app/vminsert: add /api/v1/import handler

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/6

README.md

@@ -49,11 +49,12 @@ Cluster version is available [here](https://github.com/VictoriaMetrics/VictoriaM
 * Storage is protected from corruption on unclean shutdown (i.e. OOM, hardware reset or `kill -9`) thanks to [the storage architecture](https://medium.com/@valyala/how-victoriametrics-makes-instant-snapshots-for-multi-terabyte-time-series-data-e1f3fb0e0282).
 * Supports metrics' ingestion and [backfilling](#backfilling) via the following protocols:
   * [Prometheus remote write API](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#remote_write)
-  * [InfluxDB line protocol](https://docs.influxdata.com/influxdb/v1.7/write_protocols/line_protocol_tutorial/)
-  * [Graphite plaintext protocol](https://graphite.readthedocs.io/en/latest/feeding-carbon.html) with [tags](https://graphite.readthedocs.io/en/latest/tags.html#carbon)
+  * [InfluxDB line protocol](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#how-to-send-data-from-influxdb-compatible-agents-such-as-telegraf)
+  * [Graphite plaintext protocol](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#how-to-send-data-from-graphite-compatible-agents-such-as-statsd) with [tags](https://graphite.readthedocs.io/en/latest/tags.html#carbon)
     if `-graphiteListenAddr` is set.
-  * [OpenTSDB put message](http://opentsdb.net/docs/build/html/api_telnet/put.html) if `-opentsdbListenAddr` is set.
-  * [HTTP OpenTSDB /api/put requests](http://opentsdb.net/docs/build/html/api_http/put.html) if `-opentsdbHTTPListenAddr` is set.
+  * [OpenTSDB put message](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#sending-data-via-telnet-put-protocol) if `-opentsdbListenAddr` is set.
+  * [HTTP OpenTSDB /api/put requests](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#sending-opentsdb-data-via-http-apiput-requests) if `-opentsdbHTTPListenAddr` is set.
+  * [/api/v1/import](#how-to-import-time-series-data)
 * Ideally works with big amounts of time series data from Kubernetes, IoT sensors, connected cars, industrial telemetry, financial data and various Enterprise workloads.
 * Has open source [cluster version](https://github.com/VictoriaMetrics/VictoriaMetrics/tree/cluster).
 
@@ -84,6 +85,7 @@ Cluster version is available [here](https://github.com/VictoriaMetrics/VictoriaM
   - [How to work with snapshots?](#how-to-work-with-snapshots)
   - [How to delete time series?](#how-to-delete-time-series)
   - [How to export time series?](#how-to-export-time-series)
+  - [How to import time series data?](#how-to-import-time-series-data)
   - [Federation](#federation)
   - [Capacity planning](#capacity-planning)
   - [High availability](#high-availability)
@@ -513,6 +515,33 @@ Each JSON line would contain data for a single time series. An example output:
 Optional `start` and `end` args may be added to the request in order to limit the time frame for the exported data. These args may contain either
 unix timestamp in seconds or [RFC3339](https://www.ietf.org/rfc/rfc3339.txt) values.
 
+Exported data can be imported via POST'ing it to [/api/v1/import](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#how-to-import-time-series-data).
+
+
+### How to import time series data?
+
+Time series data can be imported via any supported ingestion protocol:
+
+* [Prometheus remote_write API](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#remote_write)
+* [Influx line protocol](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#how-to-send-data-from-influxdb-compatible-agents-such-as-telegraf)
+* [Graphite plaintext protocol](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#how-to-send-data-from-graphite-compatible-agents-such-as-statsd)
+* [OpenTSDB telnet put protocol](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#sending-data-via-telnet-put-protocol)
+* [OpenTSDB http /api/put](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#sending-opentsdb-data-via-http-apiput-requests)
+* `/api/v1/import` http POST handler, which accepts data from [/api/v1/export](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#how-to-export-time-series).
+
+The most efficient protocol for importing data into VictoriaMetrics is `/api/v1/import`. Example for importing data obtained via `/api/v1/export`:
+
+```
+# Export the data from <source-victoriametrics>:
+curl -s 'http://source-victoriametrics:8428/api/v1/export' -d 'match={__name__!=""}' > exported_data.jsonl
+
+# Import the data to <destination-victoriametrics>:
+curl -X POST 'http://destination-victoriametrics:8428/api/v1/import' -T exported_data.jsonl
+```
+
+Each request to `/api/v1/import` can load up to a single vCPU core on VictoriaMetrics. Import speed can be improved by splitting the original file into smaller parts
+and importing them concurrently. Note that the original file must be split on newlines.
+
 
