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()),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');

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