Review regex declarations in innodb and global variables collectors

Move regex vars to package level to avoid re-compilation on each scrape.

Signed-off-by: Cristian Greco <[email protected]>

Author: cristiangreco

Diff for: collector/engine_innodb.go

@@ -32,6 +32,13 @@ const (
 	engineInnodbStatusQuery = `SHOW ENGINE INNODB STATUS`
 )
 
+var (
+	// 0 queries inside InnoDB, 0 queries in queue
+	// 0 read views open inside InnoDB
+	rQueries = regexp.MustCompile(`(\d+) queries inside InnoDB, (\d+) queries in queue`)
+	rViews   = regexp.MustCompile(`(\d+) read views open inside InnoDB`)
+)
+
 // ScrapeEngineInnodbStatus scrapes from `SHOW ENGINE INNODB STATUS`.
 type ScrapeEngineInnodbStatus struct{}
 
@@ -67,11 +74,6 @@ func (ScrapeEngineInnodbStatus) Scrape(ctx context.Context, instance *instance,
 		}
 	}
 
-	// 0 queries inside InnoDB, 0 queries in queue
-	// 0 read views open inside InnoDB
-	rQueries, _ := regexp.Compile(`(\d+) queries inside InnoDB, (\d+) queries in queue`)
-	rViews, _ := regexp.Compile(`(\d+) read views open inside InnoDB`)
-
 	for _, line := range strings.Split(statusCol, "\n") {
 		if data := rQueries.FindStringSubmatch(line); data != nil {
 			value, _ := strconv.ParseFloat(data[1], 64)

Diff for: collector/global_variables.go

@@ -34,6 +34,9 @@ const (
 )
 
 var (
+	promNameRe         = regexp.MustCompile("([^a-zA-Z0-9_])")
+	wsrespGcacheSizeRe = regexp.MustCompile(`gcache.size = (\d+)([MG]?);`)
+
 	// Map known global variables to help strings. Unknown will be mapped to generic gauges.
 	globalVariablesHelp = map[string]string{
 		// https://github.com/facebook/mysql-5.6/wiki/New-MySQL-RocksDB-Server-Variables
@@ -148,7 +151,7 @@ func (ScrapeGlobalVariables) Scrape(ctx context.Context, instance *instance, ch
 
 	var key string
 	var val sql.RawBytes
-	var textItems = map[string]string{
+	textItems := map[string]string{
 		"innodb_version":         "",
 		"version":                "",
 		"version_comment":        "",
@@ -226,13 +229,12 @@ func (ScrapeGlobalVariables) Scrape(ctx context.Context, instance *instance, ch
 
 // parseWsrepProviderOptions parse wsrep_provider_options to get gcache.size in bytes.
 func parseWsrepProviderOptions(opts string) float64 {
-	var val float64
-	r, _ := regexp.Compile(`gcache.size = (\d+)([MG]?);`)
-	data := r.FindStringSubmatch(opts)
+	data := wsrespGcacheSizeRe.FindStringSubmatch(opts)
 	if data == nil {
 		return 0
 	}
 
+	var val float64
 	val, _ = strconv.ParseFloat(data[1], 64)
 	switch data[2] {
 	case "M":
@@ -245,8 +247,7 @@ func parseWsrepProviderOptions(opts string) float64 {
 }
 
 func validPrometheusName(s string) string {
-	nameRe := regexp.MustCompile("([^a-zA-Z0-9_])")
-	s = nameRe.ReplaceAllString(s, "_")
+	s = promNameRe.ReplaceAllString(s, "_")
 	s = strings.ToLower(s)
 	return s
 }