Merge pull request #106 from nats-io/improve_error

improve error handling

internal/jsch/README.md

@@ -1,20 +1,27 @@
 ## Overview
 
-This is a helper library for managing and interacting with JetStream we are exploring a few options for how such a library will look and to determine what will go into core NATS clients and what will be left as an external library.
+This is a helper library for managing and interacting with JetStream.
 
-This library is not an official blessed way for interacting with JetStream yet but as a set of examples of all the capabilities this is valuable and it's for us a starting point to learning what patterns work well
+This library provides API access to all the abilities of the `nats` CLI utility.
 
 ## Setup
 
 As some parts of this library will go into the core NATS client and others not we are not sure how it will get a NATS connection, for now we did a basic - but ugly - thing just to delay answering that.
 
 ```go
-nc, _ := nats.Connect("localhost")
-
+nc, _ := nats.Connect("localhost:4222", nats.UserCredentials("user.creds"))
 jsch.SetConnection(nc)
 ```
 
-This will then use the NATS Connection you supply for all future interaction with JetStream
+or
+
+```go
+err := jsch.Connect("localhost:4222", nats.UserCredentials("user.creds"))
+```
+
+This will then use the NATS Connection you supply for all future interaction with JetStream.
+
+If you want access to this connection you can use `jsch.Connection()`
 
 ## Streams
 ### Creating Streams

internal/jsch/consumers.go

@@ -88,15 +88,11 @@ func createDurableConsumer(request server.CreateConsumerRequest) (name string, e
 		return "", err
 	}
 
-	response, err := nrequest(fmt.Sprintf(server.JetStreamCreateConsumerT, request.Stream, request.Config.Durable), jreq, timeout)
+	_, err = nrequest(fmt.Sprintf(server.JetStreamCreateConsumerT, request.Stream, request.Config.Durable), jreq, timeout)
 	if err != nil {
 		return "", err
 	}
 
-	if IsErrorResponse(response) {
-		return "", fmt.Errorf(string(response.Data))
-	}
-
 	return request.Config.Durable, nil
 }
 
@@ -111,10 +107,6 @@ func createEphemeralConsumer(request server.CreateConsumerRequest) (name string,
 		return "", err
 	}
 
-	if IsErrorResponse(response) {
-		return "", fmt.Errorf(string(response.Data))
-	}
-
 	parts := strings.Split(string(response.Data), " ")
 	if len(parts) != 2 {
 		return "", fmt.Errorf("invalid ephemeral OK response from server: %q", response.Data)
@@ -187,10 +179,6 @@ func loadConsumerInfo(s string, c string) (info server.ConsumerInfo, err error)
 		return info, err
 	}
 
-	if IsErrorResponse(response) {
-		return info, fmt.Errorf(string(response.Data))
-	}
-
 	info = server.ConsumerInfo{}
 	err = json.Unmarshal(response.Data, &info)
 	if err != nil {
@@ -501,10 +489,6 @@ func (c *Consumer) Delete() (err error) {
 		return err
 	}
 
-	if IsErrorResponse(response) {
-		return fmt.Errorf(string(response.Data))
-	}
-
 	if IsOKResponse(response) {
 		return nil
 	}

internal/jsch/jsch.go

@@ -41,7 +41,7 @@ var timeout = 5 * time.Second
 var nc *nats.Conn
 var mu sync.Mutex
 
-// Connect connects to NATS and configures it to use the connection in future interaction
+// Connect connects to NATS and configures it to use the connection in future interactions with JetStream
 func Connect(servers string, opts ...nats.Option) (err error) {
 	mu.Lock()
 	defer mu.Unlock()
@@ -78,6 +78,15 @@ func IsErrorResponse(m *nats.Msg) bool {
 	return strings.HasPrefix(string(m.Data), server.ErrPrefix)
 }
 
+// ParseErrorResponse parses the JetStream response, if it's an error returns an error instance holding the message else nil
+func ParseErrorResponse(m *nats.Msg) error {
+	if !IsErrorResponse(m) {
+		return nil
+	}
+
+	return fmt.Errorf(strings.TrimSuffix(strings.TrimPrefix(strings.TrimPrefix(string(m.Data), server.ErrPrefix), " '"), "'"))
+}
+
 // IsOKResponse checks if the message holds a standard JetStream error
 func IsOKResponse(m *nats.Msg) bool {
 	return strings.HasPrefix(string(m.Data), server.OK)
@@ -138,10 +147,6 @@ func JetStreamAccountInfo() (info server.JetStreamAccountStats, err error) {
 		return info, err
 	}
 
