nim-libp2p-experimental/libp2p/connmanager.nim

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## Nim-LibP2P
## Copyright (c) 2020 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/[options, tables, sequtils, sets]
import chronos, chronicles, metrics
import peerinfo,
stream/connection,
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muxers/muxer,
errors
logScope:
topics = "connmanager"
declareGauge(libp2p_peers, "total connected peers")
const MaxConnectionsPerPeer = 5
type
TooManyConnections* = object of CatchableError
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ConnEventKind* {.pure.} = enum
Connected, # A connection was made and securely upgraded - there may be
# more than one concurrent connection thus more than one upgrade
# event per peer.
Disconnected # Peer disconnected - this event is fired once per upgrade
# when the associated connection is terminated.
ConnEvent* = object
case kind*: ConnEventKind
of ConnEventKind.Connected:
incoming*: bool
else:
discard
ConnEventHandler* =
proc(peerId: PeerID, event: ConnEvent): Future[void] {.gcsafe.}
PeerEvent* {.pure.} = enum
Left,
Joined
PeerEventHandler* =
proc(peerId: PeerID, event: PeerEvent): Future[void] {.gcsafe.}
MuxerHolder = object
muxer: Muxer
handle: Future[void]
ConnManager* = ref object of RootObj
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maxConns: int
# NOTE: don't change to PeerInfo here
# the reference semantics on the PeerInfo
# object itself make it susceptible to
# copies and mangling by unrelated code.
conns: Table[PeerID, HashSet[Connection]]
muxed: Table[Connection, MuxerHolder]
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connEvents: Table[ConnEventKind, OrderedSet[ConnEventHandler]]
peerEvents: Table[PeerEvent, OrderedSet[PeerEventHandler]]
proc newTooManyConnections(): ref TooManyConnections {.inline.} =
result = newException(TooManyConnections, "too many connections for peer")
proc init*(C: type ConnManager,
maxConnsPerPeer: int = MaxConnectionsPerPeer): ConnManager =
C(maxConns: maxConnsPerPeer,
conns: initTable[PeerID, HashSet[Connection]](),
muxed: initTable[Connection, MuxerHolder]())
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proc connCount*(c: ConnManager, peerId: PeerID): int =
c.conns.getOrDefault(peerId).len
proc addConnEventHandler*(c: ConnManager,
handler: ConnEventHandler, kind: ConnEventKind) =
## Add peer event handler - handlers must not raise exceptions!
##
if isNil(handler): return
c.connEvents.mgetOrPut(kind,
initOrderedSet[ConnEventHandler]()).incl(handler)
proc removeConnEventHandler*(c: ConnManager,
handler: ConnEventHandler, kind: ConnEventKind) =
c.connEvents.withValue(kind, handlers) do:
handlers[].excl(handler)
proc triggerConnEvent*(c: ConnManager, peerId: PeerID, event: ConnEvent) {.async, gcsafe.} =
try:
if event.kind in c.connEvents:
var connEvents: seq[Future[void]]
for h in c.connEvents[event.kind]:
connEvents.add(h(peerId, event))
checkFutures(await allFinished(connEvents))
except CancelledError as exc:
raise exc
except CatchableError as exc: # handlers should not raise!
warn "Exception in triggerConnEvents",
msg = exc.msg, peerId, event = $event
proc addPeerEventHandler*(c: ConnManager,
handler: PeerEventHandler,
kind: PeerEvent) =
## Add peer event handler - handlers must not raise exceptions!
##
if isNil(handler): return
c.peerEvents.mgetOrPut(kind,
initOrderedSet[PeerEventHandler]()).incl(handler)
proc removePeerEventHandler*(c: ConnManager,
handler: PeerEventHandler,
kind: PeerEvent) =
c.peerEvents.withValue(kind, handlers) do:
handlers[].excl(handler)
proc triggerPeerEvents*(c: ConnManager,
peerId: PeerID,
event: PeerEvent) {.async, gcsafe.} =
trace "About to trigger peer events", peer = peerId
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if event notin c.peerEvents:
return
try:
let count = c.connCount(peerId)
if event == PeerEvent.Joined and count != 1:
trace "peer already joined", peerId, event = $event
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return
elif event == PeerEvent.Left and count != 0:
trace "peer still connected or already left", peerId, event = $event
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return
trace "triggering peer events", peerId, event = $event
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var peerEvents: seq[Future[void]]
for h in c.peerEvents[event]:
peerEvents.add(h(peerId, event))
checkFutures(await allFinished(peerEvents))
except CancelledError as exc:
raise exc
except CatchableError as exc: # handlers should not raise!
