89 lines
2.6 KiB
Python
89 lines
2.6 KiB
Python
from contextlib import contextmanager
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from itertools import count
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from jeepney import HeaderFields, Message, MessageFlag, MessageType
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class MessageFilters:
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def __init__(self):
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self.filters = {}
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self.filter_ids = count()
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def matches(self, message):
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for handle in self.filters.values():
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if handle.rule.matches(message):
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yield handle
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class FilterHandle:
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def __init__(self, filters: MessageFilters, rule, queue):
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self._filters = filters
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self._filter_id = next(filters.filter_ids)
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self.rule = rule
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self.queue = queue
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self._filters.filters[self._filter_id] = self
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def close(self):
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del self._filters.filters[self._filter_id]
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def __enter__(self):
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return self.queue
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def __exit__(self, exc_type, exc_val, exc_tb):
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self.close()
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return False
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class ReplyMatcher:
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def __init__(self):
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self._futures = {}
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@contextmanager
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def catch(self, serial, future):
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"""Context manager to capture a reply for the given serial number"""
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self._futures[serial] = future
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try:
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yield future
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finally:
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del self._futures[serial]
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def dispatch(self, msg):
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"""Dispatch an incoming message which may be a reply
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Returns True if a task was waiting for it, otherwise False.
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"""
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rep_serial = msg.header.fields.get(HeaderFields.reply_serial, -1)
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if rep_serial in self._futures:
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self._futures[rep_serial].set_result(msg)
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return True
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else:
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return False
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def drop_all(self, exc: Exception = None):
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"""Throw an error in any task still waiting for a reply"""
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if exc is None:
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exc = RouterClosed("D-Bus router closed before reply arrived")
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futures, self._futures = self._futures, {}
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for fut in futures.values():
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fut.set_exception(exc)
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class RouterClosed(Exception):
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"""Raised in tasks waiting for a reply when the router is closed
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This will also be raised if the receiver task crashes, so tasks are not
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stuck waiting for a reply that can never come. The router object will not
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be usable after this is raised.
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"""
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pass
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def check_replyable(msg: Message):
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"""Raise an error if we wouldn't expect a reply for msg"""
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if msg.header.message_type != MessageType.method_call:
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raise TypeError("Only method call messages have replies "
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f"(not {msg.header.message_type})")
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if MessageFlag.no_reply_expected & msg.header.flags:
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raise ValueError("This message has the no_reply_expected flag set")
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