diff options
| -rw-r--r-- | synapse/storage/chunk_ordered_table.py | 298 | ||||
| -rw-r--r-- | synapse/storage/events.py | 9 | ||||
| -rw-r--r-- | synapse/storage/schema/delta/49/event_chunks.sql | 49 | ||||
| -rw-r--r-- | synapse/util/katriel_bodlaender.py | 298 | ||||
| -rw-r--r-- | tests/storage/test_chunk_linearizer_table.py | 181 | ||||
| -rw-r--r-- | tests/util/test_katriel_bodlaender.py | 58 |
6 files changed, 893 insertions, 0 deletions
diff --git a/synapse/storage/chunk_ordered_table.py b/synapse/storage/chunk_ordered_table.py new file mode 100644 index 0000000000..33089c2c60 --- /dev/null +++ b/synapse/storage/chunk_ordered_table.py @@ -0,0 +1,298 @@ +# -*- coding: utf-8 -*- +# 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 math +import logging + +from synapse.storage._base import SQLBaseStore +from synapse.util.katriel_bodlaender import OrderedListStore +from synapse.util.metrics import Measure + +import synapse.metrics + +metrics = synapse.metrics.get_metrics_for(__name__) +rebalance_counter = metrics.register_counter("rebalances") + + +logger = logging.getLogger(__name__) + + +class ChunkDBOrderedListStore(OrderedListStore): + """Used as the list store for room chunks, efficiently maintaining them in + topological order on updates. + + The class is designed for use inside transactions and so takes a + transaction object in the constructor. This means that it needs to be + re-instantiated in each transaction, so all state needs to be stored + in the database. + + Internally the ordering is implemented using floats, and the average is + taken when a node is inserted inbetween other nodes. To avoid presicion + errors a minimum difference between sucessive orderings is attempted to be + kept; whenever the difference is too small we attempt to rebalance. See + the `_rebalance` function for implementation details. + + Note that OrderedListStore orders nodes such that source of an edge + comes before the target. This is counter intuitive when edges represent + causality, so for the purposes of ordering algorithm we invert the edge + directions, i.e. if chunk A has a prev chunk of B then we say that the + edge is from B to A. This ensures that newer chunks get inserted at the + end (rather than the start). + + Args: + txn + room_id (str) + clock + rebalance_digits (int): When a rebalance is triggered we rebalance + in a range around the node, where the bounds are rounded to this + number of digits. + min_difference (int): A rebalance is triggered when the difference + between two successive orderings are less than the reverse of + this. + """ + def __init__(self, + txn, room_id, clock, + rebalance_digits=3, + min_difference=1000000): + self.txn = txn + self.room_id = room_id + self.clock = clock + + self.rebalance_digits = rebalance_digits + self.min_difference = 1. / min_difference + + def is_before(self, a, b): + """Implements OrderedListStore""" + return self._get_order(a) < self._get_order(b) + + def get_prev(self, node_id): + """Implements OrderedListStore""" + order = self._get_order(node_id) + + sql = """ + SELECT chunk_id FROM chunk_linearized + WHERE ordering < ? AND room_id = ? + ORDER BY ordering DESC + LIMIT 1 + """ + + self.txn.execute(sql, (order, self.room_id,)) + + row = self.txn.fetchone() + if row: + return row[0] + return None + + def get_next(self, node_id): + """Implements OrderedListStore""" + order = self._get_order(node_id) + + sql = """ + SELECT chunk_id FROM chunk_linearized + WHERE ordering > ? AND room_id = ? + ORDER BY ordering ASC + LIMIT 1 + """ + + self.txn.execute(sql, (order, self.room_id,)) + + row = self.txn.fetchone() + if row: + return row[0] + return None + + def insert_before(self, node_id, target_id): + """Implements OrderedListStore""" + + rebalance = False # Set to true if we need to trigger a rebalance + + if target_id: + target_order = self._get_order(target_id) + before_id = self.get_prev(target_id) + + if before_id: + before_order = self._get_order(before_id) + new_order = (target_order + before_order) / 2. + + rebalance = math.fabs(target_order - before_order) < self.min_difference + else: + new_order = math.floor(target_order) - 1 + else: + # If target_id is None then we insert at the end. + self.txn.execute(""" + SELECT COALESCE(MAX(ordering), 0) + 1 + FROM chunk_linearized + WHERE room_id = ? + """, (self.room_id,)) + + new_order, = self.txn.fetchone() + + self._insert(node_id, new_order) + + if rebalance: + self._rebalance(node_id) + + def insert_after(self, node_id, target_id): + """Implements OrderedListStore""" + + rebalance = False # Set to true if we need to trigger a rebalance + + if target_id: + target_order = self._get_order(target_id) + after_id = self.get_next(target_id) + if after_id: + after_order = self._get_order(after_id) + new_order = (target_order + after_order) / 2. + + rebalance = math.fabs(target_order - after_order) < self.min_difference + else: + new_order = math.ceil(target_order) + 1 + else: + # If target_id is None then we insert at the start. + self.txn.execute(""" + SELECT COALESCE(MIN(ordering), 0) - 1 + FROM chunk_linearized + WHERE room_id = ? + """, (self.room_id,)) + + new_order, = self.txn.fetchone() + + self._insert(node_id, new_order) + + if rebalance: + self._rebalance(node_id) + + def get_nodes_with_edges_to(self, node_id): + """Implements OrderedListStore""" + + # Note that we use the inverse relation here + sql = """ + SELECT l.ordering, l.chunk_id FROM chunk_graph AS g + INNER JOIN chunk_linearized AS l ON g.prev_id = l.chunk_id + WHERE g.chunk_id = ? + """ + self.txn.execute(sql, (node_id,)) + return self.txn.fetchall() + + def get_nodes_with_edges_from(self, node_id): + """Implements OrderedListStore""" + + # Note that we use the inverse relation here + sql = """ + SELECT l.ordering, l.chunk_id FROM chunk_graph AS g + INNER JOIN chunk_linearized AS l ON g.chunk_id = l.chunk_id + WHERE g.prev_id = ? + """ + self.txn.execute(sql, (node_id,)) + return self.txn.fetchall() + + def _delete_ordering(self, node_id): + """Implements OrderedListStore""" + + SQLBaseStore._simple_delete_txn( + self.txn, + table="chunk_linearized", + keyvalues={"chunk_id": node_id}, + ) + + def _add_edge_to_graph(self, source_id, target_id): + """Implements OrderedListStore""" + + # Note that we use the inverse relation + SQLBaseStore._simple_insert_txn( + self.txn, + table="chunk_graph", + values={"chunk_id": target_id, "prev_id": source_id} + ) + + def _insert(self, node_id, order): + """Inserts the node with the given ordering. + """ + SQLBaseStore._simple_insert_txn( + self.txn, + table="chunk_linearized", + values={ + "chunk_id": node_id, + "room_id": self.room_id, + "ordering": order, + } + ) + + def _get_order(self, node_id): + """Get the ordering of the given node. + """ + + return SQLBaseStore._simple_select_one_onecol_txn( + self.txn, + table="chunk_linearized", + keyvalues={"chunk_id": node_id}, + retcol="ordering" + ) + + def _rebalance(self, node_id): + """Rebalances the list around the given node to ensure that the + ordering floats don't get too small. + + This works by finding a range that includes the given node, and + recalculating the ordering floats such that they're equidistant in + that range. + """ + + logger.info("Rebalancing room %s, chunk %s", self.room_id, node_id) + + with Measure(self.clock, "chunk_rebalance"): + # We pick the interval to try and minimise the number of decimal + # places, i.e. we round to nearest float with `rebalance_digits` and + # use that as the middle of the interval + order = self._get_order(node_id) + a = round(order, self.rebalance_digits) + if order > a: + min_order = a + max_order = a + 10 ** -self.rebalance_digits + else: + min_order = a - 10 ** -self.rebalance_digits + max_order = a + + # Now we get all the nodes in the range. We add the minimum difference + # to the bounds to ensure that we don't accidentally move a node to be + # within the minimum difference of a node outside the range. + sql = """ + SELECT chunk_id FROM chunk_linearized + WHERE ordering >= ? AND ordering <= ? AND room_id = ? + """ + self.txn.execute(sql, ( + min_order - self.min_difference, + max_order + self.min_difference, + self.room_id, + )) + + chunk_ids = [c for c, in self.txn] + + sql = """ + UPDATE chunk_linearized + SET ordering = ? + WHERE chunk_id = ? + """ + + step = (max_order - min_order) / len(chunk_ids) + self.txn.executemany( + sql, + ( + ((idx * step + min_order), chunk_id) + for idx, chunk_id in enumerate(chunk_ids) + ) + ) + + rebalance_counter.inc() diff --git a/synapse/storage/events.py b/synapse/storage/events.py index 05cde96afc..70b9041eee 100644 --- a/synapse/storage/events.py +++ b/synapse/storage/events.py @@ -232,6 +232,15 @@ class EventsStore(EventsWorkerStore): psql_only=True, ) + self.register_background_index_update( + "events_chunk_index", + index_name="events_chunk_index", + table="events", + columns=["room_id", "chunk_id", "topological_ordering", "stream_ordering"], + unique=True, + psql_only=True, + ) + self._event_persist_queue = _EventPeristenceQueue() self._state_resolution_handler = hs.get_state_resolution_handler() diff --git a/synapse/storage/schema/delta/49/event_chunks.sql b/synapse/storage/schema/delta/49/event_chunks.sql new file mode 100644 index 0000000000..6b428b4ef8 --- /dev/null +++ b/synapse/storage/schema/delta/49/event_chunks.sql @@ -0,0 +1,49 @@ +/* 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. + */ + +ALTER TABLE events ADD COLUMN chunk_id BIGINT; + +INSERT INTO background_updates (update_name, progress_json) VALUES + ('events_chunk_index', '{}'); + +-- Stores how chunks of graph relate to each other +CREATE TABLE chunk_graph ( + chunk_id BIGINT NOT NULL, + prev_id BIGINT NOT NULL +); + +CREATE UNIQUE INDEX chunk_graph_id ON chunk_graph (chunk_id, prev_id); +CREATE INDEX chunk_graph_prev_id ON chunk_graph (prev_id); + +-- The extremities in each chunk. Note that these are pointing to events that +-- we don't have, rather than boundary between chunks. +CREATE TABLE chunk_backwards_extremities ( + chunk_id BIGINT NOT NULL, + event_id TEXT NOT NULL +); + +CREATE INDEX chunk_backwards_extremities_id ON chunk_backwards_extremities(chunk_id, event_id); +CREATE INDEX chunk_backwards_extremities_event_id ON chunk_backwards_extremities(event_id); + +-- Maintains an absolute ordering of chunks. Gets updated when we see new +-- edges between chunks. +CREATE TABLE chunk_linearized ( + chunk_id BIGINT NOT NULL, + room_id TEXT NOT NULL, + ordering DOUBLE PRECISION NOT NULL +); + +CREATE UNIQUE INDEX chunk_linearized_id ON chunk_linearized (chunk_id); +CREATE INDEX chunk_linearized_ordering ON chunk_linearized (room_id, ordering); diff --git a/synapse/util/katriel_bodlaender.py b/synapse/util/katriel_bodlaender.py new file mode 100644 index 0000000000..b924a4cfdf --- /dev/null +++ b/synapse/util/katriel_bodlaender.py @@ -0,0 +1,298 @@ +# -*- coding: utf-8 -*- +# 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. + +"""This module contains an implementation of the Katriel-Bodlaender algorithm, +which is used to do online topological ordering of graphs. + +Note that the ordering derived from the graph has the first node one with no +incoming edges at the start, and the last node one with no outgoing edges. + +This ordering is therefore opposite to what one