Reuse token retrieve function in BrokerClient

The MetaFunction used to retrieve IAM API Client tokens in the
BrokerClient created when initialising the Client creates a new Token
Retrieve Function and a Token Handler each time that it is called. This
means that an IAM call is made on every call and there is no IAM Token
reuse.  We fix this so that we create just the one handler and token
retrive function and reuse in the MetaFunction.

pkg/utils/meta.go

@@ -35,15 +35,15 @@ func SetMeta(apiClient *client.APIClient, r *schema.ResourceData) {
 
 // SetMetaFnAndVersion sets the token-generation function and version for the Broker API client
 func SetMetaFnAndVersion(apiClient *client.APIClient, r *schema.ResourceData, version int) {
+	// Initialise token handler
+	h, err := serviceclient.NewHandler(r)
+	if err != nil {
+		log.Printf("[WARN] Unable to create token handler: %s", err)
+	}
+	// Get token retrieve func
+	trf := retrieve.NewTokenRetrieveFunc(h)
+	// We'll use trf from above in this closure
 	apiClient.SetMetaFnAndVersion(nil, version, func(ctx *context.Context, meta interface{}) {
-		// Initialise token handler
-		h, err := serviceclient.NewHandler(r)
-		if err != nil {
-			log.Printf("[WARN] Unable to fetch token for SCM client: %s", err)
-		}
-
-		// Get token retrieve func and put in c
-		trf := retrieve.NewTokenRetrieveFunc(h)
 		token, err := trf(*ctx)
 		if err != nil {
 			log.Printf("[WARN] Unable to fetch token for SCM client: %s", err)