5百万 uid 白名单 之 PHP Bitmap 处理
近日，有同事说有个 5百万 的白名单处理， 到网上查找 相似案例， 说是有个bitmap的解法，
再次 google ，baidu 无相关 PHP 的解法， 于是自己写了一个：
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handler = @fopen($file , 'r+') OR die('open bitmap file failed');
else
$this->handler = @fopen($file , 'w+') OR die('open bitmap file failed');
$this->max = file_exists($file) ? (filesize($file) * 8 - 1) : 0;
}
public function __destruct()
{
@fclose($this->handler);
}
private function binary_dump($binary_data)
{
return sprintf('%08d',decbin(hexdec(bin2hex($binary_data))));
}
private function num_check($num)
{
($num > -1) OR die('number must be greater than -1');
($num < 4294967296) or die('number must be less than 4294967296'); // 2^32
if ($this->max < $num) {
fseek($this->handler, 0, SEEK_END);
fwrite($this->handler , str_repeat("\x00",ceil(($num - $this->max)/8))); // fill with 0
$this->max = ceil($num/8)*8 - 1;
}
}
public function set($num)
{
$this->num_check($num);
fseek($this->handler, floor($num/8), SEEK_SET);
$bin = fread($this->handler, 1) | pack('C',0x100 >> fmod($num,8)+1); // mark with 1
fseek($this->handler, ftell($this->handler)-1, SEEK_SET); // write a new byte
fwrite($this->handler, $bin);
fflush($this->handler);
}
public function del($num)
{
$this->num_check($num);
fseek($this->handler, floor($num/8), SEEK_SET);
$bin = fread($this->handler, 1) & ~pack('C',0x100 >> fmod($num,8)+1); // mark with 0
fseek($this->handler, ftell($this->handler)-1, SEEK_SET); // write a new byte
fwrite($this->handler, $bin);
fflush($this->handler);
}
public function find($num)
{
if (fseek($this->handler, floor($num/8), SEEK_SET) == -1) return FALSE;
$bin = fread($this->handler , 1);
if ($bin === FALSE || strlen($bin) == 0) return FALSE;
$bin = $bin & pack('C',0x100 >> fmod($num,8)+1);
if($bin === "\x00") return FALSE;
return TRUE;
}
}
$b = new Bitmap('/dev/shm/bitmapdata');
// 设置白名单
$b->set(1); $b->set(3); $b->set(5);
$b->set(7); $b->set(9); $b->set(501);
$uid = 501;
var_dump($b->find($uid)); // 查找白名单
$b->del($uid); // 删除白名单
var_dump($b->find($uid)); // 查找白名单
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其中 “$b = new Bitmap('/dev/shm/bitmapdata');”? 把文件，放在内存里，增加读写速度
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执行结果如下：
hu@xunleiman-desktop:~/web/test/shm$ /bin/sh ./geany_run_script.sh
bool(true)
bool(false)
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生成的bitmapdata文件 在附件里面：
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