Refactor module state reporting to be reusable (#7536)

This makes the state reporting reusable for Filebeat modules and inputs.

auditbeat/module/auditd/show_linux.go

@@ -1,3 +1,20 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
 package auditd
 
 import (

libbeat/monitoring/list.go

@@ -0,0 +1,72 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package monitoring
+
+import (
+	"sync"
+)
+
+// UniqueList is used to collect a list of items (strings) and get the total count and all unique strings.
+type UniqueList struct {
+	sync.Mutex
+	list map[string]int
+}
+
+// NewUniqueList create a new UniqueList
+func NewUniqueList() *UniqueList {
+	return &UniqueList{
+		list: map[string]int{},
+	}
+}
+
+// Add adds an item to the list and increases the count for it.
+func (l *UniqueList) Add(item string) {
+	l.Lock()
+	defer l.Unlock()
+	l.list[item]++
+}
+
+// Remove removes and item for the list and decreases the count.
+func (l *UniqueList) Remove(item string) {
+	l.Lock()
+	defer l.Unlock()
+	l.list[item]--
+}
+
+// Report can be used as reporting function for monitoring.
+// It reports a total count value and a names array with all the items.
+func (l *UniqueList) Report(m Mode, V Visitor) {
+	V.OnRegistryStart()
+	defer V.OnRegistryFinished()
+
+	var items []string
+	var count int64
+
+	l.Lock()
+	defer l.Unlock()
+
+	for key, val := range l.list {
+		if val > 0 {
+			items = append(items, key)
+		}
+		count += int64(val)
+	}
+
+	ReportInt(V, "count", count)
+	ReportStringSlice(V, "names", items)
+}

metricbeat/mb/module/runner.go

@@ -26,13 +26,12 @@ import (
 )
 
 var (
-	moduleList     map[string]int
-	moduleListLock sync.Mutex
+	moduleList *monitoring.UniqueList
 )
 
 func init() {
-	moduleList = map[string]int{}
-	monitoring.NewFunc(monitoring.GetNamespace("state").GetRegistry(), "module", reportModules, monitoring.Report)
+	moduleList = monitoring.NewUniqueList()
+	monitoring.NewFunc(monitoring.GetNamespace("state").GetRegistry(), "module", moduleList.Report, monitoring.Report)
 }
 
 // Runner is a facade for a Wrapper that provides a simple interface
@@ -72,7 +71,7 @@ func (mr *runner) Start() {
 	mr.startOnce.Do(func() {
 		output := mr.mod.Start(mr.done)
 		mr.wg.Add(1)
-		addModule(mr.mod.Name())
+		moduleList.Add(mr.mod.Name())
 		go func() {
 			defer mr.wg.Done()
 			PublishChannels(mr.client, output)
@@ -85,43 +84,10 @@ func (mr *runner) Stop() {
 		close(mr.done)
 		mr.client.Close()
 		mr.wg.Wait()
-		removeModule(mr.mod.Name())
+		moduleList.Remove(mr.mod.Name())
 	})
 }
 
 func (mr *runner) String() string {
 	return fmt.Sprintf("%s [metricsets=%d]", mr.mod.Name(), len(mr.mod.metricSets))
 }
-
-func addModule(module string) {
-	moduleListLock.Lock()
-	defer moduleListLock.Unlock()
-	moduleList[module]++
-}
-
-func removeModule(module string) {
-	moduleListLock.Lock()
-	defer moduleListLock.Unlock()
-	moduleList[module]--
-}
-
-func reportModules(m monitoring.Mode, V monitoring.Visitor) {
-	V.OnRegistryStart()
-	defer V.OnRegistryFinished()
-
-	var modules []string
-	var count int64
-
-	moduleListLock.Lock()
-	defer moduleListLock.Unlock()
-
-	for key, val := range moduleList {
-		if val > 0 {
-			modules = append(modules, key)
-		}
-		count += int64(val)
-	}
-
-	monitoring.ReportInt(V, "count", count)
-	monitoring.ReportStringSlice(V, "names", modules)
-}