From b6427d0ce9ef839c2fe14d4fb4b4ee2b23b39d1d Mon Sep 17 00:00:00 2001
From: Cody Roseborough <Cody.Roseborough@gmail.com>
Date: Thu, 22 Sep 2016 16:36:03 -0700
Subject: [PATCH] Fixes #1229: Empty metric catalog no longer errors

Empty metric catalog no longer logs or returns an error when queried
via the rest API (or any other method). Will instead return an empty
list of metrics, leaving choice of how to display that to the caller.

Removes the empty metric catalog error and modifies client_func_test to
reflect the changes in behavior.
---
 control/metrics.go                   | 15 ++++-----------
 control/mttrie.go                    |  2 +-
 mgmt/rest/client/client_func_test.go |  3 +--
 3 files changed, 6 insertions(+), 14 deletions(-)

diff --git a/control/metrics.go b/control/metrics.go
index 4a7c2e428..3bea73456 100644
--- a/control/metrics.go
+++ b/control/metrics.go
@@ -38,10 +38,9 @@ import (
 )
 
 var (
-	errMetricNotFound     = errors.New("metric not found")
-	errEmptyMetricCatalog = errors.New("metric catalog is empty, no plugin loaded")
-	errNegativeSubCount   = serror.New(errors.New("subscription count cannot be < 0"))
-	hostnameReader        hostnamer
+	errMetricNotFound   = errors.New("metric not found")
+	errNegativeSubCount = serror.New(errors.New("subscription count cannot be < 0"))
+	hostnameReader      hostnamer
 )
 
 // hostnameReader, hostnamer created for mocking
@@ -96,10 +95,6 @@ func errorMetricNotFound(ns string, ver ...int) error {
 }
 
 func errorMetricsNotFound(ns string, ver ...int) error {
-	if ns == "/" {
-		// when fetching all cataloged metrics failed
-		return errEmptyMetricCatalog
-	}
 	if len(ver) > 0 {
 		return fmt.Errorf("No metric found below the given namespace: %s (version: %d)", ns, ver[0])
 	}
@@ -428,9 +423,7 @@ func (mc *metricCatalog) GetMetrics(requested core.Namespace, version int) ([]*m
 			returnedmts = append(returnedmts, returnedmt)
 		}
 	}
-	if len(returnedmts) == 0 {
-		return nil, errorMetricsNotFound(requested.String(), version)
-	}
+
 	return returnedmts, nil
 }
 
diff --git a/control/mttrie.go b/control/mttrie.go
index 8e371b17d..d17625570 100644
--- a/control/mttrie.go
+++ b/control/mttrie.go
@@ -148,7 +148,7 @@ func (mtt *mttNode) Fetch(ns []string) ([]*metricType, error) {
 			mts = append(mts, mt)
 		}
 	}
-	if len(mts) == 0 {
+	if len(mts) == 0 && len(ns) > 0 {
 		return nil, errorMetricsNotFound("/" + strings.Join(ns, "/"))
 	}
 	return mts, nil
diff --git a/mgmt/rest/client/client_func_test.go b/mgmt/rest/client/client_func_test.go
index 06ce73383..0a7bb6a95 100644
--- a/mgmt/rest/client/client_func_test.go
+++ b/mgmt/rest/client/client_func_test.go
@@ -134,9 +134,8 @@ func TestSnapClient(t *testing.T) {
 			})
 			Convey("empty catalog", func() {
 				m := c.GetMetricCatalog()
-				So(m.Err, ShouldNotBeNil)
+				So(m.Err, ShouldBeNil)
 				So(m.Len(), ShouldEqual, 0)
-				So(m.Err.Error(), ShouldEqual, "metric catalog is empty, no plugin loaded")
 			})
 			Convey("load directory error", func() {
 				p := c.LoadPlugin(DIRECTORY_PATH)