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

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## Nim-LibP2P
## Copyright (c) 2019 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.
import std/[tables, sequtils, sets]
import chronos, chronicles, metrics
import pubsubpeer,
rpc/[message, messages],
../../switch,
../protocol,
../../stream/connection,
../../peerid,
../../peerinfo,
../../errors
export PubSubPeer
export PubSubObserver
logScope:
topics = "pubsub"
declareGauge(libp2p_pubsub_peers, "pubsub peer instances")
declareGauge(libp2p_pubsub_topics, "pubsub subscribed topics")
declareCounter(libp2p_pubsub_validation_success, "pubsub successfully validated messages")
declareCounter(libp2p_pubsub_validation_failure, "pubsub failed validated messages")
when defined(libp2p_expensive_metrics):
declarePublicCounter(libp2p_pubsub_messages_published, "published messages", labels = ["topic"])
type
TopicHandler* = proc(topic: string,
data: seq[byte]): Future[void] {.gcsafe.}
ValidatorHandler* = proc(topic: string,
message: Message): Future[bool] {.gcsafe, closure.}
TopicPair* = tuple[topic: string, handler: TopicHandler]
MsgIdProvider* =
proc(m: Message): string {.noSideEffect, raises: [Defect], nimcall, gcsafe.}
Topic* = object
name*: string
handler*: seq[TopicHandler]
PubSub* = ref object of LPProtocol
switch*: Switch # the switch used to dial/connect to peers
peerInfo*: PeerInfo # this peer's info
topics*: Table[string, Topic] # local topics
peers*: Table[PeerID, PubSubPeer] # peerid to peer map
triggerSelf*: bool # trigger own local handler on publish
verifySignature*: bool # enable signature verification
sign*: bool # enable message signing
validators*: Table[string, HashSet[ValidatorHandler]]
observers: ref seq[PubSubObserver] # ref as in smart_ptr
msgIdProvider*: MsgIdProvider # Turn message into message id (not nil)
msgSeqno*: uint64
lifetimeFut*: Future[void] # pubsub liftime future
method unsubscribePeer*(p: PubSub, peerId: PeerID) {.base.} =
## handle peer disconnects
##
trace "unsubscribing pubsub peer", peer = $peerId
p.peers.del(peerId)
libp2p_pubsub_peers.set(p.peers.len.int64)
proc send*(p: PubSub, peer: PubSubPeer, msg: RPCMsg) =
## Attempt to send `msg` to remote peer
##
trace "sending pubsub message to peer", peer = $peer, msg = shortLog(msg)
peer.send(msg)
proc broadcast*(
p: PubSub,
sendPeers: openArray[PubSubPeer],
msg: RPCMsg) = # raises: [Defect]
## Attempt to send `msg` to the given peers
trace "broadcasting messages to peers",
peers = sendPeers.len, msg = shortLog(msg)
for peer in sendPeers:
p.send(peer, msg)
proc sendSubs*(p: PubSub,
peer: PubSubPeer,
topics: seq[string],
subscribe: bool) =
## send subscriptions to remote peer
p.send(peer, RPCMsg.withSubs(topics, subscribe))
method subscribeTopic*(p: PubSub,
topic: string,
subscribe: bool,
peer: PubSubPeer) {.base.} =
# called when remote peer subscribes to a topic
discard
method rpcHandler*(p: PubSub,
peer: PubSubPeer,
rpcMsg: RPCMsg) {.async, base.} =
## handle rpc messages
trace "processing RPC message", msg = rpcMsg.shortLog, peer
for s in rpcMsg.subscriptions: # subscribe/unsubscribe the peer for each topic
trace "about to subscribe to topic", topicId = s.topic, peer
p.subscribeTopic(s.topic, s.subscribe, peer)
proc getOrCreatePeer*(
p: PubSub,
peer: PeerID,
proto: string): PubSubPeer =
if peer in p.peers:
return p.peers[peer]
proc getConn(): Future[(Connection, RPCMsg)] {.async.} =
let conn = await p.switch.dial(peer, proto)
return (conn, RPCMsg.withSubs(toSeq(p.topics.keys), true))
# create new pubsub peer
let pubSubPeer = newPubSubPeer(peer, getConn, proto)
trace "created new pubsub peer", peerId = $peer
p.peers[peer] = pubSubPeer
pubSubPeer.observers = p.observers
libp2p_pubsub_peers.set(p.peers.len.int64)
pubsubPeer.connect()
return pubSubPeer
proc handleData*(p: PubSub, topic: string, data: seq[byte]): Future[void] {.async.} =
if topic notin p.topics: return # Not subscribed
for h in p.topics[topic].handler:
trace "triggering handler", topicID = topic
try:
await h(topic, data)
except CancelledError as exc:
raise exc
except CatchableError as exc:
# Handlers should never raise exceptions
warn "Error in topic handler", msg = exc.msg
method handleConn*(p: PubSub,
conn: Connection,
proto: string) {.base, async.} =
## handle incoming connections
##
## this proc will:
## 1) register a new PubSubPeer for the connection
## 2) register a handler with the peer;
## this handler gets called on every rpc message
## that the peer receives
## 3) ask the peer to subscribe us to every topic
## that we're interested in
##
if isNil(conn.peerInfo):
trace "no valid PeerId for peer"
