Browse Source

Make the http server handle coroutine-making REST servlets (#5475)

Amber Brown 5 years ago
parent
commit
f40a7dc41f

+ 1 - 0
changelog.d/5475.misc

@@ -0,0 +1 @@
+Synapse can now handle RestServlets that return coroutines.

+ 41 - 36
synapse/http/server.py

@@ -16,10 +16,11 @@
 
 import cgi
 import collections
+import http.client
 import logging
-
-from six import PY3
-from six.moves import http_client, urllib
+import types
+import urllib
+from io import BytesIO
 
 from canonicaljson import encode_canonical_json, encode_pretty_printed_json, json
 
@@ -41,11 +42,6 @@ from synapse.api.errors import (
 from synapse.util.caches import intern_dict
 from synapse.util.logcontext import preserve_fn
 
-if PY3:
-    from io import BytesIO
-else:
-    from cStringIO import StringIO as BytesIO
-
 logger = logging.getLogger(__name__)
 
 HTML_ERROR_TEMPLATE = """<!DOCTYPE html>
@@ -75,10 +71,9 @@ def wrap_json_request_handler(h):
     deferred fails with any other type of error we send a 500 reponse.
     """
 
-    @defer.inlineCallbacks
-    def wrapped_request_handler(self, request):
+    async def wrapped_request_handler(self, request):
         try:
-            yield h(self, request)
+            await h(self, request)
         except SynapseError as e:
             code = e.code
             logger.info("%s SynapseError: %s - %s", request, code, e.msg)
@@ -142,10 +137,12 @@ def wrap_html_request_handler(h):
     where "request" must be a SynapseRequest.
     """
 
-    def wrapped_request_handler(self, request):
-        d = defer.maybeDeferred(h, self, request)
-        d.addErrback(_return_html_error, request)
-        return d
+    async def wrapped_request_handler(self, request):
+        try:
+            return await h(self, request)
+        except Exception:
+            f = failure.Failure()
+            return _return_html_error(f, request)
 
     return wrap_async_request_handler(wrapped_request_handler)
 
@@ -171,7 +168,7 @@ def _return_html_error(f, request):
                 exc_info=(f.type, f.value, f.getTracebackObject()),
             )
     else:
-        code = http_client.INTERNAL_SERVER_ERROR
+        code = http.client.INTERNAL_SERVER_ERROR
         msg = "Internal server error"
 
         logger.error(
@@ -201,10 +198,9 @@ def wrap_async_request_handler(h):
     logged until the deferred completes.
     """
 
-    @defer.inlineCallbacks
-    def wrapped_async_request_handler(self, request):
+    async def wrapped_async_request_handler(self, request):
         with request.processing():
-            yield h(self, request)
+            await h(self, request)
 
     # we need to preserve_fn here, because the synchronous render method won't yield for
     # us (obviously)
@@ -270,12 +266,11 @@ class JsonResource(HttpServer, resource.Resource):
     def render(self, request):
         """ This gets called by twisted every time someone sends us a request.
         """
-        self._async_render(request)
+        defer.ensureDeferred(self._async_render(request))
         return NOT_DONE_YET
 
     @wrap_json_request_handler
-    @defer.inlineCallbacks
-    def _async_render(self, request):
+    async def _async_render(self, request):
         """ This gets called from render() every time someone sends us a request.
             This checks if anyone has registered a callback for that method and
             path.
@@ -292,26 +287,19 @@ class JsonResource(HttpServer, resource.Resource):
         # Now trigger the callback. If it returns a response, we send it
         # here. If it throws an exception, that is handled by the wrapper
         # installed by @request_handler.
-
-        def _unquote(s):
-            if PY3:
-                # On Python 3, unquote is unicode -> unicode
-                return urllib.parse.unquote(s)
-            else:
-                # On Python 2, unquote is bytes -> bytes We need to encode the
-                # URL again (as it was decoded by _get_handler_for request), as
-                # ASCII because it's a URL, and then decode it to get the UTF-8
-                # characters that were quoted.
-                return urllib.parse.unquote(s.encode("ascii")).decode("utf8")
-
         kwargs = intern_dict(
             {
-                name: _unquote(value) if value else value
+                name: urllib.parse.unquote(value) if value else value
                 for name, value in group_dict.items()
             }
         )
 
