Compile the regexp outside of the loop

Author: Emilien Kenler

collectd/checker.go

@@ -3,7 +3,6 @@ package collectd
 import (
 	"bytes"
 	"fmt"
-	"regexp"
 	"strings"
 	"sync"
 	"sync/atomic"
@@ -91,17 +90,19 @@ func (checker *Checker) checkRecord(record CollectdRecord) ([]shared.CheckResult
 
 			// Load host specific thresholds
 			for pattern, threshold := range rule.Check.HostThresholds {
-				matched, err := regexp.MatchString(pattern, record.Host)
-				if err != nil {
-					checker.logger.Error(err)
+				if threshold.Regexp == nil {
 					continue
 				}
-				if matched {
-					matchName = fmt.Sprintf("host:%s", pattern)
-					critical = threshold.Critical
-					warning = threshold.Warning
-					break
+
+				if !threshold.Regexp.MatchString(record.Host) {
+					continue
 				}
+
+				matchName = fmt.Sprintf("host:%s", pattern)
+
+				critical = threshold.Critical
+				warning = threshold.Warning
+				break
 			}
 
 			// CRITICAL CHECK

config/config.go

@@ -3,6 +3,7 @@ package config
 import (
 	"fmt"
 	"io/ioutil"
+	"regexp"
 	"text/template"
 
 	"github.com/hashicorp/hcl"
@@ -23,6 +24,7 @@ type CheckThreshold struct {
 	CriticalTpl string               `hcl:"critical"`
 	Warning     hil.EvaluationResult `hcl:"-"`
 	Critical    hil.EvaluationResult `hcl:"-"`
+	Regexp      *regexp.Regexp       `hcl:"-"`
 }
 
 type CheckThresholdMap map[string]CheckThreshold
@@ -44,6 +46,18 @@ func (m CheckThresholdMap) Parse(hilConfig *hil.EvalConfig) (err error) {
 	return
 }
 
+func (m CheckThresholdMap) CompileRegexp() error {
+	for pattern, threshold := range m {
+		r, err := regexp.Compile(pattern)
+		if err != nil {
+			return err
+		}
+		threshold.Regexp = r
+		m[pattern] = threshold
+	}
+	return nil
+}
+
 type Check struct {
 	Plugin         string               `hcl:"plugin"`
 	PluginInstance string               `hcl:"plugin_instance"`
@@ -121,6 +135,9 @@ func loadFileHcl(root string) (*Config, error) {
 		}
 
 		check.HostThresholds.Parse(hilConfig)
+		if err := check.HostThresholds.CompileRegexp(); err != nil {
+			return nil, err
+		}
 		check.MetaThresholds.Parse(hilConfig)
 
 		out.Checks[name] = check