Return truncated message length in JMSExceptionImpl - #77

Author: matrober-uk

jms20subset/JMSException.go

@@ -24,9 +24,10 @@ type JMSException interface {
 
 // JMSExceptionImpl is a struct that implements the JMSException interface
 type JMSExceptionImpl struct {
-	reason    string
-	errorCode string
-	linkedErr error
+	reason        string
+	errorCode     string
+	linkedErr     error
+	messageLength int
 }
 
 // GetReason returns the provider-specific reason string describing the error.
@@ -51,6 +52,15 @@ func (ex JMSExceptionImpl) GetLinkedError() error {
 
 }
 
+// GetMessageLength gives the data length that was returned by a Receive (GET) call,
+// for example if the message was truncated, or could not be read because the receive
+// buffer was too small.
+func (ex JMSExceptionImpl) GetMessageLength() int {
+
+	return ex.messageLength
+
+}
+
 // Error allows the JMSExceptionImpl struct to be treated as a Golang error,
 // while also returning a human readable string representation of the error.
 func (ex JMSExceptionImpl) Error() string {
@@ -66,11 +76,17 @@ func (ex JMSExceptionImpl) Error() string {
 
 // CreateJMSException is a helper function for creating a JMSException
 func CreateJMSException(reason string, errorCode string, linkedErr error) JMSException {
+	return CreateJMSExceptionWithExtraParams(reason, errorCode, linkedErr, 0)
+}
+
+// CreateJMSException is a helper function for creating a JMSException
+func CreateJMSExceptionWithExtraParams(reason string, errorCode string, linkedErr error, messageLength int) JMSException {
 
 	ex := JMSExceptionImpl{
-		reason:    reason,
-		errorCode: errorCode,
-		linkedErr: linkedErr,
+		reason:        reason,
+		errorCode:     errorCode,
+		linkedErr:     linkedErr,
+		messageLength: messageLength,
 	}
 
 	return ex

largemessage_test.go

@@ -62,9 +62,20 @@ func TestLargeTextMessage(t *testing.T) {
 
 	// The message is still left on the queue since it failed to be received successfully.
 
-	// Since the buffer size is configured using the ConnectionFactoy we will
-	// create a second connection in order to successfully retrieve the message.
-	cf.ReceiveBufferSize = len(txtOver32kb) + 50
+	// Use a special attribute of the returned exception to look up what the actual length of the
+	// message is, so that we can correctly increase the buffer size in order to receive the message.
+	switch jmsExc := errRcv.(type) {
+	case jms20subset.JMSExceptionImpl:
+		realMessageLength := jmsExc.GetMessageLength()
+		assert.Equal(t, len(txtOver32kb), realMessageLength) // check it matches the original (long) length
+
+		// Since the buffer size is configured using the ConnectionFactory we will
+		// create a second connection in order to successfully retrieve the message.
+		cf.ReceiveBufferSize = realMessageLength
+
+	default:
+		assert.Fail(t, "Got something other than a JMSExceptionImpl")
+	}
 
 	context2, ctxErr2 := cf.CreateContext()
 	assert.Nil(t, ctxErr2)
@@ -78,7 +89,7 @@ func TestLargeTextMessage(t *testing.T) {
 		defer consumer2.Close()
 	}
 
-	rcvMsg2, errRcv2 := consumer2.ReceiveNoWait()
+	rcvMsg2, errRcv2 := consumer2.ReceiveNoWait() // receive the message using the correct (larger) buffer size
 	assert.Nil(t, errRcv2)
 	assert.NotNil(t, rcvMsg2)
 
@@ -134,9 +145,20 @@ func TestLargeReceiveStringBodyTextMessage(t *testing.T) {
 
 	// The message is still left on the queue since it failed to be received successfully.
 
-	// Since the buffer size is configured using the ConnectionFactory we will
-	// create a second connection in order to successfully retrieve the message.
-	cf.ReceiveBufferSize = len(txtOver32kb) + 50
+	// Use a special attribute of the returned exception to look up what the actual length of the
+	// message is, so that we can correctly increase the buffer size in order to receive the message.
+	switch jmsExc := errRcv.(type) {
+	case jms20subset.JMSExceptionImpl:
+		realMessageLength := jmsExc.GetMessageLength()
+		assert.Equal(t, len(txtOver32kb), realMessageLength) // check it matches the original (long) length
+
+		// Since the buffer size is configured using the ConnectionFactory we will
+		// create a second connection in order to successfully retrieve the message.
+		cf.ReceiveBufferSize = realMessageLength
+
+	default:
+		assert.Fail(t, "Got something other than a JMSExceptionImpl")
+	}
 
 	context2, ctxErr2 := cf.CreateContext()
 	assert.Nil(t, ctxErr2)
@@ -200,9 +222,20 @@ func TestLargeBytesMessage(t *testing.T) {
 
 	// The message is still left on the queue since it failed to be received successfully.
 
