Code cleanup (#343)

* Small code cleanup: remove Request from params

* Extract common params to all export handlers

* Renamed ExportParams -> exportParams

* wip

Co-authored-by: Dzmitry Lazerka <dlazerka@gmail.com>
Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>

app/vmselect/prometheus/prometheus.go

@@ -118,7 +118,6 @@ var federateDuration = metrics.NewSummary(`vm_request_duration_seconds{path="/fe
 func ExportCSVHandler(startTime time.Time, w http.ResponseWriter, r *http.Request) error {
 	defer exportCSVDuration.UpdateDuration(startTime)
 
-	ct := startTime.UnixNano() / 1e6
 	if err := r.ParseForm(); err != nil {
 		return fmt.Errorf("cannot parse request form values: %w", err)
 	}
@@ -127,21 +126,13 @@ func ExportCSVHandler(startTime time.Time, w http.ResponseWriter, r *http.Reques
 		return fmt.Errorf("missing `format` arg; see https://docs.victoriametrics.com/#how-to-export-csv-data")
 	}
 	fieldNames := strings.Split(format, ",")
-	start, err := searchutils.GetTime(r, "start", 0)
-	if err != nil {
-		return err
-	}
-	end, err := searchutils.GetTime(r, "end", ct)
-	if err != nil {
-		return err
-	}
 	reduceMemUsage := searchutils.GetBool(r, "reduce_mem_usage")
-	deadline := searchutils.GetDeadlineForExport(r, startTime)
+	ep, err := getExportParams(r, startTime)
-	tagFilterss, err := getTagFilterssFromRequest(r)
 	if err != nil {
 		return err
 	}
-	sq := storage.NewSearchQuery(start, end, tagFilterss, *maxExportSeries)
+
+	sq := storage.NewSearchQuery(ep.start, ep.end, ep.filterss, *maxExportSeries)
 	w.Header().Set("Content-Type", "text/csv; charset=utf-8")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
@@ -157,7 +148,7 @@ func ExportCSVHandler(startTime time.Time, w http.ResponseWriter, r *http.Reques
 	}
 	doneCh := make(chan error, 1)
 	if !reduceMemUsage {
-		rss, err := netstorage.ProcessSearchQuery(sq, true, deadline)
+		rss, err := netstorage.ProcessSearchQuery(sq, true, ep.deadline)
 		if err != nil {
 			return fmt.Errorf("cannot fetch data for %q: %w", sq, err)
 		}
@@ -180,7 +171,7 @@ func ExportCSVHandler(startTime time.Time, w http.ResponseWriter, r *http.Reques
 		}()
 	} else {
 		go func() {
-			err := netstorage.ExportBlocks(sq, deadline, func(mn *storage.MetricName, b *storage.Block, tr storage.TimeRange) error {
+			err := netstorage.ExportBlocks(sq, ep.deadline, func(mn *storage.MetricName, b *storage.Block, tr storage.TimeRange) error {
 				if err := bw.Error(); err != nil {
 					return err
 				}
@@ -221,36 +212,27 @@ var exportCSVDuration = metrics.NewSummary(`vm_request_duration_seconds{path="/a
 func ExportNativeHandler(startTime time.Time, w http.ResponseWriter, r *http.Request) error {
 	defer exportNativeDuration.UpdateDuration(startTime)
 
-	ct := startTime.UnixNano() / 1e6
 	if err := r.ParseForm(); err != nil {
 		return fmt.Errorf("cannot parse request form values: %w", err)
 	}
-	start, err := searchutils.GetTime(r, "start", 0)
+	ep, err := getExportParams(r, startTime)
 	if err != nil {
 		return err
 	}
-	end, err := searchutils.GetTime(r, "end", ct)
+
-	if err != nil {
+	sq := storage.NewSearchQuery(ep.start, ep.end, ep.filterss, *maxExportSeries)
-		return err
-	}
-	deadline := searchutils.GetDeadlineForExport(r, startTime)
-	tagFilterss, err := getTagFilterssFromRequest(r)
-	if err != nil {
-		return err
-	}
-	sq := storage.NewSearchQuery(start, end, tagFilterss, *maxExportSeries)
 	w.Header().Set("Content-Type", "VictoriaMetrics/native")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 
 	// Marshal tr
 	trBuf := make([]byte, 0, 16)
-	trBuf = encoding.MarshalInt64(trBuf, start)
+	trBuf = encoding.MarshalInt64(trBuf, ep.start)
-	trBuf = encoding.MarshalInt64(trBuf, end)
+	trBuf = encoding.MarshalInt64(trBuf, ep.end)
 	_, _ = bw.Write(trBuf)
 
