Look for loops in the trigger data

looper.py

# encoding: utf-8
"""
Detects loops in the triggers

Heavily based on https://git.bbcarchdev.net/res/docker/blob/master/graphite/collect.py
"""
import logging
logging.basicConfig(level=logging.INFO)

import psycopg2
from psycopg2.extensions import ISOLATION_LEVEL_AUTOCOMMIT
DSN = 'host=192.168.99.100 dbname=spindle user=postgres port=32768'

QUERY = 'SELECT * FROM "triggers"'

# Connect to the DB
db = psycopg2.connect(DSN)
db.set_isolation_level(ISOLATION_LEVEL_AUTOCOMMIT)
logging.info("Database connection established")

def find_loop(edges, visited_ids):
    current_id = visited_ids[-1]
    logging.debug('Visited ids: {}'.format(visited_ids))
    if current_id in edges:
        for next_id in edges[current_id]:
            new_path = [visited_id for visited_id in visited_ids]
            new_path.append(next_id)
            if next_id in visited_ids:
                logging.info('Found a loop: {}'.format(new_path))
            else:
                find_loop(edges, new_path)

try:
    # Get all the data
    curs = db.cursor()
    curs.execute(QUERY)
    values = curs.fetchall()
    
    # Extract a list of edges
    trigger_ids = set()
    edges = {}
    for (target_id, trigger_uri, trigger_id, flags) in values:
        # Create the edge
        if trigger_id != None:
            edges.setdefault(trigger_id, set())
            if target_id in edges[trigger_id]:
                logging.warning("Duplicate trigger for {} ({})".format(trigger_uri, trigger_id))
            if target_id == trigger_id:
                logging.warning("Self trigger for {} ({})".format(trigger_uri, trigger_id))
            if target_id != trigger_id:
                edges[trigger_id].add(target_id)
            # Add the ids to the set
            trigger_ids.add(trigger_id)
            trigger_ids.add(target_id)
    logging.info("Got {} edges".format(len(edges)))
            
    # Compose all the paths
    logging.info("Will check {} starting point".format(len(trigger_ids)))
    for trigger_id in trigger_ids:
        logging.debug("=== {} ===".format(trigger_id))
        find_loop(edges, [trigger_id])
        
except Exception as e:
    logging.error(e)
finally:
    logging.info("Closing database connection")
    db.close()