Remove asyncCheck from codebase. (#345)

* Remove asyncCheck from codebase.

* Replace all `discard` statements with new `asyncSpawn`.

* Bump `nim-chronos` requirement.

libp2p.nimble

@@ -11,7 +11,7 @@ requires "nim >= 1.2.0",
          "nimcrypto >= 0.4.1",
          "bearssl >= 0.1.4",
          "chronicles >= 0.7.2",
-         "chronos >= 2.3.8",
+         "chronos >= 2.5.2",
          "metrics",
          "secp256k1",
          "stew >= 0.1.0"

libp2p/connmanager.nim

@@ -120,10 +120,17 @@ proc onClose(c: ConnManager, conn: Connection) {.async.} =
   ##
   ## triggers the connections resource cleanup
   ##
-
-  await conn.join()
-  trace "triggering connection cleanup", peer = $conn.peerInfo
-  await c.cleanupConn(conn)
+  try:
+    await conn.join()
+    trace "triggering connection cleanup", peer = $conn.peerInfo
+    await c.cleanupConn(conn)
+  except CancelledError:
+    # This is top-level procedure which will work as separate task, so it
+    # do not need to propogate CancelledError.
+    trace "Unexpected cancellation in connection manager's cleanup"
+  except CatchableError as exc:
+    trace "Unexpected exception in connection manager's cleanup",
+          errMsg = exc.msg
 
 proc selectConn*(c: ConnManager,
                 peerId: PeerID,
@@ -184,8 +191,9 @@ proc storeConn*(c: ConnManager, conn: Connection) =
 
   c.conns[peerId].incl(conn)
 
-  # launch on close listener
-  asyncCheck c.onClose(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", connections = c.conns.len, peer = peerId

libp2p/muxers/mplex/lpchannel.nim

@@ -66,18 +66,6 @@ template withWriteLock(lock: AsyncLock, body: untyped): untyped =
     if not(isNil(lock)) and lock.locked:
       lock.release()
 
-template withEOFExceptions(body: untyped): untyped =
-  try:
-      body
-  except CancelledError as exc:
-    raise exc
-  except LPStreamEOFError as exc:
-    trace "muxed connection EOF", exc = exc.msg
-  except LPStreamClosedError as exc:
-    trace "muxed connection closed", exc = exc.msg
-  except LPStreamIncompleteError as exc:
-    trace "incomplete message", exc = exc.msg
-
 proc closeMessage(s: LPChannel) {.async.} =
   logScope:
     id = s.id
@@ -104,11 +92,22 @@ proc resetMessage(s: LPChannel) {.async.} =
     # stack = getStackTrace()
 
   ## send reset message - this will not raise
-  withEOFExceptions:
+  try:
     withWriteLock(s.writeLock):
       trace "sending reset message"
-
       await s.conn.writeMsg(s.id, s.resetCode) # write reset
+  except CancelledError:
+    # This procedure is called from one place and never awaited, so there no
+    # need to re-raise CancelledError.
+    trace "Unexpected cancellation while resetting channel"
+  except LPStreamEOFError as exc:
+    trace "muxed connection EOF", exc = exc.msg
+  except LPStreamClosedError as exc:
+    trace "muxed connection closed", exc = exc.msg
+  except LPStreamIncompleteError as exc:
+    trace "incomplete message", exc = exc.msg
+  except CatchableError as exc:
+    trace "Unhandled exception leak", exc = exc.msg
 
 proc open*(s: LPChannel) {.async, gcsafe.} =
   logScope:
@@ -170,10 +169,7 @@ method reset*(s: LPChannel) {.base, async, gcsafe.} =
 
   trace "resetting channel"
 