 	// Marshal native blocks.
-	err = netstorage.ExportBlocks(sq, deadline, func(mn *storage.MetricName, b *storage.Block, tr storage.TimeRange) error {
+	err = netstorage.ExportBlocks(sq, ep.deadline, func(mn *storage.MetricName, b *storage.Block, tr storage.TimeRange) error {
 		if err := bw.Error(); err != nil {
 			return err
 		}
@@ -295,42 +277,25 @@ var bbPool bytesutil.ByteBufferPool
 func ExportHandler(startTime time.Time, w http.ResponseWriter, r *http.Request) error {
 	defer exportDuration.UpdateDuration(startTime)
 
-	ct := startTime.UnixNano() / 1e6
 	if err := r.ParseForm(); err != nil {
 		return fmt.Errorf("cannot parse request form values: %w", err)
 	}
-	matches := getMatchesFromRequest(r)
+	ep, err := getExportParams(r, startTime)
-	if len(matches) == 0 {
-		return fmt.Errorf("missing `match[]` query arg")
-	}
-	start, err := searchutils.GetTime(r, "start", 0)
-	if err != nil {
-		return err
-	}
-	end, err := searchutils.GetTime(r, "end", ct)
 	if err != nil {
 		return err
 	}
 	format := r.FormValue("format")
 	maxRowsPerLine := int(fastfloat.ParseInt64BestEffort(r.FormValue("max_rows_per_line")))
 	reduceMemUsage := searchutils.GetBool(r, "reduce_mem_usage")
-	deadline := searchutils.GetDeadlineForExport(r, startTime)
+	if err := exportHandler(w, ep, format, maxRowsPerLine, reduceMemUsage); err != nil {
-	if start >= end {
+		return fmt.Errorf("error when exporting data on the time range (start=%d, end=%d): %w", ep.start, ep.end, err)
-		end = start + defaultStep
-	}
-	etfs, err := searchutils.GetExtraTagFilters(r)
-	if err != nil {
-		return err
-	}
-	if err := exportHandler(w, matches, etfs, start, end, format, maxRowsPerLine, reduceMemUsage, deadline); err != nil {
-		return fmt.Errorf("error when exporting data for queries=%q on the time range (start=%d, end=%d): %w", matches, start, end, err)
 	}
 	return nil
 }
 
 var exportDuration = metrics.NewSummary(`vm_request_duration_seconds{path="/api/v1/export"}`)
 
-func exportHandler(w http.ResponseWriter, matches []string, etfs [][]storage.TagFilter, start, end int64, format string, maxRowsPerLine int, reduceMemUsage bool, deadline searchutils.Deadline) error {
+func exportHandler(w http.ResponseWriter, ep *exportParams, format string, maxRowsPerLine int, reduceMemUsage bool) error {
 	writeResponseFunc := WriteExportStdResponse
 	writeLineFunc := func(xb *exportBlock, resultsCh chan<- *quicktemplate.ByteBuffer) {
 		bb := quicktemplate.AcquireByteBuffer()
@@ -383,13 +348,7 @@ func exportHandler(w http.ResponseWriter, matches []string, etfs [][]storage.Tag
 		}
 	}
 
