# -*- coding: utf-8 -*-
# Copyright 2016 OpenMarket Ltd
# Copyright 2018 New Vector Ltd.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from six.moves import range

from twisted.internet import defer, reactor
from twisted.internet.defer import CancelledError

from synapse.util import Clock, logcontext
from synapse.util.async import Linearizer

from tests import unittest


class LinearizerTestCase(unittest.TestCase):

    @defer.inlineCallbacks
    def test_linearizer(self):
        linearizer = Linearizer()

        key = object()

        d1 = linearizer.queue(key)
        cm1 = yield d1

        d2 = linearizer.queue(key)
        self.assertFalse(d2.called)

        with cm1:
            self.assertFalse(d2.called)

        with (yield d2):
            pass

    def test_lots_of_queued_things(self):
        # we have one slow thing, and lots of fast things queued up behind it.
        # it should *not* explode the stack.
        linearizer = Linearizer()

        @defer.inlineCallbacks
        def func(i, sleep=False):
            with logcontext.LoggingContext("func(%s)" % i) as lc:
                with (yield linearizer.queue("")):
                    self.assertEqual(
                        logcontext.LoggingContext.current_context(), lc)
                    if sleep:
                        yield Clock(reactor).sleep(0)

                self.assertEqual(
                    logcontext.LoggingContext.current_context(), lc)

        func(0, sleep=True)
        for i in range(1, 100):
            func(i)

        return func(1000)

    @defer.inlineCallbacks
    def test_multiple_entries(self):
        limiter = Linearizer(max_count=3)

        key = object()

        d1 = limiter.queue(key)
        cm1 = yield d1

        d2 = limiter.queue(key)
        cm2 = yield d2

        d3 = limiter.queue(key)
        cm3 = yield d3

        d4 = limiter.queue(key)
        self.assertFalse(d4.called)

        d5 = limiter.queue(key)
        self.assertFalse(d5.called)

        with cm1:
            self.assertFalse(d4.called)
            self.assertFalse(d5.called)

        cm4 = yield d4
        self.assertFalse(d5.called)

        with cm3:
            self.assertFalse(d5.called)

        cm5 = yield d5

        with cm2:
            pass

        with cm4:
            pass

        with cm5:
            pass

        d6 = limiter.queue(key)
        with (yield d6):
            pass

    @defer.inlineCallbacks
    def test_cancellation(self):
        linearizer = Linearizer()

        key = object()

        d1 = linearizer.queue(key)
        cm1 = yield d1

        d2 = linearizer.queue(key)
        self.assertFalse(d2.called)

        d3 = linearizer.queue(key)
        self.assertFalse(d3.called)

        d2.cancel()

        with cm1:
            pass

        self.assertTrue(d2.called)
        try:
            yield d2
            self.fail("Expected d2 to raise CancelledError")
        except CancelledError:
            pass

        with (yield d3):
            pass