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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<?php/* 5百万 uid 白名单 之 PHP Bitmap 处理 * author: hushuilong * email: hushuilong at gmail dot com * */class Bitmap { private $handler = NULL; private $max = 0; public function __construct($file) { clearstatcache(true, $file); if(file_exists($file)) $this->handler = @fopen($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?
其中 “$b = new Bitmap('/dev/shm/bitmapdata');”? 把文件，放在内存里，增加读写速度
执行结果如下：
[email protected]:~/web/test/shm$ /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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