-  # we asyncCheck here because the other end
-  # might be dead already - reset is always
-  # optimistic
-  asyncCheck s.resetMessage()
+  asyncSpawn s.resetMessage()
 
   try:
     # drain the buffer before closing
@@ -210,9 +206,11 @@ method close*(s: LPChannel) {.async, gcsafe.} =
       await s.closeMessage().wait(2.minutes)
       if s.atEof: # already closed by remote close parent buffer immediately
         await procCall BufferStream(s).close()
-    except CancelledError as exc:
+    except CancelledError:
+      trace "Unexpected cancellation while closing channel"
       await s.reset()
-      raise exc
+      # This is top-level procedure which will work as separate task, so it
+      # do not need to propogate CancelledError.
     except CatchableError as exc:
       trace "exception closing channel", exc = exc.msg
       await s.reset()
@@ -220,7 +218,8 @@ method close*(s: LPChannel) {.async, gcsafe.} =
     trace "lpchannel closed local"
 
   s.closedLocal = true
-  asyncCheck closeInternal()
+  # All the errors are handled inside `closeInternal()` procedure.
+  asyncSpawn closeInternal()
 
 method initStream*(s: LPChannel) =
   if s.objName.len == 0:

libp2p/muxers/mplex/mplex.nim

@@ -48,14 +48,21 @@ proc newTooManyChannels(): ref TooManyChannels =
 proc cleanupChann(m: Mplex, chann: LPChannel) {.async, inline.} =
   ## remove the local channel from the internal tables
   ##
-  await chann.join()
-  m.channels[chann.initiator].del(chann.id)
-  trace "cleaned up channel", id = chann.id, oid = $chann.oid
+  try:
+    await chann.join()
+    m.channels[chann.initiator].del(chann.id)
+    trace "cleaned up channel", id = chann.id, oid = $chann.oid
 
-  when defined(libp2p_expensive_metrics):
-    libp2p_mplex_channels.set(
-      m.channels[chann.initiator].len.int64,
-      labelValues = [$chann.initiator, $m.connection.peerInfo])
+    when defined(libp2p_expensive_metrics):
+      libp2p_mplex_channels.set(
+        m.channels[chann.initiator].len.int64,
+        labelValues = [$chann.initiator, $m.connection.peerInfo])
+  except CancelledError:
+    # This is top-level procedure which will work as separate task, so it
+    # do not need to propogate CancelledError.
+    trace "Unexpected cancellation in mplex channel cleanup"
+  except CatchableError as exc:
+    trace "error cleaning up mplex channel", exc = exc.msg
 
 proc newStreamInternal*(m: Mplex,
                         initiator: bool = true,
@@ -90,7 +97,8 @@ proc newStreamInternal*(m: Mplex,
 
   m.channels[initiator][id] = result
 
-  asyncCheck m.cleanupChann(result)
+  # All the errors are handled inside `cleanupChann()` procedure.
+  asyncSpawn m.cleanupChann(result)
 
   when defined(libp2p_expensive_metrics):
     libp2p_mplex_channels.set(
@@ -104,12 +112,13 @@ proc handleStream(m: Mplex, chann: LPChannel) {.async.} =
     await m.streamHandler(chann)
     trace "finished handling stream"
     doAssert(chann.closed, "connection not closed by handler!")
-  except CancelledError as exc:
-    trace "cancelling stream handler", exc = exc.msg
+  except CancelledError:
+    trace "Unexpected cancellation in stream handler"
     await chann.reset()
-    raise exc
+    # This is top-level procedure which will work as separate task, so it
+    # do not need to propogate CancelledError.
   except CatchableError as exc:
-    trace "exception in stream handler", exc = exc.msg
+    trace "Exception in mplex stream handler", exc = exc.msg
     await chann.reset()
 
 method handle*(m: Mplex) {.async, gcsafe.} =
@@ -145,7 +154,8 @@ method handle*(m: Mplex) {.async, gcsafe.} =
           tmp
         else:
           if m.channels[false].len > m.maxChannCount - 1:
-            warn "too many channels created by remote peer", allowedMax = MaxChannelCount
+            warn "too many channels created by remote peer",
+                  allowedMax = MaxChannelCount
             raise newTooManyChannels()
 
           let name = string.fromBytes(data)
@@ -160,12 +170,14 @@ method handle*(m: Mplex) {.async, gcsafe.} =
           trace "created channel"
 
           if not isNil(m.streamHandler):
-            # launch handler task
-            asyncCheck m.handleStream(channel)
+            # Launch handler task
+            # All the errors are handled inside `handleStream()` procedure.
+            asyncSpawn m.handleStream(channel)
 
