promote formatLabels to mapper package

Signed-off-by: Wangchong Zhou <fffonion@gmail.com>

pkg/mapper/fsm/formatter.go

@@ -24,17 +24,17 @@ var (
 	templateReplaceCaptureRE = regexp.MustCompile(`\$\{?([a-zA-Z0-9_\$]+)\}?`)
 )
 
-type templateFormatter struct {
+type TemplateFormatter struct {
 	captureIndexes []int
 	captureCount   int
 	fmtString      string
 }
 
-func newTemplateFormatter(valueExpr string, captureCount int) *templateFormatter {
+func NewTemplateFormatter(valueExpr string, captureCount int) *TemplateFormatter {
 	matches := templateReplaceCaptureRE.FindAllStringSubmatch(valueExpr, -1)
 	if len(matches) == 0 {
 		// if no regex reference found, keep it as it is
-		return &templateFormatter{captureCount: 0, fmtString: valueExpr}
+		return &TemplateFormatter{captureCount: 0, fmtString: valueExpr}
 	}
 
 	var indexes []int
@@ -51,14 +51,14 @@ func newTemplateFormatter(valueExpr string, captureCount int) *templateFormatter
 			indexes = append(indexes, idx-1)
 		}
 	}
-	return &templateFormatter{
+	return &TemplateFormatter{
 		captureIndexes: indexes,
 		captureCount:   len(indexes),
 		fmtString:      valueFormatter,
 	}
 }
 
-func (formatter *templateFormatter) format(captures map[int]string) string {
+func (formatter *TemplateFormatter) Format(captures []string) string {
 	if formatter.captureCount == 0 {
 		// no label substitution, keep as it is
 		return formatter.fmtString

pkg/mapper/fsm/fsm.go

@@ -17,7 +17,6 @@ import (
 	"regexp"
 	"strings"
 
-	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/common/log"
 )
 
@@ -26,10 +25,8 @@ type mappingState struct {
 	minRemainingLength int
 	maxRemainingLength int
 	// result* members are nil unless there's a metric ends with this state
-	result                interface{}
-	resultPriority        int
-	resultNameFormatter   *templateFormatter
-	resultLabelsFormatter map[string]*templateFormatter
+	Result         interface{}
+	ResultPriority int
 }
 
 type fsmBacktrackStackCursor struct {
@@ -69,8 +66,7 @@ func NewFSM(metricTypes []string, maxPossibleTransitions int, orderingDisabled b
 }
 
 // AddState adds a state into the existing FSM
-func (f *FSM) AddState(match string, name string, labels prometheus.Labels, matchMetricType string,
-	maxPossibleTransitions int, result interface{}) {
+func (f *FSM) AddState(match string, name string, matchMetricType string, maxPossibleTransitions int, result interface{}) int {
 	// first split by "."
 	matchFields := strings.Split(match, ".")
 	// fill into our FSM
@@ -97,7 +93,7 @@ func (f *FSM) AddState(match string, name string, labels prometheus.Labels, matc
 				root.transitions[field] = state
 				// if this is last field, set result to currentMapping instance
 				if i == len(matchFields)-1 {
-					root.transitions[field].result = result
+					root.transitions[field].Result = result
 				}
 			} else {
 				(*state).maxRemainingLength = max(len(matchFields)-i-1, (*state).maxRemainingLength)
@@ -112,26 +108,18 @@ func (f *FSM) AddState(match string, name string, labels prometheus.Labels, matc
 		}
 		finalStates = append(finalStates, root)
 	}
-	nameFmt := newTemplateFormatter(name, captureCount)
-
-	currentLabelFormatter := make(map[string]*templateFormatter, captureCount)
-	for label, valueExpr := range labels {
-		lblFmt := newTemplateFormatter(valueExpr, captureCount)
-		currentLabelFormatter[label] = lblFmt
-	}
 
 	for _, state := range finalStates {
-		state.resultNameFormatter = nameFmt
-		state.resultLabelsFormatter = currentLabelFormatter
-		state.resultPriority = f.statesCount
+		state.ResultPriority = f.statesCount
 	}
 
 	f.statesCount++
 
+	return captureCount
 }
 
 // GetMapping implements a mapping algorithm for Glob pattern
-func (f *FSM) GetMapping(statsdMetric string, statsdMetricType string) (interface{}, string, prometheus.Labels, bool) {
+func (f *FSM) GetMapping(statsdMetric string, statsdMetricType string) (*mappingState, []string) {
 	matchFields := strings.Split(statsdMetric, ".")
 	currentState := f.root.transitions[statsdMetricType]
 
@@ -142,7 +130,7 @@ func (f *FSM) GetMapping(statsdMetric string, statsdMetricType string) (interfac
 	// the return variable
 	var finalState *mappingState
 