might expect when considering +the room DAG, as newer messages would be added to the start rather than the +end. + +***We therefore invert the direction of edges when using the algorithm*** + +See https://www.sciencedirect.com/science/article/pii/S0304397507006573 +""" + +from abc import ABCMeta, abstractmethod + + +class OrderedListStore(object): + """An abstract base class that is used to store a topological ordering of + a graph. Suitable for use with the Katriel-Bodlaender algorithm. + """ + + __metaclass__ = ABCMeta + + @abstractmethod + def is_before(self, first_node, second_node): + """Returns whether the first node is before the second node. + + Args: + first_node (str) + second_node (str) + + Returns: + bool: True if first_node is before second_node + """ + pass + + @abstractmethod + def get_prev(self, node_id): + """Gets the node immediately before the given node + + Args: + node_id (str) + + Returns: + str|None: A node ID or None if no preceding node exists + """ + pass + + @abstractmethod + def get_next(self, node_id): + """Gets the node immediately after the given node + + Args: + node_id (str) + + Returns: + str|None: A node ID or None if no proceding node exists + """ + pass + + @abstractmethod + def insert_before(self, node_id, target_id): + """Inserts node immediately before target node. + + If target_id is None then the node is inserted at the end of the list + + Args: + node_id (str) + target_id (str|None) + """ + pass + + @abstractmethod + def insert_after(self, node_id, target_id): + """Inserts node immediately after target node. + + If target_id is None then the node is inserted at the start of the list + + Args: + node_id (str) + target_id (str|None) + """ + pass + + @abstractmethod + def get_nodes_with_edges_to(self, node_id): + """Get all nodes with edges to the given node + + Args: + node_id (str) + + Returns: + list[tuple[float, str]]: Returns a list of tuple of an ordering + term and the node ID. The ordering term can be used to sort the + returned list. + The ordering is valid until subsequent calls to insert_* functions + """ + pass + + @abstractmethod + def get_nodes_with_edges_from(self, node_id): + """Get all nodes with edges from the given node + + Args: + node_id (str) + + Returns: + list[tuple[float, str]]: Returns a list of tuple of an ordering + term and the node ID. The ordering term can be used to sort the + returned list. + The ordering is valid until subsequent calls to insert_* functions + """ + pass + + @abstractmethod + def _delete_ordering(self, node_id): + """Deletes the given node from the ordered list (but not the graph). + + Used when we want to reinsert it into a different position + + Args: + node_id (str) + """ + pass + + @abstractmethod + def _add_edge_to_graph(self, source_id, target_id): + """Adds an edge to the graph from source to target. + + Does not update ordering. + + Args: + source_id (str) + target_id (str) + """ + pass + + def add_node(self, node_id): + """Adds a node to the graph. + + Args: + node_id (str) + """ + self.insert_before(node_id, None) + + def add_edge(self, source, target): + """Adds a new edge is added to the graph and updates the ordering. + + See module level docs. + + Note that both the source and target nodes must have been inserted into + the store (at an arbitrary position) already. + + Args: + source (str): The source node of the new edge + target (str): The target node of the new edge + """ + + # The following is the Katriel-Bodlaender algorithm. + + to_s = [] + from_t = [] + to_s_neighbours = [] + from_t_neighbours = [] + to_s_indegree = 0 + from_t_outdegree = 0 + s = source + t = target + + while s and t and not self.is_before(s, t): + m_s = to_s_indegree + m_t = from_t_outdegree + + pe_s = self.get_nodes_with_edges_to(s) + fe_t = self.get_nodes_with_edges_from(t) + + l_s = len(pe_s) + l_t = len(fe_t) + + if m_s + l_s <= m_t + l_t: + to_s.append(s) + to_s_neighbours.extend(pe_s) + to_s_indegree += l_s + + if to_s_neighbours: + to_s_neighbours.sort() + _, s = to_s_neighbours.pop() + else: + s = None + + if m_s + l_s >= m_t + l_t: + from_t.append(t) + from_t_neighbours.extend(fe_t) + from_t_outdegree += l_t + + if from_t_neighbours: + from_t_neighbours.sort(reverse=True) + _, t = from_t_neighbours.pop() + else: + t = None + + if s is None: + s = self.get_prev(target) + + if t is None: + t = self.get_next(source) + + while to_s: + s1 = to_s.pop() + self._delete_ordering(s1) + self.insert_after(s1, s) + s = s1 + + while from_t: + t1 = from_t.pop() + self._delete_ordering(t1) + self.insert_before(t1, t) + t = t1 + + self._add_edge_to_graph(source, target) + + +class InMemoryOrderedListStore(OrderedListStore): + """An in memory OrderedListStore + """ + + def __init__(self): + # The ordered list of nodes + self.list = [] + + # Map from node to set of nodes that it references + self.edges_from = {} + + # Map from node to set of nodes that it is referenced by + self.edges_to = {} + + def is_before(self, first_node, second_node): + return self.list.index(first_node) < self.list.index(second_node) + + def get_prev(self, node_id): + idx = self.list.index(node_id) - 1 + if idx >= 0: + return self.list[idx] + else: + return None + + def get_next(self, node_id): + idx = self.list.index(node_id) + 1 + if idx < len(self.list): + return self.list[idx] + else: + return None + + def insert_before(self, node_id, target_id): + if target_id is not None: + idx = self.list.index(target_id) + self.list.insert(idx, node_id) + else: + self.list.append(node_id) + + def insert_after(self, node_id, target_id): + if target_id is not None: + idx = self.list.index(target_id) + 1 + self.list.insert(idx, node_id) + else: + self.list.insert(0, node_id) + + def _delete_ordering(self, node_id): + self.list.remove(node_id) + + def get_nodes_with_edges_to(self, node_id): + to_nodes = self.edges_to.get(node_id, []) + return [(self.list.index(nid), nid) for nid in to_nodes] + + def get_nodes_with_edges_from(self, node_id): + from_nodes = self.edges_from.get(node_id, []) + return [(self.list.index(nid), nid) for nid in from_nodes] + + def _add_edge_to_graph(self, source_id, target_id): + self.edges_from.setdefault(source_id, set()).add(target_id) + self.edges_to.setdefault(target_id, set()).add(source_id) diff --git a/tests/storage/test_chunk_linearizer_table.py b/tests/storage/test_chunk_linearizer_table.py new file mode 100644 index 0000000000..5ca436c555 --- /dev/null +++ b/tests/storage/test_chunk_linearizer_table.py @@ -0,0 +1,181 @@ +# -*- coding: utf-8 -*- +# 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. + +from twisted.internet import defer + +import random +import tests.unittest +import tests.utils + +from synapse.storage.chunk_ordered_table import ChunkDBOrderedListStore + + +class ChunkLinearizerStoreTestCase(tests.unittest.TestCase): + def __init__(self, *args, **kwargs): + super(ChunkLinearizerStoreTestCase, self).__init__(*args, **kwargs) + + @defer.inlineCallbacks + def setUp(self): + hs = yield tests.utils.setup_test_homeserver() + self.store = hs.get_datastore() + self.clock = hs.get_clock() + + @defer.inlineCallbacks + def test_simple_insert_fetch(self): + room_id = "foo_room1" + + def test_txn(txn): + table = ChunkDBOrderedListStore( + txn, room_id, self.clock, 1, 100, + ) + + table.add_node("A") + table.insert_after("B", "A") + table.insert_before("C", "A") + + sql = """ + SELECT chunk_id FROM chunk_linearized + WHERE room_id = ? + ORDER BY ordering ASC + """ + txn.execute(sql, (room_id,)) + + ordered = [r for r, in