s3: re-implement multipart upload to fix memory issues

There have been quite a few reports of problems with the multipart
uploader using too much memory and not retrying possible errors.

Before this change the multipart uploader used the s3manager
abstraction in the AWS SDK.  There are numerous bug reports of this
using up too much memory.

This change re-implements a much simplified version of the s3manager
code specialized for rclone's purposes.

This should use much less memory and retry chunks properly.

See: https://forum.rclone.org/t/memory-usage-s3-alike-to-glacier-without-big-directories/13563
See: https://forum.rclone.org/t/copy-from-local-to-s3-has-high-memory-usage/13405
See: https://forum.rclone.org/t/big-file-upload-to-s3-fails/13575

backend/s3/s3.go

@@ -14,7 +14,9 @@ What happens if you CTRL-C a multipart upload
 */
 
 import (
+	"bytes"
 	"context"
+	"crypto/md5"
 	"encoding/base64"
 	"encoding/hex"
 	"encoding/xml"
@@ -24,6 +26,7 @@ import (
 	"net/url"
 	"path"
 	"regexp"
+	"sort"
 	"strconv"
 	"strings"
 	"sync"
@@ -39,7 +42,6 @@ import (
 	"github.com/aws/aws-sdk-go/aws/request"
 	"github.com/aws/aws-sdk-go/aws/session"
 	"github.com/aws/aws-sdk-go/service/s3"
-	"github.com/aws/aws-sdk-go/service/s3/s3manager"
 	"github.com/ncw/swift"
 	"github.com/pkg/errors"
 	"github.com/rclone/rclone/fs"
@@ -52,7 +54,9 @@ import (
 	"github.com/rclone/rclone/fs/walk"
 	"github.com/rclone/rclone/lib/bucket"
 	"github.com/rclone/rclone/lib/pacer"
+	"github.com/rclone/rclone/lib/readers"
 	"github.com/rclone/rclone/lib/rest"
+	"golang.org/x/sync/errgroup"
 )
 
 const enc = encodings.S3
@@ -814,7 +818,8 @@ const (
 	metaMD5Hash         = "Md5chksum"            // the meta key to store md5hash in
 	maxRetries          = 10                     // number of retries to make of operations
 	maxSizeForCopy      = 5 * 1024 * 1024 * 1024 // The maximum size of object we can COPY
-	minChunkSize        = fs.SizeSuffix(s3manager.MinUploadPartSize)
+	maxUploadParts      = 10000                  // maximum allowed number of parts in a multi-part upload
+	minChunkSize        = fs.SizeSuffix(1024 * 1024 * 5)
 	defaultUploadCutoff = fs.SizeSuffix(200 * 1024 * 1024)
 	maxUploadCutoff     = fs.SizeSuffix(5 * 1024 * 1024 * 1024)
 	minSleep            = 10 * time.Millisecond // In case of error, start at 10ms sleep.
@@ -2023,6 +2028,193 @@ func (o *Object) Open(ctx context.Context, options ...fs.OpenOption) (in io.Read
 
