[olalonde]

IME, race conditions are quite rare and pretty easy to solve in JS, because the flow of code execution is only susceptible to be interrupted at known locations (async function calls). Here's an example of how you could solve the problem you mentioned in a few lines of JavaScript:

    function createRunExclusive() {
      let runningTask = Promise.resolve();
      return async (asyncFn) => {
        runningTask = runningTask.then(async () => {
          return await asyncFn();
        });
        return runningTask;
      }
    }

    // Example usage:
    // The idea is that any command that should not overlap should use the same "runExclusive" function
    const runExclusive = createRunExclusive();
    function handleIpTablesCommand() {
      runExclusive(async () => {
        await doSomethingWithIpTables();
      })
    }

Although it's probably best to just use one of the queue libraries on npm. This one for example: https://www.npmjs.com/package/p-queue

[joeycumines]

Hey, that's a neat little trick to implement locking in JS, thanks.

I oversimplified my example perhaps - it also involved handling interruptions (certain system events), maintaining a lifecycle (set up and tear down), and scenarios where it allowed a certain subset of operations to be performed, while performing one of several operations. That last requirement was due to it using shell scripts to perform configuration of the system, and it needing to extract runtime and configuration information from the main daemon.

Still though, thanks very much for your comments, I've enjoyed reading them.