Files
DECNET/decnet/bus/factory.py
anti 3ed6d5dfc6 refactor: consolidate writable-dir probe into decnet/paths.py
bus.factory and vectorstore.factory carried byte-identical copies of the
'env override -> writable runtime dir -> ~/.decnet fallback' probe. Move
it to decnet.paths.resolve_runtime_path and call it from both.

The mkdir-create variants (deployer topologies dir, _pid_dir candidate
iteration, personas_pool existence-precedence) are deliberately left
inline: they're different policies, not the same probe.
2026-06-18 21:27:36 -04:00

86 lines
3.0 KiB
Python

# SPDX-License-Identifier: AGPL-3.0-or-later
"""Bus factory — selects a :class:`~decnet.bus.base.BaseBus` implementation.
Dispatch key: the ``DECNET_BUS_TYPE`` environment variable.
* ``unix`` (default) → :class:`~decnet.bus.unix_client.UnixSocketBus`
* ``fake`` → :class:`~decnet.bus.fake.FakeBus` (in-process)
If ``DECNET_BUS_ENABLED`` is ``"false"`` the factory short-circuits to
:class:`~decnet.bus.fake.NullBus` regardless of ``DECNET_BUS_TYPE`` — a
cheap way for dev environments to run workers without a bus daemon.
Mirrors :mod:`decnet.web.db.factory` (lazy imports inside each branch,
env-driven dispatch, optional telemetry wrapping). Callers MUST use
:func:`get_bus` rather than instantiating transports directly.
"""
from __future__ import annotations
import os
from typing import Any, cast
from decnet.bus.base import BaseBus
from decnet.paths import resolve_runtime_path
def get_bus(**kwargs: Any) -> BaseBus:
"""Instantiate the bus implementation selected by environment.
Keyword arguments are forwarded to the concrete transport:
* ``UnixSocketBus`` accepts ``socket_path`` (overrides
``DECNET_BUS_SOCKET``) and ``client_name``.
* ``FakeBus`` accepts ``queue_size``.
"""
if os.environ.get("DECNET_BUS_ENABLED", "true").lower() == "false":
from decnet.bus.fake import NullBus
return NullBus()
bus_type = os.environ.get("DECNET_BUS_TYPE", "unix").lower()
if bus_type == "unix":
from decnet.bus.unix_client import UnixSocketBus
socket_path = kwargs.pop("socket_path", None) or _default_socket_path()
bus: BaseBus = UnixSocketBus(socket_path=socket_path, **kwargs)
elif bus_type == "fake":
from decnet.bus.fake import FakeBus
bus = FakeBus(**kwargs)
else:
raise ValueError(f"Unsupported bus type: {bus_type}")
return _maybe_wrap_telemetry(bus)
def _default_socket_path() -> str:
"""Return the bus socket path honoring ``DECNET_BUS_SOCKET`` and falling
back to ``/run/decnet/bus.sock`` → ``~/.decnet/bus.sock``.
The runtime path (``/run/decnet``) is preferred because systemd
``RuntimeDirectory=decnet`` sets it up with the right perms; the home
fallback keeps dev boxes usable without systemd.
"""
return resolve_runtime_path(
"bus.sock",
env_var="DECNET_BUS_SOCKET",
runtime_dir="/run/decnet",
user_fallback="~/.decnet/bus.sock",
)
def _maybe_wrap_telemetry(bus: BaseBus) -> BaseBus:
"""Wrap *bus* in a tracing proxy if OTEL is enabled, else return as-is.
Uses :func:`decnet.telemetry.wrap_repository` as the underlying proxy —
its implementation is generic (wraps any async method in a span), so we
reuse it with a bus-appropriate tracer name. If telemetry isn't wired
up at all we no-op.
"""
try:
from decnet.telemetry import wrap_repository
except ImportError:
return bus
try:
return cast(BaseBus, wrap_repository(bus))
except Exception: # pragma: no cover - defensive
return bus