zulip/zerver/lib/profile.py

34 lines
1.2 KiB
Python

import cProfile
from functools import wraps
from typing import Callable, TypeVar, cast
FuncT = TypeVar('FuncT', bound=Callable[..., object])
def profiled(func: FuncT) -> FuncT:
"""
This decorator should obviously be used only in a dev environment.
It works best when surrounding a function that you expect to be
called once. One strategy is to write a backend test and wrap the
test case with the profiled decorator.
You can run a single test case like this:
# edit zerver/tests/test_external.py and place @profiled above the test case below
./tools/test-backend zerver.tests.test_external.RateLimitTests.test_ratelimit_decrease
Then view the results like this:
./tools/show-profile-results test_ratelimit_decrease.profile
"""
func_: Callable[..., object] = func # work around https://github.com/python/mypy/issues/9075
@wraps(func)
def wrapped_func(*args: object, **kwargs: object) -> object:
fn = func.__name__ + ".profile"
prof = cProfile.Profile()
retval = prof.runcall(func_, *args, **kwargs)
prof.dump_stats(fn)
return retval
return cast(FuncT, wrapped_func) # https://github.com/python/mypy/issues/1927