changedetection.io/changedetectionio/update_worker.py

import os
import threading
import queue
import time

from changedetectionio import content_fetcher
from changedetectionio.html_tools import FilterNotFoundInResponse

# A single update worker
#
# Requests for checking on a single site(watch) from a queue of watches
# (another process inserts watches into the queue that are time-ready for checking)

import logging
import sys

class update_worker(threading.Thread):
    current_uuid = None

    def __init__(self, q, notification_q, app, datastore, *args, **kwargs):
        logging.basicConfig(stream=sys.stderr, level=logging.DEBUG)
        self.q = q
        self.app = app
        self.notification_q = notification_q
        self.datastore = datastore
        super().__init__(*args, **kwargs)

    def send_content_changed_notification(self, t, watch_uuid):

        from changedetectionio import diff

        from changedetectionio.notification import (
            default_notification_format_for_watch
        )

        n_object = {}
        watch = self.datastore.data['watching'].get(watch_uuid, False)
        if not watch:
            return

        watch_history = watch.history
        dates = list(watch_history.keys())
        # Theoretically it's possible that this could be just 1 long,
        # - In the case that the timestamp key was not unique
        if len(dates) == 1:
            raise ValueError(
                "History index had 2 or more, but only 1 date loaded, timestamps were not unique? maybe two of the same timestamps got written, needs more delay?"
            )

        n_object['notification_urls'] = watch['notification_urls'] if len(watch['notification_urls']) else \
            self.datastore.data['settings']['application']['notification_urls']

        n_object['notification_title'] = watch['notification_title'] if watch['notification_title'] else \
            self.datastore.data['settings']['application']['notification_title']

        n_object['notification_body'] = watch['notification_body'] if watch['notification_body'] else \
            self.datastore.data['settings']['application']['notification_body']

        n_object['notification_format'] = watch['notification_format'] if watch['notification_format'] != default_notification_format_for_watch else \
            self.datastore.data['settings']['application']['notification_format']


        # Only prepare to notify if the rules above matched
        if 'notification_urls' in n_object and n_object['notification_urls']:
            # HTML needs linebreak, but MarkDown and Text can use a linefeed
            if n_object['notification_format'] == 'HTML':
                line_feed_sep = "</br>"
            else:
                line_feed_sep = "\n"

            with open(watch_history[dates[-1]], 'rb') as f:
                snapshot_contents = f.read()

            n_object.update({
                'watch_url': watch['url'],
                'uuid': watch_uuid,
                'current_snapshot': snapshot_contents.decode('utf-8'),
                'diff': diff.render_diff(watch_history[dates[-2]], watch_history[dates[-1]], line_feed_sep=line_feed_sep),
                'diff_full': diff.render_diff(watch_history[dates[-2]], watch_history[dates[-1]], True, line_feed_sep=line_feed_sep)
            })
            logging.info (">> SENDING NOTIFICATION")
            self.notification_q.put(n_object)
        else:
            logging.info (">> NO Notification sent, notification_url was empty in both watch and system")

    def send_filter_failure_notification(self, watch_uuid):

        threshold = self.datastore.data['settings']['application'].get('filter_failure_notification_threshold_attempts')
        watch = self.datastore.data['watching'].get(watch_uuid, False)
        if not watch:
            return

        n_object = {'notification_title': 'Changedetection.io - Alert - CSS/xPath filter was not present in the page',
                    'notification_body': "Your configured CSS/xPath filter of '{}' for {{watch_url}} did not appear on the page after {} attempts, did the page change layout?\n\nLink: {{base_url}}/edit/{{watch_uuid}}\n\nThanks - Your omniscient changedetection.io installation :)\n".format(
                        watch['css_filter'],
                        threshold),
                    'notification_format': 'text'}

        if len(watch['notification_urls']):
            n_object['notification_urls'] = watch['notification_urls']

        elif len(self.datastore.data['settings']['application']['notification_urls']):
            n_object['notification_urls'] = self.datastore.data['settings']['application']['notification_urls']

