test_descriptors.py

# 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 typing import Set
from unittest import mock

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

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, lru_cache

from tests import unittest
from tests.test_utils import get_awaitable_result

logger = logging.getLogger(__name__)


class LruCacheDecoratorTestCase(unittest.TestCase):
    def test_base(self):
        class Cls:
            def __init__(self):
                self.mock = mock.Mock()

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

        obj = Cls()
        obj.mock.return_value = "fish"
        r = 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 = 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 = obj.fn(1, 2)
        self.assertEqual(r, "fish")
        r = obj.fn(1, 3)
        self.assertEqual(r, "chips")
        obj.mock.assert_not_called()


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


class DescriptorTestCase(unittest.TestCase):
    @defer.inlineCallbacks
    def test_cache(self):
        class Cls:
            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:
            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:
            @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_with_async_exception(self):
        """The wrapped function returns a failure"""

        class Cls:
            result = None
            call_count = 0

            @cached()
            def fn(self, arg1):
                self.call_count += 1
                return self.result

        obj = Cls()
        callbacks: Set[str] = set()

        # set off an asynchronous request
        obj.result = origin_d = defer.Deferred()

        d1 = obj.fn(1, on_invalidate=lambda: callbacks.add("d1"))
        self.assertFalse(d1.called)

        # a second request should also return a deferred, but should not call the
        # function itself.
        d2 = obj.fn(1, on_invalidate=lambda: callbacks.add("d2"))
        self.assertFalse(d2.called)
        self.assertEqual(obj.call_count, 1)

        # no callbacks yet
        self.assertEqual(callbacks, set())

        # the original request fails
        e = Exception("bzz")
        origin_d.errback(e)

        # ... which should cause the lookups to fail similarly
        self.assertIs(self.failureResultOf(d1, Exception).value, e)
        self.assertIs(self.failureResultOf(d2, Exception).value, e)

        # ... and the callbacks to have been, uh, called.
        self.assertEqual(callbacks, {"d1", "d2"})

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

        # and a second call should work as normal
        obj.result = defer.succeed(100)
        d3 = obj.fn(1)
        self.assertEqual(self.successResultOf(d3), 100)
        self.assertEqual(obj.call_count, 2)

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

        complete_lookup = defer.Deferred()

        class Cls:
            @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("c1") as 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:
            @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("c1") as 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:
            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:
            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:
            @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)

    def test_invalidate_cascade(self):
        """Invalidations should cascade up through cache contexts"""

        class Cls:
            @cached(cache_context=True)
            async def func1(self, key, cache_context):
                return await self.func2(key, on_invalidate=cache_context.invalidate)

            @cached(cache_context=True)
            async def func2(self, key, cache_context):
                return self.func3(key, on_invalidate=cache_context.invalidate)

            @lru_cache(cache_context=True)
            def func3(self, key, cache_context):
                self.invalidate = cache_context.invalidate
                return 42

        obj = Cls()

        top_invalidate = mock.Mock()
        r = get_awaitable_result(obj.func1("k1", on_invalidate=top_invalidate))
        self.assertEqual(r, 42)
        obj.invalidate()
        top_invalidate.assert_called_once()


class CacheDecoratorTestCase(unittest.HomeserverTestCase):
    """More tests for @cached

    The following is a set of tests that got lost in a different file for a while.

    There are probably duplicates of the tests in DescriptorTestCase. Ideally the
    duplicates would be removed and the two sets of classes combined.
    """

    @defer.inlineCallbacks
    def test_passthrough(self):
        class A:
            @cached()
            def func(self, key):
                return key

        a = A()

        self.assertEqual((yield a.func("foo")), "foo")
        self.assertEqual((yield a.func("bar")), "bar")

    @defer.inlineCallbacks
    def test_hit(self):
        callcount = [0]

        class A:
            @cached()
            def func(self, key):
                callcount[0] += 1
                return key

        a = A()
        yield a.func("foo")

        self.assertEqual(callcount[0], 1)

        self.assertEqual((yield a.func("foo")), "foo")
        self.assertEqual(callcount[0], 1)

    @defer.inlineCallbacks
    def test_invalidate(self):
        callcount = [0]

        class A:
            @cached()
            def func(self, key):
                callcount[0] += 1
                return key

        a = A()
        yield a.func("foo")

        self.assertEqual(callcount[0], 1)

        a.func.invalidate(("foo",))

        yield a.func("foo")

        self.assertEqual(callcount[0], 2)

    def test_invalidate_missing(self):
        class A:
            @cached()
            def func(self, key):
                return key

        A().func.invalidate(("what",))

    @defer.inlineCallbacks
    def test_max_entries(self):
        callcount = [0]

        class A:
            @cached(max_entries=10)
            def func(self, key):
                callcount[0] += 1
                return key

        a = A()

        for k in range(0, 12):
            yield a.func(k)

        self.assertEqual(callcount[0], 12)

        # There must have been at least 2 evictions, meaning if we calculate
        # all 12 values again, we must get called at least 2 more times
        for k in range(0, 12):
            yield a.func(k)

        self.assertTrue(
            callcount[0] >= 14, msg="Expected callcount >= 14, got %d" % (callcount[0])
        )

    def test_prefill(self):
        callcount = [0]

        d = defer.succeed(123)

        class A:
            @cached()
            def func(self, key):
                callcount[0] += 1
                return d

        a = A()

        a.func.prefill(("foo",), 456)

        self.assertEqual(a.func("foo").result, 456)
        self.assertEqual(callcount[0], 0)

