PHP执行过程中的log

function Dmess($msg, $prefix='') {
    $debugMethod = 1;// 0-> print out stnd; 1-> write log file;
    $traceArr = debug_backtrace();
    $lastTrace = end($traceArr);
    if( strlen($prefix)>0 )
    	$line = "[".date("Y-m-d H:i:s")."][".$prefix."] ".$msg;
    else {
    	$line = "[".date("Y-m-d H:i:s")."][";
    	for($i=count($traceArr);$i>0;$i--){
    		$trace = $traceArr[$i-1];
    		$line .= basename($trace['file']).":".$trace['line'];
    		if( $i==count($traceArr) )
    			$line .= "|".$trace['function'];
    		$line .= "=>";
    	}
    	$line = substr($line, 0, -2);
    	$line .= "] " . $msg;
    }
    if( $debugMethod==0 ) {
        print "\n<!--<debug>$msg</debug>//-->\n";
        //print "\nDEBUG:: $msg</debug><br/>\n";
        flush();
        ob_flush();
    }
    else {
        $logfile = "./logs/debug.log";
        write2file($line."\n", $logfile);
    }
}

function write2file($msg,$fileName)
{
    $fp = @fopen($fileName, 'a');
    if($fp==false)
    {
        $fp=@fopen($fileName,'w+');
        if($fp==false)
        {
            if($fileName!=DEBUGFILE) {
                echo "ERROR:: file ".$fileName." can not be created for writing";
                exit();
            }
            else
            {
                echo " file ".$fileName." can not be created for writing";
                return 0;
            }
        }
    }
    $lfp = flock($fp,LOCK_EX);
    $i = 0;
    while ($lfp == False)
    {
        $i++;
        $lfp = flock($fp,LOCK_EX);
        if ($i==10){return(0);}
    }
    fputs($fp,$msg);
    flock($fp,LOCK_UN);
    fclose($fp);
    return 1;
}