-        callback_return = yield callback(request, **kwargs)
+        callback_return = callback(request, **kwargs)
+
+        # Is it synchronous? We'll allow this for now.
+        if isinstance(callback_return, (defer.Deferred, types.CoroutineType)):
+            callback_return = await callback_return
+
         if callback_return is not None:
             code, response = callback_return
             self._send_response(request, code, response)
@@ -360,6 +348,23 @@ class JsonResource(HttpServer, resource.Resource):
         )
 
 
+class DirectServeResource(resource.Resource):
+    def render(self, request):
+        """
+        Render the request, using an asynchronous render handler if it exists.
+        """
+        render_callback_name = "_async_render_" + request.method.decode("ascii")
+
+        if hasattr(self, render_callback_name):
+            # Call the handler
+            callback = getattr(self, render_callback_name)
+            defer.ensureDeferred(callback(request))
+
+            return NOT_DONE_YET
+        else:
+            super().render(request)
+
+
 def _options_handler(request):
     """Request handler for OPTIONS requests
 

+ 12 - 23
synapse/rest/consent/consent_resource.py

@@ -23,13 +23,13 @@ from six.moves import http_client
 import jinja2
 from jinja2 import TemplateNotFound
 
-from twisted.internet import defer
-from twisted.web.resource import Resource
-from twisted.web.server import NOT_DONE_YET
-
 from synapse.api.errors import NotFoundError, StoreError, SynapseError
 from synapse.config import ConfigError
-from synapse.http.server import finish_request, wrap_html_request_handler
+from synapse.http.server import (
+    DirectServeResource,
+    finish_request,
+    wrap_html_request_handler,
+)
 from synapse.http.servlet import parse_string
 from synapse.types import UserID
 
@@ -47,7 +47,7 @@ else:
         return a == b
 
 
-class ConsentResource(Resource):
+class ConsentResource(DirectServeResource):
     """A twisted Resource to display a privacy policy and gather consent to it
 
     When accessed via GET, returns the privacy policy via a template.
@@ -87,7 +87,7 @@ class ConsentResource(Resource):
         Args:
             hs (synapse.server.HomeServer): homeserver
         """
-        Resource.__init__(self)
+        super().__init__()
 
         self.hs = hs
         self.store = hs.get_datastore()
@@ -118,18 +118,12 @@ class ConsentResource(Resource):
 
         self._hmac_secret = hs.config.form_secret.encode("utf-8")
 
-    def render_GET(self, request):
-        self._async_render_GET(request)
-        return NOT_DONE_YET
-
     @wrap_html_request_handler
-    @defer.inlineCallbacks
-    def _async_render_GET(self, request):
+    async def _async_render_GET(self, request):
         """
         Args:
             request (twisted.web.http.Request):
         """
-
         version = parse_string(request, "v", default=self._default_consent_version)
         username = parse_string(request, "u", required=False, default="")
         userhmac = None
@@ -145,7 +139,7 @@ class ConsentResource(Resource):
             else:
                 qualified_user_id = UserID(username, self.hs.hostname).to_string()
 
-            u = yield self.store.get_user_by_id(qualified_user_id)
+            u = await self.store.get_user_by_id(qualified_user_id)
             if u is None:
                 raise NotFoundError("Unknown user")
 
@@ -165,13 +159,8 @@ class ConsentResource(Resource):
         except TemplateNotFound:
             raise NotFoundError("Unknown policy version")
 
