nim-libp2p/libp2p/protocols/pubsub/mcache.nim

69 lines
1.8 KiB
Nim

# Nim-LibP2P
# Copyright (c) 2023 Status Research & Development GmbH
# Licensed under either of
# * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
# * MIT license ([LICENSE-MIT](LICENSE-MIT))
# at your option.
# This file may not be copied, modified, or distributed except according to
# those terms.
{.push raises: [].}
import std/[sets, tables]
import rpc/[messages]
import results
export sets, tables, messages, results
type
CacheEntry* = object
msgId*: MessageId
topic*: string
MCache* = object of RootObj
msgs*: Table[MessageId, Message]
history*: seq[seq[CacheEntry]]
pos*: int
windowSize*: Natural
func get*(c: MCache, msgId: MessageId): Opt[Message] =
if msgId in c.msgs:
try: Opt.some(c.msgs[msgId])
except KeyError: raiseAssert "checked"
else:
Opt.none(Message)
func contains*(c: MCache, msgId: MessageId): bool =
msgId in c.msgs
func put*(c: var MCache, msgId: MessageId, msg: Message) =
if not c.msgs.hasKeyOrPut(msgId, msg):
# Only add cache entry if the message was not already in the cache
c.history[c.pos].add(CacheEntry(msgId: msgId, topic: msg.topic))
func window*(c: MCache, topic: string): HashSet[MessageId] =
let
len = min(c.windowSize, c.history.len)
for i in 0..<len:
# Work backwards from `pos` in the circular buffer
for entry in c.history[(c.pos + c.history.len - i) mod c.history.len]:
if entry.topic == topic:
result.incl(entry.msgId)
func shift*(c: var MCache) =
# Shift circular buffer to write to a new position, clearing it from past
# iterations
c.pos = (c.pos + 1) mod c.history.len
for entry in c.history[c.pos]:
c.msgs.del(entry.msgId)
reset(c.history[c.pos])
func init*(T: type MCache, window, history: Natural): T =
T(
history: newSeq[seq[CacheEntry]](history),
windowSize: window
)