-	// Since the buffer size is configured using the ConnectionFactoy we will
-	// create a second connection in order to successfully retrieve the message.
-	cf.ReceiveBufferSize = len(bytesOver32kb) + 50
+	// Use a special attribute of the returned exception to look up what the actual length of the
+	// message is, so that we can correctly increase the buffer size in order to receive the message.
+	switch jmsExc := errRcv.(type) {
+	case jms20subset.JMSExceptionImpl:
+		realMessageLength := jmsExc.GetMessageLength()
+		assert.Equal(t, len(txtOver32kb), realMessageLength) // check it matches the original (long) length
+
+		// Since the buffer size is configured using the ConnectionFactory we will
+		// create a second connection in order to successfully retrieve the message.
+		cf.ReceiveBufferSize = realMessageLength
+
+	default:
+		assert.Fail(t, "Got something other than a JMSExceptionImpl")
+	}
 
 	context2, ctxErr2 := cf.CreateContext()
 	assert.Nil(t, ctxErr2)
@@ -273,9 +306,20 @@ func TestLargeReceiveBytesBodyBytesMessage(t *testing.T) {
 
 	// The message is still left on the queue since it failed to be received successfully.
 
-	// Since the buffer size is configured using the ConnectionFactoy we will
-	// create a second connection in order to successfully retrieve the message.
-	cf.ReceiveBufferSize = len(bytesOver32kb) + 50
+	// Use a special attribute of the returned exception to look up what the actual length of the
+	// message is, so that we can correctly increase the buffer size in order to receive the message.
+	switch jmsExc := errRcv.(type) {
+	case jms20subset.JMSExceptionImpl:
+		realMessageLength := jmsExc.GetMessageLength()
+		assert.Equal(t, len(txtOver32kb), realMessageLength) // check it matches the original (long) length
+
+		// Since the buffer size is configured using the ConnectionFactory we will
+		// create a second connection in order to successfully retrieve the message.
+		cf.ReceiveBufferSize = realMessageLength
+
+	default:
+		assert.Fail(t, "Got something other than a JMSExceptionImpl")
+	}
 
 	context2, ctxErr2 := cf.CreateContext()
 	assert.Nil(t, ctxErr2)
@@ -348,8 +392,21 @@ func TestTruncatedTextMessage(t *testing.T) {
 		assert.Fail(t, "Got something other than a text message")
 	}
 
-	// Make sure we tidy up in case the previous part of the test failed.
-	cf.ReceiveBufferSize = len(txtOver32kb) + 50
+	// Use a special attribute of the returned exception to look up what the actual length of the
+	// message is, so that we can tidy up the message (read successfully) in the event the previous
+	// step failed.
+	switch jmsExc := errRcv.(type) {
+	case jms20subset.JMSExceptionImpl:
+		realMessageLength := jmsExc.GetMessageLength()
+		assert.Equal(t, len(txtOver32kb), realMessageLength) // check it matches the original (long) length
+
+		// Since the buffer size is configured using the ConnectionFactory we will
+		// create a second connection in order to successfully retrieve the message.
+		cf.ReceiveBufferSize = realMessageLength
+
+	default:
+		assert.Fail(t, "Got something other than a JMSExceptionImpl")
+	}
 
 	context2, ctxErr2 := cf.CreateContext()
 	assert.Nil(t, ctxErr2)

mqjms/ConsumerImpl.go

@@ -123,7 +123,7 @@ func (consumer ConsumerImpl) receiveInternal(gmo *ibmmq.MQGMO) (jms20subset.Mess
 
 		// In the truncated message case we want to return the warning object as well as the message
 		// so that the application can tell that some of the data is missing.
-		jmsErr = CreateJMSExceptionFromMQReturn(err)
+		jmsErr = CreateJMSExceptionFromMQReturn(err, datalen)
 	}
 
 	// Golden path - typically a message was received without error.
@@ -194,7 +194,7 @@ func (consumer ConsumerImpl) receiveInternal(gmo *ibmmq.MQGMO) (jms20subset.Mess
 
 			// Parse the details of the error and return it to the caller as
 			// a JMSException
-			jmsErr = CreateJMSExceptionFromMQReturn(err)
+			jmsErr = CreateJMSExceptionFromMQReturn(err, datalen)
 		}
 
 	}
@@ -436,7 +436,7 @@ func (consumer ConsumerImpl) Close() {
 	return
 }
 
-func CreateJMSExceptionFromMQReturn(mqretError error) jms20subset.JMSException {
+func CreateJMSExceptionFromMQReturn(mqretError error, datalen int) jms20subset.JMSException {
 
 	// Assumes this error code was returned from MQ call.
 	mqret := mqretError.(*ibmmq.MQReturn)
@@ -447,7 +447,7 @@ func CreateJMSExceptionFromMQReturn(mqretError error) jms20subset.JMSException {
 	errCode := strconv.Itoa(rcInt)
 	reason := ibmmq.MQItoString("RC", rcInt)
 
-	jmsErr := jms20subset.CreateJMSException(reason, errCode, mqretError)
+	jmsErr := jms20subset.CreateJMSExceptionWithExtraParams(reason, errCode, mqretError, datalen)
 
 	return jmsErr