 ### Federation
 

app/vminsert/common/insert_ctx.go

@@ -47,7 +47,7 @@ func (ctx *InsertCtx) marshalMetricNameRaw(prefix []byte, labels []prompb.Label)
 	return metricNameRaw[:len(metricNameRaw):len(metricNameRaw)]
 }
 
-// WriteDataPoint writes (timestamp, value) with the given prefix and lables into ctx buffer.
+// WriteDataPoint writes (timestamp, value) with the given prefix and labels into ctx buffer.
 func (ctx *InsertCtx) WriteDataPoint(prefix []byte, labels []prompb.Label, timestamp int64, value float64) {
 	metricNameRaw := ctx.marshalMetricNameRaw(prefix, labels)
 	ctx.addRow(metricNameRaw, timestamp, value)
@@ -78,6 +78,26 @@ func (ctx *InsertCtx) addRow(metricNameRaw []byte, timestamp int64, value float6
 	mr.Value = value
 }
 
+// AddLabelBytes adds (name, value) label to ctx.Labels.
+//
+// name and value must exist until ctx.Labels is used.
+func (ctx *InsertCtx) AddLabelBytes(name, value []byte) {
+	labels := ctx.Labels
+	if cap(labels) > len(labels) {
+		labels = labels[:len(labels)+1]
+	} else {
+		labels = append(labels, prompb.Label{})
+	}
+	label := &labels[len(labels)-1]
+
+	// Do not copy name and value contents for performance reasons.
+	// This reduces GC overhead on the number of objects and allocations.
+	label.Name = name
+	label.Value = value
+
+	ctx.Labels = labels
+}
+
 // AddLabel adds (name, value) label to ctx.Labels.
 //
 // name and value must exist until ctx.Labels is used.

app/vminsert/common/lines_reader.go

@@ -20,6 +20,17 @@ const defaultBlockSize = 64 * 1024
 //
 // Returns (dstBuf, tailBuf).
 func ReadLinesBlock(r io.Reader, dstBuf, tailBuf []byte) ([]byte, []byte, error) {
+	return ReadLinesBlockExt(r, dstBuf, tailBuf, maxLineSize)
+}
+
+// ReadLinesBlockExt reads a block of lines delimited by '\n' from tailBuf and r into dstBuf.
+//
+// Trailing chars after the last newline are put into tailBuf.
+//
+// Returns (dstBuf, tailBuf).
+//
+// maxLineLen limits the maximum length of a single line.
+func ReadLinesBlockExt(r io.Reader, dstBuf, tailBuf []byte, maxLineLen int) ([]byte, []byte, error) {
 	if cap(dstBuf) < defaultBlockSize {
 		dstBuf = bytesutil.Resize(dstBuf, defaultBlockSize)
 	}
@@ -48,8 +59,8 @@ again:
 	nn := bytes.LastIndexByte(dstBuf[len(dstBuf)-n:], '\n')
 	if nn < 0 {
 		// Didn't found at least a single line.
-		if len(dstBuf) > maxLineSize {
-			return dstBuf, tailBuf, fmt.Errorf("too long line: more than %d bytes", maxLineSize)
+		if len(dstBuf) > maxLineLen {
+			return dstBuf, tailBuf, fmt.Errorf("too long line: more than %d bytes", maxLineLen)
 		}
 		if cap(dstBuf) < 2*len(dstBuf) {
 			// Increase dsbBuf capacity, so more data could be read into it.

