django_sleep.py

"""
This module provides very simple Django middleware that sleeps on every request.

This is useful when you want to simulate slow response times (as might be
encountered, say, on a cell network).

To use, add this middleware, and add a value for SLEEP_TIME to your settings.

New feature: Look for an X-Django-Sleep header on each request,
to let the client specify per-request sleep time. The header override your settings.
X-Django-Sleep can be an float or an integer. If you use Firefox you can use the 'Modify Headers' addon
( https://addons.mozilla.org/en-US/firefox/addon/modify-headers/ ).
"""

import time

import django.core.exceptions
from django.conf import settings


class SleepMiddleware(object):

    def __init__(self):
        try:
            self.sleep_time = settings.SLEEP_TIME
        except AttributeError:
            raise django.core.exceptions.MiddlewareNotUsed
        if not isinstance(self.sleep_time, (int, float)) or self.sleep_time <= 0:
            raise django.core.exceptions.MiddlewareNotUsed

    def process_request(self, request):
        try:
            header = float(request.META['HTTP_X_DJANGO_SLEEP'])
        except (KeyError, ValueError):
            header = None
        
        if header >= 0:
            time.sleep(header)
        else:
            time.sleep(self.sleep_time)