-    def render_POST(self, request):
-        self._async_render_POST(request)
-        return NOT_DONE_YET
-
     @wrap_html_request_handler
-    @defer.inlineCallbacks
-    def _async_render_POST(self, request):
+    async def _async_render_POST(self, request):
         """
         Args:
             request (twisted.web.http.Request):
@@ -188,12 +177,12 @@ class ConsentResource(Resource):
             qualified_user_id = UserID(username, self.hs.hostname).to_string()
 
         try:
-            yield self.store.user_set_consent_version(qualified_user_id, version)
+            await self.store.user_set_consent_version(qualified_user_id, version)
         except StoreError as e:
             if e.code != 404:
                 raise
             raise NotFoundError("Unknown user")
-        yield self.registration_handler.post_consent_actions(qualified_user_id)
+        await self.registration_handler.post_consent_actions(qualified_user_id)
 
         try:
             self._render_template(request, "success.html")

+ 10 - 18
synapse/rest/key/v2/remote_key_resource.py

@@ -16,18 +16,20 @@ import logging
 from io import BytesIO
 
 from twisted.internet import defer
-from twisted.web.resource import Resource
-from twisted.web.server import NOT_DONE_YET
 
 from synapse.api.errors import Codes, SynapseError
 from synapse.crypto.keyring import ServerKeyFetcher
-from synapse.http.server import respond_with_json_bytes, wrap_json_request_handler
+from synapse.http.server import (
+    DirectServeResource,
+    respond_with_json_bytes,
+    wrap_json_request_handler,
+)
 from synapse.http.servlet import parse_integer, parse_json_object_from_request
 
 logger = logging.getLogger(__name__)
 
 
-class RemoteKey(Resource):
+class RemoteKey(DirectServeResource):
     """HTTP resource for retreiving the TLS certificate and NACL signature
     verification keys for a collection of servers. Checks that the reported
     X.509 TLS certificate matches the one used in the HTTPS connection. Checks
@@ -94,13 +96,8 @@ class RemoteKey(Resource):
         self.clock = hs.get_clock()
         self.federation_domain_whitelist = hs.config.federation_domain_whitelist
 
-    def render_GET(self, request):
-        self.async_render_GET(request)
-        return NOT_DONE_YET
-
     @wrap_json_request_handler
-    @defer.inlineCallbacks
-    def async_render_GET(self, request):
+    async def _async_render_GET(self, request):
         if len(request.postpath) == 1:
             server, = request.postpath
             query = {server.decode("ascii"): {}}
@@ -114,20 +111,15 @@ class RemoteKey(Resource):
         else:
             raise SynapseError(404, "Not found %r" % request.postpath, Codes.NOT_FOUND)
 
-        yield self.query_keys(request, query, query_remote_on_cache_miss=True)
-
-    def render_POST(self, request):
-        self.async_render_POST(request)
-        return NOT_DONE_YET
+        await self.query_keys(request, query, query_remote_on_cache_miss=True)
 
     @wrap_json_request_handler
-    @defer.inlineCallbacks
-    def async_render_POST(self, request):
+    async def _async_render_POST(self, request):
         content = parse_json_object_from_request(request)
 
         query = content["server_keys"]
 
-        yield self.query_keys(request, query, query_remote_on_cache_miss=True)
+        await self.query_keys(request, query, query_remote_on_cache_miss=True)
 
     @defer.inlineCallbacks
     def query_keys(self, request, query, query_remote_on_cache_miss=False):

+ 9 - 12
synapse/rest/media/v1/config_resource.py

@@ -14,31 +14,28 @@
 # limitations under the License.
 #
 
-from twisted.internet import defer
-from twisted.web.resource import Resource
 from twisted.web.server import NOT_DONE_YET
 
-from synapse.http.server import respond_with_json, wrap_json_request_handler
+from synapse.http.server import (
+    DirectServeResource,
+    respond_with_json,
+    wrap_json_request_handler,
+)
 
 
-class MediaConfigResource(Resource):
+class MediaConfigResource(DirectServeResource):
     isLeaf = True
 
     def __init__(self, hs):
-        Resource.__init__(self)
+        super().__init__()
         config = hs.get_config()
         self.clock = hs.get_clock()
         self.auth = hs.get_auth()
         self.limits_dict = {"m.upload.size": config.max_upload_size}
 