app/vminsert/influx/request_handler.go

@@ -82,7 +82,7 @@ func (ctx *pushCtx) InsertRows(db string) error {
 	rows := ctx.Rows.Rows
 	rowsLen := 0
 	for i := range rows {
-		rowsLen += len(rows[i].Tags)
+		rowsLen += len(rows[i].Fields)
 	}
 	ic := &ctx.Common
 	ic.Reset(rowsLen)

app/vminsert/main.go

@@ -12,6 +12,7 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vminsert/opentsdb"
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vminsert/opentsdbhttp"
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vminsert/prometheus"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vminsert/vmimport"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/storage"
 	"github.com/VictoriaMetrics/metrics"
@@ -67,6 +68,14 @@ func RequestHandler(w http.ResponseWriter, r *http.Request) bool {
 		}
 		w.WriteHeader(http.StatusNoContent)
 		return true
+	case "/api/v1/import":
+		vmimportRequests.Inc()
+		if err := vmimport.InsertHandler(r); err != nil {
+			vmimportErrors.Inc()
+			httpserver.Errorf(w, "error in %q: %s", r.URL.Path, err)
+			return true
+		}
+		return true
 	case "/write", "/api/v2/write":
 		influxWriteRequests.Inc()
 		if err := influx.InsertHandler(r); err != nil {
@@ -92,6 +101,9 @@ var (
 	prometheusWriteRequests = metrics.NewCounter(`vm_http_requests_total{path="/api/v1/write", protocol="prometheus"}`)
 	prometheusWriteErrors   = metrics.NewCounter(`vm_http_request_errors_total{path="/api/v1/write", protocol="prometheus"}`)
 
+	vmimportRequests = metrics.NewCounter(`vm_http_requests_total{path="/api/v1/import", protocol="vm"}`)
+	vmimportErrors   = metrics.NewCounter(`vm_http_request_errors_total{path="/api/v1/import", protocol="vm"}`)
+
 	influxWriteRequests = metrics.NewCounter(`vm_http_requests_total{path="/write", protocol="influx"}`)
 	influxWriteErrors   = metrics.NewCounter(`vm_http_request_errors_total{path="/write", protocol="influx"}`)
 