-	if IsErrorResponse(response) {
-		return info, fmt.Errorf(string(response.Data))
-	}
-
 	err = json.Unmarshal(response.Data, &info)
 	if err != nil {
 		return info, err
@@ -159,10 +164,6 @@ func StreamNames() (streams []string, err error) {
 		return streams, err
 	}
 
-	if IsErrorResponse(response) {
-		return streams, fmt.Errorf(string(response.Data))
-	}
-
 	err = json.Unmarshal(response.Data, &streams)
 	if err != nil {
 		return streams, err
@@ -182,10 +183,6 @@ func StreamTemplateNames() (templates []string, err error) {
 		return templates, err
 	}
 
-	if IsErrorResponse(response) {
-		return templates, fmt.Errorf(string(response.Data))
-	}
-
 	err = json.Unmarshal(response.Data, &templates)
 	if err != nil {
 		return templates, err
@@ -205,10 +202,6 @@ func ConsumerNames(stream string) (consumers []string, err error) {
 		return consumers, err
 	}
 
-	if IsErrorResponse(response) {
-		return consumers, fmt.Errorf(string(response.Data))
-	}
-
 	err = json.Unmarshal(response.Data, &consumers)
 	if err != nil {
 		return consumers, err
@@ -268,6 +261,11 @@ func Flush() error {
 	return nc.Flush()
 }
 
+// Connection is the active NATS connection being used
+func Connection() *nats.Conn {
+	return nconn()
+}
+
 func nconn() *nats.Conn {
 	mu.Lock()
 	defer mu.Unlock()
@@ -281,5 +279,10 @@ func nrequest(subj string, data []byte, timeout time.Duration) (*nats.Msg, error
 		return nil, fmt.Errorf("nats connection is not set, use SetConnection()")
 	}
 
-	return nc.Request(subj, data, timeout)
+	res, err := nc.Request(subj, data, timeout)
+	if err != nil {
+		return nil, err
+	}
+
+	return res, ParseErrorResponse(res)
 }

internal/jsch/jsch_test.go

@@ -83,11 +83,24 @@ func TestIsErrorResponse(t *testing.T) {
 		t.Fatalf("OK is Error")
 	}
 
-	if !jsch.IsErrorResponse(&nats.Msg{Data: []byte("-ERR error")}) {
+	if !jsch.IsErrorResponse(&nats.Msg{Data: []byte("-ERR 'error'")}) {
 		t.Fatalf("ERR is not Error")
 	}
 }
 
+func TestParseErrorResponse(t *testing.T) {
+	checkErr(t, jsch.ParseErrorResponse(&nats.Msg{Data: []byte("+OK")}), "expected nil got error")
+
+	err := jsch.ParseErrorResponse(&nats.Msg{Data: []byte("-ERR 'test error")})
+	if err == nil {
+		t.Fatalf("expected an error got nil")
+	}
+
+	if err.Error() != "test error" {
+		t.Fatalf("expected 'test error' got '%v'", err)
+	}
+}
+
 func TestIsOKResponse(t *testing.T) {
 	if !jsch.IsOKResponse(&nats.Msg{Data: []byte("+OK")}) {
 		t.Fatalf("OK is Error")

internal/jsch/streams.go

@@ -72,15 +72,11 @@ func NewStreamFromDefault(name string, dflt server.StreamConfig, opts ...StreamO
 		return nil, err
 	}
 
-	response, err := nrequest(fmt.Sprintf(server.JetStreamCreateStreamT, name), jreq, timeout)
+	_, err = nrequest(fmt.Sprintf(server.JetStreamCreateStreamT, name), jreq, timeout)
 	if err != nil {
 		return nil, err
 	}
 
-	if IsErrorResponse(response) {
-		return nil, fmt.Errorf(string(response.Data))
-	}
-
 	return LoadStream(name)
 }
 
@@ -149,10 +145,6 @@ func loadStreamInfo(stream string) (info *server.StreamInfo, err error) {
 		return nil, err
 	}
 
-	if IsErrorResponse(response) {
-		return nil, fmt.Errorf(string(response.Data))
-	}
-
 	info = &server.StreamInfo{}
 	err = json.Unmarshal(response.Data, info)
 	if err != nil {
@@ -265,15 +257,11 @@ func (s *Stream) UpdateConfiguration(cfg server.StreamConfig, opts ...StreamOpti
 		return err
 	}
 
-	response, err := nrequest(fmt.Sprintf(server.JetStreamUpdateStreamT, s.Name()), jcfg, timeout)
+	_, err = nrequest(fmt.Sprintf(server.JetStreamUpdateStreamT, s.Name()), jcfg, timeout)
 	if err != nil {
 		return err
 	}
 