-    def render_GET(self, request):
-        self._async_render_GET(request)
-        return NOT_DONE_YET
-
     @wrap_json_request_handler
-    @defer.inlineCallbacks
-    def _async_render_GET(self, request):
-        yield self.auth.get_user_by_req(request)
+    async def _async_render_GET(self, request):
+        await self.auth.get_user_by_req(request)
         respond_with_json(request, 200, self.limits_dict, send_cors=True)
 
     def render_OPTIONS(self, request):

+ 10 - 16
synapse/rest/media/v1/download_resource.py

@@ -14,37 +14,31 @@
 # limitations under the License.
 import logging
 
-from twisted.internet import defer
-from twisted.web.resource import Resource
-from twisted.web.server import NOT_DONE_YET
-
 import synapse.http.servlet
-from synapse.http.server import set_cors_headers, wrap_json_request_handler
+from synapse.http.server import (
+    DirectServeResource,
+    set_cors_headers,
+    wrap_json_request_handler,
+)
 
 from ._base import parse_media_id, respond_404
 
 logger = logging.getLogger(__name__)
 
 
-class DownloadResource(Resource):
+class DownloadResource(DirectServeResource):
     isLeaf = True
 
     def __init__(self, hs, media_repo):
-        Resource.__init__(self)
-
+        super().__init__()
         self.media_repo = media_repo
         self.server_name = hs.hostname
 
         # this is expected by @wrap_json_request_handler
         self.clock = hs.get_clock()
 
-    def render_GET(self, request):
-        self._async_render_GET(request)
-        return NOT_DONE_YET
-
     @wrap_json_request_handler
-    @defer.inlineCallbacks
-    def _async_render_GET(self, request):
+    async def _async_render_GET(self, request):
         set_cors_headers(request)
         request.setHeader(
             b"Content-Security-Policy",
@@ -58,7 +52,7 @@ class DownloadResource(Resource):
         )
         server_name, media_id, name = parse_media_id(request)
         if server_name == self.server_name:
-            yield self.media_repo.get_local_media(request, media_id, name)
+            await self.media_repo.get_local_media(request, media_id, name)
         else:
             allow_remote = synapse.http.servlet.parse_boolean(
                 request, "allow_remote", default=True
@@ -72,4 +66,4 @@ class DownloadResource(Resource):
                 respond_404(request)
                 return
 
-            yield self.media_repo.get_remote_media(request, server_name, media_id, name)
+            await self.media_repo.get_remote_media(request, server_name, media_id, name)

+ 6 - 12
synapse/rest/media/v1/preview_url_resource.py

@@ -32,12 +32,11 @@ from canonicaljson import json
 
 from twisted.internet import defer
 from twisted.internet.error import DNSLookupError
-from twisted.web.resource import Resource
-from twisted.web.server import NOT_DONE_YET
 
 from synapse.api.errors import Codes, SynapseError
 from synapse.http.client import SimpleHttpClient
 from synapse.http.server import (
+    DirectServeResource,
     respond_with_json,
     respond_with_json_bytes,
     wrap_json_request_handler,
@@ -58,11 +57,11 @@ _charset_match = re.compile(br"<\s*meta[^>]*charset\s*=\s*([a-z0-9-]+)", flags=r
 _content_type_match = re.compile(r'.*; *charset="?(.*?)"?(;|$)', flags=re.I)
 
 
-class PreviewUrlResource(Resource):
+class PreviewUrlResource(DirectServeResource):
     isLeaf = True
 
     def __init__(self, hs, media_repo, media_storage):
-        Resource.__init__(self)
+        super().__init__()
 
         self.auth = hs.get_auth()
         self.clock = hs.get_clock()
@@ -98,16 +97,11 @@ class PreviewUrlResource(Resource):
     def render_OPTIONS(self, request):
         return respond_with_json(request, 200, {}, send_cors=True)
 
