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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
if peerId in p.peers:
p.peers.del(peerId)
libp2p_pubsub_peers.set(p.peers.len.int64)
proc send*(
p: PubSub,
peer: PubSubPeer,
msg: RPCMsg,
timeout: Duration): Future[bool] {.async.} =
## send to remote peer
##
trace "sending pubsub message to peer", peer = $peer, msg = shortLog(msg)
try:
await peer.send(msg, timeout)
return true
except CancelledError as exc:
raise exc
except CatchableError as exc:
trace "exception sending pubsub message to peer",
peer = $peer, msg = shortLog(msg)
p.unsubscribePeer(peer.peerId)
proc broadcast*(
p: PubSub,
sendPeers: seq[PubSubPeer],
msg: RPCMsg,
timeout: Duration): Future[int] {.async.} =
## send messages and cleanup failed peers
##
trace "broadcasting messages to peers",
peers = sendPeers.len, message = shortLog(msg)
let sent = await allFinished(
sendPeers.mapIt( p.send(it, msg, timeout) ))
return sent.filterIt( it.finished and it.read ).len
proc sendSubs*(p: PubSub,
peer: PubSubPeer,
topics: seq[string],
subscribe: bool): Future[bool] =
## send subscriptions to remote peer
p.send(
peer,
RPCMsg(
subscriptions: topics.mapIt(SubOpts(subscribe: subscribe, topic: it))),
DefaultSendTimeout)
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,
rpcMsgs: seq[RPCMsg]) {.async, base.} =
## handle rpc messages
trace "processing RPC message", peer = peer.id, msgs = rpcMsgs.len
for m in rpcMsgs: # for all RPC messages
trace "processing messages", msg = m.shortLog
if m.subscriptions.len > 0: # if there are any subscriptions
for s in m.subscriptions: # subscribe/unsubscribe the peer for each topic
trace "about to subscribe to topic", topicId = s.topic
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]
# create new pubsub peer
let pubSubPeer = newPubSubPeer(peer, p.switch, proto)
trace "created new pubsub peer", peerId = $peer
p.peers[peer] = pubSubPeer
pubSubPeer.observers = p.observers
libp2p_pubsub_peers.set(p.peers.len.int64)
return pubSubPeer
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, msgs: seq[RPCMsg]) {.async.} =
# call pubsub rpc handler
await p.rpcHandler(peer, msgs)
try:
let peer = p.getOrCreatePeer(conn.peerInfo.peerId, proto)
if p.topics.len > 0:
discard await p.sendSubs(peer, toSeq(p.topics.keys), true)
peer.handler = handler
await peer.handle(conn) # spawn peer read loop
trace "pubsub peer handler ended", peer = peer.id
except CancelledError as exc:
raise exc
except CatchableError as exc:
trace "exception ocurred in pubsub handle", exc = exc.msg
finally:
await conn.close()
method subscribePeer*(p: PubSub, peer: PeerID) {.base.} =
## subscribe to remote peer to receive/send pubsub
## messages
##
let pubsubPeer = p.getOrCreatePeer(peer, p.codec)
if p.topics.len > 0:
# TODO sendSubs may raise, but doing asyncCheck here causes the exception
# to escape to the poll loop.
# With a bit of luck, it may be harmless to ignore exceptions here -
# some cleanup is eventually done in PubSubPeer.send
asyncCheck p.sendSubs(pubsubPeer, toSeq(p.topics.keys), true)
pubsubPeer.subscribed = true
method unsubscribe*(p: PubSub,
topics: seq[TopicPair]) {.base, async.} =
## unsubscribe from a list of ``topic`` strings
for t in topics:
for i, h in p.topics[t.topic].handler:
if h == t.handler:
p.topics[t.topic].handler.del(i)
# make sure we delete the topic if
# no more handlers are left
if p.topics[t.topic].handler.len <= 0:
p.topics.del(t.topic)
# metrics
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)
var sent: seq[Future[bool]]
for peer in toSeq(p.peers.values):
sent.add(p.sendSubs(peer, @[topic], true))
checkFutures(await allFinished(sent))
# metrics
libp2p_pubsub_topics.set(p.topics.len.int64)
method publish*(p: PubSub,
topic: string,
data: seq[byte],
timeout: Duration = InfiniteDuration): Future[int] {.base, async.} =
## publish to a ``topic``
if p.triggerSelf and topic in p.topics:
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:
# TODO these exceptions are ignored since it's likely that if writes are
# are failing, the underlying connection is already closed - this needs
# more cleanup though
debug "Could not write to pubsub connection", msg = exc.msg
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 =
result = P(switch: switch,
peerInfo: switch.peerInfo,
triggerSelf: triggerSelf,
verifySignature: verifySignature,
sign: sign,
peers: initTable[PeerID, PubSubPeer](),
topics: initTable[string, Topic](),
msgIdProvider: msgIdProvider)
result.initPubSub()
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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