tractor/tractor/_testing/addr.py

97 lines
3.6 KiB
Python

# tractor: structured concurrent "actors".
# Copyright 2018-eternity Tyler Goodlet.
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Affero General Public License for more details.
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <https://www.gnu.org/licenses/>.
'''
Random IPC addr generation for isolating
the discovery space between test sessions.
Might be eventually useful to expose as a util set from
our `tractor.discovery` subsys?
'''
import os
import random
from typing import (
Type,
)
from tractor.discovery import _addr
def get_rando_addr(
tpt_proto: str,
) -> tuple[str, str|int]:
'''
Used to globally override the runtime to the
per-test-session-dynamic addr so that all tests never conflict
with any other actor tree using the default.
Cross-process isolation: TCP-port picks salt
`random.randint()` with `os.getpid()` so two parallel
pytest sessions (e.g. one running `--tpt-proto=tcp` and
another `--tpt-proto=uds` concurrently) almost-never
collide on the same port. Without the salt, the prior
impl's import-time `random.randint(1000, 9999)` default
arg was effectively a process-singleton with a 1/9000
chance of cross-run collision per pair — and when it
happened EVERY `reg_addr`-using test in BOTH runs would
fight over the bind, cascading into a chain of
"Address already in use" failures.
For UDS this concern doesn't apply: `UDSAddress.get_random()`
already builds socket paths from `os.getpid()` so each
pytest process gets its own socket-path namespace.
'''
addr_type: Type[_addr.Addres] = _addr._address_types[tpt_proto]
def_reg_addr: tuple[str, int] = _addr._default_lo_addrs[tpt_proto]
# this is the "unwrapped" form expected to be passed to
# `.open_root_actor()` by test body.
testrun_reg_addr: tuple[str, int|str]
match tpt_proto:
case 'tcp':
# Per-call randomness mixed with `os.getpid()` —
# see the docstring above for the cross-process
# isolation rationale. The mix means:
# - within one pytest session, two calls return
# distinct ports (good for tests that need a
# second-different-reg-addr in one fn body, e.g.
# `test_tpt_bind_addrs::bind-subset-reg`),
# - across parallel pytest sessions, the pid bias
# makes coincident port choices unlikely.
port: int = 1000 + (
random.randint(0, 8999) + os.getpid()
) % 9000
testrun_reg_addr = (
addr_type.def_bindspace,
port,
)
# NOTE, file-name uniqueness (no-collisions) will be based on
# the runtime-directory and root (pytest-proc's) pid.
case 'uds':
from tractor.ipc._uds import UDSAddress
addr: UDSAddress = addr_type.get_random()
assert addr.is_valid
assert addr.sockpath.resolve()
testrun_reg_addr = addr.unwrap()
# XXX, as sanity it should never the same as the default for the
# host-singleton registry actor.
assert def_reg_addr != testrun_reg_addr
return testrun_reg_addr