5 files changed, 100 insertions, 8 deletions
diff --git a/synapse/config/cache.py b/synapse/config/cache.py
index 0672538796..aff5b21ab2 100644
--- a/synapse/config/cache.py
+++ b/synapse/config/cache.py
@@ -15,6 +15,7 @@
 
 import os
 import re
+import threading
 from typing import Callable, Dict
 
 from ._base import Config, ConfigError
@@ -25,6 +26,9 @@ _CACHE_PREFIX = "SYNAPSE_CACHE_FACTOR"
 # Map from canonicalised cache name to cache.
 _CACHES = {}
 
+# a lock on the contents of _CACHES
+_CACHES_LOCK = threading.Lock()
+
 _DEFAULT_FACTOR_SIZE = 0.5
 _DEFAULT_EVENT_CACHE_SIZE = "10K"
 
@@ -66,7 +70,10 @@ def add_resizable_cache(cache_name: str, cache_resize_callback: Callable):
     # Some caches have '*' in them which we strip out.
     cache_name = _canonicalise_cache_name(cache_name)
 
-    _CACHES[cache_name] = cache_resize_callback
+    # sometimes caches are initialised from background threads, so we need to make
+    # sure we don't conflict with another thread running a resize operation
+    with _CACHES_LOCK:
+        _CACHES[cache_name] = cache_resize_callback
 
     # Ensure all loaded caches are sized appropriately
     #
@@ -87,7 +94,8 @@ class CacheConfig(Config):
             os.environ.get(_CACHE_PREFIX, _DEFAULT_FACTOR_SIZE)
         )
         properties.resize_all_caches_func = None
-        _CACHES.clear()
+        with _CACHES_LOCK:
+            _CACHES.clear()
 
     def generate_config_section(self, **kwargs):
         return """\
@@ -193,6 +201,8 @@ class CacheConfig(Config):
         For each cache, run the mapped callback function with either
         a specific cache factor or the default, global one.
         """
-        for cache_name, callback in _CACHES.items():
-            new_factor = self.cache_factors.get(cache_name, self.global_factor)
-            callback(new_factor)
+        # block other threads from modifying _CACHES while we iterate it.
+        with _CACHES_LOCK:
+            for cache_name, callback in _CACHES.items():
+                new_factor = self.cache_factors.get(cache_name, self.global_factor)
+                callback(new_factor)
diff --git a/synapse/config/homeserver.py b/synapse/config/homeserver.py
index 2c7b3a699f..264c274c52 100644
--- a/synapse/config/homeserver.py
+++ b/synapse/config/homeserver.py
@@ -36,6 +36,7 @@ from .ratelimiting import RatelimitConfig
 from .redis import RedisConfig
 from .registration import RegistrationConfig
 from .repository import ContentRepositoryConfig
+from .room import RoomConfig
 from .room_directory import RoomDirectoryConfig
 from .saml2_config import SAML2Config
 from .server import ServerConfig
@@ -79,6 +80,7 @@ class HomeServerConfig(RootConfig):
         PasswordAuthProviderConfig,
         PushConfig,
         SpamCheckerConfig,
+        RoomConfig,
         GroupsConfig,
         UserDirectoryConfig,
         ConsentConfig,
diff --git a/synapse/config/room.py b/synapse/config/room.py
new file mode 100644
index 0000000000..6aa4de0672
--- /dev/null
+++ b/synapse/config/room.py
@@ -0,0 +1,80 @@
+# -*- 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.
+
+import logging
+
+from synapse.api.constants import RoomCreationPreset
+
+from ._base import Config, ConfigError
+
+logger = logging.Logger(__name__)
+
+
+class RoomDefaultEncryptionTypes(object):
+    """Possible values for the encryption_enabled_by_default_for_room_type config option"""
+
+    ALL = "all"
+    INVITE = "invite"
+    OFF = "off"
+
+
+class RoomConfig(Config):
+    section = "room"
+
+    def read_config(self, config, **kwargs):
+        # Whether new, locally-created rooms should have encryption enabled
+        encryption_for_room_type = config.get(
+            "encryption_enabled_by_default_for_room_type",
+            RoomDefaultEncryptionTypes.OFF,
+        )
+        if encryption_for_room_type == RoomDefaultEncryptionTypes.ALL:
+            self.encryption_enabled_by_default_for_room_presets = [
+                RoomCreationPreset.PRIVATE_CHAT,
+                RoomCreationPreset.TRUSTED_PRIVATE_CHAT,
+                RoomCreationPreset.PUBLIC_CHAT,
+            ]
+        elif encryption_for_room_type == RoomDefaultEncryptionTypes.INVITE:
+            self.encryption_enabled_by_default_for_room_presets = [
+                RoomCreationPreset.PRIVATE_CHAT,
+                RoomCreationPreset.TRUSTED_PRIVATE_CHAT,
+            ]
+        elif encryption_for_room_type == RoomDefaultEncryptionTypes.OFF:
+            self.encryption_enabled_by_default_for_room_presets = []
+        else:
+            raise ConfigError(
+                "Invalid value for encryption_enabled_by_default_for_room_type"
+            )
+
+    def generate_config_section(self, **kwargs):
+        return """\
+        ## Rooms ##
+
+        # Controls whether locally-created rooms should be end-to-end encrypted by
+        # default.
+        #
+        # Possible options are "all", "invite", and "off". They are defined as:
+        #
+        # * "all": any locally-created room
+        # * "invite": any room created with the "private_chat" or "trusted_private_chat"
+        #             room creation presets
+        # * "off": this option will take no effect
+        #
+        # The default value is "off".
+        #
+        # Note that this option will only affect rooms created after it is set. It
+        # will also not affect rooms created by other servers.
+        #
+        #encryption_enabled_by_default_for_room_type: invite
+        """
diff --git a/synapse/config/saml2_config.py b/synapse/config/saml2_config.py
index d0a19751e8..293643b2de 100644
--- a/synapse/config/saml2_config.py
+++ b/synapse/config/saml2_config.py
@@ -160,7 +160,7 @@ class SAML2Config(Config):
 
         # session lifetime: in milliseconds
         self.saml2_session_lifetime = self.parse_duration(
-            saml2_config.get("saml_session_lifetime", "5m")
+            saml2_config.get("saml_session_lifetime", "15m")
         )
 
         template_dir = saml2_config.get("template_dir")
@@ -286,7 +286,7 @@ class SAML2Config(Config):
 
           # The lifetime of a SAML session. This defines how long a user has to
           # complete the authentication process, if allow_unsolicited is unset.
-          # The default is 5 minutes.
+          # The default is 15 minutes.
           #
           #saml_session_lifetime: 5m
 
diff --git a/synapse/config/server.py b/synapse/config/server.py
index f57eefc99c..73226e63d5 100644
--- a/synapse/config/server.py
+++ b/synapse/config/server.py
@@ -856,7 +856,7 @@ class ServerConfig(Config):
         # number of monthly active users.
         #
         # 'limit_usage_by_mau' disables/enables monthly active user blocking. When
-        # anabled and a limit is reached the server returns a 'ResourceLimitError'
+        # enabled and a limit is reached the server returns a 'ResourceLimitError'
         # with error type Codes.RESOURCE_LIMIT_EXCEEDED
         #
         # 'max_mau_value' is the hard limit of monthly active users above which