Question

I am going to need to make changes to a php file in runtime.
This is a configuration file that upon emergency would need a change to one of its settings.
My question is whether it is possible to lock the file before writing so that other sessions that try to access that file would postpone until the file is rewritten, and not crash the session saying the file was not found ?

Answer 1

是的,请见flock 功能

手册实例:

<?php

$fp = fopen("/tmp/lock.txt", "r+");

if (flock($fp, LOCK_EX)) {  // acquire an exclusive lock
    ftruncate($fp, 0);      // truncate file
    fwrite($fp, "Write something here
");
    fflush($fp);            // flush output before releasing the lock
    flock($fp, LOCK_UN);    // release the lock
} else {
    echo "Couldn t get the lock!";
}

fclose($fp);

?>

显然存在一些警告,例如,如果你重新使用陈旧的档案系统(FAT)<代码>flock(<>,则永远不会退回。如果你重新使用PHP作为ISAPI的延伸,那么flock将不会将文档从由其他PHP的双向校转/阅读。

友情链接