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synapse/tests/storage/test_id_generators.py
Erik Johnston 8de3703d21
Make event persisters periodically announce position over replication. (#8499)
Currently background proccesses stream the events stream use the "minimum persisted position" (i.e. `get_current_token()`) rather than the vector clock style tokens. This is broadly fine as it doesn't matter if the background processes lag a small amount. However, in extreme cases (i.e. SyTests) where we only write to one event persister the background processes will never make progress.

This PR changes it so that the `MultiWriterIDGenerator` keeps the current position of a given instance as up to date as possible (i.e using the latest token it sees if its not in the process of persisting anything), and then periodically announces that over replication. This then allows the "minimum persisted position" to advance, albeit with a small lag.
2020-10-12 15:51:41 +01:00

581 lines
22 KiB
Python

# -*- coding: utf-8 -*-
# Copyright 2020 The Matrix.org Foundation C.I.C.
#
# 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 synapse.storage.database import DatabasePool
from synapse.storage.engines import IncorrectDatabaseSetup
from synapse.storage.util.id_generators import MultiWriterIdGenerator
from tests.unittest import HomeserverTestCase
from tests.utils import USE_POSTGRES_FOR_TESTS
class MultiWriterIdGeneratorTestCase(HomeserverTestCase):
if not USE_POSTGRES_FOR_TESTS:
skip = "Requires Postgres"
def prepare(self, reactor, clock, hs):
self.store = hs.get_datastore()
self.db_pool = self.store.db_pool # type: DatabasePool
self.get_success(self.db_pool.runInteraction("_setup_db", self._setup_db))
def _setup_db(self, txn):
txn.execute("CREATE SEQUENCE foobar_seq")
txn.execute(
"""
CREATE TABLE foobar (
stream_id BIGINT NOT NULL,
instance_name TEXT NOT NULL,
data TEXT
);
"""
)
def _create_id_generator(
self, instance_name="master", writers=["master"]
) -> MultiWriterIdGenerator:
def _create(conn):
return MultiWriterIdGenerator(
conn,
self.db_pool,
stream_name="test_stream",
instance_name=instance_name,
table="foobar",
instance_column="instance_name",
id_column="stream_id",
sequence_name="foobar_seq",
writers=writers,
)
return self.get_success_or_raise(self.db_pool.runWithConnection(_create))
def _insert_rows(self, instance_name: str, number: int):
"""Insert N rows as the given instance, inserting with stream IDs pulled
from the postgres sequence.
"""
def _insert(txn):
for _ in range(number):
txn.execute(
"INSERT INTO foobar VALUES (nextval('foobar_seq'), ?)",
(instance_name,),
)
txn.execute(
"""
INSERT INTO stream_positions VALUES ('test_stream', ?, lastval())
ON CONFLICT (stream_name, instance_name) DO UPDATE SET stream_id = lastval()
""",
(instance_name,),
)
self.get_success(self.db_pool.runInteraction("_insert_rows", _insert))
def _insert_row_with_id(self, instance_name: str, stream_id: int):
"""Insert one row as the given instance with given stream_id, updating
the postgres sequence position to match.
"""
def _insert(txn):
txn.execute(
"INSERT INTO foobar VALUES (?, ?)", (stream_id, instance_name,),
)
txn.execute("SELECT setval('foobar_seq', ?)", (stream_id,))
txn.execute(
"""
INSERT INTO stream_positions VALUES ('test_stream', ?, ?)
ON CONFLICT (stream_name, instance_name) DO UPDATE SET stream_id = ?
""",
(instance_name, stream_id, stream_id),
)
self.get_success(self.db_pool.runInteraction("_insert_row_with_id", _insert))
def test_empty(self):
"""Test an ID generator against an empty database gives sensible
current positions.
"""
id_gen = self._create_id_generator()
# The table is empty so we expect an empty map for positions
self.assertEqual(id_gen.get_positions(), {})
def test_single_instance(self):
"""Test that reads and writes from a single process are handled
correctly.