-	if IsErrorResponse(response) {
-		return fmt.Errorf(string(response.Data))
-	}
-
 	return s.Reset()
 }
 
@@ -314,10 +302,6 @@ func (s *Stream) ConsumerNames() (names []string, err error) {
 		return names, err
 	}
 
-	if IsErrorResponse(response) {
-		return names, fmt.Errorf(string(response.Data))
-	}
-
 	err = json.Unmarshal(response.Data, &names)
 	if err != nil {
 		return names, err
@@ -363,29 +347,21 @@ func (s *Stream) State() (stats server.StreamState, err error) {
 
 // Delete deletes the Stream, after this the Stream object should be disposed
 func (s *Stream) Delete() error {
-	response, err := nrequest(fmt.Sprintf(server.JetStreamDeleteStreamT, s.Name()), nil, timeout)
+	_, err := nrequest(fmt.Sprintf(server.JetStreamDeleteStreamT, s.Name()), nil, timeout)
 	if err != nil {
 		return err
 	}
 
-	if IsErrorResponse(response) {
-		return fmt.Errorf(string(response.Data))
-	}
-
 	return nil
 }
 
 // Purge deletes all messages from the Stream
 func (s *Stream) Purge() error {
-	response, err := nrequest(fmt.Sprintf(server.JetStreamPurgeStreamT, s.Name()), nil, timeout)
+	_, err := nrequest(fmt.Sprintf(server.JetStreamPurgeStreamT, s.Name()), nil, timeout)
 	if err != nil {
 		return err
 	}
 
-	if IsErrorResponse(response) {
-		return fmt.Errorf(string(response.Data))
-	}
-
 	return nil
 }
 
@@ -396,10 +372,6 @@ func (s *Stream) LoadMessage(seq int) (msg server.StoredMsg, err error) {
 		return server.StoredMsg{}, err
 	}
 
-	if IsErrorResponse(response) {
-		return server.StoredMsg{}, fmt.Errorf(string(response.Data))
-	}
-
 	msg = server.StoredMsg{}
 	err = json.Unmarshal(response.Data, &msg)
 	if err != nil {
@@ -411,15 +383,11 @@ func (s *Stream) LoadMessage(seq int) (msg server.StoredMsg, err error) {
 
 // DeleteMessage deletes a specific message from the Stream by overwriting it with random data
 func (s *Stream) DeleteMessage(seq int) (err error) {
-	response, err := nrequest(fmt.Sprintf(server.JetStreamDeleteMsgT, s.Name()), []byte(strconv.Itoa(seq)), timeout)
+	_, err = nrequest(fmt.Sprintf(server.JetStreamDeleteMsgT, s.Name()), []byte(strconv.Itoa(seq)), timeout)
 	if err != nil {
 		return err
 	}
 
-	if IsErrorResponse(response) {
-		return fmt.Errorf(string(response.Data))
-	}
-
 	return nil
 }
 

internal/jsch/templates.go

@@ -30,15 +30,11 @@ func NewStreamTemplate(name string, maxStreams uint32, config server.StreamConfi
 		return nil, err
 	}
 
-	response, err := nrequest(fmt.Sprintf(server.JetStreamCreateTemplateT, name), jreq, timeout)
+	_, err = nrequest(fmt.Sprintf(server.JetStreamCreateTemplateT, name), jreq, timeout)
 	if err != nil {
 		return nil, err
 	}
 
-	if IsErrorResponse(response) {
-		return nil, fmt.Errorf(string(response.Data))
-	}
-
 	return LoadStreamTemplate(name)
 }
 
@@ -69,10 +65,6 @@ func loadConfigForStreamTemplate(template *StreamTemplate) (err error) {
 		return err
 	}
 
-	if IsErrorResponse(response) {
-		return fmt.Errorf(string(response.Data))
-	}
-
 	info := server.StreamTemplateInfo{}
 	err = json.Unmarshal(response.Data, &info)
 	if err != nil {
@@ -87,15 +79,11 @@ func loadConfigForStreamTemplate(template *StreamTemplate) (err error) {
 
 // Delete deletes the StreamTemplate, after this the StreamTemplate object should be disposed
 func (t *StreamTemplate) Delete() error {
-	response, err := nrequest(fmt.Sprintf(server.JetStreamDeleteTemplateT, t.Name()), nil, timeout)
+	_, err := nrequest(fmt.Sprintf(server.JetStreamDeleteTemplateT, t.Name()), nil, timeout)
 	if err != nil {
 		return err
 	}
 
-	if IsErrorResponse(response) {
-		return fmt.Errorf(string(response.Data))
-	}
-
 	return nil
 }