Watch the config folder for file changes

[nicoverbruggen]

Currently, there's a manual refresh option in v3.3 (added via #24) but in the future I'd like to watch the config folder for file changes, so that when a file in the config folder changes, PHP Monitor automatically reloads the PHP installation information.

Important note: The folder watcher should stop watching when the PHP version changes, and start watching again. It should do this without leaking memory, so I should be careful about retain cycles here.

[nicoverbruggen]

I've got a preliminary version of this up and running. Was a bit interesting to figure out, but if you're into the deets here's how it works so far:

• The config folder is located
• The following paths are checked: /php.ini, /conf.d and watchers are created for these
• The contents of conf.d is checked; for each file that ends with .ini, an additional watcher is set up
• Whenever a watcher reports a file change, PHP Monitor reloads

So far, it works great, but the watchers don't dynamically update based on new files. So if you add a new .ini file, the watcher will trigger once, but subsequent changes to that .ini file aren't tracked.

Also, if you install an extension this watcher event may trigger like 20 times in < 1 second, so that needs to be debounced as well. Otherwise, it attempts to load PHP info that many times as well, blocking the main thread.

More on that next time I work on this.

[nicoverbruggen]

Planned for 4.2 or later, since this is a big change. Not sure I'll have time to polish this by the end of the year. It's gonna depend :)