mysql: do not use plugin-wide maps to avoid data race

closes #1236

plugins/inputs/mysql/mysql.go

@@ -32,6 +32,10 @@ type Mysql struct {
 	GatherFileEventsStats               bool     `toml:"gather_file_events_stats"`
 	GatherPerfEventsStatements          bool     `toml:"gather_perf_events_statements"`
 	IntervalSlow                        string   `toml:"interval_slow"`
+
+	mappings            []*mapping
+	generalThreadStates map[string]uint32
+	stateStatusMappings map[string]string
 }
 
 var sampleConfig = `
@@ -145,7 +149,9 @@ type mapping struct {
 	inExport string
 }
 
-var mappings = []*mapping{
+func NewMysql() *Mysql {
+	out := &Mysql{}
+	out.mappings = []*mapping{
 		{
 			onServer: "Aborted_",
 			inExport: "aborted_",
@@ -306,11 +312,9 @@ var mappings = []*mapping{
 			onServer: "Threadpool_",
 			inExport: "threadpool_",
 		},
-}
+	}
 
-var (
-	// status counter
-	generalThreadStates = map[string]uint32{
+	out.generalThreadStates = map[string]uint32{
 		"after create":              uint32(0),
 		"altering table":            uint32(0),
 		"analyzing":                 uint32(0),
@@ -363,8 +367,8 @@ var (
 		"writing to net":            uint32(0),
 		"other":                     uint32(0),
 	}
-	// plaintext statuses
-	stateStatusMappings = map[string]string{
+
+	out.stateStatusMappings = map[string]string{
 		"user sleep":                               "idle",
 		"creating index":                           "altering table",
 		"committing alter table to storage engine": "altering table",
@@ -385,7 +389,9 @@ var (
 		"deleting from main table":                 "deleting",
 		"deleting from reference tables":           "deleting",
 	}
-)
+
+	return out
+}
 
 func dsnAddTimeout(dsn string) (string, error) {
 
@@ -825,7 +831,7 @@ func (m *Mysql) gatherGlobalStatuses(db *sql.DB, serv string, acc telegraf.Accum
 		var found bool
 
 		// iterate over mappings and gather metrics that is provided on mapping
-		for _, mapped := range mappings {
+		for _, mapped := range m.mappings {
 			if strings.HasPrefix(name, mapped.onServer) {
 				// convert numeric values to integer
 				i, _ := strconv.Atoi(string(val.([]byte)))
@@ -927,9 +933,9 @@ func (m *Mysql) GatherProcessListStatuses(db *sql.DB, serv string, acc telegraf.
 	}
 
 	// mapping of state with its counts
-	stateCounts := make(map[string]uint32, len(generalThreadStates))
+	stateCounts := make(map[string]uint32, len(m.generalThreadStates))
 	// set map with keys and default values
-	for k, v := range generalThreadStates {
+	for k, v := range m.generalThreadStates {
 		stateCounts[k] = v
 	}
 
@@ -939,7 +945,8 @@ func (m *Mysql) GatherProcessListStatuses(db *sql.DB, serv string, acc telegraf.
 			return err
 		}
 		// each state has its mapping
-		foundState := findThreadState(command, state)
+		foundState := findThreadState(m.generalThreadStates,
+			m.stateStatusMappings, command, state)
 		// count each state
 		stateCounts[foundState] += count
 	}
@@ -1510,7 +1517,12 @@ func parseValue(value sql.RawBytes) (float64, bool) {
 }
 
 // findThreadState can be used to find thread state by command and plain state
-func findThreadState(rawCommand, rawState string) string {
+func findThreadState(
+	generalThreadStates map[string]uint32,
+	stateStatusMappings map[string]string,
+	rawCommand string,
+	rawState string,
+) string {
 	var (
 		// replace '_' symbol with space
 		command = strings.Replace(strings.ToLower(rawCommand), "_", " ", -1)
@@ -1560,6 +1572,6 @@ func copyTags(in map[string]string) map[string]string {
 
 func init() {
 	inputs.Add("mysql", func() telegraf.Input {
-		return &Mysql{}
+		return NewMysql()
 	})
 }