Increment waitgroups before goroutines are started.

This commit changes the code so that all calls to .Add on waitgroups
happen before the associated goroutines are launched.   Doing this after
the goroutine could technically cause a race where the goroutine started
and finished before the main goroutine has a chance to increment the
counter.  In our particular case none of the goroutines exit quickly
enough for this to be an issue, but nevertheless the correct way should be
used.

addrmanager.go

@@ -103,8 +103,8 @@ func (a *AddrManager) Start() {
 
 	log.Trace("[AMGR] Starting address manager")
 
-	go a.addressHandler()
 	a.wg.Add(1)
+	go a.addressHandler()
 	a.started = true
 }
 

blockmanager.go

@@ -350,10 +350,10 @@ func (b *blockManager) Start() {
 	}
 
 	log.Trace("[BMGR] Starting block manager")
+	b.wg.Add(3)
 	go b.syncHandler()
 	go b.blockHandler()
 	go b.chainNotificationHandler()
-	b.wg.Add(3)
 	b.started = true
 }
 

rpcserver.go

@@ -44,13 +44,13 @@ func (s *rpcServer) Start() {
 	})
 	httpServer := &http.Server{}
 	for _, listener := range s.listeners {
+		s.wg.Add(1)
 		go func(listener net.Listener) {
 			log.Infof("[RPCS] RPC server listening on %s", listener.Addr())
 			httpServer.Serve(listener)
 			log.Tracef("[RPCS] RPC listener done for %s", listener.Addr())
 			s.wg.Done()
 		}(listener)
-		s.wg.Add(1)
 	}
 	s.started = true
 }

server.go

@@ -337,14 +337,14 @@ func (s *server) Start() {
 	// Start all the listeners.  There will not be any if listening is
 	// disabled.
 	for _, listener := range s.listeners {
-		go s.listenHandler(listener)
 		s.wg.Add(1)
+		go s.listenHandler(listener)
 	}
 
 	// Start the peer handler which in turn starts the address and block
 	// managers.
-	go s.peerHandler()
 	s.wg.Add(1)
+	go s.peerHandler()
 
 	// Start the RPC server if it's not disabled.
 	if !cfg.DisableRpc {