app/vminsert/vmimport/parser.go

@@ -0,0 +1,202 @@
+package vmimport
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+	"github.com/VictoriaMetrics/metrics"
+	"github.com/valyala/fastjson"
+)
+
+// Rows contains parsed rows from `/api/v1/import` request.
+type Rows struct {
+	Rows []Row
+
+	tu tagsUnmarshaler
+}
+
+// Reset resets rs.
+func (rs *Rows) Reset() {
+	for i := range rs.Rows {
+		rs.Rows[i].reset()
+	}
+	rs.Rows = rs.Rows[:0]
+
+	rs.tu.reset()
+}
+
+// Unmarshal unmarshals influx line protocol rows from s.
+//
+// See https://docs.influxdata.com/influxdb/v1.7/write_protocols/line_protocol_tutorial/
+//
+// s must be unchanged until rs is in use.
+func (rs *Rows) Unmarshal(s string) {
+	rs.tu.reset()
+	rs.Rows = unmarshalRows(rs.Rows[:0], s, &rs.tu)
+}
+
+// Row is a single row from `/api/v1/import` request.
+type Row struct {
+	Tags       []Tag
+	Values     []float64
+	Timestamps []int64
+}
+
+func (r *Row) reset() {
+	r.Tags = nil
+	r.Values = r.Values[:0]
+	r.Timestamps = r.Timestamps[:0]
+}
+
+func (r *Row) unmarshal(s string, tu *tagsUnmarshaler) error {
+	r.reset()
+	v, err := tu.p.Parse(s)
+	if err != nil {
+		return fmt.Errorf("cannot parse json line: %s", err)
+	}
+
+	// Unmarshal tags
+	metric := v.GetObject("metric")
+	if metric == nil {
+		return fmt.Errorf("missing `metric` object")
+	}
+	tagsStart := len(tu.tagsPool)
+	if err := tu.unmarshalTags(metric); err != nil {
+		return fmt.Errorf("cannot unmarshal `metric`: %s", err)
+	}
+	tags := tu.tagsPool[tagsStart:]
+	r.Tags = tags[:len(tags):len(tags)]
+	if len(r.Tags) == 0 {
+		return fmt.Errorf("missing tags")
+	}
+
+	// Unmarshal values
+	values := v.GetArray("values")
+	if len(values) == 0 {
+		return fmt.Errorf("missing `values` array")
+	}
+	for i, v := range values {
+		f, err := v.Float64()
+		if err != nil {
+			return fmt.Errorf("cannot unmarshal value at position %d: %s", i, err)
+		}
+		r.Values = append(r.Values, f)
+	}
+
+	// Unmarshal timestamps
+	timestamps := v.GetArray("timestamps")
+	if len(timestamps) == 0 {
+		return fmt.Errorf("missing `timestamps` array")
+	}
+	for i, v := range timestamps {
+		ts, err := v.Int64()
+		if err != nil {
+			return fmt.Errorf("cannot unmarshal timestamp at position %d: %s", i, err)
+		}
+		r.Timestamps = append(r.Timestamps, ts)
+	}
+
+	if len(r.Timestamps) != len(r.Values) {
+		return fmt.Errorf("`timestamps` array size must match `values` array size; got %d; want %d", len(r.Timestamps), len(r.Values))
+	}
+	return nil
+}
+
+// Tag represents `/api/v1/import` tag.
+type Tag struct {
+	Key   []byte
+	Value []byte
+}
+
+func (tag *Tag) reset() {
+	// tag.Key and tag.Value point to tu.bytesPool, so there is no need in keeping these byte slices here.
+	tag.Key = nil
+	tag.Value = nil
+}
+
+type tagsUnmarshaler struct {
+	p         fastjson.Parser
+	tagsPool  []Tag
+	bytesPool []byte
+	err       error
+}
+
+func (tu *tagsUnmarshaler) reset() {
+	for i := range tu.tagsPool {
+		tu.tagsPool[i].reset()
+	}
+	tu.tagsPool = tu.tagsPool[:0]
+
+	tu.bytesPool = tu.bytesPool[:0]
+	tu.err = nil
+}
+
+func (tu *tagsUnmarshaler) addTag() *Tag {
+	dst := tu.tagsPool
+	if cap(dst) > len(dst) {
+		dst = dst[:len(dst)+1]
+	} else {
+		dst = append(dst, Tag{})
+	}
+	tag := &dst[len(dst)-1]
+	tu.tagsPool = dst
+	return tag
+}
+
+func (tu *tagsUnmarshaler) addBytes(b []byte) []byte {
+	bytesPoolLen := len(tu.bytesPool)
+	tu.bytesPool = append(tu.bytesPool, b...)
+	bCopy := tu.bytesPool[bytesPoolLen:]
+	return bCopy[:len(bCopy):len(bCopy)]
+}
+
+func (tu *tagsUnmarshaler) unmarshalTags(o *fastjson.Object) error {
+	tu.err = nil
+	o.Visit(func(key []byte, v *fastjson.Value) {
+		tag := tu.addTag()
+		tag.Key = tu.addBytes(key)
+		sb, err := v.StringBytes()
+		if err != nil && tu.err != nil {
+			tu.err = fmt.Errorf("cannot parse value for tag %q: %s", tag.Key, err)
+		}
+		tag.Value = tu.addBytes(sb)
+	})
+	return tu.err
+}
+
+func unmarshalRows(dst []Row, s string, tu *tagsUnmarshaler) []Row {
+	for len(s) > 0 {
+		n := strings.IndexByte(s, '\n')
+		if n < 0 {
+			// The last line.
+			return unmarshalRow(dst, s, tu)
+		}
+		dst = unmarshalRow(dst, s[:n], tu)
+		s = s[n+1:]
+	}
+	return dst
+}
+
+func unmarshalRow(dst []Row, s string, tu *tagsUnmarshaler) []Row {
+	if len(s) > 0 && s[len(s)-1] == '\r' {
+		s = s[:len(s)-1]
+	}
+	if len(s) == 0 {
+		return dst
+	}
+	if cap(dst) > len(dst) {
+		dst = dst[:len(dst)+1]
+	} else {
+		dst = append(dst, Row{})
+	}
+	r := &dst[len(dst)-1]
+	if err := r.unmarshal(s, tu); err != nil {
+		dst = dst[:len(dst)-1]
+		logger.Errorf("cannot unmarshal json line %q: %s; skipping it", s, err)
+		invalidLines.Inc()
+	}
+	return dst
+}
+
+var invalidLines = metrics.NewCounter(`vm_rows_invalid_total{type="vmimport"}`)