    @defer.inlineCallbacks
    def test_invalidate_context(self):
        callcount = [0]
        callcount2 = [0]

        class A:
            @cached()
            def func(self, key):
                callcount[0] += 1
                return key

            @cached(cache_context=True)
            def func2(self, key, cache_context):
                callcount2[0] += 1
                return self.func(key, on_invalidate=cache_context.invalidate)

        a = A()
        yield a.func2("foo")

        self.assertEqual(callcount[0], 1)
        self.assertEqual(callcount2[0], 1)

        a.func.invalidate(("foo",))
        yield a.func("foo")

        self.assertEqual(callcount[0], 2)
        self.assertEqual(callcount2[0], 1)

        yield a.func2("foo")

        self.assertEqual(callcount[0], 2)
        self.assertEqual(callcount2[0], 2)

    @defer.inlineCallbacks
    def test_eviction_context(self):
        callcount = [0]
        callcount2 = [0]

        class A:
            @cached(max_entries=2)
            def func(self, key):
                callcount[0] += 1
                return key

            @cached(cache_context=True)
            def func2(self, key, cache_context):
                callcount2[0] += 1
                return self.func(key, on_invalidate=cache_context.invalidate)

        a = A()
        yield a.func2("foo")
        yield a.func2("foo2")

        self.assertEqual(callcount[0], 2)
        self.assertEqual(callcount2[0], 2)

        yield a.func2("foo")
        self.assertEqual(callcount[0], 2)
        self.assertEqual(callcount2[0], 2)

        yield a.func("foo3")

        self.assertEqual(callcount[0], 3)
        self.assertEqual(callcount2[0], 2)

        yield a.func2("foo")

        self.assertEqual(callcount[0], 4)
        self.assertEqual(callcount2[0], 3)

    @defer.inlineCallbacks
    def test_double_get(self):
        callcount = [0]
        callcount2 = [0]

        class A:
            @cached()
            def func(self, key):
                callcount[0] += 1
                return key

            @cached(cache_context=True)
            def func2(self, key, cache_context):
                callcount2[0] += 1
                return self.func(key, on_invalidate=cache_context.invalidate)

        a = A()
        a.func2.cache.cache = mock.Mock(wraps=a.func2.cache.cache)

        yield a.func2("foo")

        self.assertEqual(callcount[0], 1)
        self.assertEqual(callcount2[0], 1)

        a.func2.invalidate(("foo",))
        self.assertEqual(a.func2.cache.cache.del_multi.call_count, 1)

        yield a.func2("foo")
        a.func2.invalidate(("foo",))
        self.assertEqual(a.func2.cache.cache.del_multi.call_count, 2)

        self.assertEqual(callcount[0], 1)
        self.assertEqual(callcount2[0], 2)

        a.func.invalidate(("foo",))
        self.assertEqual(a.func2.cache.cache.del_multi.call_count, 3)
        yield a.func("foo")

        self.assertEqual(callcount[0], 2)
        self.assertEqual(callcount2[0], 2)

        yield a.func2("foo")

        self.assertEqual(callcount[0], 2)
        self.assertEqual(callcount2[0], 3)


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

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

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

        with LoggingContext("c1") as c1:
            obj = Cls()
            obj.mock.return_value = {10: "fish", 20: "chips"}

            # start the lookup off
            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"})

            # we should also be able to use a (single-use) iterable, and should
            # deduplicate the keys
            obj.mock.reset_mock()
            obj.mock.return_value = {40: "gravy"}
            iterable = (x for x in [10, 40, 40])
            r = yield obj.list_fn(iterable, 2)
            obj.mock.assert_called_once_with({40}, 2)
            self.assertEqual(r, {10: "fish", 40: "gravy"})

    def test_concurrent_lookups(self):
        """All concurrent lookups should get the same result"""

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

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

            @descriptors.cachedList("fn", "args1")
            def list_fn(self, args1) -> "Deferred[dict]":
                return self.mock(args1)

        obj = Cls()
        deferred_result = Deferred()
        obj.mock.return_value = deferred_result

        # start off several concurrent lookups of the same key
        d1 = obj.list_fn([10])
        d2 = obj.list_fn([10])
        d3 = obj.list_fn([10])

        # the mock should have been called exactly once
        obj.mock.assert_called_once_with({10})
        obj.mock.reset_mock()

        # ... and none of the calls should yet be complete
        self.assertFalse(d1.called)
        self.assertFalse(d2.called)
        self.assertFalse(d3.called)

        # complete the lookup. @cachedList functions need to complete with a map
        # of input->result
        deferred_result.callback({10: "peas"})

        # ... which should give the right result to all the callers
        self.assertEqual(self.successResultOf(d1), {10: "peas"})
        self.assertEqual(self.successResultOf(d2), {10: "peas"})
        self.assertEqual(self.successResultOf(d3), {10: "peas"})

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

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

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

            @descriptors.cachedList("fn", "args1")
            async def list_fn(self, args1, arg2):
                # we want this to behave like an asynchronous function
                await 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()