synapse/tests/util/caches/test_descriptors.py

# -*- 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.
import logging
from functools import partial

import mock

from twisted.internet import defer, reactor

from synapse.api.errors import SynapseError
from synapse.logging.context import (
    SENTINEL_CONTEXT,
    LoggingContext,
    PreserveLoggingContext,
    current_context,
    make_deferred_yieldable,
)
from synapse.util.caches import descriptors
from synapse.util.caches.descriptors import cached

from tests import unittest

logger = logging.getLogger(__name__)


def run_on_reactor():
    d = defer.Deferred()
    reactor.callLater(0, d.callback, 0)
    return make_deferred_yieldable(d)


class CacheTestCase(unittest.TestCase):
    def test_invalidate_all(self):
        cache = descriptors.Cache("testcache")

        callback_record = [False, False]

        def record_callback(idx):
            callback_record[idx] = True

        # add a couple of pending entries
        d1 = defer.Deferred()
        cache.set("key1", d1, partial(record_callback, 0))

        d2 = defer.Deferred()
        cache.set("key2", d2, partial(record_callback, 1))

        # lookup should return observable deferreds
        self.assertFalse(cache.get("key1").has_called())
        self.assertFalse(cache.get("key2").has_called())

        # let one of the lookups complete
        d2.callback("result2")

        # for now at least, the cache will return real results rather than an
        # observabledeferred
        self.assertEqual(cache.get("key2"), "result2")

        # now do the invalidation
        cache.invalidate_all()

        # lookup should return none
        self.assertIsNone(cache.get("key1", None))
        self.assertIsNone(cache.get("key2", None))

        # both callbacks should have been callbacked
        self.assertTrue(callback_record[0], "Invalidation callback for key1 not called")
        self.assertTrue(callback_record[1], "Invalidation callback for key2 not called")

        # letting the other lookup complete should do nothing
        d1.callback("result1")
        self.assertIsNone(cache.get("key1", None))


class DescriptorTestCase(unittest.TestCase):
    @defer.inlineCallbacks
    def test_cache(self):
        class Cls(object):
            def __init__(self):
                self.mock = mock.Mock()

            @descriptors.cached()
            def fn(self, arg1, arg2):
                return self.mock(arg1, arg2)

        obj = Cls()

        obj.mock.return_value = "fish"
        r = yield obj.fn(1, 2)
        self.assertEqual(r, "fish")
        obj.mock.assert_called_once_with(1, 2)
        obj.mock.reset_mock()

        # a call with different params should call the mock again
        obj.mock.return_value = "chips"
        r = yield obj.fn(1, 3)
        self.assertEqual(r, "chips")
        obj.mock.assert_called_once_with(1, 3)
        obj.mock.reset_mock()

        # the two values should now be cached
        r = yield obj.fn(1, 2)
        self.assertEqual(r, "fish")
        r = yield obj.fn(1, 3)
        self.assertEqual(r, "chips")
        obj.mock.assert_not_called()

    @defer.inlineCallbacks
    def test_cache_num_args(self):
        """Only the first num_args arguments should matter to the cache"""

        class Cls(object):
            def __init__(self):
                self.mock = mock.Mock()

            @descriptors.cached(num_args=1)
            def fn(self, arg1, arg2):
                return self.mock(arg1, arg2)

        obj = Cls()
        obj.mock.return_value = "fish"
        r = yield obj.fn(1, 2)
        self.assertEqual(r, "fish")
        obj.mock.assert_called_once_with(1, 2)
        obj.mock.reset_mock()

        # a call with different params should call the mock again
        obj.mock.return_value = "chips"
        r = yield obj.fn(2, 3)
        self.assertEqual(r, "chips")
        obj.mock.assert_called_once_with(2, 3)
        obj.mock.reset_mock()

        # the two values should now be cached; we should be able to vary
        # the second argument and still get the cached result.
        r = yield obj.fn(1, 4)
        self.assertEqual(r, "fish")
        r = yield obj.fn(2, 5)
        self.assertEqual(r, "chips")
        obj.mock.assert_not_called()

    def test_cache_with_sync_exception(self):
        """If the wrapped function throws synchronously, things should continue to work
        """

        class Cls(object):
            @cached()
            def fn(self, arg1):
                raise SynapseError(100, "mai spoon iz too big!!1")

        obj = Cls()

