mirror of
https://git.anonymousland.org/anonymousland/synapse.git
synced 2024-10-01 11:49:51 -04:00
54172924c8
Rather than loading them lazily. This allows us to remove all the yield statements and spurious arguments for the get_next methods. It also allows us to replace all instances of get_next_txn with get_next since get_next no longer needs to access the db.
127 lines
3.7 KiB
Python
127 lines
3.7 KiB
Python
# -*- coding: utf-8 -*-
|
|
# Copyright 2014-2016 OpenMarket 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 collections import deque
|
|
import contextlib
|
|
import threading
|
|
|
|
|
|
class IdGenerator(object):
|
|
def __init__(self, db_conn, table, column):
|
|
self.table = table
|
|
self.column = column
|
|
self._lock = threading.Lock()
|
|
cur = db_conn.cursor()
|
|
self._next_id = self._load_next_id(cur)
|
|
cur.close()
|
|
|
|
def _load_next_id(self, txn):
|
|
txn.execute("SELECT MAX(%s) FROM %s" % (self.column, self.table,))
|
|
val, = txn.fetchone()
|
|
return val + 1 if val else 1
|
|
|
|
def get_next(self):
|
|
with self._lock:
|
|
i = self._next_id
|
|
self._next_id += 1
|
|
return i
|
|
|
|
|
|
class StreamIdGenerator(object):
|
|
"""Used to generate new stream ids when persisting events while keeping
|
|
track of which transactions have been completed.
|
|
|
|
This allows us to get the "current" stream id, i.e. the stream id such that
|
|
all ids less than or equal to it have completed. This handles the fact that
|
|
persistence of events can complete out of order.
|
|
|
|
Usage:
|
|
with stream_id_gen.get_next() as stream_id:
|
|
# ... persist event ...
|
|
"""
|
|
def __init__(self, db_conn, table, column):
|
|
self.table = table
|
|
self.column = column
|
|
|
|
self._lock = threading.Lock()
|
|
|
|
cur = db_conn.cursor()
|
|
self._current_max = self._load_current_max(cur)
|
|
cur.close()
|
|
|
|
self._unfinished_ids = deque()
|
|
|
|
def _load_current_max(self, txn):
|
|
txn.execute("SELECT MAX(%s) FROM %s" % (self.column, self.table))
|
|
rows = txn.fetchall()
|
|
val, = rows[0]
|
|
return int(val) if val else 1
|
|
|
|
def get_next(self):
|
|
"""
|
|
Usage:
|
|
with stream_id_gen.get_next() as stream_id:
|
|
# ... persist event ...
|
|
"""
|
|
with self._lock:
|
|
self._current_max += 1
|
|
next_id = self._current_max
|
|
|
|
self._unfinished_ids.append(next_id)
|
|
|
|
@contextlib.contextmanager
|
|
def manager():
|
|
try:
|
|
yield next_id
|
|
finally:
|
|
with self._lock:
|
|
self._unfinished_ids.remove(next_id)
|
|
|
|
return manager()
|
|
|
|
def get_next_mult(self, n):
|
|
"""
|
|
Usage:
|
|
with stream_id_gen.get_next(n) as stream_ids:
|
|
# ... persist events ...
|
|
"""
|
|
with self._lock:
|
|
next_ids = range(self._current_max + 1, self._current_max + n + 1)
|
|
self._current_max += n
|
|
|
|
for next_id in next_ids:
|
|
self._unfinished_ids.append(next_id)
|
|
|
|
@contextlib.contextmanager
|
|
def manager():
|
|
try:
|
|
yield next_ids
|
|
finally:
|
|
with self._lock:
|
|
for next_id in next_ids:
|
|
self._unfinished_ids.remove(next_id)
|
|
|
|
return manager()
|
|
|
|
def get_max_token(self):
|
|
"""Returns the maximum stream id such that all stream ids less than or
|
|
equal to it have been successfully persisted.
|
|
"""
|
|
with self._lock:
|
|
if self._unfinished_ids:
|
|
return self._unfinished_ids[0] - 1
|
|
|
|
return self._current_max
|