-	tagFilterss, err := getTagFilterssFromMatches(matches)
+	sq := storage.NewSearchQuery(ep.start, ep.end, ep.filterss, *maxExportSeries)
-	if err != nil {
-		return err
-	}
-	tagFilterss = searchutils.JoinTagFilterss(tagFilterss, etfs)
-
-	sq := storage.NewSearchQuery(start, end, tagFilterss, *maxExportSeries)
 	w.Header().Set("Content-Type", contentType)
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
@@ -397,7 +356,7 @@ func exportHandler(w http.ResponseWriter, matches []string, etfs [][]storage.Tag
 	resultsCh := make(chan *quicktemplate.ByteBuffer, cgroup.AvailableCPUs())
 	doneCh := make(chan error, 1)
 	if !reduceMemUsage {
-		rss, err := netstorage.ProcessSearchQuery(sq, true, deadline)
+		rss, err := netstorage.ProcessSearchQuery(sq, true, ep.deadline)
 		if err != nil {
 			return fmt.Errorf("cannot fetch data for %q: %w", sq, err)
 		}
@@ -420,7 +379,7 @@ func exportHandler(w http.ResponseWriter, matches []string, etfs [][]storage.Tag
 		}()
 	} else {
 		go func() {
-			err := netstorage.ExportBlocks(sq, deadline, func(mn *storage.MetricName, b *storage.Block, tr storage.TimeRange) error {
+			err := netstorage.ExportBlocks(sq, ep.deadline, func(mn *storage.MetricName, b *storage.Block, tr storage.TimeRange) error {
 				if err := bw.Error(); err != nil {
 					return err
 				}
@@ -447,7 +406,7 @@ func exportHandler(w http.ResponseWriter, matches []string, etfs [][]storage.Tag
 	if err := bw.Flush(); err != nil {
 		return err
 	}
-	err = <-doneCh
+	err := <-doneCh
 	if err != nil {
 		return fmt.Errorf("error during sending the data to remote client: %w", err)
 	}
@@ -1049,7 +1008,20 @@ func QueryHandler(startTime time.Time, w http.ResponseWriter, r *http.Request) e
 		if end < start {
 			end = start
 		}
-		if err := exportHandler(w, []string{childQuery}, etfs, start, end, "promapi", 0, false, deadline); err != nil {
+
+		tagFilterss, err := getTagFilterssFromMatches([]string{childQuery})
+		if err != nil {
+			return err
+		}
+		filterss := searchutils.JoinTagFilterss(tagFilterss, etfs)
+
+		ep := &exportParams{
+			deadline: deadline,
+			start:    start,
+			end:      end,
+			filterss: filterss,
+		}
+		if err := exportHandler(w, ep, "promapi", 0, false); err != nil {
 			return fmt.Errorf("error when exporting data for query=%q on the time range (start=%d, end=%d): %w", childQuery, start, end, err)
 		}
 		queryDuration.UpdateDuration(startTime)
@@ -1379,3 +1351,56 @@ func QueryStatsHandler(startTime time.Time, w http.ResponseWriter, r *http.Reque
 }
 
 var queryStatsDuration = metrics.NewSummary(`vm_request_duration_seconds{path="/api/v1/status/top_queries"}`)
+
+// exportParams contains common parameters for all /api/v1/export* handlers
+//
+// deadline, start, end, match[], extra_label, extra_filters
+type exportParams struct {
+	deadline searchutils.Deadline
+	start    int64
+	end      int64
+	filterss [][]storage.TagFilter
+}
+
+// getExportParams obtains common params from r, which are used for /api/v1/export* handlers
+func getExportParams(r *http.Request, startTime time.Time) (*exportParams, error) {
+	deadline := searchutils.GetDeadlineForExport(r, startTime)
+	start, err := searchutils.GetTime(r, "start", 0)
+	if err != nil {
+		return nil, err
+	}
+	ct := startTime.UnixNano() / 1e6
+	end, err := searchutils.GetTime(r, "end", ct)
+	if err != nil {
+		return nil, err
+	}
+	if end < start {
+		end = start
+	}
+
+	matches := r.Form["match[]"]
+	if len(matches) == 0 {
+		// Maintain backwards compatibility
+		match := r.FormValue("match")
+		if len(match) == 0 {
+			return nil, fmt.Errorf("missing `match[]` arg")
+		}
+		matches = []string{match}
+	}
+	tagFilterss, err := getTagFilterssFromMatches(matches)
+	if err != nil {
+		return nil, err
+	}
+	etfs, err := searchutils.GetExtraTagFilters(r)
+	if err != nil {
+		return nil, err
+	}
+	filterss := searchutils.JoinTagFilterss(tagFilterss, etfs)
+
+	return &exportParams{
+		deadline: deadline,
+		start:    start,
+		end:      end,
+		filterss: filterss,
+	}, nil
+}