await conn.close()
return
proc handler(peer: PubSubPeer, msg: RPCMsg): Future[void] =
# call pubsub rpc handler
p.rpcHandler(peer, msg)
let peer = p.getOrCreatePeer(conn.peerInfo.peerId, proto)
try:
peer.handler = handler
await peer.handle(conn) # spawn peer read loop
trace "pubsub peer handler ended", conn
except CancelledError as exc:
raise exc
except CatchableError as exc:
trace "exception ocurred in pubsub handle", exc = exc.msg, conn
finally:
await conn.close()
method subscribePeer*(p: PubSub, peer: PeerID) {.base.} =
## subscribe to remote peer to receive/send pubsub
## messages
##
discard p.getOrCreatePeer(peer, p.codec)
method unsubscribe*(p: PubSub,
topics: seq[TopicPair]) {.base, async.} =
## unsubscribe from a list of ``topic`` strings
for t in topics:
p.topics.withValue(t.topic, topic):
topic[].handler.keepIf(proc (x: auto): bool = x != t.handler)
if topic[].handler.len == 0:
# make sure we delete the topic if
# no more handlers are left
p.topics.del(t.topic)
libp2p_pubsub_topics.set(p.topics.len.int64)
proc unsubscribe*(p: PubSub,
topic: string,
handler: TopicHandler): Future[void] =
## unsubscribe from a ``topic`` string
##
p.unsubscribe(@[(topic, handler)])
method unsubscribeAll*(p: PubSub, topic: string) {.base, async.} =
p.topics.del(topic)
libp2p_pubsub_topics.set(p.topics.len.int64)
method subscribe*(p: PubSub,
topic: string,
handler: TopicHandler) {.base, async.} =
## subscribe to a topic
##
## ``topic`` - a string topic to subscribe to
##
## ``handler`` - is a user provided proc
## that will be triggered
## on every received message
##
if topic notin p.topics:
trace "subscribing to topic", name = topic
p.topics[topic] = Topic(name: topic)
p.topics[topic].handler.add(handler)
for _, peer in p.peers:
p.sendSubs(peer, @[topic], true)
# metrics
libp2p_pubsub_topics.set(p.topics.len.int64)
method publish*(p: PubSub,
topic: string,
data: seq[byte]): Future[int] {.base, async.} =
## publish to a ``topic``
## The return value is the number of neighbours that we attempted to send the
## message to, excluding self. Note that this is an optimistic number of
## attempts - the number of peers that actually receive the message might
## be lower.
if p.triggerSelf:
await handleData(p, topic, data)
return 0
method initPubSub*(p: PubSub) {.base.} =
## perform pubsub initialization
p.observers = new(seq[PubSubObserver])
if p.msgIdProvider == nil:
p.msgIdProvider = defaultMsgIdProvider
method start*(p: PubSub) {.async, base.} =
## start pubsub
discard
method stop*(p: PubSub) {.async, base.} =
## stopt pubsub
discard
method addValidator*(p: PubSub,
topic: varargs[string],
hook: ValidatorHandler) {.base.} =
for t in topic:
if t notin p.validators:
p.validators[t] = initHashSet[ValidatorHandler]()
trace "adding validator for topic", topicId = t
p.validators[t].incl(hook)
method removeValidator*(p: PubSub,
topic: varargs[string],
hook: ValidatorHandler) {.base.} =
for t in topic:
if t in p.validators:
p.validators[t].excl(hook)
method validate*(p: PubSub, message: Message): Future[bool] {.async, base.} =
var pending: seq[Future[bool]]
trace "about to validate message"
for topic in message.topicIDs:
trace "looking for validators on topic", topicID = topic,
registered = toSeq(p.validators.keys)
if topic in p.validators:
trace "running validators for topic", topicID = topic
# TODO: add timeout to validator
pending.add(p.validators[topic].mapIt(it(topic, message)))
let futs = await allFinished(pending)
result = futs.allIt(not it.failed and it.read())
if result:
libp2p_pubsub_validation_success.inc()
else:
libp2p_pubsub_validation_failure.inc()
proc init*(
P: typedesc[PubSub],
switch: Switch,
triggerSelf: bool = false,
verifySignature: bool = true,
sign: bool = true,
msgIdProvider: MsgIdProvider = defaultMsgIdProvider): P =
let pubsub = P(
switch: switch,
peerInfo: switch.peerInfo,
triggerSelf: triggerSelf,
verifySignature: verifySignature,
sign: sign,
peers: initTable[PeerID, PubSubPeer](),
topics: initTable[string, Topic](),
msgIdProvider: msgIdProvider)
proc peerEventHandler(peerId: PeerID, event: PeerEvent) {.async.} =
if event == PeerEvent.Joined:
pubsub.subscribePeer(peerId)
else:
pubsub.unsubscribePeer(peerId)
switch.addPeerEventHandler(peerEventHandler, PeerEvent.Joined)
switch.addPeerEventHandler(peerEventHandler, PeerEvent.Left)
pubsub.initPubSub()
return pubsub
proc addObserver*(p: PubSub; observer: PubSubObserver) =
p.observers[] &= observer
proc removeObserver*(p: PubSub; observer: PubSubObserver) =
let idx = p.observers[].find(observer)
if idx != -1:
p.observers[].del(idx)
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