txn] + + self.assertEqual(["C", "A", "B"], ordered) + + yield self.store.runInteraction("test", test_txn) + + @defer.inlineCallbacks + def test_many_insert_fetch(self): + room_id = "foo_room2" + + def test_txn(txn): + table = ChunkDBOrderedListStore( + txn, room_id, self.clock, 1, 20, + ) + + nodes = [(i, "node_%d" % (i,)) for i in xrange(1, 1000)] + expected = [n for _, n in nodes] + + already_inserted = [] + + random.shuffle(nodes) + while nodes: + i, node_id = nodes.pop() + if not already_inserted: + table.add_node(node_id) + else: + for j, target_id in already_inserted: + if j > i: + break + + if j < i: + table.insert_after(node_id, target_id) + else: + table.insert_before(node_id, target_id) + + already_inserted.append((i, node_id)) + already_inserted.sort() + + sql = """ + SELECT chunk_id FROM chunk_linearized + WHERE room_id = ? + ORDER BY ordering ASC + """ + txn.execute(sql, (room_id,)) + + ordered = [r for r, in txn] + + self.assertEqual(expected, ordered) + + yield self.store.runInteraction("test", test_txn) + + @defer.inlineCallbacks + def test_prepend_and_append(self): + room_id = "foo_room3" + + def test_txn(txn): + table = ChunkDBOrderedListStore( + txn, room_id, self.clock, 1, 20, + ) + + table.add_node("a") + + expected = ["a"] + + for i in xrange(1, 1000): + node_id = "node_id_before_%d" % i + table.insert_before(node_id, expected[0]) + expected.insert(0, node_id) + + for i in xrange(1, 1000): + node_id = "node_id_after_%d" % i + table.insert_after(node_id, expected[-1]) + expected.append(node_id) + + sql = """ + SELECT chunk_id FROM chunk_linearized + WHERE room_id = ? + ORDER BY ordering ASC + """ + txn.execute(sql, (room_id,)) + + ordered = [r for r, in txn] + + self.assertEqual(expected, ordered) + + yield self.store.runInteraction("test", test_txn) + + @defer.inlineCallbacks + def test_worst_case(self): + room_id = "foo_room3" + + def test_txn(txn): + table = ChunkDBOrderedListStore( + txn, room_id, self.clock, 1, 100, + ) + + table.add_node("a") + + prev_node = "a" + + expected_prefix = ["a"] + expected_suffix = [] + + for i in xrange(1, 100): + node_id = "node_id_%d" % i + if i % 2 == 0: + table.insert_before(node_id, prev_node) + expected_prefix.append(node_id) + else: + table.insert_after(node_id, prev_node) + expected_suffix.append(node_id) + prev_node = node_id + + sql = """ + SELECT chunk_id FROM chunk_linearized + WHERE room_id = ? + ORDER BY ordering ASC + """ + txn.execute(sql, (room_id,)) + + ordered = [r for r, in txn] + + expected = expected_prefix + list(reversed(expected_suffix)) + + self.assertEqual(expected, ordered) + + yield self.store.runInteraction("test", test_txn) diff --git a/tests/util/test_katriel_bodlaender.py b/tests/util/test_katriel_bodlaender.py new file mode 100644 index 0000000000..5768408604 --- /dev/null +++ b/tests/util/test_katriel_bodlaender.py @@ -0,0 +1,58 @@ +# -*- coding: utf-8 -*- +# 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. + +from synapse.util.katriel_bodlaender import InMemoryOrderedListStore + +from tests import unittest + + +class KatrielBodlaenderTests(unittest.TestCase): + def test_simple_graph(self): + store = InMemoryOrderedListStore() + + nodes = [ + "node_1", + "node_2", + "node_3", + "node_4", + ] + + for node in nodes: + store.add_node(node) + + store.add_edge("node_2", "node_3") + store.add_edge("node_1", "node_2") + store.add_edge("node_3", "node_4") + + self.assertEqual(nodes, store.list) + + def test_reverse_graph(self): + store = InMemoryOrderedListStore() + + nodes = [ + "node_1", + "node_2", + "node_3", + "node_4", + ] + + for node in nodes: + store.add_node(node) + + store.add_edge("node_3", "node_2") + store.add_edge("node_2", "node_1") + store.add_edge("node_4", "node_3") + + self.assertEqual(list(reversed(nodes)), store.list) |