Simple parsing nginx metrics [parseStubStats] (#207)

Author: mirecl

client/nginx.go

@@ -1,14 +1,19 @@
 package client
 
 import (
+	"bytes"
 	"context"
 	"fmt"
 	"io"
 	"net/http"
-	"strconv"
-	"strings"
 )
 
+const templateMetrics string = `Active connections: %d 
+server accepts handled requests
+%d %d %d 
+Reading: %d Writing: %d Waiting: %d 
+`
+
 // NginxClient allows you to fetch NGINX metrics from the stub_status page.
 type NginxClient struct {
 	apiEndpoint string
@@ -66,79 +71,26 @@ func (client *NginxClient) GetStubStats() (*StubStats, error) {
 		return nil, fmt.Errorf("failed to read the response body: %w", err)
 	}
 
-	var stats StubStats
-	err = parseStubStats(body, &stats)
+	r := bytes.NewReader(body)
+	stats, err := parseStubStats(r)
 	if err != nil {
 		return nil, fmt.Errorf("failed to parse response body %q: %w", string(body), err)
 	}
 
-	return &stats, nil
+	return stats, nil
 }
 
-func parseStubStats(data []byte, stats *StubStats) error {
-	dataStr := string(data)
-
-	parts := strings.Split(dataStr, "\n")
-	if len(parts) != 5 {
-		return fmt.Errorf("invalid input %q", dataStr)
-	}
-
-	activeConsParts := strings.Split(strings.TrimSpace(parts[0]), " ")
-	if len(activeConsParts) != 3 {
-		return fmt.Errorf("invalid input for active connections %q", parts[0])
-	}
-
-	actCons, err := strconv.ParseInt(activeConsParts[2], 10, 64)
-	if err != nil {
-		return fmt.Errorf("invalid input for active connections %q: %w", activeConsParts[2], err)
-	}
-	stats.Connections.Active = actCons
-
-	miscParts := strings.Split(strings.TrimSpace(parts[2]), " ")
-	if len(miscParts) != 3 {
-		return fmt.Errorf("invalid input for connections and requests %q", parts[2])
-	}
-
-	acceptedCons, err := strconv.ParseInt(miscParts[0], 10, 64)
-	if err != nil {
-		return fmt.Errorf("invalid input for accepted connections %q: %w", miscParts[0], err)
-	}
-	stats.Connections.Accepted = acceptedCons
-
-	handledCons, err := strconv.ParseInt(miscParts[1], 10, 64)
-	if err != nil {
-		return fmt.Errorf("invalid input for handled connections %q: %w", miscParts[1], err)
-	}
-	stats.Connections.Handled = handledCons
-
-	requests, err := strconv.ParseInt(miscParts[2], 10, 64)
-	if err != nil {
-		return fmt.Errorf("invalid input for requests %q: %w", miscParts[2], err)
-	}
-	stats.Requests = requests
-
-	consParts := strings.Split(strings.TrimSpace(parts[3]), " ")
-	if len(consParts) != 6 {
-		return fmt.Errorf("invalid input for connections %q", parts[3])
-	}
-
-	readingCons, err := strconv.ParseInt(consParts[1], 10, 64)
-	if err != nil {
-		return fmt.Errorf("invalid input for reading connections %q: %w", consParts[1], err)
-	}
-	stats.Connections.Reading = readingCons
-
-	writingCons, err := strconv.ParseInt(consParts[3], 10, 64)
-	if err != nil {
-		return fmt.Errorf("invalid input for writing connections %q: %w", consParts[3], err)
-	}
-	stats.Connections.Writing = writingCons
-
-	waitingCons, err := strconv.ParseInt(consParts[5], 10, 64)
-	if err != nil {
-		return fmt.Errorf("invalid input for waiting connections %q: %w", consParts[5], err)
-	}
-	stats.Connections.Waiting = waitingCons
-
-	return nil
+func parseStubStats(r io.Reader) (*StubStats, error) {
+	var s StubStats
+	if _, err := fmt.Fscanf(r, templateMetrics,
+		&s.Connections.Active,
+		&s.Connections.Accepted,
+		&s.Connections.Handled,
+		&s.Requests,
+		&s.Connections.Reading,
+		&s.Connections.Writing,
+		&s.Connections.Waiting); err != nil {
+		return nil, fmt.Errorf("failed to scan template metrics: %w", err)
+	}
+	return &s, nil
 }

client/nginx_test.go

@@ -1,6 +1,9 @@
 package client
 
-import "testing"
+import (
+	"bytes"
+	"testing"
+)
 
 const validStabStats = "Active connections: 1457 \nserver accepts handled requests\n 6717066 6717066 65844359 \nReading: 1 Writing: 8 Waiting: 1448 \n"
 
@@ -32,15 +35,14 @@ func TestParseStubStatsValidInput(t *testing.T) {
 	}
 
 	for _, test := range tests {
-		var result StubStats
-
-		err := parseStubStats(test.input, &result)
+		r := bytes.NewReader(test.input)
+		result, err := parseStubStats(r)
 
 		if err != nil && !test.expectedError {
 			t.Errorf("parseStubStats() returned error for valid input %q: %v", string(test.input), err)
 		}
 
-		if !test.expectedError && test.expectedResult != result {
+		if !test.expectedError && test.expectedResult != *result {
 			t.Errorf("parseStubStats() result %v != expected %v for input %q", result, test.expectedResult, test.input)
 		}
 	}