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Speedup tests by caching HomeServerConfig instances #15284

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Apr 18, 2023
Merged

Speedup tests by caching HomeServerConfig instances #15284

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743af2e
Speedup tests by caching HomeServerConfig instances
progval Mar 18, 2023
22865fa
Help mypy figure the types out
progval Mar 19, 2023
a4027d4
Fix changelog id
progval Mar 19, 2023
64e9d5d
Re-run linters
progval Mar 19, 2023
02bcd46
Fix py <3.7 support
progval Mar 28, 2023
11f78e8
Simplify typing
progval Mar 28, 2023
dd086ad
Merge branch 'develop' into setup-speedup
progval Mar 28, 2023
4e589d3
Remove unused imports
progval Mar 28, 2023
813dc8a
Merge branch 'develop' into setup-speedup
erikjohnston Apr 18, 2023
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1 change: 1 addition & 0 deletions changelog.d/15284.misc
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Speedup tests by caching HomeServerConfig instances.
62 changes: 60 additions & 2 deletions tests/unittest.py
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Expand Up @@ -16,6 +16,7 @@
import gc
import hashlib
import hmac
import json
import logging
import secrets
import time
Expand Down Expand Up @@ -53,6 +54,7 @@
from synapse import events
from synapse.api.constants import EventTypes
from synapse.api.room_versions import KNOWN_ROOM_VERSIONS, RoomVersion
from synapse.config._base import Config, RootConfig
from synapse.config.homeserver import HomeServerConfig
from synapse.config.server import DEFAULT_ROOM_VERSION
from synapse.crypto.event_signing import add_hashes_and_signatures
Expand Down Expand Up @@ -124,6 +126,63 @@ def new(*args: P.args, **kwargs: P.kwargs) -> R:
return _around


_TConfig = TypeVar("_TConfig", Config, RootConfig)


def deepcopy_config(config: _TConfig) -> _TConfig:
new_config: _TConfig

if isinstance(config, RootConfig):
new_config = config.__class__(config.config_files) # type: ignore[arg-type]
else:
new_config = config.__class__(config.root)

for attr_name in config.__dict__:
if attr_name.startswith("__") or attr_name == "root":
continue
attr = getattr(config, attr_name)
if isinstance(attr, Config):
new_attr = deepcopy_config(attr)
else:
new_attr = attr

setattr(new_config, attr_name, new_attr)

return new_config


_make_homeserver_config_obj_cache: Dict[str, Union[RootConfig, Config]] = {}


def make_homeserver_config_obj(config: Dict[str, Any]) -> RootConfig:
"""Creates a :class:`HomeServerConfig` instance with the given configuration dict.

This is equivalent to::

config_obj = HomeServerConfig()
config_obj.parse_config_dict(config, "", "")

but it keeps a cache of `HomeServerConfig` instances and deepcopies them as needed,
to avoid validating the whole configuration every time.
Comment on lines +165 to +166
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I don't follow why we're doing the deepcopying. Is it to allow tests to mutate config at test-time?

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Or, put differently: what sort of validation are we avoiding here?

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@progval progval Mar 22, 2023 •
edited
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Is it to allow tests to mutate config at test-time?

Yes, many of them do.

Or, put differently: what sort of validation are we avoiding here?

jsonschema and compiling Jinja templates. Profiling interfers heavily with the runtimes there, so I cannot easily get exact timings.

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I wonder if its easier to return the config wrapped in a class that stores any modifications on itself, e.g.:

class WrappedConfig:
    def __init__(self, config):
        self.config = config

    def __getattr__(self, name):
        return getattr(self.config, name)

that way you avoid having to try and write a deep copy mechanism, while ensuring the underlying config object doesn't change?

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This would only work when setting attributes directly to the root attribute. Otherwise, root.foo.bar = "abc" would add an attribute to the object root.foo, but we still need to somehow get rid of it when resetting root.

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Ah yup, you're totally right.

"""
cache_key = json.dumps(config)

if cache_key in _make_homeserver_config_obj_cache:
# Cache hit: reuse the existing instance
config_obj = _make_homeserver_config_obj_cache[cache_key]
else:
# Cache miss; create the actual instance
config_obj = HomeServerConfig()
config_obj.parse_config_dict(config, "", "")

# Add to the cache
_make_homeserver_config_obj_cache[cache_key] = config_obj

assert isinstance(config_obj, RootConfig)

return deepcopy_config(config_obj)


class TestCase(unittest.TestCase):
"""A subclass of twisted.trial's TestCase which looks for 'loglevel'
attributes on both itself and its individual test methods, to override the
Expand Down Expand Up @@ -528,8 +587,7 @@ def setup_test_homeserver(self, *args: Any, **kwargs: Any) -> HomeServer:
config = kwargs["config"]

# Parse the config from a config dict into a HomeServerConfig
config_obj = HomeServerConfig()
config_obj.parse_config_dict(config, "", "")
config_obj = make_homeserver_config_obj(config)
kwargs["config"] = config_obj

async def run_bg_updates() -> None:
Expand Down