"""
# Prefill table with 7 rows written by 'master'
self._insert_rows("master", 7)
id_gen = self._create_id_generator()
self.assertEqual(id_gen.get_positions(), {"master": 7})
self.assertEqual(id_gen.get_current_token_for_writer("master"), 7)
# Try allocating a new ID gen and check that we only see position
# advanced after we leave the context manager.
async def _get_next_async():
async with id_gen.get_next() as stream_id:
self.assertEqual(stream_id, 8)
self.assertEqual(id_gen.get_positions(), {"master": 7})
self.assertEqual(id_gen.get_current_token_for_writer("master"), 7)
self.get_success(_get_next_async())
self.assertEqual(id_gen.get_positions(), {"master": 8})
self.assertEqual(id_gen.get_current_token_for_writer("master"), 8)
def test_out_of_order_finish(self):
"""Test that IDs persisted out of order are correctly handled
"""
# Prefill table with 7 rows written by 'master'
self._insert_rows("master", 7)
id_gen = self._create_id_generator()
self.assertEqual(id_gen.get_positions(), {"master": 7})
self.assertEqual(id_gen.get_current_token_for_writer("master"), 7)
ctx1 = self.get_success(id_gen.get_next())
ctx2 = self.get_success(id_gen.get_next())
ctx3 = self.get_success(id_gen.get_next())
ctx4 = self.get_success(id_gen.get_next())
s1 = self.get_success(ctx1.__aenter__())
s2 = self.get_success(ctx2.__aenter__())
s3 = self.get_success(ctx3.__aenter__())
s4 = self.get_success(ctx4.__aenter__())
self.assertEqual(s1, 8)
self.assertEqual(s2, 9)
self.assertEqual(s3, 10)
self.assertEqual(s4, 11)
self.assertEqual(id_gen.get_positions(), {"master": 7})
self.assertEqual(id_gen.get_current_token_for_writer("master"), 7)
self.get_success(ctx2.__aexit__(None, None, None))
self.assertEqual(id_gen.get_positions(), {"master": 7})
self.assertEqual(id_gen.get_current_token_for_writer("master"), 7)
self.get_success(ctx1.__aexit__(None, None, None))
self.assertEqual(id_gen.get_positions(), {"master": 9})
self.assertEqual(id_gen.get_current_token_for_writer("master"), 9)
self.get_success(ctx4.__aexit__(None, None, None))
self.assertEqual(id_gen.get_positions(), {"master": 9})
self.assertEqual(id_gen.get_current_token_for_writer("master"), 9)
self.get_success(ctx3.__aexit__(None, None, None))
self.assertEqual(id_gen.get_positions(), {"master": 11})
self.assertEqual(id_gen.get_current_token_for_writer("master"), 11)
def test_multi_instance(self):
"""Test that reads and writes from multiple processes are handled
correctly.
"""
self._insert_rows("first", 3)
self._insert_rows("second", 4)
first_id_gen = self._create_id_generator("first", writers=["first", "second"])
second_id_gen = self._create_id_generator("second", writers=["first", "second"])
# The first ID gen will notice that it can advance its token to 7 as it
# has no in progress writes...
self.assertEqual(first_id_gen.get_positions(), {"first": 7, "second": 7})
self.assertEqual(first_id_gen.get_current_token_for_writer("first"), 7)
self.assertEqual(first_id_gen.get_current_token_for_writer("second"), 7)
# ... but the second ID gen doesn't know that.
self.assertEqual(second_id_gen.get_positions(), {"first": 3, "second": 7})
self.assertEqual(second_id_gen.get_current_token_for_writer("first"), 3)
self.assertEqual(second_id_gen.get_current_token_for_writer("second"), 7)
# Try allocating a new ID gen and check that we only see position
# advanced after we leave the context manager.
async def _get_next_async():
async with first_id_gen.get_next() as stream_id:
self.assertEqual(stream_id, 8)
self.assertEqual(
first_id_gen.get_positions(), {"first": 7, "second": 7}
)
self.get_success(_get_next_async())
self.assertEqual(first_id_gen.get_positions(), {"first": 8, "second": 7})
# However the ID gen on the second instance won't have seen the update
self.assertEqual(second_id_gen.get_positions(), {"first": 3, "second": 7})
# ... but calling `get_next` on the second instance should give a unique
# stream ID
async def _get_next_async():
async with second_id_gen.get_next() as stream_id:
self.assertEqual(stream_id, 9)
self.assertEqual(
second_id_gen.get_positions(), {"first": 3, "second": 7}
)
self.get_success(_get_next_async())
self.assertEqual(second_id_gen.get_positions(), {"first": 3, "second": 9})
# If the second ID gen gets told about the first, it correctly updates
second_id_gen.advance("first", 8)
self.assertEqual(second_id_gen.get_positions(), {"first": 8, "second": 9})
def test_get_next_txn(self):
"""Test that the `get_next_txn` function works correctly.