-	captures := make(map[int]string, len(matchFields))
+	captures := make([]string, len(matchFields))
 	// keep track of captured group so we don't need to do append() on captures
 	captureIdx := 0
 	filedsCount := len(matchFields)
@@ -191,11 +179,11 @@ func (f *FSM) GetMapping(statsdMetric string, statsdMetricType string) (interfac
 			} // backtrack will resume from here
 
 			// do we reach a final state?
-			if state.result != nil && i == filedsCount-1 {
+			if state.Result != nil && i == filedsCount-1 {
 				if f.OrderingDisabled {
 					finalState = state
-					return formatLabels(finalState, captures)
-				} else if finalState == nil || finalState.resultPriority > state.resultPriority {
+					return finalState, captures
+				} else if finalState == nil || finalState.ResultPriority > state.ResultPriority {
 					// if we care about ordering, try to find a result with highest prioity
 					finalState = state
 				}
@@ -230,7 +218,7 @@ func (f *FSM) GetMapping(statsdMetric string, statsdMetricType string) (interfac
 		}
 	}
 
-	return formatLabels(finalState, captures)
+	return finalState, captures
 }
 
 // TestIfNeedBacktracking test if backtrack is needed for current mappings
@@ -323,17 +311,3 @@ func TestIfNeedBacktracking(mappings []string, orderingDisabled bool) bool {
 
 	return !orderingDisabled || backtrackingNeeded
 }
-
-func formatLabels(finalState *mappingState, captures map[int]string) (interface{}, string, prometheus.Labels, bool) {
-	// format name and labels
-	if finalState != nil {
-		name := finalState.resultNameFormatter.format(captures)
-
-		labels := prometheus.Labels{}
-		for key, formatter := range finalState.resultLabelsFormatter {
-			labels[key] = formatter.format(captures)
-		}
-		return finalState.result, name, labels, true
-	}
-	return nil, "", nil, false
-}

pkg/mapper/mapper.go

@@ -57,8 +57,11 @@ type matchMetricType string
 type MetricMapping struct {
 	Match           string `yaml:"match"`
 	Name            string `yaml:"name"`
+	nameFormatter   *fsm.TemplateFormatter
 	regex           *regexp.Regexp
 	Labels          prometheus.Labels `yaml:"labels"`
+	labelKeys       []string
+	labelFormatters []*fsm.TemplateFormatter
 	TimerType       TimerType         `yaml:"timer_type"`
 	Buckets         []float64         `yaml:"buckets"`
 	Quantiles       []metricObjective `yaml:"quantiles"`
@@ -137,9 +140,22 @@ func (m *MetricMapper) InitFromYAMLString(fileContents string) error {
 				return fmt.Errorf("invalid match: %s", currentMapping.Match)
 			}
 
-			n.FSM.AddState(currentMapping.Match, currentMapping.Name, currentMapping.Labels, string(currentMapping.MatchMetricType),
+			captureCount := n.FSM.AddState(currentMapping.Match, currentMapping.Name, string(currentMapping.MatchMetricType),
 				remainingMappingsCount, currentMapping)
 
+			currentMapping.nameFormatter = fsm.NewTemplateFormatter(currentMapping.Name, captureCount)
+
+			labelKeys := make([]string, len(currentMapping.Labels))
+			labelFormatters := make([]*fsm.TemplateFormatter, len(currentMapping.Labels))
+			labelIndex := 0
+			for label, valueExpr := range currentMapping.Labels {
+				labelKeys[labelIndex] = label
+				labelFormatters[labelIndex] = fsm.NewTemplateFormatter(valueExpr, captureCount)
+				labelIndex++
+			}
+			currentMapping.labelFormatters = labelFormatters
+			currentMapping.labelKeys = labelKeys
+
 		} else {
 			if regex, err := regexp.Compile(currentMapping.Match); err != nil {
 				return fmt.Errorf("invalid regex %s in mapping: %v", currentMapping.Match, err)
@@ -200,11 +216,17 @@ func (m *MetricMapper) InitFromFile(fileName string) error {
 func (m *MetricMapper) GetMapping(statsdMetric string, statsdMetricType MetricType) (*MetricMapping, prometheus.Labels, bool) {
 	// glob matching
 	if m.doFSM {
-		mapping, mappingName, labels, matched := m.FSM.GetMapping(statsdMetric, string(statsdMetricType))
-		if matched {
-			mapping.(*MetricMapping).Name = mappingName
-			return mapping.(*MetricMapping), labels, matched
-		} else if !matched && !m.doRegex {
+		finalState, captures := m.FSM.GetMapping(statsdMetric, string(statsdMetricType))
+		if finalState != nil && finalState.Result != nil {
+			result := finalState.Result.(*MetricMapping)
+			result.Name = result.nameFormatter.Format(captures)
+
+			labels := prometheus.Labels{}
+			for index, formatter := range result.labelFormatters {
+				labels[result.labelKeys[index]] = formatter.Format(captures)
+			}
+			return result, labels, true
+		} else if !m.doRegex {
 			// if there's no regex match type, return immediately
 			return nil, nil, false
 		}