-    def render_GET(self, request):
-        self._async_render_GET(request)
-        return NOT_DONE_YET
-
     @wrap_json_request_handler
-    @defer.inlineCallbacks
-    def _async_render_GET(self, request):
+    async def _async_render_GET(self, request):
 
         # XXX: if get_user_by_req fails, what should we do in an async render?
-        requester = yield self.auth.get_user_by_req(request)
+        requester = await self.auth.get_user_by_req(request)
         url = parse_string(request, "url")
         if b"ts" in request.args:
             ts = parse_integer(request, "ts")
@@ -159,7 +153,7 @@ class PreviewUrlResource(Resource):
         else:
             logger.info("Returning cached response")
 
-        og = yield make_deferred_yieldable(observable.observe())
+        og = await make_deferred_yieldable(defer.maybeDeferred(observable.observe))
         respond_with_json_bytes(request, 200, og, send_cors=True)
 
     @defer.inlineCallbacks

+ 12 - 15
synapse/rest/media/v1/thumbnail_resource.py

@@ -17,10 +17,12 @@
 import logging
 
 from twisted.internet import defer
-from twisted.web.resource import Resource
-from twisted.web.server import NOT_DONE_YET
 
-from synapse.http.server import set_cors_headers, wrap_json_request_handler
+from synapse.http.server import (
+    DirectServeResource,
+    set_cors_headers,
+    wrap_json_request_handler,
+)
 from synapse.http.servlet import parse_integer, parse_string
 
 from ._base import (
@@ -34,11 +36,11 @@ from ._base import (
 logger = logging.getLogger(__name__)
 
 
-class ThumbnailResource(Resource):
+class ThumbnailResource(DirectServeResource):
     isLeaf = True
 
     def __init__(self, hs, media_repo, media_storage):
-        Resource.__init__(self)
+        super().__init__()
 
         self.store = hs.get_datastore()
         self.media_repo = media_repo
@@ -47,13 +49,8 @@ class ThumbnailResource(Resource):
         self.server_name = hs.hostname
         self.clock = hs.get_clock()
 
-    def render_GET(self, request):
-        self._async_render_GET(request)
-        return NOT_DONE_YET
-
     @wrap_json_request_handler
-    @defer.inlineCallbacks
-    def _async_render_GET(self, request):
+    async def _async_render_GET(self, request):
         set_cors_headers(request)
         server_name, media_id, _ = parse_media_id(request)
         width = parse_integer(request, "width", required=True)
@@ -63,21 +60,21 @@ class ThumbnailResource(Resource):
 
         if server_name == self.server_name:
             if self.dynamic_thumbnails:
-                yield self._select_or_generate_local_thumbnail(
+                await self._select_or_generate_local_thumbnail(
                     request, media_id, width, height, method, m_type
                 )
             else:
-                yield self._respond_local_thumbnail(
+                await self._respond_local_thumbnail(
                     request, media_id, width, height, method, m_type
                 )
             self.media_repo.mark_recently_accessed(None, media_id)
         else:
             if self.dynamic_thumbnails:
-                yield self._select_or_generate_remote_thumbnail(
+                await self._select_or_generate_remote_thumbnail(
                     request, server_name, media_id, width, height, method, m_type
                 )
             else:
-                yield self._respond_remote_thumbnail(
+                await self._respond_remote_thumbnail(
                     request, server_name, media_id, width, height, method, m_type
                 )
             self.media_repo.mark_recently_accessed(server_name, media_id)

+ 10 - 13
synapse/rest/media/v1/upload_resource.py

@@ -15,22 +15,24 @@
 
 import logging
 
-from twisted.internet import defer
-from twisted.web.resource import Resource
 from twisted.web.server import NOT_DONE_YET
 
 from synapse.api.errors import SynapseError
-from synapse.http.server import respond_with_json, wrap_json_request_handler
+from synapse.http.server import (
+    DirectServeResource,
+    respond_with_json,
+    wrap_json_request_handler,
+)
 from synapse.http.servlet import parse_string
 
 logger = logging.getLogger(__name__)
 
