104 lines
2.9 KiB
Python
104 lines
2.9 KiB
Python
from typing import Dict, List, Optional, Sequence, Tuple
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from .pb import rpc_pb2
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class CacheEntry:
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mid: Tuple[bytes, bytes]
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topics: List[str]
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"""
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A logical representation of an entry in the mcache's _history_.
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"""
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def __init__(self, mid: Tuple[bytes, bytes], topics: Sequence[str]) -> None:
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"""
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Constructor.
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:param mid: (seqno, from_id) of the msg
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:param topics: list of topics this message was sent on
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"""
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self.mid = mid
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self.topics = list(topics)
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class MessageCache:
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window_size: int
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history_size: int
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msgs: Dict[Tuple[bytes, bytes], rpc_pb2.Message]
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history: List[List[CacheEntry]]
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def __init__(self, window_size: int, history_size: int) -> None:
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"""
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Constructor.
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:param window_size: Size of the window desired.
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:param history_size: Size of the history desired.
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:return: the MessageCache
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"""
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self.window_size = window_size
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self.history_size = history_size
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# (seqno, from_id) -> rpc message
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self.msgs = dict()
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# max length of history_size. each item is a list of CacheEntry.
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# messages lost upon shift().
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self.history = [[] for _ in range(history_size)]
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def put(self, msg: rpc_pb2.Message) -> None:
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"""
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Put a message into the mcache.
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:param msg: The rpc message to put in. Should contain seqno and from_id
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"""
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mid: Tuple[bytes, bytes] = (msg.seqno, msg.from_id)
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self.msgs[mid] = msg
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self.history[0].append(CacheEntry(mid, msg.topicIDs))
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def get(self, mid: Tuple[bytes, bytes]) -> Optional[rpc_pb2.Message]:
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"""
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Get a message from the mcache.
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:param mid: (seqno, from_id) of the message to get.
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:return: The rpc message associated with this mid
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"""
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if mid in self.msgs:
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return self.msgs[mid]
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return None
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def window(self, topic: str) -> List[Tuple[bytes, bytes]]:
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"""
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Get the window for this topic.
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:param topic: Topic whose message ids we desire.
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:return: List of mids in the current window.
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"""
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mids: List[Tuple[bytes, bytes]] = []
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for entries_list in self.history[: self.window_size]:
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for entry in entries_list:
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for entry_topic in entry.topics:
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if entry_topic == topic:
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mids.append(entry.mid)
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return mids
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def shift(self) -> None:
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"""
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Shift the window over by 1 position, dropping the last element of the history.
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"""
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last_entries: List[CacheEntry] = self.history[len(self.history) - 1]
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for entry in last_entries:
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del self.msgs[entry.mid]
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i: int = len(self.history) - 2
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while i >= 0:
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self.history[i + 1] = self.history[i]
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i -= 1
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self.history[0] = []
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