php解决高并发状态下文件读写的两种方法

一、对文件进行加锁时，设置一个超时时间

if($fp = fopen($fileName, 'a')) {
    $startTime = microtime();
    do {
            $canWrite = flock($fp, LOCK_EX);
        if(!$canWrite) usleep(round(rand(0, 100)*1000));
    } while ((!$canWrite) ＆＆ ((microtime()-$startTime) < 1000));
 
    if ($canWrite) {
      fwrite($fp, $dataToSave);
    }
    fclose($fp);
}

二、不使用flock函数，借用临时文件来解决读写冲突的问题

$dir_fileopen = "tmp";
  
function randomid() {
    return time().substr(md5(microtime()), 0, rand(5, 12));
}
function cfopen($filename, $mode） {
    global $dir_fileopen;
    clearstatcache();
    do {
        $id = md5(randomid(rand(), TRUE));
        $tempfilename = $dir_fileopen."/".$id.md5($filename);
    } while(file_exists($tempfilename));
    if (file_exists($filename)) {
        $newfile = false;
        copy($filename, $tempfilename);
    }else{
        $newfile = true;
    }
    $fp = fopen($tempfilename, $mode);
    return $fp ? array($fp, $filename, $id, @filemtime($filename)) : false;
}
/* http://www.manongjc.com/article/1359.html */
function cfwrite($fp,$string) { return fwrite($fp[0], $string); }
function cfclose($fp, $debug = "off") {
    global $dir_fileopen;
    $success = fclose($fp[0]);
    clearstatcache();
    $tempfilename = $dir_fileopen."/".$fp[2].md5($fp[1]);
    if ((@filemtime($fp[1]) == $fp[3]) || ($fp[4]==true && !file_exists($fp[1])) || $fp[5]==true) {
        rename($tempfilename, $fp[1]);
    }else{
        unlink($tempfilename);
        //说明有其它进程 在操作目标文件，当前进程被拒绝
        $success = false;
    }
    return $success;
}
$fp = cfopen('lock.txt','a+');
cfwrite($fp,"welcome to beijing.\n");
fclose($fp,'on');