2015-04-09 10:41:36 +00:00
|
|
|
# -*- coding: utf-8 -*-
|
|
|
|
# Copyright 2014, 2015 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 twisted.internet import defer
|
|
|
|
|
|
|
|
from collections import deque
|
|
|
|
import contextlib
|
|
|
|
import threading
|
|
|
|
|
|
|
|
|
|
|
|
class IdGenerator(object):
|
|
|
|
def __init__(self, table, column, store):
|
|
|
|
self.table = table
|
|
|
|
self.column = column
|
|
|
|
self.store = store
|
|
|
|
self._lock = threading.Lock()
|
|
|
|
self._next_id = None
|
|
|
|
|
|
|
|
@defer.inlineCallbacks
|
|
|
|
def get_next(self):
|
2015-04-29 18:17:00 +00:00
|
|
|
if self._next_id is None:
|
|
|
|
yield self.store.runInteraction(
|
|
|
|
"IdGenerator_%s" % (self.table,),
|
|
|
|
self.get_next_txn,
|
|
|
|
)
|
2015-04-09 10:41:36 +00:00
|
|
|
|
2015-04-29 18:17:00 +00:00
|
|
|
with self._lock:
|
2015-04-09 10:41:36 +00:00
|
|
|
i = self._next_id
|
|
|
|
self._next_id += 1
|
|
|
|
defer.returnValue(i)
|
|
|
|
|
|
|
|
def get_next_txn(self, txn):
|
|
|
|
with self._lock:
|
|
|
|
if self._next_id:
|
|
|
|
i = self._next_id
|
|
|
|
self._next_id += 1
|
|
|
|
return i
|
|
|
|
else:
|
|
|
|
txn.execute(
|
|
|
|
"SELECT MAX(%s) FROM %s" % (self.column, self.table,)
|
|
|
|
)
|
|
|
|
|
|
|
|
val, = txn.fetchone()
|
2015-04-14 08:54:44 +00:00
|
|
|
cur = val or 0
|
|
|
|
cur += 1
|
|
|
|
self._next_id = cur + 1
|
2015-04-09 10:41:36 +00:00
|
|
|
|
2015-04-14 08:54:44 +00:00
|
|
|
return cur
|
2015-04-09 10:41:36 +00:00
|
|
|
|
|
|
|
|
|
|
|
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_txn(txn) as stream_id:
|
|
|
|
# ... persist event ...
|
|
|
|
"""
|
|
|
|
def __init__(self):
|
|
|
|
self._lock = threading.Lock()
|
|
|
|
|
|
|
|
self._current_max = None
|
|
|
|
self._unfinished_ids = deque()
|
|
|
|
|
|
|
|
def get_next_txn(self, txn):
|
|
|
|
"""
|
|
|
|
Usage:
|
|
|
|
with stream_id_gen.get_next_txn(txn) as stream_id:
|
|
|
|
# ... persist event ...
|
|
|
|
"""
|
2015-04-29 18:15:23 +00:00
|
|
|
if not self._current_max:
|
|
|
|
self._compute_current_max(txn)
|
2015-04-09 10:41:36 +00:00
|
|
|
|
2015-04-29 18:15:23 +00:00
|
|
|
with self._lock:
|
2015-04-09 10:41:36 +00:00
|
|
|
self._current_max += 1
|
|
|
|
next_id = self._current_max
|
|
|
|
|
|
|
|
self._unfinished_ids.append(next_id)
|
|
|
|
|
|
|
|
@contextlib.contextmanager
|
|
|
|
def manager():
|
2015-04-15 09:25:43 +00:00
|
|
|
try:
|
|
|
|
yield next_id
|
|
|
|
finally:
|
|
|
|
with self._lock:
|
|
|
|
self._unfinished_ids.remove(next_id)
|
2015-04-09 10:41:36 +00:00
|
|
|
|
|
|
|
return manager()
|
|
|
|
|
2015-04-27 14:19:44 +00:00
|
|
|
@defer.inlineCallbacks
|
2015-04-09 10:41:36 +00:00
|
|
|
def get_max_token(self, store):
|
|
|
|
"""Returns the maximum stream id such that all stream ids less than or
|
|
|
|
equal to it have been successfully persisted.
|
|
|
|
"""
|
2015-04-29 18:15:23 +00:00
|
|
|
if not self._current_max:
|
|
|
|
yield store.runInteraction(
|
|
|
|
"_compute_current_max",
|
|
|
|
self._get_or_compute_current_max,
|
|
|
|
)
|
|
|
|
|
2015-04-09 10:41:36 +00:00
|
|
|
with self._lock:
|
|
|
|
if self._unfinished_ids:
|
2015-04-27 14:19:44 +00:00
|
|
|
defer.returnValue(self._unfinished_ids[0] - 1)
|
2015-04-09 10:41:36 +00:00
|
|
|
|
2015-04-27 14:19:44 +00:00
|
|
|
defer.returnValue(self._current_max)
|
2015-04-09 10:41:36 +00:00
|
|
|
|
2015-04-29 18:15:23 +00:00
|
|
|
def _get_or_compute_current_max(self, txn):
|
|
|
|
with self._lock:
|
|
|
|
txn.execute("SELECT MAX(stream_ordering) FROM events")
|
|
|
|
rows = txn.fetchall()
|
|
|
|
val, = rows[0]
|
2015-04-09 10:41:36 +00:00
|
|
|
|
2015-04-29 18:15:23 +00:00
|
|
|
self._current_max = int(val) if val else 1
|
2015-04-09 10:41:36 +00:00
|
|
|
|
2015-04-29 18:15:23 +00:00
|
|
|
return self._current_max
|