        # this should fail immediately
        d = obj.fn(1)
        self.failureResultOf(d, SynapseError)

        # ... leaving the cache empty
        self.assertEqual(len(obj.fn.cache.cache), 0)

        # and a second call should result in a second exception
        d = obj.fn(1)
        self.failureResultOf(d, SynapseError)

    def test_cache_logcontexts(self):
        """Check that logcontexts are set and restored correctly when
        using the cache."""

        complete_lookup = defer.Deferred()

        class Cls(object):
            @descriptors.cached()
            def fn(self, arg1):
                @defer.inlineCallbacks
                def inner_fn():
                    with PreserveLoggingContext():
                        yield complete_lookup
                    return 1

                return inner_fn()

        @defer.inlineCallbacks
        def do_lookup():
            with LoggingContext() as c1:
                c1.name = "c1"
                r = yield obj.fn(1)
                self.assertEqual(current_context(), c1)
            return r

        def check_result(r):
            self.assertEqual(r, 1)

        obj = Cls()

        # set off a deferred which will do a cache lookup
        d1 = do_lookup()
        self.assertEqual(current_context(), SENTINEL_CONTEXT)
        d1.addCallback(check_result)

        # and another
        d2 = do_lookup()
        self.assertEqual(current_context(), SENTINEL_CONTEXT)
        d2.addCallback(check_result)

        # let the lookup complete
        complete_lookup.callback(None)

        return defer.gatherResults([d1, d2])

    def test_cache_logcontexts_with_exception(self):
        """Check that the cache sets and restores logcontexts correctly when
        the lookup function throws an exception"""

        class Cls(object):
            @descriptors.cached()
            def fn(self, arg1):
                @defer.inlineCallbacks
                def inner_fn():
                    # we want this to behave like an asynchronous function
                    yield run_on_reactor()
                    raise SynapseError(400, "blah")

                return inner_fn()

        @defer.inlineCallbacks
        def do_lookup():
            with LoggingContext() as c1:
                c1.name = "c1"
                try:
                    d = obj.fn(1)
                    self.assertEqual(
                        current_context(), SENTINEL_CONTEXT,
                    )
                    yield d
                    self.fail("No exception thrown")
                except SynapseError:
                    pass

                self.assertEqual(current_context(), c1)

            # the cache should now be empty
            self.assertEqual(len(obj.fn.cache.cache), 0)

        obj = Cls()

        # set off a deferred which will do a cache lookup
        d1 = do_lookup()
        self.assertEqual(current_context(), SENTINEL_CONTEXT)

        return d1

    @defer.inlineCallbacks
    def test_cache_default_args(self):
        class Cls(object):
            def __init__(self):
                self.mock = mock.Mock()

            @descriptors.cached()
            def fn(self, arg1, arg2=2, arg3=3):
                return self.mock(arg1, arg2, arg3)

        obj = Cls()

        obj.mock.return_value = "fish"
        r = yield obj.fn(1, 2, 3)
        self.assertEqual(r, "fish")
        obj.mock.assert_called_once_with(1, 2, 3)
        obj.mock.reset_mock()

        # a call with same params shouldn't call the mock again
        r = yield obj.fn(1, 2)
        self.assertEqual(r, "fish")
        obj.mock.assert_not_called()
        obj.mock.reset_mock()

        # a call with different params should call the mock again
        obj.mock.return_value = "chips"
        r = yield obj.fn(2, 3)
        self.assertEqual(r, "chips")
        obj.mock.assert_called_once_with(2, 3, 3)
        obj.mock.reset_mock()

        # the two values should now be cached
        r = yield obj.fn(1, 2)
        self.assertEqual(r, "fish")
        r = yield obj.fn(2, 3)
        self.assertEqual(r, "chips")
        obj.mock.assert_not_called()

    def test_cache_iterable(self):
        class Cls(object):
            def __init__(self):
                self.mock = mock.Mock()

            @descriptors.cached(iterable=True)
            def fn(self, arg1, arg2):
                return self.mock(arg1, arg2)

        obj = Cls()

        obj.mock.return_value = ["spam", "eggs"]
        r = obj.fn(1, 2)
        self.assertEqual(r.result, ["spam", "eggs"])
        obj.mock.assert_called_once_with(1, 2)
        obj.mock.reset_mock()

