Decouple StartHTTP{,AndTLS}Server from Listen() (#2791)

* Decouple StartHTTP{,AndTLS}Server from Listen()

This should help solve cosmos/cosmos-sdk#2715

* Fix small mistake

* Update StartGRPCServer

* s/rpc/rpcserver/

* Start grpccore.StartGRPCServer in a goroutine

* Reinstate l.Close()

* Fix rpc/lib/test/main.go

* Update code comment

* update changelog and comments

* fix tm-monitor. more comments

tools/tm-monitor/main.go

@@ -48,13 +48,13 @@ Examples:
 		logger = log.NewTMLogger(log.NewSyncWriter(os.Stdout))
 	}
 
-	m := startMonitor(flag.Arg(0))
+	monitor := startMonitor(flag.Arg(0))
 
-	startRPC(listenAddr, m, logger)
+	listener := startRPC(listenAddr, monitor, logger)
 
 	var ton *Ton
 	if !noton {
-		ton = NewTon(m)
+		ton = NewTon(monitor)
 		ton.Start()
 	}
 
@@ -62,7 +62,8 @@ Examples:
 		if !noton {
 			ton.Stop()
 		}
-		m.Stop()
+		monitor.Stop()
+		listener.Close()
 	})
 }
 

tools/tm-monitor/rpc.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"errors"
+	"net"
 	"net/http"
 
 	"github.com/tendermint/tendermint/libs/log"
@@ -9,16 +10,19 @@ import (
 	monitor "github.com/tendermint/tendermint/tools/tm-monitor/monitor"
 )
 
-func startRPC(listenAddr string, m *monitor.Monitor, logger log.Logger) {
+func startRPC(listenAddr string, m *monitor.Monitor, logger log.Logger) net.Listener {
 	routes := routes(m)
 
 	mux := http.NewServeMux()
 	wm := rpc.NewWebsocketManager(routes, nil)
 	mux.HandleFunc("/websocket", wm.WebsocketHandler)
 	rpc.RegisterRPCFuncs(mux, routes, cdc, logger)
-	if _, err := rpc.StartHTTPServer(listenAddr, mux, logger, rpc.Config{}); err != nil {
+	listener, err := rpc.Listen(listenAddr, rpc.Config{})
+	if err != nil {
 		panic(err)
 	}
+	go rpc.StartHTTPServer(listener, mux, logger)
+	return listener
 }
 
 func routes(m *monitor.Monitor) map[string]*rpc.RPCFunc {