Py-mon

what's your favourite pokemon? Mine is "Greninja".

python3 -m src.cli run "your command"

or

pip install -e .
pymon run "app.py"
pymon run "app.py" --ignore .venv

Scratchpad for me(you can ignore)

For related infos either go to knowledge dump or optimising storing paths

TODO

[x] inotify event bitmaks [x] inotify event structures [x] parsing event from the structure and event_buffer

[x] init inotify [x] close inotify [x] add watch [x] add watch to dir => watch every files [x] reading all registered events => queue [x] run the registered command [ ] Using epoll instead of plain reading fds using os.read [ ] extend api and cli to watch and control and taking actions for each files. May be a few tweaks

Watcher API design plan

class Watcher:
    def __init__(self):
        pass
watcher = Watcher()

class Events:
    CREATE = "create"
    DELETE = "delete"
    MODIFY = "modify"
    MOVE = "move"

class Path:
    pass

class Command:
    pass

observer = watcher.add(Path(),Path()).ignore(Path()).on(Events.CREATE).run(Command)
status_code = observer.observe()

CLI tool plan

py-mon "python3 app.py"

py-mon "fastapi dev --port 8000"

Resources

• Watchdog python (src/watchdog/observers/inotify_c.py)
• https://gist.github.com/quiver/3609972#file-inotify_test-py-L62
• https://developer.ibm.com/tutorials/l-ubuntu-inotify/

About inotify and related system calls

• inotify_init() for creating instance of inotify. Returns a file descriptor or -1(in case of failure)

• inotify_add_watch() for adding a watcher to a pathname and an event to monitor. Event are bitmask and multiple events can be combined by pipe operator or bitwise and. Returns an unique identifier for the watch. -1 in case of failure

• inotify_rm_watch() removes a watch. Takes the unique identifier

• read(fd) – Block and wait for events.

• close(fd) – Cleanup resources when done.

What makes the thing synchronous?

Synchronous read() is blocking. When you call read() on an inotify file descriptor, the process stops and waits until an event happens.

• While waiting:
  • The process can't handle other tasks.
  • The CPU is idle or underutilized.
  • The app can become unresponsive.