"""
# Prefill table with 7 rows written by 'master'
self._insert_rows("master", 7)
id_gen = self._create_id_generator()
self.assertEqual(id_gen.get_positions(), {"master": 7})
self.assertEqual(id_gen.get_current_token_for_writer("master"), 7)
# Try allocating a new ID gen and check that we only see position
# advanced after we leave the context manager.
def _get_next_txn(txn):
stream_id = id_gen.get_next_txn(txn)
self.assertEqual(stream_id, 8)
self.assertEqual(id_gen.get_positions(), {"master": 7})
self.assertEqual(id_gen.get_current_token_for_writer("master"), 7)
self.get_success(self.db_pool.runInteraction("test", _get_next_txn))
self.assertEqual(id_gen.get_positions(), {"master": 8})
self.assertEqual(id_gen.get_current_token_for_writer("master"), 8)
def test_get_persisted_upto_position(self):
"""Test that `get_persisted_upto_position` correctly tracks updates to
positions.
"""
# The following tests are a bit cheeky in that we notify about new
# positions via `advance` without *actually* advancing the postgres
# sequence.
self._insert_row_with_id("first", 3)
self._insert_row_with_id("second", 5)
id_gen = self._create_id_generator("worker", writers=["first", "second"])
self.assertEqual(id_gen.get_positions(), {"first": 3, "second": 5})
# Min is 3 and there is a gap between 5, so we expect it to be 3.
self.assertEqual(id_gen.get_persisted_upto_position(), 3)
# We advance "first" straight to 6. Min is now 5 but there is no gap so
# we expect it to be 6
id_gen.advance("first", 6)
self.assertEqual(id_gen.get_persisted_upto_position(), 6)
# No gap, so we expect 7.
id_gen.advance("second", 7)
self.assertEqual(id_gen.get_persisted_upto_position(), 7)
# We haven't seen 8 yet, so we expect 7 still.
id_gen.advance("second", 9)
self.assertEqual(id_gen.get_persisted_upto_position(), 7)
# Now that we've seen 7, 8 and 9 we can got straight to 9.
id_gen.advance("first", 8)
self.assertEqual(id_gen.get_persisted_upto_position(), 9)
# Jump forward with gaps. The minimum is 11, even though we haven't seen
# 10 we know that everything before 11 must be persisted.
id_gen.advance("first", 11)
id_gen.advance("second", 15)
self.assertEqual(id_gen.get_persisted_upto_position(), 11)
def test_get_persisted_upto_position_get_next(self):
"""Test that `get_persisted_upto_position` correctly tracks updates to
positions when `get_next` is called.
"""
self._insert_row_with_id("first", 3)
self._insert_row_with_id("second", 5)
id_gen = self._create_id_generator("first", writers=["first", "second"])
self.assertEqual(id_gen.get_positions(), {"first": 5, "second": 5})
self.assertEqual(id_gen.get_persisted_upto_position(), 5)
async def _get_next_async():
async with id_gen.get_next() as stream_id:
self.assertEqual(stream_id, 6)
self.assertEqual(id_gen.get_persisted_upto_position(), 5)
self.get_success(_get_next_async())
self.assertEqual(id_gen.get_persisted_upto_position(), 6)
# We assume that so long as `get_next` does correctly advance the
# `persisted_upto_position` in this case, then it will be correct in the
# other cases that are tested above (since they'll hit the same code).
def test_restart_during_out_of_order_persistence(self):
"""Test that restarting a process while another process is writing out
of order updates are handled correctly.
