Small Metadata refactor.

experiments/example/main.go

@@ -58,7 +58,7 @@ func main() {
 
 	// Connect to metadata database (Cassandra is the only supported database).
 	// Besides experiment results and platform metrics (we use Snap to gather them) we save certain deta about experiment configuration and environment (metadata).
-	metadata, err := experiment.NewMetadata(uid, experiment.MetadataConfigFromFlags())
+	metadata, err := experiment.NewMetadata(uid, experiment.DefaultMetadataConfig())
 	// errutil.CheckWithContext() is a helper function that will panic on error and provide some additional information about error origin.
 	errutil.CheckWithContext(err, "Cannot connect to Cassandra Metadata Database")
 

experiments/memcached-cat/main.go

@@ -73,7 +73,7 @@ func main() {
 	logger.Initialize(appName, uid)
 
 	// Connect to metadata database
-	metadata, err := experiment.NewMetadata(uid, experiment.MetadataConfigFromFlags())
+	metadata, err := experiment.NewMetadata(uid, experiment.DefaultMetadataConfig())
 	errutil.CheckWithContext(err, "Cannot connect to Cassandra Metadata Database")
 
 	// Save experiment runtime environment (configuration, environmental variables, etc).

experiments/memcached-sensitivity-profile/main.go

@@ -54,7 +54,7 @@ func main() {
 	// Initialize logger.
 	logger.Initialize(appName, uid)
 
-	metadata, err := experiment.NewMetadata(uid, experiment.MetadataConfigFromFlags())
+	metadata, err := experiment.NewMetadata(uid, experiment.DefaultMetadataConfig())
 	errutil.CheckWithContext(err, "Cannot connect to Cassandra Metadata Database")
 
 	// Save experiment runtime environment (configuration, environmental variables, etc).

experiments/optimal-core-allocation/main.go

@@ -61,7 +61,7 @@ func main() {
 	logger.Initialize(appName, uid)
 
 	// connect to metadata database
-	metadata, err := experiment.NewMetadata(uid, experiment.MetadataConfigFromFlags())
+	metadata, err := experiment.NewMetadata(uid, experiment.DefaultMetadataConfig())
 	errutil.CheckWithContext(err, "Cannot connect to Cassandra Metadata Database")
 
 	// Save experiment runtime environment (configuration, environmental variables, etc).

experiments/specjbb-sensitivity-profile/main.go

@@ -56,7 +56,7 @@ func main() {
 	uid := uuid.New() // Initialize logger.
 	logger.Initialize(appName, uid)
 	// Create metadata associated with experiment
-	metadata, err := experiment.NewMetadata(uid, experiment.MetadataConfigFromFlags())
+	metadata, err := experiment.NewMetadata(uid, experiment.DefaultMetadataConfig())
 	errutil.Check(err)
 
 	err = metadata.RecordRuntimeEnv(experimentStart)

pkg/experiment/conf.go

@@ -56,7 +56,7 @@ func Configure() bool {
 	if *dumpConfig {
 		previousExperimentID := *dumpConfigExperimentID
 		if previousExperimentID != "" {
-			metadata, err := NewMetadata(previousExperimentID, MetadataConfigFromFlags())
+			metadata, err := NewMetadata(previousExperimentID, DefaultMetadataConfig())
 			errutil.Check(err)
 			flags, err := metadata.GetGroup("flags")
 			errutil.Check(err)

pkg/experiment/metadata.go

@@ -51,31 +51,9 @@ type MetadataConfig struct {
 	CassandraUsername          string
 }
 
-// DefaultMetadataConfig returns a setup which use a Cassandra cluster running on localhost
-// without any authentication or encryption.
-func DefaultMetadataConfig() MetadataConfig {
-	return MetadataConfig{
-		CassandraAddress:           "127.0.0.1",
-		CassandraConnectionTimeout: 0,
-		CassandraCreateKeyspace:    true,
-		CassandraIgnorePeerAddr:    false,
-		CassandraInitialHostLookup: true,
-		CassandraKeyspaceName:      "swan",
-		CassandraPassword:          "",
-		CassandraPort:              9042,
-		CassandraSslCAPath:         "",
-		CassandraSslCertPath:       "",
-		CassandraSslEnabled:        false,
-		CassandraSslHostValidation: false,
-		CassandraSslKeyPath:        "",
-		CassandraTimeout:           0,
-		CassandraUsername:          "",
-	}
-}
-
-// MetadataConfigFromFlags applies the Cassandra settings from the command line flags and
+// DefaultMetadataConfig applies the Cassandra settings from the command line flags and
 // environment variables.
-func MetadataConfigFromFlags() MetadataConfig {
+func DefaultMetadataConfig() MetadataConfig {
 	return MetadataConfig{
 		CassandraAddress:           conf.CassandraAddress.Value(),
 		CassandraConnectionTimeout: time.Duration(conf.CassandraConnectionTimeout.Value()) * time.Second,
@@ -112,7 +90,7 @@ func NewMetadata(experimentID string, config MetadataConfig) (*Metadata, error)
 		experimentID: experimentID,
 		config:       config,
 	}
-	err := metadata.Connect()
+	err := metadata.connect()
 	if err != nil {
 		return nil, err
 	}
@@ -140,8 +118,8 @@ func sslOptions(config MetadataConfig) *gocql.SslOptions {
 	return sslOptions
 }
 
-// connect creates a session to the Cassandra cluster. This function should only be called once.
-func (m *Metadata) connect() *gocql.ClusterConfig {
+// getClusterConfig prepares configuration to Cassandra cluster.
+func (m *Metadata) getClusterConfig() *gocql.ClusterConfig {
 	cluster := gocql.NewCluster(m.config.CassandraAddress)
 
 	// TODO(niklas): make consistency configurable.
@@ -157,23 +135,22 @@ func (m *Metadata) connect() *gocql.ClusterConfig {
 	return cluster
 }
 
-func (m *Metadata) createKeyspace() error {
-	connectionConfiguration := m.connect()
-	session, err := connectionConfiguration.CreateSession()
-	defer session.Close()
+func (m *Metadata) createKeyspace(clusterConfig *gocql.ClusterConfig) error {
+	session, err := clusterConfig.CreateSession()
 	if err != nil {
 		return errors.Wrap(err, "cannot create session for creating keyspace")
 	}
+	defer session.Close()
 
 	query := fmt.Sprintf("CREATE KEYSPACE IF NOT EXISTS %s WITH REPLICATION = {'class': 'SimpleStrategy', 'replication_factor': 1};", m.config.CassandraKeyspaceName)
 
 	return errors.Wrap(session.Query(query).Exec(), "cannot create keyspace")
 
 }
 
-// Connect creates a session to the Cassandra cluster. This function should only be called once.
-func (m *Metadata) Connect() error {
-	cluster := m.connect()
+// connect creates a session to the Cassandra cluster. This function should only be called once.
+func (m *Metadata) connect() error {
+	cluster := m.getClusterConfig()
 	cluster.Keyspace = m.config.CassandraKeyspaceName
 
 	if m.config.CassandraUsername != "" && m.config.CassandraPassword != "" {
@@ -195,7 +172,7 @@ func (m *Metadata) Connect() error {
 	m.session = session
 
 	if m.config.CassandraCreateKeyspace {
-		if err = m.createKeyspace(); err != nil {
+		if err = m.createKeyspace(cluster); err != nil {
 			return err
 		}
 	}