 
-class UploadResource(Resource):
+class UploadResource(DirectServeResource):
     isLeaf = True
 
     def __init__(self, hs, media_repo):
-        Resource.__init__(self)
+        super().__init__()
 
         self.media_repo = media_repo
         self.filepaths = media_repo.filepaths
@@ -41,18 +43,13 @@ class UploadResource(Resource):
         self.max_upload_size = hs.config.max_upload_size
         self.clock = hs.get_clock()
 
-    def render_POST(self, request):
-        self._async_render_POST(request)
-        return NOT_DONE_YET
-
     def render_OPTIONS(self, request):
         respond_with_json(request, 200, {}, send_cors=True)
         return NOT_DONE_YET
 
     @wrap_json_request_handler
-    @defer.inlineCallbacks
-    def _async_render_POST(self, request):
-        requester = yield self.auth.get_user_by_req(request)
+    async def _async_render_POST(self, request):
+        requester = await self.auth.get_user_by_req(request)
         # TODO: The checks here are a bit late. The content will have
         # already been uploaded to a tmp file at this point
         content_length = request.getHeader(b"Content-Length").decode("ascii")
@@ -81,7 +78,7 @@ class UploadResource(Resource):
         #     disposition = headers.getRawHeaders(b"Content-Disposition")[0]
         # TODO(markjh): parse content-dispostion
 
-        content_uri = yield self.media_repo.create_content(
+        content_uri = await self.media_repo.create_content(
             media_type, upload_name, request.content, content_length, requester.user
         )
 

+ 4 - 11
synapse/rest/saml2/response_resource.py

@@ -18,34 +18,27 @@ import logging
 import saml2
 from saml2.client import Saml2Client
 
-from twisted.web.resource import Resource
-from twisted.web.server import NOT_DONE_YET
-
 from synapse.api.errors import CodeMessageException
-from synapse.http.server import wrap_html_request_handler
+from synapse.http.server import DirectServeResource, wrap_html_request_handler
 from synapse.http.servlet import parse_string
 from synapse.rest.client.v1.login import SSOAuthHandler
 
 logger = logging.getLogger(__name__)
 
 
-class SAML2ResponseResource(Resource):
+class SAML2ResponseResource(DirectServeResource):
     """A Twisted web resource which handles the SAML response"""
 
     isLeaf = 1
 
     def __init__(self, hs):
-        Resource.__init__(self)
+        super().__init__()
 
         self._saml_client = Saml2Client(hs.config.saml2_sp_config)
         self._sso_auth_handler = SSOAuthHandler(hs)
 
-    def render_POST(self, request):
-        self._async_render_POST(request)
-        return NOT_DONE_YET
-
     @wrap_html_request_handler
-    def _async_render_POST(self, request):
+    async def _async_render_POST(self, request):
         resp_bytes = parse_string(request, "SAMLResponse", required=True)
         relay_state = parse_string(request, "RelayState", required=True)
 

+ 15 - 10
tests/rest/media/v1/test_media_storage.py

@@ -22,7 +22,6 @@ from binascii import unhexlify
 from mock import Mock
 from six.moves.urllib import parse
 
-from twisted.internet import defer, reactor
 from twisted.internet.defer import Deferred
 
 from synapse.rest.media.v1._base import FileInfo
@@ -34,15 +33,17 @@ from synapse.util.logcontext import make_deferred_yieldable
 from tests import unittest
 
 
-class MediaStorageTests(unittest.TestCase):
-    def setUp(self):
+class MediaStorageTests(unittest.HomeserverTestCase):
+
+    needs_threadpool = True
+
+    def prepare(self, reactor, clock, hs):
         self.test_dir = tempfile.mkdtemp(prefix="synapse-tests-")
+        self.addCleanup(shutil.rmtree, self.test_dir)
 
         self.primary_base_path = os.path.join(self.test_dir, "primary")
         self.secondary_base_path = os.path.join(self.test_dir, "secondary")
 