app/vminsert/vmimport/parser_test.go

@@ -0,0 +1,216 @@
+package vmimport
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestRowsUnmarshalFailure(t *testing.T) {
+	f := func(s string) {
+		t.Helper()
+		var rows Rows
+		rows.Unmarshal(s)
+		if len(rows.Rows) != 0 {
+			t.Fatalf("expecting zero rows; got %d rows", len(rows.Rows))
+		}
+
+		// Try again
+		rows.Unmarshal(s)
+		if len(rows.Rows) != 0 {
+			t.Fatalf("expecting zero rows; got %d rows", len(rows.Rows))
+		}
+	}
+
+	// Invalid json line
+	f("")
+	f("\n")
+	f("foo\n")
+	f("123")
+	f("[1,3]")
+	f("{}")
+	f("[]")
+	f(`{"foo":"bar"}`)
+
+	// Invalid metric
+	f(`{"metric":123,"values":[1,2],"timestamps":[3,4]}`)
+	f(`{"metric":[123],"values":[1,2],"timestamps":[3,4]}`)
+	f(`{"metric":[],"values":[1,2],"timestamps":[3,4]}`)
+	f(`{"metric":{},"values":[1,2],"timestamps":[3,4]}`)
+	f(`{"metric":null,"values":[1,2],"timestamps":[3,4]}`)
+	f(`{"values":[1,2],"timestamps":[3,4]}`)
+
+	// Invalid values
+	f(`{"metric":{"foo":"bar"},"values":1,"timestamps":[3,4]}`)
+	f(`{"metric":{"foo":"bar"},"values":{"x":1},"timestamps":[3,4]}`)
+	f(`{"metric":{"foo":"bar"},"values":{"x":1},"timestamps":[3,4]}`)
+	f(`{"metric":{"foo":"bar"},"values":null,"timestamps":[3,4]}`)
+	f(`{"metric":{"foo":"bar"},"timestamps":[3,4]}`)
+
+	// Invalid timestamps
+	f(`{"metric":{"foo":"bar"},"values":[1,2],"timestamps":3}`)
+	f(`{"metric":{"foo":"bar"},"values":[1,2],"timestamps":false}`)
+	f(`{"metric":{"foo":"bar"},"values":[1,2],"timestamps":{}}`)
+	f(`{"metric":{"foo":"bar"},"values":[1,2]}`)
+
+	// values and timestamps count mismatch
+	f(`{"metric":{"foo":"bar"},"values":[],"timestamps":[]}`)
+	f(`{"metric":{"foo":"bar"},"values":[],"timestamps":[1]}`)
+	f(`{"metric":{"foo":"bar"},"values":[2],"timestamps":[]}`)
+	f(`{"metric":{"foo":"bar"},"values":[2],"timestamps":[3,4]}`)
+	f(`{"metric":{"foo":"bar"},"values":[2,3],"timestamps":[4]}`)
+
+	// Garbage after the line
+	f(`{"metric":{"foo":"bar"},"values":[2],"timestamps":[4]}{}`)
+}
+
+func TestRowsUnmarshalSuccess(t *testing.T) {
+	f := func(s string, rowsExpected *Rows) {
+		t.Helper()
+		var rows Rows
+		rows.Unmarshal(s)
+		if !reflect.DeepEqual(rows.Rows, rowsExpected.Rows) {
+			t.Fatalf("unexpected rows;\ngot\n%+v;\nwant\n%+v", rows.Rows, rowsExpected.Rows)
+		}
+
+		// Try unmarshaling again
+		rows.Unmarshal(s)
+		if !reflect.DeepEqual(rows.Rows, rowsExpected.Rows) {
+			t.Fatalf("unexpected rows;\ngot\n%+v;\nwant\n%+v", rows.Rows, rowsExpected.Rows)
+		}
+
+		rows.Reset()
+		if len(rows.Rows) != 0 {
+			t.Fatalf("non-empty rows after reset: %+v", rows.Rows)
+		}
+	}
+
+	// Empty line
+	f("", &Rows{})
+	f("\n\n", &Rows{})
+	f("\n\r\n", &Rows{})
+
+	// Single line with a single tag