 var warnStreamUpload sync.Once
 
+func (o *Object) uploadMultipart(ctx context.Context, req *s3.PutObjectInput, size int64, in io.Reader) (err error) {
+	f := o.fs
+
+	// make concurrency machinery
+	concurrency := f.opt.UploadConcurrency
+	if concurrency < 1 {
+		concurrency = 1
+	}
+	bufs := make(chan []byte, concurrency)
+	defer func() {
+		// empty the channel on exit
+		close(bufs)
+		for range bufs {
+		}
+	}()
+	for i := 0; i < concurrency; i++ {
+		bufs <- nil
+	}
+
+	// calculate size of parts
+	partSize := int(f.opt.ChunkSize)
+
+	// size can be -1 here meaning we don't know the size of the incoming file.  We use ChunkSize
+	// buffers here (default 5MB). With a maximum number of parts (10,000) this will be a file of
+	// 48GB which seems like a not too unreasonable limit.
+	if size == -1 {
+		warnStreamUpload.Do(func() {
+			fs.Logf(f, "Streaming uploads using chunk size %v will have maximum file size of %v",
+				f.opt.ChunkSize, fs.SizeSuffix(partSize*maxUploadParts))
+		})
+	} else {
+		// Adjust partSize until the number of parts is small enough.
+		if size/int64(partSize) >= maxUploadParts {
+			// Calculate partition size rounded up to the nearest MB
+			partSize = int((((size / maxUploadParts) >> 20) + 1) << 20)
+		}
+	}
+
+	var cout *s3.CreateMultipartUploadOutput
+	err = f.pacer.Call(func() (bool, error) {
+		var err error
+		cout, err = f.c.CreateMultipartUploadWithContext(ctx, &s3.CreateMultipartUploadInput{
+			Bucket:               req.Bucket,
+			ACL:                  req.ACL,
+			Key:                  req.Key,
+			ContentType:          req.ContentType,
+			Metadata:             req.Metadata,
+			ServerSideEncryption: req.ServerSideEncryption,
+			SSEKMSKeyId:          req.SSEKMSKeyId,
+			StorageClass:         req.StorageClass,
+		})
+		return f.shouldRetry(err)
+	})
+	if err != nil {
+		return errors.Wrap(err, "multipart upload failed to initialise")
+	}
+	uid := cout.UploadId
+
+	defer func() {
+		if o.fs.opt.LeavePartsOnError {
+			return
+		}
+		if err != nil {
+			// We can try to abort the upload, but ignore the error.
+			fs.Debugf(o, "Cancelling multipart upload")
+			errCancel := f.pacer.Call(func() (bool, error) {
+				_, err := f.c.AbortMultipartUploadWithContext(ctx, &s3.AbortMultipartUploadInput{
+					Bucket:       req.Bucket,
+					Key:          req.Key,
+					UploadId:     uid,
+					RequestPayer: req.RequestPayer,
+				})
+				return f.shouldRetry(err)
+			})
+			if errCancel != nil {
+				fs.Debugf(o, "Failed to cancel multipart upload: %v", errCancel)
+			}
+		}
+	}()
+
+	var (
+		g, gCtx  = errgroup.WithContext(ctx)
+		finished = false
+		partsMu  sync.Mutex // to protect parts
+		parts    []*s3.CompletedPart
+		off      int64
+	)
+
+	for partNum := int64(1); !finished; partNum++ {
+		// Get a block of memory from the channel (which limits concurrency)
+		buf := <-bufs
+		if buf == nil {
+			buf = make([]byte, partSize)
+		}
+
+		// Read the chunk
+		var n int
+		n, err = readers.ReadFill(in, buf) // this can never return 0, nil
+		if err == io.EOF {
+			if n == 0 {
+				break
+			}
+			finished = true
+		} else if err != nil {
+			return errors.Wrap(err, "multipart upload failed to read source")
+		}
+		buf = buf[:n]
+
+		partNum := partNum
+		fs.Debugf(o, "multipart upload starting chunk %d size %v offset %v/%v", partNum, fs.SizeSuffix(n), fs.SizeSuffix(off), fs.SizeSuffix(size))
+		off += int64(n)
+		g.Go(func() (err error) {
+			partLength := int64(len(buf))
+
+			// create checksum of buffer for integrity checking
+			md5sumBinary := md5.Sum(buf)
+			md5sum := base64.StdEncoding.EncodeToString(md5sumBinary[:])
+
+			err = f.pacer.Call(func() (bool, error) {
+				uploadPartReq := &s3.UploadPartInput{
+					Body:                 bytes.NewReader(buf),
+					Bucket:               req.Bucket,
+					Key:                  req.Key,
+					PartNumber:           &partNum,
+					UploadId:             uid,
+					ContentMD5:           &md5sum,
+					ContentLength:        &partLength,
+					RequestPayer:         req.RequestPayer,
+					SSECustomerAlgorithm: req.SSECustomerAlgorithm,
+					SSECustomerKey:       req.SSECustomerKey,
+					SSECustomerKeyMD5:    req.SSECustomerKeyMD5,
+				}
+				uout, err := f.c.UploadPartWithContext(gCtx, uploadPartReq)
+				if err != nil {
+					if partNum <= int64(concurrency) {
+						return f.shouldRetry(err)
+					}
+					// retry all chunks once have done the first batch
+					return true, err
+				}
+				partsMu.Lock()
+				parts = append(parts, &s3.CompletedPart{
+					PartNumber: &partNum,
+					ETag:       uout.ETag,
+				})
+				partsMu.Unlock()
+
+				return false, nil
+			})
+
+			// return the memory
+			bufs <- buf[:partSize]
+
+			if err != nil {
+				return errors.Wrap(err, "multipart upload failed to upload part")
+			}
+			return nil
+		})
+	}
+	err = g.Wait()
+	if err != nil {
+		return err
+	}
+
+	// sort the completed parts by part number
+	sort.Slice(parts, func(i, j int) bool {
+		return *parts[i].PartNumber < *parts[j].PartNumber
+	})
+
+	err = f.pacer.Call(func() (bool, error) {
+		_, err := f.c.CompleteMultipartUploadWithContext(ctx, &s3.CompleteMultipartUploadInput{
+			Bucket: req.Bucket,
+			Key:    req.Key,
+			MultipartUpload: &s3.CompletedMultipartUpload{
+				Parts: parts,
+			},
+			RequestPayer: req.RequestPayer,
+			UploadId:     uid,
+		})
+		return f.shouldRetry(err)
+	})
+	if err != nil {
+		return errors.Wrap(err, "multipart upload failed to finalise")
+	}
+	return nil
+}
+
 // Update the Object from in with modTime and size
 func (o *Object) Update(ctx context.Context, in io.Reader, src fs.ObjectInfo, options ...fs.OpenOption) error {
 	bucket, bucketPath := o.split()
@@ -2034,31 +2226,6 @@ func (o *Object) Update(ctx context.Context, in io.Reader, src fs.ObjectInfo, op
 	size := src.Size()
 