        # Only prepare to notify if the rules above matched
        if 'notification_urls' in n_object:
            n_object.update({
                'watch_url': watch['url'],
                'uuid': watch_uuid
            })
            self.notification_q.put(n_object)
            print("Sent filter not found notification for {}".format(watch_uuid))

    def cleanup_error_artifacts(self, uuid):
        # All went fine, remove error artifacts
        cleanup_files = ["last-error-screenshot.png", "last-error.txt"]
        for f in cleanup_files:
            full_path = os.path.join(self.datastore.datastore_path, uuid, f)
            if os.path.isfile(full_path):
                os.unlink(full_path)

    def run(self):
        from changedetectionio import fetch_site_status

        update_handler = fetch_site_status.perform_site_check(datastore=self.datastore)

        while not self.app.config.exit.is_set():

            try:
                priority, uuid = self.q.get(block=False)
            except queue.Empty:
                pass

            else:
                self.current_uuid = uuid

                if uuid in list(self.datastore.data['watching'].keys()):
                    changed_detected = False
                    contents = b''
                    screenshot = False
                    update_obj= {}
                    xpath_data = False
                    process_changedetection_results = True
                    print("> Processing UUID {} Priority {} URL {}".format(uuid, priority, self.datastore.data['watching'][uuid]['url']))
                    now = time.time()

                    try:
                        changed_detected, update_obj, contents = update_handler.run(uuid)
                        # Re #342
                        # In Python 3, all strings are sequences of Unicode characters. There is a bytes type that holds raw bytes.
                        # We then convert/.decode('utf-8') for the notification etc
                        if not isinstance(contents, (bytes, bytearray)):
                            raise Exception("Error - returned data from the fetch handler SHOULD be bytes")
                    except PermissionError as e:
                        self.app.logger.error("File permission error updating", uuid, str(e))
                        process_changedetection_results = False
                    except content_fetcher.ReplyWithContentButNoText as e:
                        # Totally fine, it's by choice - just continue on, nothing more to care about
                        # Page had elements/content but no renderable text
                        # Backend (not filters) gave zero output
                        self.datastore.update_watch(uuid=uuid, update_obj={'last_error': "Got HTML content but no text found (With {} reply code).".format(e.status_code)})
                        if e.screenshot:
                            self.datastore.save_screenshot(watch_uuid=uuid, screenshot=e.screenshot)
                        process_changedetection_results = False

                    except content_fetcher.Non200ErrorCodeReceived as e:
                        if e.status_code == 403:
                            err_text = "Error - 403 (Access denied) received"
                        elif e.status_code == 404:
                            err_text = "Error - 404 (Page not found) received"
                        elif e.status_code == 500:
                            err_text = "Error - 500 (Internal server Error) received"
                        else:
                            err_text = "Error - Request returned a HTTP error code {}".format(str(e.status_code))

                        if e.screenshot:
                            self.datastore.save_screenshot(watch_uuid=uuid, screenshot=e.screenshot, as_error=True)
                        if e.xpath_data:
                            self.datastore.save_xpath_data(watch_uuid=uuid, data=e.xpath_data, as_error=True)
                        if e.page_text:
                            self.datastore.save_error_text(watch_uuid=uuid, contents=e.page_text)

                        self.datastore.update_watch(uuid=uuid, update_obj={'last_error': err_text,
                                                                           # So that we get a trigger when the content is added again
                                                                           'previous_md5': ''})
                        process_changedetection_results = False

                    except FilterNotFoundInResponse as e:
                        if not self.datastore.data['watching'].get(uuid):
                            continue

                        err_text = "Warning, filter '{}' not found".format(str(e))
                        self.datastore.update_watch(uuid=uuid, update_obj={'last_error': err_text,
                                                                           # So that we get a trigger when the content is added again
                                                                           'previous_md5': ''})

                        # Only when enabled, send the notification
                        if self.datastore.data['watching'][uuid].get('filter_failure_notification_send', False):
                            c = self.datastore.data['watching'][uuid].get('consecutive_filter_failures', 5)
                            c += 1
                            # Send notification if we reached the threshold?
                            threshold = self.datastore.data['settings']['application'].get('filter_failure_notification_threshold_attempts',
                                                                                           0)
                            print("Filter for {} not found, consecutive_filter_failures: {}".format(uuid, c))
                            if threshold > 0 and c >= threshold:
                                if not self.datastore.data['watching'][uuid].get('notification_muted'):
                                    self.send_filter_failure_notification(uuid)
                                c = 0

                            self.datastore.update_watch(uuid=uuid, update_obj={'consecutive_filter_failures': c})

