""" Tools for profiling.

See :ref:`profiling`."""

from __future__ import print_function

import cProfile

import itertools

from pyramid.view import view_config

@view_config(route_name='profile_ping')

def ping(request):

    """ View that handle '/_profile/ping'

    It simply reply 'ping', without requiring connection to the repository.

    It is a useful as a comparison point to evaluate the actual overhead of

    more costly views.

    """

    request.response.text = u'pong'

    return request.response

@view_config(route_name='profile_cnx')

def cnx(request):

    """ View that handle '/_profile/cnx'

    Same as :func:`ping`, but it first ask for a connection to the repository.

    Useful to evaluate the overhead of opening a connection.

    """

    request.cw_cnx

    request.response.text = u'pong'

    return request.response

def wsgi_profile(app, filename='program.prof', dump_every=50):

    """ A WSGI middleware for profiling

    It enable the profiler before passing the request to the underlying

    application, and disable it just after.

    The stats will be dumped after ``dump_every`` requests

    :param filename: The filename to dump the stats to.

    :param dump_every: Number of requests after which to dump the stats.

    """

    profile = cProfile.Profile()

    counter = itertools.count(1)

    def application(environ, start_response):

        profile.enable()

        try:

            return app(environ, start_response)

        finally:

            profile.disable()

            if not counter.next() % dump_every:

                print("Dump profile stats to %s" % filename)

                profile.create_stats()

                profile.dump_stats(filename)

    return application