Simple Actor Model in Python

base-actor-model.py

import time
import threading
from queue import Queue, Empty

class Actor(object):
    """Basic event-based actor abstract."""

    def __init__(self):
        """Initialize Actor class."""
        self.inbox = Queue()
        self.setup()

    def receive(self, message):
        """Receive message and do action."""
        raise NotImplemented()

    def setup(self):
        """Override setup method if required."""
        pass

    def start(self):
        """Start receive message."""
        self.start = True
        while self.start:
            if not self.inbox.empty():
                try:
                    message = self.inbox.get_nowait()
                    threading.Thread(target=self.receive, args=(message,)).start()
                except Empty:
                    pass
            sleep(0.2)

fetch-site-title.py

import requests
from lxml import html

class FetchSiteTitle(Actor):
    """Fetch website title."""

    def setup(self):
        """Override setup method."""
        self._db_actor = StoreDataActor()

    def _fetch_content(self, url):
        """Get all content of url."""
        try:
            file = requests.get(url)
            return file.content
        except:
            return None
 
    def _fetch_title(self, url):
        """Parse content and fetch title tag text."""
        content = self._fetch_content(url)
        if not content:
            return None
        html_obj = html.fromstring(content)
        title_tags = html_obj.xpath("/html/head/title")
        if title_tags:
            return title_tags[0].text
        return None

    def receive(self, message):
        """Implement fetch title receive method."""
        url = message.get("url")
        title = self._fetch_title(url)
        if title:
            self._db_actor.inbox.put({"title":title})

main.py

if __name__ == "__main__":
    action = FetchSiteTitle()
    action.start()
    action.inbox.put({"url": "http://mortezana.com"})
    action.inbox.put({"url": "https://google.com"})

store-data-actor.py

import sqlite3

class StoreDataActor(Actor):
    """Store data in database."""

    def setup(self):
        """Override setup method."""
        self._db = sqlite3.connect(":memory")
        self._cur = self._db.cursor()

    def receive(self, message):
        """Implement store in db receive method."""
        title = message.get("title")
        self._cur.execute("INSERT INTO site_info(title) VALUES ({})".format(title)
        self._con.commit()

Great reference: https://medium.com/@ianjuma/the-actor-model-in-python-with-gevent-b8375d0986fa