+	f(`{"metric":{"foo":"bar"},"values":[1.23],"timestamps":[456]}`, &Rows{
+		Rows: []Row{{
+			Tags: []Tag{{
+				Key:   []byte("foo"),
+				Value: []byte("bar"),
+			}},
+			Values:     []float64{1.23},
+			Timestamps: []int64{456},
+		}},
+	})
+
+	// Line with multiple tags
+	f(`{"metric":{"foo":"bar","baz":"xx"},"values":[1.23, -3.21],"timestamps" : [456,789]}`, &Rows{
+		Rows: []Row{{
+			Tags: []Tag{
+				{
+					Key:   []byte("foo"),
+					Value: []byte("bar"),
+				},
+				{
+					Key:   []byte("baz"),
+					Value: []byte("xx"),
+				},
+			},
+			Values:     []float64{1.23, -3.21},
+			Timestamps: []int64{456, 789},
+		}},
+	})
+
+	// Multiple lines
+	f(`{"metric":{"foo":"bar","baz":"xx"},"values":[1.23, -3.21],"timestamps" : [456,789]}
+{"metric":{"__name__":"xx"},"values":[34],"timestamps" : [11]}
+`, &Rows{
+		Rows: []Row{
+			{
+				Tags: []Tag{
+					{
+						Key:   []byte("foo"),
+						Value: []byte("bar"),
+					},
+					{
+						Key:   []byte("baz"),
+						Value: []byte("xx"),
+					},
+				},
+				Values:     []float64{1.23, -3.21},
+				Timestamps: []int64{456, 789},
+			},
+			{
+				Tags: []Tag{
+					{
+						Key:   []byte("__name__"),
+						Value: []byte("xx"),
+					},
+				},
+				Values:     []float64{34},
+				Timestamps: []int64{11},
+			},
+		},
+	})
+
+	// Multiple lines with invalid line in the middle.
+	f(`{"metric":{"xfoo":"bar","baz":"xx"},"values":[1.232, -3.21],"timestamps" : [456,7890]}
+garbage here
+{"metric":{"__name__":"xxy"},"values":[34],"timestamps" : [111]}`, &Rows{
+		Rows: []Row{
+			{
+				Tags: []Tag{
+					{
+						Key:   []byte("xfoo"),
+						Value: []byte("bar"),
+					},
+					{
+						Key:   []byte("baz"),
+						Value: []byte("xx"),
+					},
+				},
+				Values:     []float64{1.232, -3.21},
+				Timestamps: []int64{456, 7890},
+			},
+			{
+				Tags: []Tag{
+					{
+						Key:   []byte("__name__"),
+						Value: []byte("xxy"),
+					},
+				},
+				Values:     []float64{34},
+				Timestamps: []int64{111},
+			},
+		},
+	})
+
+	// No newline after the second line.
+	f(`{"metric":{"foo":"bar","baz":"xx"},"values":[1.23, -3.21],"timestamps" : [456,789]}
+{"metric":{"__name__":"xx"},"values":[34],"timestamps" : [11]}`, &Rows{
+		Rows: []Row{
+			{
+				Tags: []Tag{
+					{
+						Key:   []byte("foo"),
+						Value: []byte("bar"),
+					},
+					{
+						Key:   []byte("baz"),
+						Value: []byte("xx"),
+					},
+				},
+				Values:     []float64{1.23, -3.21},
+				Timestamps: []int64{456, 789},
+			},
+			{
+				Tags: []Tag{
+					{
+						Key:   []byte("__name__"),
+						Value: []byte("xx"),
+					},
+				},
+				Values:     []float64{34},
+				Timestamps: []int64{11},
+			},
+		},
+	})
+}

