Merge-sort logs from resmoke.py, mongod, and mongobridge

sort.py

import heapq
import re
import sys
from datetime import datetime
from operator import itemgetter


def parse_lines(file_name):
    ts = datetime.min
    ts_str = ""

    # Replace "service_mongo1" with "node0" and "mongo1_bridge" with "bridge1".
    file_id = None
    if (match := re.match(r'service_mongo(\d+)', file_name)):
        file_id = f'd{int(match.group(1))}'
    elif (match := re.match(r'mongo(\d+)_bridge.log', file_name)):
        file_id = f'b{int(match.group(1))}'

    # Like 2020-06-24T12:00:05.133+00:00 or 2020-06-24T12:00:33.887+0000
    # or 2020-06-24T12:00:21.985Z.
    pat = re.compile(
        r'(\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}\.\d{3})(Z|\+00:?00)')

    for line in open(file_name):
        match = pat.search(line)
        if match:
            ts_str = match.group(1)
            ts = datetime.fromisoformat(match.group(1))

        if file_id:
            out = f'[js_test:foo] {ts_str}+0000 {file_id}| {line}'
        else:
            out = f'[js_test:foo] {ts_str}+0000 {line}'

        yield ts, out


def merge_logs(*file_names):
    generators = (parse_lines(file_name) for file_name in file_names)
    return heapq.merge(*generators, key=itemgetter(0))


for ts, line in merge_logs(*sys.argv[1:]):
    sys.stdout.write(line)