Add basic example usage for Waku v2 (#52)

* Make Waku node async and gcsafe, hacky

...but the nimbus people are doing it!

* Add skeleton example usage

* Rename example to basic2 and add to Makefile

* Sketch out basic example and qualify imports etc

Loading config to start with.

Quite messy with imports/ambiguous identifiers/qualified names. Probably a
better way with exports (hide implementation details) and fully qualified names
by default?

* Example usage run, public run function

* Sketch out API usage

* Example basic RPC client usage

* waitFor run to compile

* Remove run and gsync markers; adjust example

Makefile

@@ -92,6 +92,10 @@ wakutest2:
 	echo -e $(BUILD_MSG) "build/$@" && \
 		$(ENV_SCRIPT) nim wakutest2 $(NIM_PARAMS) waku.nims
 
+wakuexample2:
+	echo -e $(BUILD_MSG) "build/$@" && \
+		$(ENV_SCRIPT) nim wakuexample2 $(NIM_PARAMS) waku.nims
+
 # symlink
 waku.nims:
 	ln -s waku.nimble $@

examples/v2/basic2.nim

@@ -0,0 +1,51 @@
+# Here's an example of how you would start a Waku node, subscribe to topics, and
+# publish to them
+
+import confutils, chronicles, chronos, os
+
+import libp2p/crypto/crypto
+import libp2p/crypto/secp
+import eth/keys
+import json_rpc/[rpcclient, rpcserver]
+
+import ../../waku/node/v2/config
+import ../../waku/node/v2/wakunode2
+
+# Loads the config in `waku/node/v2/config.nim`
+let conf = WakuNodeConf.load()
+
+# Start the node
+# Running this should give you output like this:
+# INF Listening on tid=5719 full=/ip4/127.0.0.1/tcp/60000/p2p/16Uiu2HAmNiAqr1cwhyntotP9fiSDyBvfKtB4ZiaDsrkipSCoKCB4
+# TODO Run this in background
+# See https://github.com/status-im/nim-waku/pull/59
+proc runBackground(conf: WakuNodeConf) {.async.} =
+  run(conf)
+  runForever()
+
+discard runBackground(conf)
+
+# To do more operations on this node, we can do this in two ways:
+# - We can use the Nim Node API, which is currently not exposed
+# - We can use JSON RPC
+
+# TODO Subscribe and publish to topic via Node API
+# Requires https://github.com/status-im/nim-waku/issues/53
+
+# Here's how to do it with JSON RPC
+
+# Get RPC call signatures in Nim
+from strutils import rsplit
+template sourceDir: string = currentSourcePath.parentDir().parentDir().rsplit(DirSep, 1)[0]
+const sigWakuPath = sourceDir / "waku" / "node" / "v2" / "rpc" / "wakucallsigs.nim"
+
+createRpcSigs(RpcHttpClient, sigWakuPath)
+
+# Create RPC Client and connect to it
+var node = newRpcHttpClient()
+waitfor node.connect("localhost", Port(8547))
+
+# TODO Do something with res
+var res = waitFor node.wakuSubscribe("apptopic")
+
+# TODO Use publish as well

waku.nimble

@@ -64,3 +64,8 @@ task wakunode2, "Build Experimental Waku cli":
 task wakusim2, "Build Experimental Waku simulation tools":
   buildBinary "quicksim2", "waku/node/v2/", "-d:chronicles_log_level=DEBUG"
   buildBinary "start_network2", "waku/node/v2/", "-d:chronicles_log_level=TRACE"
+
+task wakuexample2, "Build example Waku usage":
+  let name = "basic2"
+  buildBinary name, "examples/v2/", "-d:chronicles_log_level=DEBUG"
+  exec "build/" & name

waku/node/v2/config.nim

@@ -2,7 +2,8 @@ import
   confutils/defs, chronicles, chronos,
   libp2p/crypto/crypto,
   libp2p/crypto/secp,
-  nimcrypto/utils
+  nimcrypto/utils,
+  eth/keys
 