-        hs = Mock()
-        hs.get_reactor = Mock(return_value=reactor)
         hs.config.media_store_path = self.primary_base_path
 
         storage_providers = [FileStorageProviderBackend(hs, self.secondary_base_path)]
@@ -52,10 +53,6 @@ class MediaStorageTests(unittest.TestCase):
             hs, self.primary_base_path, self.filepaths, storage_providers
         )
 
-    def tearDown(self):
-        shutil.rmtree(self.test_dir)
-
-    @defer.inlineCallbacks
     def test_ensure_media_is_in_local_cache(self):
         media_id = "some_media_id"
         test_body = "Test\n"
@@ -73,7 +70,15 @@ class MediaStorageTests(unittest.TestCase):
         # Now we run ensure_media_is_in_local_cache, which should copy the file
         # to the local cache.
         file_info = FileInfo(None, media_id)
-        local_path = yield self.media_storage.ensure_media_is_in_local_cache(file_info)
+
+        # This uses a real blocking threadpool so we have to wait for it to be
+        # actually done :/
+        x = self.media_storage.ensure_media_is_in_local_cache(file_info)
+
+        # Hotloop until the threadpool does its job...
+        self.wait_on_thread(x)
+
+        local_path = self.get_success(x)
 
         self.assertTrue(os.path.exists(local_path))
 

+ 32 - 8
tests/unittest.py

@@ -17,6 +17,7 @@ import gc
 import hashlib
 import hmac
 import logging
+import time
 
 from mock import Mock
 
@@ -24,7 +25,8 @@ from canonicaljson import json
 
 import twisted
 import twisted.logger
-from twisted.internet.defer import Deferred
+from twisted.internet.defer import Deferred, succeed
+from twisted.python.threadpool import ThreadPool
 from twisted.trial import unittest
 
 from synapse.api.constants import EventTypes
@@ -164,6 +166,7 @@ class HomeserverTestCase(TestCase):
 
     servlets = []
     hijack_auth = True
+    needs_threadpool = False
 
     def setUp(self):
         """
@@ -192,15 +195,19 @@ class HomeserverTestCase(TestCase):
             if self.hijack_auth:
 
                 def get_user_by_access_token(token=None, allow_guest=False):
-                    return {
-                        "user": UserID.from_string(self.helper.auth_user_id),
-                        "token_id": 1,
-                        "is_guest": False,
-                    }
+                    return succeed(
+                        {
+                            "user": UserID.from_string(self.helper.auth_user_id),
+                            "token_id": 1,
+                            "is_guest": False,
+                        }
+                    )
 
                 def get_user_by_req(request, allow_guest=False, rights="access"):
-                    return create_requester(
-                        UserID.from_string(self.helper.auth_user_id), 1, False, None
+                    return succeed(
+                        create_requester(
+                            UserID.from_string(self.helper.auth_user_id), 1, False, None
+                        )
                     )
 
                 self.hs.get_auth().get_user_by_req = get_user_by_req
@@ -209,9 +216,26 @@ class HomeserverTestCase(TestCase):
                     return_value="1234"
                 )
 
+        if self.needs_threadpool:
+            self.reactor.threadpool = ThreadPool()
+            self.addCleanup(self.reactor.threadpool.stop)
+            self.reactor.threadpool.start()
+
         if hasattr(self, "prepare"):
             self.prepare(self.reactor, self.clock, self.hs)
 
+    def wait_on_thread(self, deferred, timeout=10):
+        """
+        Wait until a Deferred is done, where it's waiting on a real thread.
+        """
+        start_time = time.time()
+
+        while not deferred.called:
+            if start_time + timeout < time.time():
+                raise ValueError("Timed out waiting for threadpool")
+            self.reactor.advance(0.01)
+            time.sleep(0.01)
+
     def make_homeserver(self, reactor, clock):
         """
         Make and return a homeserver.