}";
        $last_line = exec($cmd, $output, $retval);
        //var_dump($last_line, $cmd, $output, $retval);

        if ($retval !== 0)
        {
            die('System cannot create sem/shm resource by php');
        }
    } while($retry_times-- > 0);
    if(!sem_acquire($sem))
    {
        die('System sem error');
    }

    $next_value = false;
    if (shm_has_var($shm, $string_seed))
    {
        $next_value = shm_get_var($shm, $string_seed) + 1;
        shm_put_var($shm, $string_seed, $next_value);
    }
    else
    {
        $next_value = 1;
        shm_put_var($shm, $serial_key, $next_value);
    }

    shm_detach($shm);
    sem_release($sem);
    return $next_value;

}

//求二进制
 1         $tr = 5672264790966273;
        $res_2 = '';
        do
        {

            $res_2 = $tr%2 . $res_2;
            $tr = $tr/2;

        }while($tr > 1);

        echo $res_2;

        exit;

        $ntime = microtime(true);
        echo "1、";
        echo $ntime;
        echo "<hr>";

        $time_sig = intval($ntime * 1000);
        echo "2、";
        echo $time_sig;
        echo "<hr>";
//这里需要服务器虚节点id
        $vsid = 4097;
        $auto_inc_sig = getNxtValFromSharedMemory（）;

        $serial_id = $time_sig << 12 | $vsid;
        echo "3、";
        echo $serial_id;
        echo "<hr>";

        $serial_id = $serial_id << 10 | ($auto_inc_sig % 1024);
        echo "4、";
        echo $serial_id;
        echo "<hr>";

        $s_r = $serial_id >> 10;
        echo "5、";
        echo $s_r;
        echo "<hr>";

        //这行
        $vsid = $s_r & (0xFFF);
        echo "6、";
        echo $vsid;
        exit;

/**
 * 从新格式全局序列ID反解出虚拟shard编号
 */
function extractVSID($serialId)
{
    if(!$serialId || !is_numeric($serialId))
        return false;
    else
        $serialId = (int)$serialId;

    return $serialId >> 10 & (0xFFF);
}

/**
 * 生成一个序列ID
 *
 * 格式：(42B microtime) + (12B vsid) + (10B autoinc)
 */
function makeSerialId($vsid)
{
    $vsid_max = 4095;
    $vsid_min = 1;
    if(!is_numeric($vsid) || $vsid < $vsid_min || $vsid > $vsid_max)
        return false;
    else
        $vsid = (int)$vsid;


    $auto_inc_sig = getNextValueByShareMemory();
    if(empty($auto_inc_sig))
        return false;

    $ntime = microtime(true);
    $time_sig = intval($ntime * 1000);
    $serial_id = $time_sig << 12 | $vsid;
    $serial_id = $serial_id << 10 | ($auto_inc_sig % 1024);
    return (string)$serial_id;
}

容易出现id冲突，待解决

/**
 * 通过本机共享内存件来生成一个auto_increment序列
 */
function getNextValueByShareMemory()
{
    $addr = '127.0.0.1';
    if(!empty($_SERVER['HTTP_X_FORWARDED_FOR']))
        $addr = $_SERVER['HTTP_X_FORWARDED_FOR'];
    elseif(!empty($_SERVER['SERVER_ADDR']))
        $addr = $_SERVER['SERVER_ADDR'];

    $skey = 'global_serial_generator_seed_'.$addr;
    $ikey = crc32($skey);

    $sem = $shm = null;
    $retry_times = 1;
    do
    {
        $sem = sem_get($ikey, 1, 0777);
        $shm = shm_attach($ikey, 128, 0777);
        if(is_resource($sem) && is_resource($shm))
            break;

        $cmd = "ipcrm -M 0x00000000; ipcrm -S 0x00000000; ipcrm -M {$ikey} ; ipcrm -S {$ikey}";
        $last_line = exec($cmd, $output, $retval);
    }while($retry_times-- > 0);

    if(!sem_acquire($sem))
        return false;

    $next_value = false;
    if(shm_has_var($shm, $ikey))
        shm_put_var($shm, $ikey, $next_value=shm_get_var($shm, $ikey)+1);
    else
        shm_put_var($shm, $ikey, $next_value=1);

    $shm && shm_detach($shm);
    $sem && sem_release($sem);
    return $next_value;
}