Fixed influxdata#4499 - replaced regexp with simple index searching, …

…as it proved to be 40x faster

plugins/inputs/win_perf_counters/win_perf_counters.go

@@ -6,7 +6,6 @@ import (
 	"errors"
 	"fmt"
 	"log"
-	"regexp"
 	"strings"
 	"time"
 
@@ -119,28 +118,46 @@ type instanceGrouping struct {
 var sanitizedChars = strings.NewReplacer("/sec", "_persec", "/Sec", "_persec",
 	" ", "_", "%", "Percent", `\`, "")
 
-//General Counter path pattern is: \\computer\object(parent/instance#index)\counter
-//parent/instance#index part is skipped in single instance objects (e.g. Memory): \\computer\object\counter
-
-var counterPathRE = regexp.MustCompile(`.*\\(.*)\\(.*)`)
-var objectInstanceRE = regexp.MustCompile(`(.*)\((.*)\)`)
-
-//extractObjectInstanceCounterFromQuery gets object name, instance name (if available) and counter name from counter path
-func extractObjectInstanceCounterFromQuery(query string) (object string, instance string, counter string, err error) {
-	pathParts := counterPathRE.FindAllStringSubmatch(query, -1)
-	if pathParts == nil || len(pathParts[0]) != 3 {
-		err = errors.New("Could not extract counter info from: " + query)
+// extractCounterInfoFromCounterPath gets object name, instance name (if available) and counter name from counter path
+// General Counter path pattern is: \\computer\object(parent/instance#index)\counter
+// parent/instance#index part is skipped in single instance objects (e.g. Memory): \\computer\object\counter
+func extractCounterInfoFromCounterPath(counterPath string) (object string, instance string, counter string, err error) {
+	//find instance
+	var leftParenthesisIndex, rightParenthesisIndex, rightObjectBorderIndex int
+
+	leftParenthesisIndex = strings.Index(counterPath, "(")
+	if leftParenthesisIndex != -1 {
+		rightParenthesisIndex = strings.LastIndex(counterPath, ")")
+		if rightParenthesisIndex == -1 {
+			err = errors.New("cannot parse instance from: " + counterPath)
+			return
+		} else {
+			instance = counterPath[leftParenthesisIndex+1 : rightParenthesisIndex]
+		}
+	} else {
+		rightParenthesisIndex = -1
+	}
+	//find object
+	rightObjectBorderIndex = leftParenthesisIndex
+	if rightObjectBorderIndex == -1 {
+		rightObjectBorderIndex = strings.LastIndex(counterPath, "\\")
+		if rightObjectBorderIndex == -1 {
+			err = errors.New("cannot parse object from: " + counterPath)
+			return
+		}
+	}
+	leftobjectBorderIndex := strings.LastIndex(counterPath[:rightObjectBorderIndex], "\\")
+	if leftobjectBorderIndex == -1 {
+		err = errors.New("cannot parse object from: " + counterPath)
 		return
 	}
-	counter = pathParts[0][2]
-	//try to get instance name
-	objectInstanceParts := objectInstanceRE.FindAllStringSubmatch(pathParts[0][1], -1)
-	if objectInstanceParts == nil || len(objectInstanceParts[0]) != 3 {
-		object = pathParts[0][1]
-	} else {
-		object = objectInstanceParts[0][1]
-		instance = objectInstanceParts[0][2]
+	object = counterPath[leftobjectBorderIndex+1 : rightObjectBorderIndex]
+	//get countername
+	leftCounterBorderIndex := rightParenthesisIndex + 1
+	if leftCounterBorderIndex == 0 {
+		leftCounterBorderIndex = rightObjectBorderIndex
 	}
+	counter = counterPath[leftCounterBorderIndex+1:]
 	return
 }
 
@@ -184,7 +201,7 @@ func (m *Win_PerfCounters) AddItem(counterPath string, objectName string, instan
 			var err error
 			counterHandle, err := m.query.AddCounterToQuery(counterPath)
 
-			objectName, instance, counterName, err = extractObjectInstanceCounterFromQuery(counterPath)
+			objectName, instance, counterName, err = extractCounterInfoFromCounterPath(counterPath)
 			if err != nil {
 				return err
 			}