Implement graceful shutdown for `wakunode2` and `chat2` (#490)

* Implement graceful shutdown

* Consistent use of QuitSuccess

docs/tutorial/chat2.md

@@ -69,6 +69,7 @@ This will bypass the random peer selection process and connect to the specified
 | `/help` | displays available in-chat commands |
 | `/connect` | interactively connect to a new peer |
 | `/nick` | change nickname for current chat session |
+| `/exit` | exits the current chat session |
 
 ## `chat2` message protobuf format
 

examples/v2/chat2.nim

@@ -30,6 +30,7 @@ const Help = """
   help: Prints this help
   connect: dials a remote peer
   nick: change nickname for current chat session
+  exit: exits chat session
 """
 
 const
@@ -203,14 +204,11 @@ proc writeAndPrint(c: Chat) {.async.} =
       c.nick = await readNick(c.transp)
       echo "You are now known as " & c.nick
 
-#    elif line.startsWith("/exit"):
-#      if p.connected and p.conn.closed.not:
-#        await p.conn.close()
-#        p.connected = false
-#
-#      await p.switch.stop()
-#      echo "quitting..."
-#      quit(0)
+    elif line.startsWith("/exit"):
+     await c.node.stop()
+
+     echo "quitting..."
+     quit(QuitSuccess)
     else:
       # XXX connected state problematic
       if c.started:
@@ -368,6 +366,7 @@ proc processInput(rfd: AsyncFD, rng: ref BrHmacDrbgContext) {.async.} =
   node.subscribe(topic, handler)
 
   await chat.readWriteLoop()
+
   runForever()
   #await allFuturesThrowing(libp2pFuts)
 

waku/v2/node/wakunode2.nim

@@ -417,9 +417,6 @@ proc mountRelay*(node: WakuNode, topics: seq[string] = newSeq[string](), rlnRela
   node.wakuRelay = wakuRelay
   node.switch.mount(wakuRelay)
 
-  # Reonnect to previous relay peers
-  waitFor node.peerManager.reconnectPeers(WakuRelayCodec)
-
   info "mounting relay"
 
   node.subscribe(defaultTopic, none(TopicHandler))
@@ -442,6 +439,9 @@ proc mountRelay*(node: WakuNode, topics: seq[string] = newSeq[string](), rlnRela
 
     info "relay mounted and started successfully"
   
+  # Reconnect to previous relay peers
+  waitFor node.peerManager.reconnectPeers(WakuRelayCodec)
+
 ## Helpers
 proc dialPeer*(n: WakuNode, address: string) {.async.} =
   info "dialPeer", address = address
@@ -496,6 +496,7 @@ proc connectToNodes*(n: WakuNode, nodes: seq[PeerInfo]) {.async.} =
 
 when isMainModule:
   import
+    system/ansi_c,
     confutils, json_rpc/rpcserver, metrics,
     ./config, 
     ./jsonrpc/[admin_api,
@@ -647,4 +648,26 @@ when isMainModule:
       startMetricsServer(conf.metricsServerAddress,
         Port(conf.metricsServerPort + conf.portsShift))
   
+  # Setup graceful shutdown
+  
+  # Handle Ctrl-C SIGINT
+  proc handleCtrlC() {.noconv.} =
+    when defined(windows):
+      # workaround for https://github.com/nim-lang/Nim/issues/4057
+      setupForeignThreadGc()
+    info "Shutting down after receiving SIGINT"
+    waitFor node.stop()
+    quit(QuitSuccess)
+  
+  setControlCHook(handleCtrlC)
+
+  # Handle SIGTERM
+  when defined(posix):
+    proc handleSigterm(signal: cint) {.noconv.} =
+      info "Shutting down after receiving SIGTERM"
+      waitFor node.stop()
+      quit(QuitSuccess)
+    
+    c_signal(SIGTERM, handleSigterm)
+
   runForever()