s3store: Implement temporary support for buffering in memory

pkg/s3store/s3store.go

@@ -461,8 +461,9 @@ func (upload *s3Upload) uploadParts(ctx context.Context, offset int64, src io.Re
 			break
 		}
 
-		partfile := fileChunk.file
+		partfile := fileChunk.reader
 		partsize := fileChunk.size
+		closePart := fileChunk.closeReader
 
 		isFinalChunk := !info.SizeIsDeferred && (size == offset+bytesUploaded+partsize)
 		if partsize >= store.MinPartSize || isFinalChunk {
@@ -474,9 +475,10 @@ func (upload *s3Upload) uploadParts(ctx context.Context, offset int64, src io.Re
 			upload.parts = append(upload.parts, part)
 
 			wg.Add(1)
-			go func(file *os.File, part *s3Part) {
+			go func(file io.ReadSeeker, part *s3Part, closePart func()) {
 				defer upload.store.uploadSemaphore.Release()
 				defer wg.Done()
+				defer closePart()
 
 				t := time.Now()
 				uploadPartInput := &s3.UploadPartInput{
@@ -492,18 +494,19 @@ func (upload *s3Upload) uploadParts(ctx context.Context, offset int64, src io.Re
 				} else {
 					part.etag = etag
 				}
-			}(partfile, part)
+			}(partfile, part, closePart)
 		} else {
 			wg.Add(1)
-			go func(file *os.File) {
+			go func(file io.ReadSeeker, closePart func()) {
 				defer upload.store.uploadSemaphore.Release()
 				defer wg.Done()
+				defer closePart()
 
 				if err := store.putIncompletePartForUpload(ctx, uploadId, file); err != nil {
 					uploadErr = err
 				}
 				upload.incompletePartSize = partsize
-			}(partfile)
+			}(partfile, closePart)
 		}
 
 		bytesUploaded += partsize
@@ -524,9 +527,7 @@ func cleanUpTempFile(file *os.File) {
 	os.Remove(file.Name())
 }
 
-func (upload *s3Upload) putPartForUpload(ctx context.Context, uploadPartInput *s3.UploadPartInput, file *os.File, size int64) (string, error) {
-	defer cleanUpTempFile(file)
-
+func (upload *s3Upload) putPartForUpload(ctx context.Context, uploadPartInput *s3.UploadPartInput, file io.ReadSeeker, size int64) (string, error) {
 	if !upload.store.DisableContentHashes {
 		// By default, use the traditional approach to upload data
 		uploadPartInput.Body = file
@@ -1101,9 +1102,7 @@ func (store S3Store) headIncompletePartForUpload(ctx context.Context, uploadId s
 	return *obj.ContentLength, nil
 }
 
-func (store S3Store) putIncompletePartForUpload(ctx context.Context, uploadId string, file *os.File) error {
-	defer cleanUpTempFile(file)
-
+func (store S3Store) putIncompletePartForUpload(ctx context.Context, uploadId string, file io.ReadSeeker) error {
 	t := time.Now()
 	_, err := store.Service.PutObjectWithContext(ctx, &s3.PutObjectInput{
 		Bucket: aws.String(store.Bucket),

pkg/s3store/s3store_part_producer.go

@@ -1,6 +1,7 @@
 package s3store
 
 import (
+	"bytes"
 	"io"
 	"io/ioutil"
 	"os"
@@ -9,6 +10,8 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 )
 
+const TEMP_DIR_USE_MEMORY = "_memory"
+
 // s3PartProducer converts a stream of bytes from the reader into a stream of files on disk
 type s3PartProducer struct {
 	tmpDir                  string
@@ -20,7 +23,8 @@ type s3PartProducer struct {
 }
 
 type fileChunk struct {
-	file *os.File
+	reader      io.ReadSeeker
+	closeReader func()
 	size        int64
 }
 
@@ -28,6 +32,10 @@ func newS3PartProducer(source io.Reader, backlog int64, tmpDir string, diskWrite
 	fileChan := make(chan fileChunk, backlog)
 	doneChan := make(chan struct{})
 
+	if os.Getenv("TUSD_S3STORE_TEMP_MEMORY") == "1" {
+		tmpDir = TEMP_DIR_USE_MEMORY
+	}
+
 	partProducer := s3PartProducer{
 		tmpDir:                  tmpDir,
 		done:                    doneChan,
@@ -47,7 +55,7 @@ func (spp *s3PartProducer) stop() {
 	// If we return while there are still files in the channel, then
 	// we may leak file descriptors. Let's ensure that those are cleaned up.
 	for fileChunk := range spp.files {
-		cleanUpTempFile(fileChunk.file)
+		fileChunk.closeReader()
 	}
 }
 
@@ -76,6 +84,7 @@ outerloop:
 }
 
 func (spp *s3PartProducer) nextPart(size int64) (fileChunk, bool, error) {
+	if spp.tmpDir != TEMP_DIR_USE_MEMORY {
 		// Create a temporary file to store the part
 		file, err := ioutil.TempFile(spp.tmpDir, "tusd-s3-tmp-")
 		if err != nil {
@@ -106,7 +115,41 @@ func (spp *s3PartProducer) nextPart(size int64) (fileChunk, bool, error) {
 		file.Seek(0, 0)
 
 		return fileChunk{
-		file: file,
+			reader: file,
+			closeReader: func() {
+				file.Close()
+				os.Remove(file.Name())
+			},
 			size: n,
 		}, true, nil
+	} else {
+		// Create a temporary buffer to store the part
+		buf := new(bytes.Buffer)
+
+		limitedReader := io.LimitReader(spp.r, size)
+		start := time.Now()
+
+		n, err := io.Copy(buf, limitedReader)
+		if err != nil {
+			return fileChunk{}, false, err
+		}
+
+		// If the entire request body is read and no more data is available,
+		// io.Copy returns 0 since it is unable to read any bytes. In that
+		// case, we can close the s3PartProducer.
+		if n == 0 {
+			return fileChunk{}, false, nil
+		}
+
+		elapsed := time.Now().Sub(start)
+		ms := float64(elapsed.Nanoseconds() / int64(time.Millisecond))
+		spp.diskWriteDurationMetric.Observe(ms)
+
+		return fileChunk{
+			// buf does not get written to anymore, so we can turn it into a reader
+			reader:      bytes.NewReader(buf.Bytes()),
+			closeReader: func() {},
+			size:        n,
+		}, true, nil
+	}
 }

pkg/s3store/s3store_part_producer_test.go

@@ -2,7 +2,6 @@ package s3store
 
 import (
 	"errors"
-	"os"
 	"strings"
 	"testing"
 	"time"
@@ -34,7 +33,7 @@ func TestPartProducerConsumesEntireReaderWithoutError(t *testing.T) {
 	actualStr := ""
 	b := make([]byte, 1)
 	for chunk := range fileChan {
-		n, err := chunk.file.Read(b)
+		n, err := chunk.reader.Read(b)
 		if err != nil {
 			t.Fatalf("unexpected error: %s", err)
 		}
@@ -46,8 +45,7 @@ func TestPartProducerConsumesEntireReaderWithoutError(t *testing.T) {
 		}
 		actualStr += string(b)
 
-		os.Remove(chunk.file.Name())
-		chunk.file.Close()
+		chunk.closeReader()
 	}
 
 	if actualStr != expectedStr {