clipper/backend/media/uploader.go

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package media
import (
"bytes"
"context"
"fmt"
"log"
"github.com/aws/aws-sdk-go-v2/aws"
"github.com/aws/aws-sdk-go-v2/service/s3"
"github.com/aws/aws-sdk-go-v2/service/s3/types"
)
// multipartUploadWriter is a Writer that uploads transparently to an S3 bucket
// in 5MB parts. It buffers data internally until a part is ready to send over
// the network. Parts are sent as soon as they exceed the minimum part size of
// 5MB.
//
// The caller must call either Complete() or Abort() after finishing writing.
// Failure to do so will leave S3 in an inconsistent state.
type multipartUploadWriter struct {
ctx context.Context
s3 S3Client
buf *bytes.Buffer
bucket, key, contentType string
uploadID string
completedParts []types.CompletedPart
bytesUploaded int64
}
const targetPartSizeBytes = 5 * 1024 * 1024 // 5MB
// newMultipartUploadWriter creates a new multipart upload writer, including
// creating the upload on S3. Either Complete or Abort must be called after
// calling this function.
func newMultipartUploadWriter(ctx context.Context, s3Client S3Client, bucket, key, contentType string) (*multipartUploadWriter, error) {
input := s3.CreateMultipartUploadInput{
Bucket: aws.String(bucket),
Key: aws.String(key),
ContentType: aws.String(contentType),
}
output, err := s3Client.CreateMultipartUpload(ctx, &input)
if err != nil {
return nil, fmt.Errorf("error creating multipart upload: %v", err)
}
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const bufferOverflowSize = 16_384
b := make([]byte, 0, targetPartSizeBytes+bufferOverflowSize)
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return &multipartUploadWriter{
ctx: ctx,
s3: s3Client,
buf: bytes.NewBuffer(b),
bucket: bucket,
key: key,
contentType: contentType,
uploadID: *output.UploadId,
}, nil
}
func (u *multipartUploadWriter) Write(p []byte) (int, error) {
n, err := u.buf.Write(p)
if err != nil {
return n, fmt.Errorf("error writing to buffer: %v", err)
}
if u.buf.Len() >= targetPartSizeBytes {
partLen := u.buf.Len()
log.Printf("uploading part num = %d, len = %d", u.partNum(), partLen)
input := s3.UploadPartInput{
Body: u.buf,
Bucket: aws.String(u.bucket),
Key: aws.String(u.key),
PartNumber: u.partNum(),
UploadId: aws.String(u.uploadID),
ContentLength: int64(partLen),
}
output, uploadErr := u.s3.UploadPart(u.ctx, &input)
if uploadErr != nil {
// TODO: retry on failure
return n, fmt.Errorf("error uploading part: %v", uploadErr)
}
log.Printf("uploaded part num = %d, etag = %s, bytes = %d", u.partNum(), *output.ETag, partLen)
u.completedParts = append(u.completedParts, types.CompletedPart{ETag: output.ETag, PartNumber: u.partNum()})
u.bytesUploaded += int64(partLen)
}
return n, err
}
func (u *multipartUploadWriter) partNum() int32 {
return int32(len(u.completedParts) + 1)
}
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// Abort aborts the upload process, cancelling the upload on S3. It accepts a
// separate context to the associated writer in case it is called during
// cleanup after the original context was killed.
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func (u *multipartUploadWriter) Abort(ctx context.Context) error {
input := s3.AbortMultipartUploadInput{
Bucket: aws.String(u.bucket),
Key: aws.String(u.key),
UploadId: aws.String(u.uploadID),
}
_, err := u.s3.AbortMultipartUpload(ctx, &input)
if err != nil {
return fmt.Errorf("error aborting upload: %v", err)
}
log.Printf("aborted upload, key = %s, bytesUploaded = %d", u.key, u.bytesUploaded)
return nil
}
// Complete completes the upload process, finalizing the upload on S3.
// If no parts have been successfully uploaded, then Abort() will be called
// transparently.
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func (u *multipartUploadWriter) Complete() (int64, error) {
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if len(u.completedParts) == 0 {
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return 0, u.Abort(u.ctx)
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}
input := s3.CompleteMultipartUploadInput{
Bucket: aws.String(u.bucket),
Key: aws.String(u.key),
UploadId: aws.String(u.uploadID),
MultipartUpload: &types.CompletedMultipartUpload{
Parts: u.completedParts,
},
}
_, err := u.s3.CompleteMultipartUpload(u.ctx, &input)
if err != nil {
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return 0, fmt.Errorf("error completing upload: %v", err)
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}
log.Printf("completed upload, key = %s, bytesUploaded = %d", u.key, u.bytesUploaded)
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return u.bytesUploaded, nil
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}