split subscribe into non-validating subscribe and addValidator (#1485)

* split subscribe into non-validating subscribe and addValidator

* stop exporting get_committee_assignments

beacon_chain/eth2_network.nim

@@ -1226,8 +1226,7 @@ func peersCount*(node: Eth2Node): int =
 
 proc subscribe*[MsgType](node: Eth2Node,
                          topic: string,
-                         msgHandler: proc(msg: MsgType) {.gcsafe.},
-                         msgValidator: proc(msg: MsgType): bool {.gcsafe.} ) {.async, gcsafe.} =
+                         msgHandler: proc(msg: MsgType) {.gcsafe.} ) {.async, gcsafe.} =
   proc execMsgHandler(topic: string, data: seq[byte]) {.async, gcsafe.} =
     inc nbc_gossip_messages_received
     trace "Incoming pubsub message received",
@@ -1238,6 +1237,11 @@ proc subscribe*[MsgType](node: Eth2Node,
       debug "Gossip msg handler error",
         msg = err.msg, len = data.len, topic, msgId = gossipId(data)
 
+  await node.switch.subscribe(topic & "_snappy", execMsgHandler)
+
+proc addValidator*[MsgType](node: Eth2Node,
+                            topic: string,
+                            msgValidator: proc(msg: MsgType): bool {.gcsafe.} ) =
   # Validate messages as soon as subscribed
   proc execValidator(
       topic: string, message: GossipMsg): Future[bool] {.async, gcsafe.} =
@@ -1252,7 +1256,15 @@ proc subscribe*[MsgType](node: Eth2Node,
 
   node.switch.addValidator(topic & "_snappy", execValidator)
 
-  await node.switch.subscribe(topic & "_snappy", execMsgHandler)
+proc subscribe*[MsgType](node: Eth2Node,
+                         topic: string,
+                         msgHandler: proc(msg: MsgType) {.gcsafe.},
+                         msgValidator: proc(msg: MsgType): bool {.gcsafe.} ) {.async, gcsafe.} =
+  node.addValidator(topic, msgValidator)
+  await node.subscribe(topic, msgHandler)
+
+proc unsubscribe*(node: Eth2Node, topic: string): Future[void] =
+  node.switch.unsubscribeAll(topic)
 
 proc traceMessage(fut: FutureBase, msgId: string) =
   fut.addCallback do (arg: pointer):

beacon_chain/spec/network.nim

@@ -92,7 +92,7 @@ func getAttestationTopic*(forkDigest: ForkDigest,
       get_committee_count_per_slot(num_active_validators),
       attestation.data.slot, attestation.data.index.CommitteeIndex))
 
-func get_committee_assignments*(
+func get_committee_assignments(
     state: BeaconState, epoch: Epoch,
     validator_indices: HashSet[ValidatorIndex]):
     seq[tuple[subnetIndex: uint64, slot: Slot]] =