app/vminsert/vmimport/parser_timing_test.go

@@ -0,0 +1,25 @@
+package vmimport
+
+import (
+	"fmt"
+	"testing"
+)
+
+func BenchmarkRowsUnmarshal(b *testing.B) {
+	s := `{"metric":{"__name__":"up","job":"node_exporter","instance":"localhost:9100"},"values":[0,0,0],"timestamps":[1549891472010,1549891487724,1549891503438]}
+{"metric":{"__name__":"up","job":"prometheus","instance":"localhost:9090"},"values":[1,1,1],"timestamps":[1549891461511,1549891476511,1549891491511]}
+{"metric":{"__name__":"up","job":"node_exporter","instance":"foobar.com:9100"},"values":[0,0,0],"timestamps":[1549891472010,1549891487724,1549891503438]}
+{"metric":{"__name__":"up","job":"prometheus","instance":"xxx.yyy.zzz:9090"},"values":[1,1,1],"timestamps":[1549891461511,1549891476511,1549891491511]}
+`
+	b.SetBytes(int64(len(s)))
+	b.ReportAllocs()
+	b.RunParallel(func(pb *testing.PB) {
+		var rows Rows
+		for pb.Next() {
+			rows.Unmarshal(s)
+			if len(rows.Rows) != 4 {
+				panic(fmt.Errorf("unexpected number of rows parsed; got %d; want 4", len(rows.Rows)))
+			}
+		}
+	})
+}

