internal/datagen/datagen.go

@@ -38,7 +38,7 @@ func (d *Datagen) Exports() modules.Exports {
 	return modules.Exports{Default: d}
 }
 
-func (d *Datagen) Generator(size int, typ string) *Generator {
-	g := NewGenerator(d.vu, size, strings.ToLower(typ))
+func (d *Datagen) Generator(size int, typ string, streaming bool) *Generator {
+	g := NewGenerator(d.vu, size, strings.ToLower(typ), streaming)
 	return &g
 }

internal/datagen/generator.go

@@ -3,6 +3,7 @@ package datagen
 import (
 	"bytes"
 	"math/rand"
+	"sync/atomic"
 	"time"
 
 	"github.com/go-loremipsum/loremipsum"
@@ -25,6 +26,9 @@ type (
 		buf    []byte
 		typ    string
 		offset int
+
+		streaming bool
+		seed      *atomic.Int64
 	}
 )
 
@@ -37,7 +41,7 @@ var payloadTypes = []string{
 	"",
 }
 
-func NewGenerator(vu modules.VU, size int, typ string) Generator {
+func NewGenerator(vu modules.VU, size int, typ string, streaming bool) Generator {
 	if size <= 0 {
 		panic("size should be positive")
 	}
@@ -52,17 +56,20 @@ func NewGenerator(vu modules.VU, size int, typ string) Generator {
 	if !found {
 		vu.InitEnv().Logger.Info("Unknown payload type '%s', random will be used.", typ)
 	}
-
-	r := rand.New(rand.NewSource(time.Now().UnixNano()))
-	buf := make([]byte, size+TailSize)
 	g := Generator{
 		vu:   vu,
 		size: size,
-		rand: r,
-		buf:  buf,
 		typ:  typ,
 	}
-	g.fillBuffer()
+
+	if streaming {
+		g.streaming = true
+		g.seed = new(atomic.Int64)
+	} else {
+		g.rand = rand.New(rand.NewSource(time.Now().UnixNano()))
+		g.buf = make([]byte, size+TailSize)
+		g.fillBuffer()
+	}
 	return g
 }
 
@@ -82,6 +89,10 @@ func (g *Generator) fillBuffer() {
 }
 
 func (g *Generator) GenPayload(calcHash bool) Payload {
+	if g.streaming {
+		return NewStreamPayload(g.size, g.seed.Add(1), g.typ)
+	}
+
 	data := g.nextSlice()
 	return NewFixedPayload(data)
 }

internal/datagen/generator_test.go

@@ -16,25 +16,25 @@ func TestGenerator(t *testing.T) {
 
 	t.Run("fails on negative size", func(t *testing.T) {
 		require.Panics(t, func() {
-			_ = NewGenerator(vu, -1, "")
+			_ = NewGenerator(vu, -1, "", false)
 		})
 	})
 
 	t.Run("fails on zero size", func(t *testing.T) {
 		require.Panics(t, func() {
-			_ = NewGenerator(vu, 0, "")
+			_ = NewGenerator(vu, 0, "", false)
 		})
 	})
 
 	t.Run("creates slice of specified size", func(t *testing.T) {
 		size := 10
-		g := NewGenerator(vu, size, "")
+		g := NewGenerator(vu, size, "", false)
 		slice := g.nextSlice()
 		require.Len(t, slice, size)
 	})
 
 	t.Run("creates a different slice on each call", func(t *testing.T) {
-		g := NewGenerator(vu, 1000, "")
+		g := NewGenerator(vu, 1000, "", false)
 		slice1 := g.nextSlice()
 		slice2 := g.nextSlice()
 		// Each slice should be unique (assuming that 1000 random bytes will never coincide
@@ -43,7 +43,7 @@ func TestGenerator(t *testing.T) {
 	})
 
 	t.Run("keeps generating slices after consuming entire tail", func(t *testing.T) {
-		g := NewGenerator(vu, 1000, "")
+		g := NewGenerator(vu, 1000, "", false)
 		initialSlice := g.nextSlice()
 		for i := 0; i < TailSize; i++ {
 			g.nextSlice()

internal/datagen/payload.go

@@ -1,10 +1,15 @@
 package datagen
 
 import (
+	"bufio"
 	"bytes"
 	"crypto/sha256"
 	"encoding/hex"
+	"hash"
 	"io"
+	"math/rand"
+
+	"github.com/go-loremipsum/loremipsum"
 )
 
