decouple rpc server and shutdown logic from cmd.

cmd/lotus/daemon.go

@@ -351,8 +351,21 @@ var DaemonCmd = &cli.Command{
 			return xerrors.Errorf("getting api endpoint: %w", err)
 		}
 
+		// Start the RPC server.
+		rpcStopper, err := node.ServeRPC(api, endpoint, int64(cctx.Int("api-max-req-size")))
+		if err != nil {
+			return fmt.Errorf("failed to start JSON-RPC API: %s", err)
+		}
+
+		// Monitor for shutdown.
+		finishCh := node.MonitorShutdown(shutdownChan,
+			node.ShutdownHandler{Component: "rpc server", StopFunc: rpcStopper},
+			node.ShutdownHandler{Component: "node", StopFunc: stop},
+		)
+		<-finishCh // fires when shutdown is complete.
+
 		// TODO: properly parse api endpoint (or make it a URL)
-		return serveRPC(api, stop, endpoint, shutdownChan, int64(cctx.Int("api-max-req-size")))
+		return nil
 	},
 	Subcommands: []*cli.Command{
 		daemonStopCmd,

cmd/lotus/main.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"os"
 
+	logging "github.com/ipfs/go-log/v2"
 	"github.com/mattn/go-isatty"
 	"github.com/urfave/cli/v2"
 	"go.opencensus.io/trace"
@@ -16,6 +17,8 @@ import (
 	"github.com/filecoin-project/lotus/node/repo"
 )
 
+var log = logging.Logger("main")
+
 var AdvanceBlockCmd *cli.Command
 
 func main() {

cmd/lotus/pprof.go

@@ -1,33 +0,0 @@
-package main
-
-import (
-	"net/http"
-	"strconv"
-)
-
-func handleFractionOpt(name string, setter func(int)) http.HandlerFunc {
-	return func(rw http.ResponseWriter, r *http.Request) {
-		if r.Method != http.MethodPost {
-			http.Error(rw, "only POST allowed", http.StatusMethodNotAllowed)
-			return
-		}
-		if err := r.ParseForm(); err != nil {
-			http.Error(rw, err.Error(), http.StatusBadRequest)
-			return
-		}
-
-		asfr := r.Form.Get("x")
-		if len(asfr) == 0 {
-			http.Error(rw, "parameter 'x' must be set", http.StatusBadRequest)
-			return
-		}
-
-		fr, err := strconv.Atoi(asfr)
-		if err != nil {
-			http.Error(rw, err.Error(), http.StatusBadRequest)
-			return
-		}
-		log.Infof("setting %s to %d", name, fr)
-		setter(fr)
-	}
-}

node/rpc.go

@@ -1,4 +1,4 @@
-package main
+package node
 
 import (
 	"context"
@@ -6,10 +6,8 @@ import (
 	"net"
 	"net/http"
 	_ "net/http/pprof"
-	"os"
-	"os/signal"
 	"runtime"
-	"syscall"
+	"strconv"
 
 	"github.com/ipfs/go-cid"
 	logging "github.com/ipfs/go-log/v2"
@@ -25,13 +23,12 @@ import (
 	"github.com/filecoin-project/lotus/api/v0api"
 	"github.com/filecoin-project/lotus/api/v1api"
 	"github.com/filecoin-project/lotus/metrics"
-	"github.com/filecoin-project/lotus/node"
 	"github.com/filecoin-project/lotus/node/impl"
 )
 
-var log = logging.Logger("main")
+var rpclog = logging.Logger("rpc")
 
-func serveRPC(a v1api.FullNode, stop node.StopFunc, addr multiaddr.Multiaddr, shutdownCh <-chan struct{}, maxRequestSize int64) error {
+func ServeRPC(a v1api.FullNode, addr multiaddr.Multiaddr, maxRequestSize int64) (StopFunc, error) {
 	serverOptions := make([]jsonrpc.ServerOption, 0)
 	if maxRequestSize != 0 { // config set
 		serverOptions = append(serverOptions, jsonrpc.WithMaxRequestSize(maxRequestSize))
@@ -62,15 +59,17 @@ func serveRPC(a v1api.FullNode, stop node.StopFunc, addr multiaddr.Multiaddr, sh
 
 	http.Handle("/debug/metrics", metrics.Exporter())
 	http.Handle("/debug/pprof-set/block", handleFractionOpt("BlockProfileRate", runtime.SetBlockProfileRate))
-	http.Handle("/debug/pprof-set/mutex", handleFractionOpt("MutexProfileFraction",
-		func(x int) { runtime.SetMutexProfileFraction(x) },
-	))
+	http.Handle("/debug/pprof-set/mutex", handleFractionOpt("MutexProfileFraction", func(x int) {
+		runtime.SetMutexProfileFraction(x)
+	}))
 
+	// Start listening to the addr; if invalid or occupied, we will fail early.
 	lst, err := manet.Listen(addr)
 	if err != nil {
-		return xerrors.Errorf("could not listen: %w", err)
+		return nil, xerrors.Errorf("could not listen: %w", err)
 	}
 
