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The function is used for two purposes: 1) for subscribers of streams to get a token they can use to get further updates with, and 2) for replication to track position of the writers of the stream. For streams with a single writer the two scenarios produce the same result, however the situation becomes complicated for streams with multiple writers. The current `MultiWriterIdGenerator` does not correctly handle the first case (which is not an issue as its only used for the `caches` stream which nothing subscribes to outside of replication).
184 lines
6.6 KiB
Python
184 lines
6.6 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2020 The Matrix.org Foundation C.I.C.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from synapse.storage.database import DatabasePool
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from synapse.storage.util.id_generators import MultiWriterIdGenerator
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from tests.unittest import HomeserverTestCase
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from tests.utils import USE_POSTGRES_FOR_TESTS
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class MultiWriterIdGeneratorTestCase(HomeserverTestCase):
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if not USE_POSTGRES_FOR_TESTS:
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skip = "Requires Postgres"
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def prepare(self, reactor, clock, hs):
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self.store = hs.get_datastore()
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self.db_pool = self.store.db_pool # type: DatabasePool
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self.get_success(self.db_pool.runInteraction("_setup_db", self._setup_db))
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def _setup_db(self, txn):
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txn.execute("CREATE SEQUENCE foobar_seq")
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txn.execute(
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"""
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CREATE TABLE foobar (
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stream_id BIGINT NOT NULL,
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instance_name TEXT NOT NULL,
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data TEXT
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);
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"""
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)
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def _create_id_generator(self, instance_name="master") -> MultiWriterIdGenerator:
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def _create(conn):
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return MultiWriterIdGenerator(
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conn,
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self.db_pool,
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instance_name=instance_name,
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table="foobar",
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instance_column="instance_name",
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id_column="stream_id",
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sequence_name="foobar_seq",
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)
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return self.get_success(self.db_pool.runWithConnection(_create))
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def _insert_rows(self, instance_name: str, number: int):
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def _insert(txn):
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for _ in range(number):
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txn.execute(
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"INSERT INTO foobar VALUES (nextval('foobar_seq'), ?)",
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(instance_name,),
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)
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self.get_success(self.db_pool.runInteraction("test_single_instance", _insert))
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def test_empty(self):
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"""Test an ID generator against an empty database gives sensible
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current positions.
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"""
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id_gen = self._create_id_generator()
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# The table is empty so we expect an empty map for positions
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self.assertEqual(id_gen.get_positions(), {})
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def test_single_instance(self):
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"""Test that reads and writes from a single process are handled
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correctly.
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"""
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# Prefill table with 7 rows written by 'master'
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self._insert_rows("master", 7)
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id_gen = self._create_id_generator()
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self.assertEqual(id_gen.get_positions(), {"master": 7})
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self.assertEqual(id_gen.get_current_token_for_writer("master"), 7)
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# Try allocating a new ID gen and check that we only see position
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# advanced after we leave the context manager.
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async def _get_next_async():
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with await id_gen.get_next() as stream_id:
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self.assertEqual(stream_id, 8)
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self.assertEqual(id_gen.get_positions(), {"master": 7})
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self.assertEqual(id_gen.get_current_token_for_writer("master"), 7)
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self.get_success(_get_next_async())
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self.assertEqual(id_gen.get_positions(), {"master": 8})
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self.assertEqual(id_gen.get_current_token_for_writer("master"), 8)
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def test_multi_instance(self):
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"""Test that reads and writes from multiple processes are handled
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correctly.
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"""
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self._insert_rows("first", 3)
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self._insert_rows("second", 4)
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first_id_gen = self._create_id_generator("first")
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second_id_gen = self._create_id_generator("second")
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self.assertEqual(first_id_gen.get_positions(), {"first": 3, "second": 7})
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self.assertEqual(first_id_gen.get_current_token_for_writer("first"), 3)
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self.assertEqual(first_id_gen.get_current_token_for_writer("second"), 7)
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# Try allocating a new ID gen and check that we only see position
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# advanced after we leave the context manager.
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async def _get_next_async():
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with await first_id_gen.get_next() as stream_id:
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self.assertEqual(stream_id, 8)
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self.assertEqual(
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first_id_gen.get_positions(), {"first": 3, "second": 7}
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)
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self.get_success(_get_next_async())
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self.assertEqual(first_id_gen.get_positions(), {"first": 8, "second": 7})
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# However the ID gen on the second instance won't have seen the update
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self.assertEqual(second_id_gen.get_positions(), {"first": 3, "second": 7})
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# ... but calling `get_next` on the second instance should give a unique
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# stream ID
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async def _get_next_async():
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with await second_id_gen.get_next() as stream_id:
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self.assertEqual(stream_id, 9)
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self.assertEqual(
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second_id_gen.get_positions(), {"first": 3, "second": 7}
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)
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self.get_success(_get_next_async())
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self.assertEqual(second_id_gen.get_positions(), {"first": 3, "second": 9})
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# If the second ID gen gets told about the first, it correctly updates
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second_id_gen.advance("first", 8)
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self.assertEqual(second_id_gen.get_positions(), {"first": 8, "second": 9})
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def test_get_next_txn(self):
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"""Test that the `get_next_txn` function works correctly.
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"""
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# Prefill table with 7 rows written by 'master'
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self._insert_rows("master", 7)
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id_gen = self._create_id_generator()
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self.assertEqual(id_gen.get_positions(), {"master": 7})
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self.assertEqual(id_gen.get_current_token_for_writer("master"), 7)
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# Try allocating a new ID gen and check that we only see position
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# advanced after we leave the context manager.
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def _get_next_txn(txn):
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stream_id = id_gen.get_next_txn(txn)
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self.assertEqual(stream_id, 8)
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self.assertEqual(id_gen.get_positions(), {"master": 7})
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self.assertEqual(id_gen.get_current_token_for_writer("master"), 7)
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self.get_success(self.db_pool.runInteraction("test", _get_next_txn))
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self.assertEqual(id_gen.get_positions(), {"master": 8})
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self.assertEqual(id_gen.get_current_token_for_writer("master"), 8)
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