app/vminsert/vmimport/request_handler.go

@@ -0,0 +1,160 @@
+package vmimport
+
+import (
+	"flag"
+	"fmt"
+	"io"
+	"net/http"
+	"runtime"
+	"sync"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vminsert/common"
+	"github.com/VictoriaMetrics/VictoriaMetrics/app/vminsert/concurrencylimiter"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/storage"
+	"github.com/VictoriaMetrics/metrics"
+)
+
+var maxLineLen = flag.Int("import.maxLineLen", 100*1024*1024, "The maximum length in bytes of a single line accepted by `/api/v1/import`")
+
+var (
+	rowsInserted  = metrics.NewCounter(`vm_rows_inserted_total{type="vmimport"}`)
+	rowsPerInsert = metrics.NewSummary(`vm_rows_per_insert{type="vmimport"}`)
+)
+
+// InsertHandler processes `/api/v1/import` request.
+//
+// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/6
+func InsertHandler(req *http.Request) error {
+	return concurrencylimiter.Do(func() error {
+		return insertHandlerInternal(req)
+	})
+}
+
+func insertHandlerInternal(req *http.Request) error {
+	readCalls.Inc()
+
+	r := req.Body
+	if req.Header.Get("Content-Encoding") == "gzip" {
+		zr, err := common.GetGzipReader(r)
+		if err != nil {
+			return fmt.Errorf("cannot read gzipped vmimport data: %s", err)
+		}
+		defer common.PutGzipReader(zr)
+		r = zr
+	}
+
+	ctx := getPushCtx()
+	defer putPushCtx(ctx)
+	for ctx.Read(r) {
+		if err := ctx.InsertRows(); err != nil {
+			return err
+		}
+	}
+	return ctx.Error()
+}
+
+func (ctx *pushCtx) InsertRows() error {
+	rows := ctx.Rows.Rows
+	rowsLen := 0
+	for i := range rows {
+		rowsLen += len(rows[i].Values)
+	}
+	ic := &ctx.Common
+	ic.Reset(rowsLen)
+	rowsTotal := 0
+	for i := range rows {
+		r := &rows[i]
+		ic.Labels = ic.Labels[:0]
+		for j := range r.Tags {
+			tag := &r.Tags[j]
+			ic.AddLabelBytes(tag.Key, tag.Value)
+		}
+		ctx.metricNameBuf = storage.MarshalMetricNameRaw(ctx.metricNameBuf[:0], ic.Labels)
+		values := r.Values
+		timestamps := r.Timestamps
+		_ = timestamps[len(values)-1]
+		for j, value := range values {
+			timestamp := timestamps[j]
+			ic.WriteDataPoint(ctx.metricNameBuf, nil, timestamp, value)
+		}
+		rowsTotal += len(values)
+	}
+	rowsInserted.Add(rowsTotal)
+	rowsPerInsert.Update(float64(rowsTotal))
+	return ic.FlushBufs()
+}
+
+func (ctx *pushCtx) Read(r io.Reader) bool {
+	if ctx.err != nil {
+		return false
+	}
+	ctx.reqBuf, ctx.tailBuf, ctx.err = common.ReadLinesBlockExt(r, ctx.reqBuf, ctx.tailBuf, *maxLineLen)
+	if ctx.err != nil {
+		if ctx.err != io.EOF {
+			readErrors.Inc()
+			ctx.err = fmt.Errorf("cannot read vmimport data: %s", ctx.err)
+		}
+		return false
+	}
+	ctx.Rows.Unmarshal(bytesutil.ToUnsafeString(ctx.reqBuf))
+	return true
+}
+
+var (
+	readCalls  = metrics.NewCounter(`vm_read_calls_total{name="vmimport"}`)
+	readErrors = metrics.NewCounter(`vm_read_errors_total{name="vmimport"}`)
+)
+
+type pushCtx struct {
+	Rows   Rows
+	Common common.InsertCtx
+
+	reqBuf        []byte
+	tailBuf       []byte
+	metricNameBuf []byte
+
+	err error
+}
+
+func (ctx *pushCtx) Error() error {
+	if ctx.err == io.EOF {
+		return nil
+	}
+	return ctx.err
+}
+
+func (ctx *pushCtx) reset() {
+	ctx.Rows.Reset()
+	ctx.Common.Reset(0)
+
+	ctx.reqBuf = ctx.reqBuf[:0]
+	ctx.tailBuf = ctx.tailBuf[:0]
+	ctx.metricNameBuf = ctx.metricNameBuf[:0]
+
+	ctx.err = nil
+}
+
+func getPushCtx() *pushCtx {
+	select {
+	case ctx := <-pushCtxPoolCh:
+		return ctx
+	default:
+		if v := pushCtxPool.Get(); v != nil {
+			return v.(*pushCtx)
+		}
+		return &pushCtx{}
+	}
+}
+
+func putPushCtx(ctx *pushCtx) {
+	ctx.reset()
+	select {
+	case pushCtxPoolCh <- ctx:
+	default:
+		pushCtxPool.Put(ctx)
+	}
+}
+
+var pushCtxPool sync.Pool
+var pushCtxPoolCh = make(chan *pushCtx, runtime.GOMAXPROCS(-1))