Django middleware to collect slow queries using force_debug_cursor

middleware.py

import logging
import time

from django.conf import settings
from django.db import connection

THRESHOLD = getattr(settings, 'SLOW_REQUEST_THRESHOLD', 1.0)
LOG_SQL = getattr(settings, 'SLOW_REQUEST_LOG_SQL', False)

LOG = logging.getLogger(__name__)


class SlowRequestMiddleware:
    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        self.before(request)
        response = self.get_response(request)
        self.after(request)
        return response

    def before(self, request):
        self.start = time.perf_counter()
        # NOTE: probably better to monkey patch
        connection.force_debug_cursor = True

    def after(self, request):
        # create metrics
        duration = time.perf_counter() - self.start
        queries_time = (float(q['time']) for q in connection.queries_log)
        query_time = sum(queries_time, 0.0)

        # check whether to log
        if duration > THRESHOLD or query_time > THRESHOLD:
            LOG.warning('%s %s: duration=%.3f, num_queries=%d, query_time=%.3f',
                request.method,
                request.path,
                duration,
                len(connection.queries_log),
                query_time)
            if LOG_SQL:
                for query in connection.queries_log:
                    LOG.warning(
                        '(%s) %s', query['time'], query['sql']
                    )