warn "Exception in triggerPeerEvents", exc = exc.msg, peerId
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proc contains*(c: ConnManager, conn: Connection): bool =
## checks if a connection is being tracked by the
## connection manager
##
if isNil(conn):
return
if isNil(conn.peerInfo):
return
return conn in c.conns[conn.peerInfo.peerId]
proc contains*(c: ConnManager, peerId: PeerID): bool =
peerId in c.conns
proc contains*(c: ConnManager, muxer: Muxer): bool =
## checks if a muxer is being tracked by the connection
## manager
##
if isNil(muxer):
return
let conn = muxer.connection
if conn notin c:
return
if conn notin c.muxed:
return
return muxer == c.muxed[conn].muxer
proc closeMuxerHolder(muxerHolder: MuxerHolder) {.async.} =
trace "Cleaning up muxer", m = muxerHolder.muxer
await muxerHolder.muxer.close()
if not(isNil(muxerHolder.handle)):
await muxerHolder.handle # TODO noraises?
trace "Cleaned up muxer", m = muxerHolder.muxer
proc delConn(c: ConnManager, conn: Connection) =
let peerId = conn.peerInfo.peerId
if peerId in c.conns:
c.conns[peerId].excl(conn)
if c.conns[peerId].len == 0:
c.conns.del(peerId)
libp2p_peers.set(c.conns.len.int64)
trace "Removed connection", conn
proc cleanupConn(c: ConnManager, conn: Connection) {.async.} =
## clean connection's resources such as muxers and streams
if isNil(conn):
return
if isNil(conn.peerInfo):
return
# Remove connection from all tables without async breaks
var muxer = some(MuxerHolder())
if not c.muxed.pop(conn, muxer.get()):
muxer = none(MuxerHolder)
delConn(c, conn)
try:
if muxer.isSome:
await closeMuxerHolder(muxer.get())
finally:
await conn.close()
trace "Connection cleaned up", conn
proc peerStartup(c: ConnManager, conn: Connection) {.async.} =
try:
trace "Triggering connect events", conn
let peerId = conn.peerInfo.peerId
await c.triggerPeerEvents(peerId, PeerEvent.Joined)
await c.triggerConnEvent(
peerId, ConnEvent(kind: ConnEventKind.Connected, incoming: conn.dir == Direction.In))
except CatchableError as exc:
# This is top-level procedure which will work as separate task, so it
# do not need to propagate CancelledError and should handle other errors
warn "Unexpected exception in switch peer connection cleanup",
conn, msg = exc.msg
proc peerCleanup(c: ConnManager, conn: Connection) {.async.} =
try:
trace "Triggering disconnect events", conn
let peerId = conn.peerInfo.peerId
await c.triggerConnEvent(
peerId, ConnEvent(kind: ConnEventKind.Disconnected))
await c.triggerPeerEvents(peerId, PeerEvent.Left)
except CatchableError as exc:
# This is top-level procedure which will work as separate task, so it
# do not need to propagate CancelledError and should handle other errors
warn "Unexpected exception peer cleanup handler",
conn, msg = exc.msg
proc onClose(c: ConnManager, conn: Connection) {.async.} =
## connection close even handler
##
## triggers the connections resource cleanup
##
try:
await conn.join()
trace "Connection closed, cleaning up", conn
await c.cleanupConn(conn)
except CancelledError:
# This is top-level procedure which will work as separate task, so it
# do not need to propagate CancelledError.
debug "Unexpected cancellation in connection manager's cleanup", conn
except CatchableError as exc:
debug "Unexpected exception in connection manager's cleanup",
errMsg = exc.msg, conn
finally:
trace "Triggering peerCleanup", conn
asyncSpawn c.peerCleanup(conn)
proc selectConn*(c: ConnManager,
peerId: PeerID,
dir: Direction): Connection =
## Select a connection for the provided peer and direction
##
let conns = toSeq(
c.conns.getOrDefault(peerId))
.filterIt( it.dir == dir )
if conns.len > 0:
return conns[0]
proc selectConn*(c: ConnManager, peerId: PeerID): Connection =
## Select a connection for the provided giving priority
## to outgoing connections
##
var conn = c.selectConn(peerId, Direction.Out)
if isNil(conn):
conn = c.selectConn(peerId, Direction.In)
if isNil(conn):
trace "connection not found", peerId
return conn
proc selectMuxer*(c: ConnManager, conn: Connection): Muxer =
## select the muxer for the provided connection
##
if isNil(conn):
return
if conn in c.muxed:
return c.muxed[conn].muxer
else:
debug "no muxer for connection", conn
proc storeConn*(c: ConnManager, conn: Connection) =
## store a connection
##
if isNil(conn):
raise newException(CatchableError, "connection cannot be nil")
if isNil(conn.peerInfo):
raise newException(CatchableError, "empty peer info")
let peerId = conn.peerInfo.peerId
if c.conns.getOrDefault(peerId).len > c.maxConns:
debug "too many connections",
conn, conns = c.conns.getOrDefault(peerId).len
raise newTooManyConnections()
if peerId notin c.conns:
c.conns[peerId] = initHashSet[Connection]()
c.conns[peerId].incl(conn)
# Launch on close listener
# All the errors are handled inside `onClose()` procedure.
asyncSpawn c.onClose(conn)
libp2p_peers.set(c.conns.len.int64)
trace "Stored connection",
conn, direction = $conn.dir, connections = c.conns.len
proc storeOutgoing*(c: ConnManager, conn: Connection) =
conn.dir = Direction.Out
c.storeConn(conn)
proc storeIncoming*(c: ConnManager, conn: Connection) =
conn.dir = Direction.In
c.storeConn(conn)
proc storeMuxer*(c: ConnManager,
muxer: Muxer,
handle: Future[void] = nil) =
## store the connection and muxer
##
if isNil(muxer):
raise newException(CatchableError, "muxer cannot be nil")
if isNil(muxer.connection):
raise newException(CatchableError, "muxer's connection cannot be nil")
c.muxed[muxer.connection] = MuxerHolder(
muxer: muxer,
handle: handle)
trace "Stored muxer",
muxer, handle = not handle.isNil, connections = c.conns.len
asyncSpawn c.peerStartup(muxer.connection)
proc getMuxedStream*(c: ConnManager,
peerId: PeerID,
dir: Direction): Future[Connection] {.async, gcsafe.} =
## get a muxed stream for the provided peer
## with the given direction
##
let muxer = c.selectMuxer(c.selectConn(peerId, dir))
if not(isNil(muxer)):
return await muxer.newStream()
proc getMuxedStream*(c: ConnManager,
peerId: PeerID): Future[Connection] {.async, gcsafe.} =
## get a muxed stream for the passed peer from any connection
##
let muxer = c.selectMuxer(c.selectConn(peerId))
if not(isNil(muxer)):
return await muxer.newStream()
proc getMuxedStream*(c: ConnManager,
conn: Connection): Future[Connection] {.async, gcsafe.} =
## get a muxed stream for the passed connection
##
let muxer = c.selectMuxer(conn)
if not(isNil(muxer)):
return await muxer.newStream()
proc dropPeer*(c: ConnManager, peerId: PeerID) {.async.} =
## drop connections and cleanup resources for peer
##
trace "Dropping peer", peerId
let conns = c.conns.getOrDefault(peerId)
for conn in conns:
trace "Removing connection", conn
delConn(c, conn)
var muxers: seq[MuxerHolder]
for conn in conns:
if conn in c.muxed:
muxers.add c.muxed[conn]
c.muxed.del(conn)
for muxer in muxers:
await closeMuxerHolder(muxer)
for conn in conns:
await conn.close()
trace "Dropped peer", peerId
trace "Peer dropped", peerId
proc close*(c: ConnManager) {.async.} =
## cleanup resources for the connection
## manager
##
trace "Closing ConnManager"
let conns = c.conns
c.conns.clear()
let muxed = c.muxed
c.muxed.clear()
for _, muxer in muxed:
await closeMuxerHolder(muxer)
for _, conns2 in conns:
for conn in conns2:
await conn.close()
trace "Closed ConnManager"