        # a call with different params should call the mock again
        obj.mock.return_value = ["chips"]
        r = obj.fn(1, 3)
        self.assertEqual(r.result, ["chips"])
        obj.mock.assert_called_once_with(1, 3)
        obj.mock.reset_mock()

        # the two values should now be cached
        self.assertEqual(len(obj.fn.cache.cache), 3)

        r = obj.fn(1, 2)
        self.assertEqual(r.result, ["spam", "eggs"])
        r = obj.fn(1, 3)
        self.assertEqual(r.result, ["chips"])
        obj.mock.assert_not_called()

    def test_cache_iterable_with_sync_exception(self):
        """If the wrapped function throws synchronously, things should continue to work
        """

        class Cls(object):
            @descriptors.cached(iterable=True)
            def fn(self, arg1):
                raise SynapseError(100, "mai spoon iz too big!!1")

        obj = Cls()

        # this should fail immediately
        d = obj.fn(1)
        self.failureResultOf(d, SynapseError)

        # ... leaving the cache empty
        self.assertEqual(len(obj.fn.cache.cache), 0)

        # and a second call should result in a second exception
        d = obj.fn(1)
        self.failureResultOf(d, SynapseError)


class CachedListDescriptorTestCase(unittest.TestCase):
    @defer.inlineCallbacks
    def test_cache(self):
        class Cls(object):
            def __init__(self):
                self.mock = mock.Mock()

            @descriptors.cached()
            def fn(self, arg1, arg2):
                pass

            @descriptors.cachedList("fn", "args1", inlineCallbacks=True)
            def list_fn(self, args1, arg2):
                assert current_context().request == "c1"
                # we want this to behave like an asynchronous function
                yield run_on_reactor()
                assert current_context().request == "c1"
                return self.mock(args1, arg2)

        with LoggingContext() as c1:
            c1.request = "c1"
            obj = Cls()
            obj.mock.return_value = {10: "fish", 20: "chips"}
            d1 = obj.list_fn([10, 20], 2)
            self.assertEqual(current_context(), SENTINEL_CONTEXT)
            r = yield d1
            self.assertEqual(current_context(), c1)
            obj.mock.assert_called_once_with([10, 20], 2)
            self.assertEqual(r, {10: "fish", 20: "chips"})
            obj.mock.reset_mock()

            # a call with different params should call the mock again
            obj.mock.return_value = {30: "peas"}
            r = yield obj.list_fn([20, 30], 2)
            obj.mock.assert_called_once_with([30], 2)
            self.assertEqual(r, {20: "chips", 30: "peas"})
            obj.mock.reset_mock()

            # all the values should now be cached
            r = yield obj.fn(10, 2)
            self.assertEqual(r, "fish")
            r = yield obj.fn(20, 2)
            self.assertEqual(r, "chips")
            r = yield obj.fn(30, 2)
            self.assertEqual(r, "peas")
            r = yield obj.list_fn([10, 20, 30], 2)
            obj.mock.assert_not_called()
            self.assertEqual(r, {10: "fish", 20: "chips", 30: "peas"})

    @defer.inlineCallbacks
    def test_invalidate(self):
        """Make sure that invalidation callbacks are called."""

        class Cls(object):
            def __init__(self):
                self.mock = mock.Mock()

            @descriptors.cached()
            def fn(self, arg1, arg2):
                pass

            @descriptors.cachedList("fn", "args1", inlineCallbacks=True)
            def list_fn(self, args1, arg2):
                # we want this to behave like an asynchronous function
                yield run_on_reactor()
                return self.mock(args1, arg2)

        obj = Cls()
        invalidate0 = mock.Mock()
        invalidate1 = mock.Mock()

        # cache miss
        obj.mock.return_value = {10: "fish", 20: "chips"}
        r1 = yield obj.list_fn([10, 20], 2, on_invalidate=invalidate0)
        obj.mock.assert_called_once_with([10, 20], 2)
        self.assertEqual(r1, {10: "fish", 20: "chips"})
        obj.mock.reset_mock()

        # cache hit
        r2 = yield obj.list_fn([10, 20], 2, on_invalidate=invalidate1)
        obj.mock.assert_not_called()
        self.assertEqual(r2, {10: "fish", 20: "chips"})

        invalidate0.assert_not_called()
        invalidate1.assert_not_called()

        # now if we invalidate the keys, both invalidations should get called
        obj.fn.invalidate((10, 2))
        invalidate0.assert_called_once()
        invalidate1.assert_called_once()