Handle ipfs command interruption by cancelling the command context

Instead of assuming the command is the daemon command and closing
the node, which resulted in bugs like ipfs#1053, we cancel the context
and let the context children detect the cancellation and gracefully
clean up after themselves.

The shutdown logging has been moved into the daemon command, where
it makes more sense, so that commands like ping will not print out
the same output on cancellation.

Author: torarnv

cmd/ipfs/daemon.go

@@ -81,6 +81,15 @@ func daemonFunc(req cmds.Request, res cmds.Response) {
 	// let the user know we're going.
 	fmt.Printf("Initializing daemon...\n")
 
+	ctx := req.Context()
+
+	go func() {
+		select {
+		case <-ctx.Context.Done():
+			fmt.Println("Received interrupt signal, shutting down...")
+		}
+	}()
+
 	// first, whether user has provided the initialization flag. we may be
 	// running in an uninitialized state.
 	initialize, _, err := req.Option(initOptionKwd).Bool()
@@ -109,7 +118,6 @@ func daemonFunc(req cmds.Request, res cmds.Response) {
 	// message.
 	// NB: It's safe to read the config without the daemon lock, but not safe
 	// to write.
-	ctx := req.Context()
 	cfg, err := ctx.GetConfig()
 	if err != nil {
 		res.SetError(err, cmds.ErrNormal)
@@ -155,7 +163,19 @@ func daemonFunc(req cmds.Request, res cmds.Response) {
 		res.SetError(err, cmds.ErrNormal)
 		return
 	}
-	defer node.Close()
+
+	defer func() {
+		// We wait for the node to close first, as the node has children
+		// that it will wait for before closing, such as the API server.
+		node.Close()
+
+		select {
+		case <-ctx.Context.Done():
+			log.Info("Gracefully shut down daemon")
+		default:
+		}
+	}()
+
 	req.Context().ConstructNode = func() (*core.IpfsNode, error) {
 		return node, nil
 	}

cmd/ipfs/main.go

@@ -142,8 +142,9 @@ func main() {
 	}
 
 	// ok, finally, run the command invocation.
-	intrh := invoc.SetupInterruptHandler()
+	intrh, ctx := invoc.SetupInterruptHandler(ctx)
 	defer intrh.Close()
+
 	output, err := invoc.Run(ctx)
 	if err != nil {
 		printErr(err)
@@ -507,14 +508,15 @@ func (ih *IntrHandler) Handle(handler func(count int, ih *IntrHandler), sigs ...
 	}()
 }
 
-func (i *cmdInvocation) SetupInterruptHandler() io.Closer {
+func (i *cmdInvocation) SetupInterruptHandler(ctx context.Context) (io.Closer, context.Context) {
 
 	intrh := NewIntrHandler()
+	ctx, cancelFunc := context.WithCancel(ctx)
+
 	handlerFunc := func(count int, ih *IntrHandler) {
 		switch count {
 		case 1:
-			// first time, try to shut down
-			fmt.Println("Received interrupt signal, shutting down...")
+			fmt.Println() // Prevent un-terminated ^C character in terminal
 
 			ctx := i.req.Context()
 
@@ -528,16 +530,7 @@ func (i *cmdInvocation) SetupInterruptHandler() io.Closer {
 			ih.wg.Add(1)
 			go func() {
 				defer ih.wg.Done()
-
-				// TODO cancel the command context instead
-				n, err := ctx.GetNode()
-				if err != nil {
-					log.Error(err)
-					os.Exit(-1)
-				}
-
-				n.Close()
-				log.Info("Gracefully shut down.")
+				cancelFunc()
 			}()
 
 		default:
@@ -548,7 +541,7 @@ func (i *cmdInvocation) SetupInterruptHandler() io.Closer {
 
 	intrh.Handle(handlerFunc, syscall.SIGHUP, syscall.SIGINT, syscall.SIGTERM)
 
-	return intrh
+	return intrh, ctx
 }
 
 func profileIfEnabled() (func(), error) {