py-libp2p/libp2p/pubsub/mcache.py
2019-08-02 23:26:06 +08:00

104 lines
2.9 KiB
Python

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