"""
# Prefill table with 7 rows written by 'master'
self._insert_rows("master", 7)
id_gen = self._create_id_generator()
self.assertEqual(id_gen.get_positions(), {"master": 7})
self.assertEqual(id_gen.get_current_token_for_writer("master"), 7)
# Persist two rows at once
ctx1 = self.get_success(id_gen.get_next())
ctx2 = self.get_success(id_gen.get_next())
s1 = self.get_success(ctx1.__aenter__())
s2 = self.get_success(ctx2.__aenter__())
self.assertEqual(s1, 8)
self.assertEqual(s2, 9)
self.assertEqual(id_gen.get_positions(), {"master": 7})
self.assertEqual(id_gen.get_current_token_for_writer("master"), 7)
# We finish persisting the second row before restart
self.get_success(ctx2.__aexit__(None, None, None))
# We simulate a restart of another worker by just creating a new ID gen.
id_gen_worker = self._create_id_generator("worker")
# Restarted worker should not see the second persisted row
self.assertEqual(id_gen_worker.get_positions(), {"master": 7})
self.assertEqual(id_gen_worker.get_current_token_for_writer("master"), 7)
# Now if we persist the first row then both instances should jump ahead
# correctly.
self.get_success(ctx1.__aexit__(None, None, None))
self.assertEqual(id_gen.get_positions(), {"master": 9})
id_gen_worker.advance("master", 9)
self.assertEqual(id_gen_worker.get_positions(), {"master": 9})
def test_writer_config_change(self):
"""Test that changing the writer config correctly works.
"""
self._insert_row_with_id("first", 3)
self._insert_row_with_id("second", 5)
# Initial config has two writers
id_gen = self._create_id_generator("worker", writers=["first", "second"])
self.assertEqual(id_gen.get_persisted_upto_position(), 3)
self.assertEqual(id_gen.get_current_token_for_writer("first"), 3)
self.assertEqual(id_gen.get_current_token_for_writer("second"), 5)
# New config removes one of the configs. Note that if the writer is
# removed from config we assume that it has been shut down and has
# finished persisting, hence why the persisted upto position is 5.
id_gen_2 = self._create_id_generator("second", writers=["second"])
self.assertEqual(id_gen_2.get_persisted_upto_position(), 5)
self.assertEqual(id_gen_2.get_current_token_for_writer("second"), 5)
# This config points to a single, previously unused writer.
id_gen_3 = self._create_id_generator("third", writers=["third"])
self.assertEqual(id_gen_3.get_persisted_upto_position(), 5)
# For new writers we assume their initial position to be the current
# persisted up to position. This stops Synapse from doing a full table
# scan when a new writer comes along.
self.assertEqual(id_gen_3.get_current_token_for_writer("third"), 5)
id_gen_4 = self._create_id_generator("fourth", writers=["third"])
self.assertEqual(id_gen_4.get_current_token_for_writer("third"), 5)
# Check that we get a sane next stream ID with this new config.
async def _get_next_async():
async with id_gen_3.get_next() as stream_id:
self.assertEqual(stream_id, 6)
self.get_success(_get_next_async())
self.assertEqual(id_gen_3.get_persisted_upto_position(), 6)
# If we add back the old "first" then we shouldn't see the persisted up
# to position revert back to 3.
id_gen_5 = self._create_id_generator("five", writers=["first", "third"])
self.assertEqual(id_gen_5.get_persisted_upto_position(), 6)
self.assertEqual(id_gen_5.get_current_token_for_writer("first"), 6)
self.assertEqual(id_gen_5.get_current_token_for_writer("third"), 6)
def test_sequence_consistency(self):
"""Test that we error out if the table and sequence diverges.
"""
# Prefill with some rows
self._insert_row_with_id("master", 3)
# Now we add a row *without* updating the stream ID
def _insert(txn):
txn.execute("INSERT INTO foobar VALUES (26, 'master')")
self.get_success(self.db_pool.runInteraction("_insert", _insert))
# Creating the ID gen should error
with self.assertRaises(IncorrectDatabaseSetup):
self._create_id_generator("first")
class BackwardsMultiWriterIdGeneratorTestCase(HomeserverTestCase):
"""Tests MultiWriterIdGenerator that produce *negative* stream IDs.