 // Payload represents arbitrary data to be packed into S3 or native object.
@@ -48,3 +53,69 @@ func (p *bytesPayload) Bytes() []byte {
 func NewFixedPayload(data []byte) Payload {
 	return &bytesPayload{data: data}
 }
+
+type randomPayload struct {
+	r    io.Reader
+	s    hash.Hash
+	h    string
+	size int
+}
+
+func NewStreamPayload(size int, seed int64, typ string) Payload {
+	var rr io.Reader
+	switch typ {
+	case "text":
+		rr = &textReader{li: loremipsum.NewWithSeed(seed)}
+	default:
+		rr = rand.New(rand.NewSource(seed))
+	}
+
+	lr := io.LimitReader(rr, int64(size))
+	// We need some buffering to write complete blocks in the TeeReader.
+	// Streaming payload read is expected to be used for big objects, thus 4k seems like a good choice.
+	br := bufio.NewReaderSize(lr, 4096)
+	s := sha256.New()
+	tr := io.TeeReader(br, s)
+	return &randomPayload{
+		r:    tr,
+		s:    s,
+		size: size,
+	}
+}
+
+func (p *randomPayload) Reader() io.Reader {
+	return p.r
+}
+
+func (p *randomPayload) Size() int {
+	return p.size
+}
+
+func (p *randomPayload) Hash() string {
+	if p.h == "" {
+		p.h = hex.EncodeToString(p.s.Sum(nil))
+		// Prevent possible misuse.
+		p.r = nil
+		p.s = nil
+	}
+	return p.h
+}
+
+func (p *randomPayload) Bytes() []byte {
+	data, err := io.ReadAll(p.r)
+	if err != nil {
+		// We use only 2 readers, either `bytes.Reader` or `rand.Reader`.
+		// None of them returns errors, thus encountering an error is a fatal error.
+		panic(err)
+	}
+	return data
+}
+
+type textReader struct {
+	li *loremipsum.LoremIpsum
+}
+
+func (r *textReader) Read(p []byte) (n int, err error) {
+	paragraph := r.li.Paragraph()
+	return copy(p, paragraph), nil
+}

internal/datagen/payload_test.go

@@ -26,3 +26,15 @@ func TestFixedPayload(t *testing.T) {
 	h := sha256.Sum256(data)
 	require.Equal(t, hex.EncodeToString(h[:]), p.Hash())
 }
+
+func TestStreamingPayload(t *testing.T) {
+	const size = 123
+
+	p := NewStreamPayload(size, 0, "")
+	require.Equal(t, size, p.Size())
+
+	actual, err := io.ReadAll(p.Reader())
+	require.NoError(t, err)
+	require.Equal(t, size, len(actual))
+	require.Equal(t, sha256.Size*2, len(p.Hash()))
+}

scenarios/libs/datagen.js

@@ -2,7 +2,7 @@ import datagen from 'k6/x/frostfs/datagen';
 
 export function newGenerator(condition) {
 	if (condition) {
-		return datagen.generator(1024 * parseInt(__ENV.WRITE_OBJ_SIZE), __ENV.PAYLOAD_TYPE || "");
+		return datagen.generator(1024 * parseInt(__ENV.WRITE_OBJ_SIZE), __ENV.PAYLOAD_TYPE || "", !!__ENV.STREAMING);
 	}
 	return undefined;
 }

scenarios/run_scenarios.md

@@ -19,6 +19,7 @@ Scenarios `grpc.js`, `local.js`, `http.js` and `s3.js` support the following opt
   * `SLEEP_READ` - time interval (in seconds) between reading VU iterations.
   * `SELECTION_SIZE` - size of batch to select for deletion (default: 1000).
   * `PAYLOAD_TYPE` - type of an object payload ("random" or "text", default: "random").
+  * `STREAMING` - if set, the payload is generated on the fly and is not read into memory fully.
 
 Additionally, the profiling extension can be enabled to generate CPU and memory profiles which can be inspected with `go tool pprof file.prof`:
 ```shell