+	// Instantiate the server and start listening.
 	srv := &http.Server{
 		Handler: http.DefaultServeMux,
 		BaseContext: func(listener net.Listener) context.Context {
@@ -79,35 +78,14 @@ func serveRPC(a v1api.FullNode, stop node.StopFunc, addr multiaddr.Multiaddr, sh
 		},
 	}
 
-	sigCh := make(chan os.Signal, 2)
-	shutdownDone := make(chan struct{})
 	go func() {
-		select {
-		case sig := <-sigCh:
-			log.Warnw("received shutdown", "signal", sig)
-		case <-shutdownCh:
-			log.Warn("received shutdown")
-		}
-
-		log.Warn("Shutting down...")
-		if err := srv.Shutdown(context.TODO()); err != nil {
-			log.Errorf("shutting down RPC server failed: %s", err)
-		}
-		if err := stop(context.TODO()); err != nil {
-			log.Errorf("graceful shutting down failed: %s", err)
-		}
-		log.Warn("Graceful shutdown successful")
-		_ = log.Sync() //nolint:errcheck
-		close(shutdownDone)
-	}()
-	signal.Notify(sigCh, syscall.SIGTERM, syscall.SIGINT)
-
 		err = srv.Serve(manet.NetListener(lst))
-	if err == http.ErrServerClosed {
-		<-shutdownDone
-		return nil
+		if err != http.ErrServerClosed {
+			log.Warnf("rpc server failed: %s", err)
 		}
-	return err
+	}()
+
+	return srv.Shutdown, err
 }
 
 func handleImport(a *impl.FullNodeAPI) func(w http.ResponseWriter, r *http.Request) {
@@ -136,3 +114,30 @@ func handleImport(a *impl.FullNodeAPI) func(w http.ResponseWriter, r *http.Reque
 		}
 	}
 }
+
+func handleFractionOpt(name string, setter func(int)) http.HandlerFunc {
+	return func(rw http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodPost {
+			http.Error(rw, "only POST allowed", http.StatusMethodNotAllowed)
+			return
+		}
+		if err := r.ParseForm(); err != nil {
+			http.Error(rw, err.Error(), http.StatusBadRequest)
+			return
+		}
+
+		asfr := r.Form.Get("x")
+		if len(asfr) == 0 {
+			http.Error(rw, "parameter 'x' must be set", http.StatusBadRequest)
+			return
+		}
+
+		fr, err := strconv.Atoi(asfr)
+		if err != nil {
+			http.Error(rw, err.Error(), http.StatusBadRequest)
+			return
+		}
+		log.Infof("setting %s to %d", name, fr)
+		setter(fr)
+	}
+}

node/shutdown.go

@@ -0,0 +1,56 @@
+package node
+
+import (
+	"context"
+	"os"
+	"os/signal"
+	"syscall"
+)
+
+type ShutdownHandler struct {
+	Component string
+	StopFunc  StopFunc
+}
+
+// MonitorShutdown manages shutdown requests, by watching signals and invoking
+// the supplied handlers in order.
+//
+// It watches SIGTERM and SIGINT OS signals, as well as the trigger channel.
+// When any of them fire, it calls the supplied handlers in order. If any of
+// them errors, it merely logs the error.
+//
+// Once the shutdown has completed, it closes the returned channel. The caller
+// can watch this channel
+func MonitorShutdown(triggerCh <-chan struct{}, handlers ...ShutdownHandler) <-chan struct{} {
+	sigCh := make(chan os.Signal, 2)
+	out := make(chan struct{})
+
+	go func() {
+		select {
+		case sig := <-sigCh:
+			log.Warnw("received shutdown", "signal", sig)
+		case <-triggerCh:
+			log.Warn("received shutdown")
+		}
+
+		log.Warn("Shutting down...")
+
+		// Call all the handlers, logging on failure and success.
+		for _, h := range handlers {
+			if err := h.StopFunc(context.TODO()); err != nil {
+				log.Errorf("shutting down %s failed: %s", h.Component, err)
+				continue
+			}
+			log.Infof("%s shut down successfully ", h.Component)
+		}
+
+		log.Warn("Graceful shutdown successful")
+
+		// Sync all loggers.
+		_ = log.Sync() //nolint:errcheck
+		close(out)
+	}()
+
+	signal.Notify(sigCh, syscall.SIGTERM, syscall.SIGINT)
+	return out
+}

node/shutdown_test.go

@@ -0,0 +1,36 @@
+package node
+
+import (
+	"context"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestMonitorShutdown(t *testing.T) {
+	signalCh := make(chan struct{})
+
+	// Three shutdown handlers.
+	var wg sync.WaitGroup
+	wg.Add(3)
+	h := ShutdownHandler{
+		Component: "handler",
+		StopFunc: func(_ context.Context) error {
+			wg.Done()
+			return nil
+		},
+	}
+
+	finishCh := MonitorShutdown(signalCh, h, h, h)
+
+	// Nothing here after 10ms.
+	time.Sleep(10 * time.Millisecond)
+	require.Len(t, finishCh, 0)
+
+	// Now trigger the shutdown.
+	close(signalCh)
+	wg.Wait()
+	<-finishCh
+}