                        process_changedetection_results = True

                    except content_fetcher.EmptyReply as e:
                        # Some kind of custom to-str handler in the exception handler that does this?
                        err_text = "EmptyReply - try increasing 'Wait seconds before extracting text', Status Code {}".format(e.status_code)
                        self.datastore.update_watch(uuid=uuid, update_obj={'last_error': err_text,
                                                                           'last_check_status': e.status_code})
                    except content_fetcher.ScreenshotUnavailable as e:
                        err_text = "Screenshot unavailable, page did not render fully in the expected time - try increasing 'Wait seconds before extracting text'"
                        self.datastore.update_watch(uuid=uuid, update_obj={'last_error': err_text,
                                                                           'last_check_status': e.status_code})
                        process_changedetection_results = False
                    except content_fetcher.JSActionExceptions as e:
                        err_text = "Error running JS Actions - Page request - "+e.message
                        if e.screenshot:
                            self.datastore.save_screenshot(watch_uuid=uuid, screenshot=e.screenshot, as_error=True)
                        self.datastore.update_watch(uuid=uuid, update_obj={'last_error': err_text,
                                                                           'last_check_status': e.status_code})
                    except content_fetcher.PageUnloadable as e:
                        err_text = "Page request from server didnt respond correctly"
                        if e.message:
                            err_text = "{} - {}".format(err_text, e.message)

                        if e.screenshot:
                            self.datastore.save_screenshot(watch_uuid=uuid, screenshot=e.screenshot, as_error=True)

                        self.datastore.update_watch(uuid=uuid, update_obj={'last_error': err_text,
                                                                           'last_check_status': e.status_code})
                    except Exception as e:
                        self.app.logger.error("Exception reached processing watch UUID: %s - %s", uuid, str(e))
                        self.datastore.update_watch(uuid=uuid, update_obj={'last_error': str(e)})
                        # Other serious error
                        process_changedetection_results = False
                    else:
                        # Crash protection, the watch entry could have been removed by this point (during a slow chrome fetch etc)
                        if not self.datastore.data['watching'].get(uuid):
                            continue

                        # Mark that we never had any failures
                        if not self.datastore.data['watching'][uuid].get('ignore_status_codes'):
                            update_obj['consecutive_filter_failures'] = 0

                        self.cleanup_error_artifacts(uuid)

                    # Different exceptions mean that we may or may not want to bump the snapshot, trigger notifications etc
                    if process_changedetection_results:
                        try:
                            watch = self.datastore.data['watching'][uuid]
                            fname = "" # Saved history text filename

                            # For the FIRST time we check a site, or a change detected, save the snapshot.
                            if changed_detected or not watch['last_checked']:
                                # A change was detected
                                watch.save_history_text(contents=contents, timestamp=str(round(time.time())))

                            self.datastore.update_watch(uuid=uuid, update_obj=update_obj)

                            # A change was detected
                            if changed_detected:
                                print (">> Change detected in UUID {} - {}".format(uuid, watch['url']))

                                # Notifications should only trigger on the second time (first time, we gather the initial snapshot)
                                if watch.history_n >= 2:
                                    if not self.datastore.data['watching'][uuid].get('notification_muted'):
                                        self.send_content_changed_notification(self, watch_uuid=uuid)


                        except Exception as e:
                            # Catch everything possible here, so that if a worker crashes, we don't lose it until restart!
                            print("!!!! Exception in update_worker !!!\n", e)
                            self.app.logger.error("Exception reached processing watch UUID: %s - %s", uuid, str(e))
                            self.datastore.update_watch(uuid=uuid, update_obj={'last_error': str(e)})


                    # Always record that we atleast tried
                    self.datastore.update_watch(uuid=uuid, update_obj={'fetch_time': round(time.time() - now, 3),
                                                                       'last_checked': round(time.time())})

                    # Always save the screenshot if it's available
                    if update_handler.screenshot:
                        self.datastore.save_screenshot(watch_uuid=uuid, screenshot=update_handler.screenshot)
                    if update_handler.xpath_data:
                        self.datastore.save_xpath_data(watch_uuid=uuid, data=update_handler.xpath_data)


                self.current_uuid = None  # Done
                self.q.task_done()

                # Give the CPU time to interrupt
                time.sleep(0.1)

            self.app.config.exit.wait(1)