Adding TTL metrics data

closes #1060

CHANGELOG.md

@@ -30,6 +30,7 @@ based on _prefix_ in addition to globs. This means that a filter like
 - [#1017](https://github.com/influxdata/telegraf/pull/1017): taginclude and tagexclude arguments.
 - [#1015](https://github.com/influxdata/telegraf/pull/1015): Docker plugin schema refactor.
 - [#889](https://github.com/influxdata/telegraf/pull/889): Improved MySQL plugin. Thanks @maksadbek!
+- [#1060](https://github.com/influxdata/telegraf/pull/1060): TTL metrics added to MongoDB input plugin
 
 ### Bugfixes
 

plugins/inputs/mongodb/README.md

@@ -48,6 +48,5 @@ and create a single measurement containing values e.g.
  * resident_megabytes
  * updates_per_sec
  * vsize_megabytes
- 
+ * ttl_deletes_per_sec
- 
+ * ttl_passes_per_sec
- 

plugins/inputs/mongodb/mongodb_data.go

@@ -42,6 +42,8 @@ var DefaultStats = map[string]string{
 	"net_in_bytes":        "NetIn",
 	"net_out_bytes":       "NetOut",
 	"open_connections":    "NumConnections",
+	"ttl_deletes_per_sec": "DeletedDocuments",
+	"ttl_passes_per_sec":  "Passes",
 }
 
 var DefaultReplStats = map[string]string{

plugins/inputs/mongodb/mongodb_data_test.go

@@ -31,6 +31,8 @@ func TestAddNonReplStats(t *testing.T) {
 			NetIn:            0,
 			NetOut:           0,
 			NumConnections:   0,
+			Passes:           0,
+			DeletedDocuments: 0,
 		},
 		tags,
 	)
@@ -128,6 +130,8 @@ func TestStateTag(t *testing.T) {
 		"resident_megabytes":    int64(0),
 		"updates_per_sec":       int64(0),
 		"vsize_megabytes":       int64(0),
+		"ttl_deletes_per_sec":   int64(0),
+		"ttl_passes_per_sec":    int64(0),
 	}
 	acc.AssertContainsTaggedFields(t, "mongodb", fields, stateTags)
 }

plugins/inputs/mongodb/mongostat.go

@@ -54,6 +54,7 @@ type ServerStatus struct {
 	ShardCursorType    map[string]interface{} `bson:"shardCursorType"`
 	StorageEngine      map[string]string      `bson:"storageEngine"`
 	WiredTiger         *WiredTiger            `bson:"wiredTiger"`
+	Metrics            *MetricsStats          `bson:"metrics"`
 }
 
 // WiredTiger stores information related to the WiredTiger storage engine.
@@ -194,6 +195,17 @@ type OpcountStats struct {
 	Command int64 `bson:"command"`
 }
 
+// MetricsStats stores information related to metrics
+type MetricsStats struct {
+	TTL *TTLStats `bson:"ttl"`
+}
+
+// TTLStats stores information related to documents with a ttl index.
+type TTLStats struct {
+	DeletedDocuments int64 `bson:"deletedDocuments"`
+	Passes           int64 `bson:"passes"`
+}
+
 // ReadWriteLockTimes stores time spent holding read/write locks.
 type ReadWriteLockTimes struct {
 	Read       int64 `bson:"R"`
@@ -332,6 +344,9 @@ type StatLine struct {
 	// Opcounter fields
 	Insert, Query, Update, Delete, GetMore, Command int64
 
+	// TTL fields
+	Passes, DeletedDocuments int64
+
 	// Collection locks (3.0 mmap only)
 	CollectionLocks *CollectionLockStatus
 
@@ -423,6 +438,11 @@ func NewStatLine(oldStat, newStat ServerStatus, key string, all bool, sampleSecs
 		returnVal.Command = diff(newStat.Opcounters.Command, oldStat.Opcounters.Command, sampleSecs)
 	}
 
+	if newStat.Metrics.TTL != nil && oldStat.Metrics.TTL != nil {
+		returnVal.Passes = diff(newStat.Metrics.TTL.Passes, oldStat.Metrics.TTL.Passes, sampleSecs)
+		returnVal.DeletedDocuments = diff(newStat.Metrics.TTL.DeletedDocuments, oldStat.Metrics.TTL.DeletedDocuments, sampleSecs)
+	}
+
 	if newStat.OpcountersRepl != nil && oldStat.OpcountersRepl != nil {
 		returnVal.InsertR = diff(newStat.OpcountersRepl.Insert, oldStat.OpcountersRepl.Insert, sampleSecs)
 		returnVal.QueryR = diff(newStat.OpcountersRepl.Query, oldStat.OpcountersRepl.Query, sampleSecs)