         of MessageType.MsgIn, MessageType.MsgOut:
           if data.len > MaxMsgSize:
-            warn "attempting to send a packet larger than allowed", allowed = MaxMsgSize
+            warn "attempting to send a packet larger than allowed",
+                 allowed = MaxMsgSize
             raise newLPStreamLimitError()
 
           trace "pushing data to channel"
@@ -180,8 +192,10 @@ method handle*(m: Mplex) {.async, gcsafe.} =
           trace "resetting channel"
           await channel.reset()
           trace "reset channel"
-  except CancelledError as exc:
-    raise exc
+  except CancelledError:
+    # This procedure is spawned as task and it is not part of public API, so
+    # there no way for this procedure to be cancelled implicitely.
+    trace "Unexpected cancellation in mplex handler"
   except CatchableError as exc:
     trace "Exception occurred", exception = exc.msg, oid = $m.oid
 

libp2p/protocols/pubsub/floodsub.nim

@@ -100,8 +100,14 @@ method init*(f: FloodSub) =
     ## connection for a protocol string
     ## e.g. ``/floodsub/1.0.0``, etc...
     ##
-
-    await f.handleConn(conn, proto)
+    try:
+      await f.handleConn(conn, proto)
+    except CancelledError:
+      # This is top-level procedure which will work as separate task, so it
+      # do not need to propogate CancelledError.
+      trace "Unexpected cancellation in floodsub handler"
+    except CatchableError as exc:
+      trace "FloodSub handler leaks an error", exc = exc.msg
 
   f.handler = handler
   f.codec = FloodSubCodec

libp2p/protocols/pubsub/gossipsub.nim

@@ -75,8 +75,14 @@ method init*(g: GossipSub) =
     ## connection for a protocol string
     ## e.g. ``/floodsub/1.0.0``, etc...
     ##
-
-    await g.handleConn(conn, proto)
+    try:
+      await g.handleConn(conn, proto)
+    except CancelledError:
+      # This is top-level procedure which will work as separate task, so it
+      # do not need to propogate CancelledError.
+      trace "Unexpected cancellation in gossipsub handler"
+    except CatchableError as exc:
+      trace "GossipSub handler leaks an error", exc = exc.msg
 
   g.handler = handler
   g.codec = GossipSubCodec

libp2p/protocols/pubsub/pubsubpeer.nim

@@ -107,8 +107,10 @@ proc handle*(p: PubSubPeer, conn: Connection) {.async.} =
       if p.sendConn == conn:
         p.sendConn = nil
 
-  except CancelledError as exc:
-    raise exc
+  except CancelledError:
+    # This is top-level procedure which will work as separate task, so it
+    # do not need to propogate CancelledError.
+    trace "Unexpected cancellation in PubSubPeer.handle"
   except CatchableError as exc:
     trace "Exception occurred in PubSubPeer.handle", exc = exc.msg
   finally:
@@ -174,7 +176,9 @@ proc getSendConn(p: PubSubPeer): Future[Connection] {.async.} =
 
     trace "Caching new send connection", oid = $newConn.oid
     p.sendConn = newConn
-    asyncCheck p.handle(newConn) # start a read loop on the new connection
+    # Start a read loop on the new connection.
+    # All the errors are handled inside `handle()` procedure.
+    asyncSpawn p.handle(newConn)
     return newConn
   except CancelledError as exc:
     raise exc

libp2p/protocols/secure/secure.nim

@@ -61,10 +61,21 @@ proc handleConn*(s: Secure,
                  conn: Connection,
                  initiator: bool): Future[Connection] {.async, gcsafe.} =
   var sconn = await s.handshake(conn, initiator)
+
+  proc cleanup() {.async.} =
+    try:
+      await conn.join()
+      await sconn.close()
+    except CancelledError:
+      # This is top-level procedure which will work as separate task, so it
+      # do not need to propogate CancelledError.
+      discard
+    except CatchableError as exc:
+      trace "error cleaning up secure connection", errMsg = exc.msg
+
   if not isNil(sconn):
-    conn.join()
-      .addCallback do(udata: pointer = nil):
-        asyncCheck sconn.close()
+    # All the errors are handled inside `cleanup()` procedure.
+    asyncSpawn cleanup()
 
   return sconn
 

libp2p/switch.nim

@@ -354,10 +354,21 @@ proc internalConnect(s: Switch,
   if isNil(conn): # None of the addresses connected
     raise newException(CatchableError, "Unable to establish outgoing link")
 
