phpの重複実行を避けるスクリプト

execute_only_once.php

<?php

if(count($argv) < 1){
    echo "no argument.";
    return;
}

$script_name = $argv[1];

// check script existance
if(!file_exists("./{$script_name}")){
    echo "no script.";
    return;
}

// check lockfile
$lockfile = "./{$script_name}.lock";
if(file_exists($lockfile)){
    echo "{$script_name} is already executing now.";
    return;
}

// execute
touch($lockfile);
require("./{$script_name}");
unlink($lockfile);