 	multipart := size < 0 || size >= int64(o.fs.opt.UploadCutoff)
-	var uploader *s3manager.Uploader
-	if multipart {
-		uploader = s3manager.NewUploader(o.fs.ses, func(u *s3manager.Uploader) {
-			u.Concurrency = o.fs.opt.UploadConcurrency
-			u.LeavePartsOnError = o.fs.opt.LeavePartsOnError
-			u.S3 = o.fs.c
-			u.PartSize = int64(o.fs.opt.ChunkSize)
-
-			// size can be -1 here meaning we don't know the size of the incoming file.  We use ChunkSize
-			// buffers here (default 5MB). With a maximum number of parts (10,000) this will be a file of
-			// 48GB which seems like a not too unreasonable limit.
-			if size == -1 {
-				warnStreamUpload.Do(func() {
-					fs.Logf(o.fs, "Streaming uploads using chunk size %v will have maximum file size of %v",
-						o.fs.opt.ChunkSize, fs.SizeSuffix(u.PartSize*s3manager.MaxUploadParts))
-				})
-				return
-			}
-			// Adjust PartSize until the number of parts is small enough.
-			if size/u.PartSize >= s3manager.MaxUploadParts {
-				// Calculate partition size rounded up to the nearest MB
-				u.PartSize = (((size / s3manager.MaxUploadParts) >> 20) + 1) << 20
-			}
-		})
-	}
 
 	// Set the mtime in the meta data
 	metadata := map[string]*string{
@@ -2083,52 +2250,32 @@ func (o *Object) Update(ctx context.Context, in io.Reader, src fs.ObjectInfo, op
 
 	// Guess the content type
 	mimeType := fs.MimeType(ctx, src)
+	req := s3.PutObjectInput{
+		Bucket:      &bucket,
+		ACL:         &o.fs.opt.ACL,
+		Key:         &bucketPath,
+		ContentType: &mimeType,
+		Metadata:    metadata,
+	}
+	if md5sum != "" {
+		req.ContentMD5 = &md5sum
+	}
+	if o.fs.opt.ServerSideEncryption != "" {
+		req.ServerSideEncryption = &o.fs.opt.ServerSideEncryption
+	}
+	if o.fs.opt.SSEKMSKeyID != "" {
+		req.SSEKMSKeyId = &o.fs.opt.SSEKMSKeyID
+	}
+	if o.fs.opt.StorageClass != "" {
+		req.StorageClass = &o.fs.opt.StorageClass
+	}
+
 	if multipart {
-		req := s3manager.UploadInput{
-			Bucket:      &bucket,
-			ACL:         &o.fs.opt.ACL,
-			Key:         &bucketPath,
-			Body:        in,
-			ContentType: &mimeType,
-			Metadata:    metadata,
-			//ContentLength: &size,
-		}
-		if o.fs.opt.ServerSideEncryption != "" {
-			req.ServerSideEncryption = &o.fs.opt.ServerSideEncryption
-		}
-		if o.fs.opt.SSEKMSKeyID != "" {
-			req.SSEKMSKeyId = &o.fs.opt.SSEKMSKeyID
-		}
-		if o.fs.opt.StorageClass != "" {
-			req.StorageClass = &o.fs.opt.StorageClass
-		}
-		err = o.fs.pacer.CallNoRetry(func() (bool, error) {
-			_, err = uploader.UploadWithContext(ctx, &req)
-			return o.fs.shouldRetry(err)
-		})
+		err = o.uploadMultipart(ctx, &req, size, in)
 		if err != nil {
 			return err
 		}
 	} else {
-		req := s3.PutObjectInput{
-			Bucket:      &bucket,
-			ACL:         &o.fs.opt.ACL,
-			Key:         &bucketPath,
-			ContentType: &mimeType,
-			Metadata:    metadata,
-		}
-		if md5sum != "" {
-			req.ContentMD5 = &md5sum
-		}
-		if o.fs.opt.ServerSideEncryption != "" {
-			req.ServerSideEncryption = &o.fs.opt.ServerSideEncryption
-		}
-		if o.fs.opt.SSEKMSKeyID != "" {
-			req.SSEKMSKeyId = &o.fs.opt.SSEKMSKeyID
-		}
-		if o.fs.opt.StorageClass != "" {
-			req.StorageClass = &o.fs.opt.StorageClass
-		}
 
 		// Create the request
 		putObj, _ := o.fs.c.PutObjectRequest(&req)