 type
   Fleet* =  enum
@@ -88,8 +89,8 @@ type
     # NOTE: Signature is different here, we return PrivateKey and not KeyPair
     nodekey* {.
       desc: "P2P node private key as hex.",
-      defaultValue: PrivateKey.random(Secp256k1, keys.newRng()[]).tryGet()
-      name: "nodekey" }: PrivateKey
+      defaultValue: crypto.PrivateKey.random(Secp256k1, keys.newRng()[]).tryGet()
+      name: "nodekey" }: crypto.PrivateKey
     # TODO: Add nodekey file option
 
     bootnodeOnly* {.
@@ -137,15 +138,15 @@ type
     # - mailserver functionality
 
 # NOTE: Keys are different in nim-libp2p
-proc parseCmdArg*(T: type PrivateKey, p: TaintedString): T =
+proc parseCmdArg*(T: type crypto.PrivateKey, p: TaintedString): T =
   try:
     let key = SkPrivateKey.init(utils.fromHex(p)).tryGet()
     # XXX: Here at the moment
-    result = PrivateKey(scheme: Secp256k1, skkey: key)
+    result = crypto.PrivateKey(scheme: Secp256k1, skkey: key)
   except CatchableError as e:
     raise newException(ConfigurationError, "Invalid private key")
 
-proc completeCmdArg*(T: type PrivateKey, val: TaintedString): seq[string] =
+proc completeCmdArg*(T: type crypto.PrivateKey, val: TaintedString): seq[string] =
   return @[]
 
 proc parseCmdArg*(T: type IpAddress, p: TaintedString): T =

waku/node/v2/wakunode2.nim

@@ -63,7 +63,7 @@ proc connectToNodes(p: WakuProto, nodes: openArray[string]) =
 # NOTE: Looks almost identical to beacon_chain/eth2_network.nim
 proc setupNat(conf: WakuNodeConf): tuple[ip: IpAddress,
                                            tcpPort: Port,
-                                           udpPort: Port] =
+                                           udpPort: Port] {.gcsafe.} =
   # defaults
   result.ip = globalListeningAddr
   result.tcpPort = Port(conf.tcpPort + conf.portsShift)
@@ -92,9 +92,11 @@ proc setupNat(conf: WakuNodeConf): tuple[ip: IpAddress,
     let extIP = getExternalIP(nat)
     if extIP.isSome:
       result.ip = extIP.get()
-      let extPorts = redirectPorts(tcpPort = result.tcpPort,
-                                   udpPort = result.udpPort,
-                                   description = clientId)
+      # XXX: GC safety danger zone! See NBC eth2_network.nim
+      let extPorts = ({.gcsafe.}:
+        redirectPorts(tcpPort = result.tcpPort,
+                      udpPort = result.udpPort,
+                      description = clientId))
       if extPorts.isSome:
         (result.tcpPort, result.udpPort) = extPorts.get()
 
@@ -109,13 +111,14 @@ proc newWakuProto(switch: Switch): WakuProto =
   wakuproto.handler = handle
   return wakuproto
 
-proc run(config: WakuNodeConf) =
+proc run*(config: WakuNodeConf) =
 
   info "libp2p support WIP"
 
   if config.logLevel != LogLevel.NONE:
     setLogLevel(config.logLevel)
 
+  # TODO Clean up host and announced IP a la eth2_network.nim
   let
     # External TCP and UDP ports
     (ip, tcpPort, udpPort) = setupNat(config)
@@ -131,7 +134,7 @@ proc run(config: WakuNodeConf) =
     nodekey = config.nodekey
     seckey = nodekey
     pubkey = seckey.getKey.get()
-    keys = KeyPair(seckey: seckey, pubkey: pubkey)
+    keys = crypto.KeyPair(seckey: seckey, pubkey: pubkey)
 
     peerInfo = PeerInfo.init(nodekey)