"""
if not USE_POSTGRES_FOR_TESTS:
skip = "Requires Postgres"
def prepare(self, reactor, clock, hs):
self.store = hs.get_datastore()
self.db_pool = self.store.db_pool # type: DatabasePool
self.get_success(self.db_pool.runInteraction("_setup_db", self._setup_db))
def _setup_db(self, txn):
txn.execute("CREATE SEQUENCE foobar_seq")
txn.execute(
"""
CREATE TABLE foobar (
stream_id BIGINT NOT NULL,
instance_name TEXT NOT NULL,
data TEXT
);
"""
)
def _create_id_generator(
self, instance_name="master", writers=["master"]
) -> MultiWriterIdGenerator:
def _create(conn):
return MultiWriterIdGenerator(
conn,
self.db_pool,
stream_name="test_stream",
instance_name=instance_name,
table="foobar",
instance_column="instance_name",
id_column="stream_id",
sequence_name="foobar_seq",
writers=writers,
positive=False,
)
return self.get_success(self.db_pool.runWithConnection(_create))
def _insert_row(self, instance_name: str, stream_id: int):
"""Insert one row as the given instance with given stream_id.
"""
def _insert(txn):
txn.execute(
"INSERT INTO foobar VALUES (?, ?)", (stream_id, instance_name,),
)
txn.execute(
"""
INSERT INTO stream_positions VALUES ('test_stream', ?, ?)
ON CONFLICT (stream_name, instance_name) DO UPDATE SET stream_id = ?
""",
(instance_name, -stream_id, -stream_id),
)
self.get_success(self.db_pool.runInteraction("_insert_row", _insert))
def test_single_instance(self):
"""Test that reads and writes from a single process are handled
correctly.
"""
id_gen = self._create_id_generator()
async def _get_next_async():
async with id_gen.get_next() as stream_id:
self._insert_row("master", stream_id)
self.get_success(_get_next_async())
self.assertEqual(id_gen.get_positions(), {"master": -1})
self.assertEqual(id_gen.get_current_token_for_writer("master"), -1)
self.assertEqual(id_gen.get_persisted_upto_position(), -1)
async def _get_next_async2():
async with id_gen.get_next_mult(3) as stream_ids:
for stream_id in stream_ids:
self._insert_row("master", stream_id)
self.get_success(_get_next_async2())
self.assertEqual(id_gen.get_positions(), {"master": -4})
self.assertEqual(id_gen.get_current_token_for_writer("master"), -4)
self.assertEqual(id_gen.get_persisted_upto_position(), -4)
# Test loading from DB by creating a second ID gen
second_id_gen = self._create_id_generator()
self.assertEqual(second_id_gen.get_positions(), {"master": -4})
self.assertEqual(second_id_gen.get_current_token_for_writer("master"), -4)
self.assertEqual(second_id_gen.get_persisted_upto_position(), -4)
def test_multiple_instance(self):
"""Tests that having multiple instances that get advanced over
federation works corretly.
"""
id_gen_1 = self._create_id_generator("first", writers=["first", "second"])
id_gen_2 = self._create_id_generator("second", writers=["first", "second"])
async def _get_next_async():
async with id_gen_1.get_next() as stream_id:
self._insert_row("first", stream_id)
id_gen_2.advance("first", stream_id)
self.get_success(_get_next_async())
self.assertEqual(id_gen_1.get_positions(), {"first": -1})
self.assertEqual(id_gen_2.get_positions(), {"first": -1})
self.assertEqual(id_gen_1.get_persisted_upto_position(), -1)
self.assertEqual(id_gen_2.get_persisted_upto_position(), -1)
async def _get_next_async2():
async with id_gen_2.get_next() as stream_id:
self._insert_row("second", stream_id)
id_gen_1.advance("second", stream_id)
self.get_success(_get_next_async2())
self.assertEqual(id_gen_1.get_positions(), {"first": -2, "second": -2})
self.assertEqual(id_gen_2.get_positions(), {"first": -1, "second": -2})
self.assertEqual(id_gen_1.get_persisted_upto_position(), -2)
self.assertEqual(id_gen_2.get_persisted_upto_position(), -2)