app/{vmagent,vminsert}: follow-up for 1cfa183c2b

- Call httpserver.GetQuotedRemoteAddr() and httpserver.GetRequestURI() only when the error occurs.
  This saves CPU time on fast path when there are no parsing errors.
- Create a helper function - httpserver.LogError() - for logging the error with the request uri and remote addr context.

app/vmagent/prometheusimport/request_handler.go

@@ -7,7 +7,6 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/remotewrite"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/auth"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
 	parserCommon "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/common"
 	parser "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/prometheus"
@@ -31,13 +30,11 @@ func InsertHandler(at *auth.Token, req *http.Request) error {
 	if err != nil {
 		return err
 	}
-	remoteAddr := httpserver.GetQuotedRemoteAddr(req)
-	uri := httpserver.GetRequestURI(req)
 	isGzipped := req.Header.Get("Content-Encoding") == "gzip"
 	return parser.ParseStream(req.Body, defaultTimestamp, isGzipped, func(rows []parser.Row) error {
 		return insertRows(at, rows, extraLabels)
 	}, func(s string) {
-		logger.Errorf("error parsing prometheus text protocol, uri - %s, remote address - %q: %s", uri, remoteAddr, s)
+		httpserver.LogError(req, s)
 	})
 }
 

app/vmagent/prometheusimport/request_handler_test.go

@@ -27,8 +27,9 @@ go_memstats_alloc_bytes_total 1`))
 	if err := InsertHandler(nil, req); err != nil {
 		t.Errorf("unxepected error %s", err)
 	}
-	if msg := "error parsing prometheus text protocol"; !strings.Contains(testOutput.String(), msg) {
+	expectedMsg := "cannot unmarshal Prometheus line"
-		t.Errorf("output %q should contain %q", testOutput.String(), msg)
+	if !strings.Contains(testOutput.String(), expectedMsg) {
+		t.Errorf("output %q should contain %q", testOutput.String(), expectedMsg)
 	}
 }
 

app/vminsert/prometheusimport/request_handler.go

@@ -6,7 +6,6 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vminsert/common"
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vminsert/relabel"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
 	parserCommon "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/common"
 	parser "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/prometheus"
@@ -28,13 +27,11 @@ func InsertHandler(req *http.Request) error {
 	if err != nil {
 		return err
 	}
-	remoteAddr := httpserver.GetQuotedRemoteAddr(req)
-	uri := httpserver.GetRequestURI(req)
 	isGzipped := req.Header.Get("Content-Encoding") == "gzip"
 	return parser.ParseStream(req.Body, defaultTimestamp, isGzipped, func(rows []parser.Row) error {
 		return insertRows(rows, extraLabels)
 	}, func(s string) {
-		logger.Errorf("error parsing prometheus text protocol, uri - %s, remote address - %q: %s", uri, remoteAddr, s)
+		httpserver.LogError(req, s)
 	})
 }
 

lib/httpserver/httpserver.go

@@ -705,3 +705,10 @@ func Redirect(w http.ResponseWriter, url string) {
 	// This may require browser cache cleaning after the incorrect redirect is fixed.
 	w.WriteHeader(http.StatusFound)
 }
+
+// LogError logs the errStr with the context from req.
+func LogError(req *http.Request, errStr string) {
+	uri := GetRequestURI(req)
+	remoteAddr := GetQuotedRemoteAddr(req)
+	logger.Errorf("uri: %s, remote address: %q: %s", uri, remoteAddr, errStr)
+}