-  conn.closeEvent.wait()
-    .addCallback do(udata: pointer):
-      asyncCheck s.triggerConnEvent(
-        peerId, ConnEvent(kind: ConnEventKind.Disconnected))
+  proc peerCleanup() {.async.} =
+    try:
+      await conn.closeEvent.wait()
+      await s.triggerConnEvent(peerId,
+                               ConnEvent(kind: ConnEventKind.Disconnected))
+    except CancelledError:
+      # This is top-level procedure which will work as separate task, so it
+      # do not need to propogate CancelledError.
+      trace "Unexpected cancellation in switch peer connect cleanup"
+    except CatchableError as exc:
+      trace "Unexpected exception in switch peer connect cleanup",
+            errMsg = exc.msg
+
+  # All the errors are handled inside `cleanup()` procedure.
+  asyncSpawn peerCleanup()
 
   await s.triggerConnEvent(
     peerId, ConnEvent(kind: ConnEventKind.Connected, incoming: false))
@@ -489,13 +500,37 @@ proc muxerHandler(s: Switch, muxer: Muxer) {.async, gcsafe.} =
     await s.identify(muxer)
 
     let peerId = muxer.connection.peerInfo.peerId
-    muxer.connection.closeEvent.wait()
-      .addCallback do(udata: pointer):
-        asyncCheck s.triggerConnEvent(
-          peerId, ConnEvent(kind: ConnEventKind.Disconnected))
 
-    asyncCheck s.triggerConnEvent(
-      peerId, ConnEvent(kind: ConnEventKind.Connected, incoming: true))
+    proc peerCleanup() {.async.} =
+      try:
+        await muxer.connection.closeEvent.wait()
+        await s.triggerConnEvent(peerId,
+                                 ConnEvent(kind: ConnEventKind.Disconnected))
+      except CancelledError:
+        # This is top-level procedure which will work as separate task, so it
+        # do not need to propogate CancelledError.
+        trace "Unexpected cancellation in switch muxer cleanup"
+      except CatchableError as exc:
+        trace "Unexpected exception in switch muxer cleanup",
+              errMsg = exc.msg
+
+    proc peerStartup() {.async.} =
+      try:
+        await s.triggerConnEvent(peerId,
+                                 ConnEvent(kind: ConnEventKind.Connected,
+                                           incoming: true))
+      except CancelledError:
+        # This is top-level procedure which will work as separate task, so it
+        # do not need to propogate CancelledError.
+        trace "Unexpected cancellation in switch muxer startup"
+      except CatchableError as exc:
+        trace "Unexpected exception in switch muxer startup",
+              errMsg = exc.msg
+
+    # All the errors are handled inside `peerCleanup()` procedure.
+    asyncSpawn peerCleanup()
+    # All the errors are handled inside `peerStartup()` procedure.
+    asyncSpawn peerStartup()
 
   except CancelledError as exc:
     await muxer.close()

libp2p/transports/tcptransport.nim

@@ -76,13 +76,16 @@ proc connHandler*(t: TcpTransport,
       if not(isNil(conn)):
         await conn.close()
       t.clients.keepItIf(it != client)
-    except CancelledError as exc:
-      raise exc
+    except CancelledError:
+      # This is top-level procedure which will work as separate task, so it
+      # do not need to propogate CancelledError.
+      trace "Unexpected cancellation in transport's cleanup"
     except CatchableError as exc:
       trace "error cleaning up client", exc = exc.msg
 
   t.clients.add(client)
-  asyncCheck cleanup()
+  # All the errors are handled inside `cleanup()` procedure.
+  asyncSpawn cleanup()
   result = conn
 
 proc connCb(server: StreamServer,