bugfix: node teardown is the last man to go down

Warning: during normal execution node teardown must be the
last thing that happens because command requests return
io.Readers, which may still be constructing or processing
their output. The node (and its subservices) is needed for
this. good night and good luck.

cmd/ipfs2/main.go

@@ -42,6 +42,7 @@ type cmdInvocation struct {
 	path []string
 	cmd  *cmds.Command
 	req  cmds.Request
+	node *core.IpfsNode
 }
 
 // main roadmap:
@@ -51,8 +52,9 @@ type cmdInvocation struct {
 // - output the response
 // - if anything fails, print error, maybe with help
 func main() {
-	var invoc cmdInvocation
 	var err error
+	var invoc cmdInvocation
+	defer invoc.close()
 
 	// we'll call this local helper to output errors.
 	// this is so we control how to print errors in one place.
@@ -162,6 +164,37 @@ func (i *cmdInvocation) Run() (output io.Reader, err error) {
 	return res.Reader()
 }
 
+func (i *cmdInvocation) constructNode() (*core.IpfsNode, error) {
+	if i.req == nil {
+		return nil, errors.New("constructing node without a request")
+	}
+
+	ctx := i.req.Context()
+	if ctx == nil {
+		return nil, errors.New("constructing node without a request context")
+	}
+
+	cfg, err := ctx.GetConfig()
+	if err != nil {
+		return nil, fmt.Errorf("constructing node without a config: %s", err)
+	}
+
+	// ok everything is good. set it on the invocation (for ownership)
+	// and return it.
+	i.node, err = core.NewIpfsNode(cfg, false)
+	return i.node, err
+}
+
+func (i *cmdInvocation) close() {
+	// let's not forget teardown. If a node was initialized, we must close it.
+	// Note that this means the underlying req.Context().Node variable is exposed.
+	// this is gross, and should be changed when we extract out the exec Context.
+	if i.node != nil {
+		log.Info("Shutting down node...")
+		i.node.Close()
+	}
+}
+
 func (i *cmdInvocation) Parse(args []string) error {
 	var err error
 
@@ -180,6 +213,9 @@ func (i *cmdInvocation) Parse(args []string) error {
 	ctx := i.req.Context()
 	ctx.ConfigRoot = configPath
 	ctx.LoadConfig = loadConfig
+	// this sets up the function that will initialize the node
+	// this is so that we can construct the node lazily.
+	ctx.ConstructNode = i.constructNode
 
 	// if no encoding was specified by user, default to plaintext encoding
 	// (if command doesn't support plaintext, use JSON instead)
@@ -293,29 +329,9 @@ func callCommand(req cmds.Request, root *cmds.Command) (cmds.Response, error) {
 	} else {
 		log.Info("Executing command locally")
 
-		// this sets up the function that will initialize the node
-		// this is so that we can construct the node lazily.
-		ctx := req.Context()
-
-		ctx.ConstructNode = func() (*core.IpfsNode, error) {
-			cfg, err := ctx.GetConfig()
-			if err != nil {
-				return nil, err
-			}
-			return core.NewIpfsNode(cfg, false)
-		}
-
 		// Okay!!!!! NOW we can call the command.
 		res = root.Call(req)
 
-		// let's not forget teardown. If a node was initialized, we must close it.
-		// Note that this means the underlying req.Context().Node variable is exposed.
-		// this is gross, and should be changed when we extract out the exec Context.
-		node := req.Context().NodeWithoutConstructing()
-		if node != nil {
-			log.Info("Shutting down node...")
-			node.Close()
-		}
 	}
 	return res, nil
 }