193 lines
5.2 KiB
Go
193 lines
5.2 KiB
Go
package media
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import (
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"bytes"
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"context"
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"errors"
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"fmt"
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"log"
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"sync"
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"github.com/aws/aws-sdk-go-v2/aws"
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"github.com/aws/aws-sdk-go-v2/service/s3"
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"github.com/aws/aws-sdk-go-v2/service/s3/types"
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)
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// multipartUploadWriter is a Writer that uploads transparently to an S3 bucket
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// in 5MB parts. It buffers data internally until a part is ready to send over
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// the network. Parts are sent as soon as they exceed the minimum part size of
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// 5MB.
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//
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// The caller must call either Complete() or Abort() after finishing writing.
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// Failure to do so will leave S3 in an inconsistent state.
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type multipartUploadWriter struct {
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ctx context.Context
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wg sync.WaitGroup
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s3 S3Client
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buf *bytes.Buffer
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bucket, key, contentType string
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partNum int32
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uploadResults chan uploadResult
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uploadID string
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}
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type uploadResult struct {
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completedPart types.CompletedPart
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size int64
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err error
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}
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const targetPartSizeBytes = 5 * 1024 * 1024 // 5MB
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// newMultipartUploadWriter creates a new multipart upload writer, including
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// creating the upload on S3. Either Complete or Abort must be called after
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// calling this function.
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func newMultipartUploadWriter(ctx context.Context, s3Client S3Client, bucket, key, contentType string) (*multipartUploadWriter, error) {
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input := s3.CreateMultipartUploadInput{
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Bucket: aws.String(bucket),
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Key: aws.String(key),
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ContentType: aws.String(contentType),
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}
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output, err := s3Client.CreateMultipartUpload(ctx, &input)
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if err != nil {
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return nil, fmt.Errorf("error creating multipart upload: %v", err)
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}
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const bufferOverflowSize = 16_384
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b := make([]byte, 0, targetPartSizeBytes+bufferOverflowSize)
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return &multipartUploadWriter{
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ctx: ctx,
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s3: s3Client,
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buf: bytes.NewBuffer(b),
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bucket: bucket,
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key: key,
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contentType: contentType,
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partNum: 1,
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uploadResults: make(chan uploadResult),
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uploadID: *output.UploadId,
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}, nil
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}
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func (u *multipartUploadWriter) Write(p []byte) (int, error) {
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n, err := u.buf.Write(p)
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if err != nil {
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return n, fmt.Errorf("error writing to buffer: %v", err)
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}
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if u.buf.Len() >= targetPartSizeBytes {
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buf := make([]byte, u.buf.Len())
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copy(buf, u.buf.Bytes())
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u.buf.Truncate(0)
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u.wg.Add(1)
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go u.uploadPart(buf, u.partNum)
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u.partNum++
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}
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return n, err
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}
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func (u *multipartUploadWriter) uploadPart(buf []byte, partNum int32) {
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defer u.wg.Done()
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partLen := len(buf)
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log.Printf("uploading part num = %d, len = %d", partNum, partLen)
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input := s3.UploadPartInput{
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Body: bytes.NewReader(buf),
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Bucket: aws.String(u.bucket),
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Key: aws.String(u.key),
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PartNumber: partNum,
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UploadId: aws.String(u.uploadID),
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ContentLength: int64(partLen),
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}
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output, uploadErr := u.s3.UploadPart(u.ctx, &input)
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if uploadErr != nil {
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// TODO: retry on failure
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u.uploadResults <- uploadResult{err: fmt.Errorf("error uploading part: %v", uploadErr)}
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return
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}
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log.Printf("uploaded part num = %d, etag = %s, bytes = %d", partNum, *output.ETag, partLen)
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u.uploadResults <- uploadResult{
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completedPart: types.CompletedPart{ETag: output.ETag, PartNumber: partNum},
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size: int64(partLen),
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}
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}
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// Complete waits for all currently uploading parts to be uploaded, and
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// finalizes the object in S3. Close() must be called first.
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func (u *multipartUploadWriter) Complete() (int64, error) {
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var completedParts []types.CompletedPart
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var uploadedBytes int64
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// we wait for all parts to be completed before collecting the results:
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wgDone := make(chan struct{})
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go func() {
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u.wg.Wait()
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close(u.uploadResults)
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wgDone <- struct{}{}
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}()
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outer:
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for {
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select {
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case uploadResult := <-u.uploadResults:
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if uploadResult.err != nil {
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return 0, uploadResult.err
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}
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completedParts = append(completedParts, uploadResult.completedPart)
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uploadedBytes += uploadResult.size
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case <-wgDone:
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break outer
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case <-u.ctx.Done():
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return 0, u.ctx.Err()
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}
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}
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if len(completedParts) == 0 {
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return 0, errors.New("no parts available to upload")
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}
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input := s3.CompleteMultipartUploadInput{
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Bucket: aws.String(u.bucket),
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Key: aws.String(u.key),
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UploadId: aws.String(u.uploadID),
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MultipartUpload: &types.CompletedMultipartUpload{Parts: completedParts},
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}
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_, err := u.s3.CompleteMultipartUpload(u.ctx, &input)
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if err != nil {
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return 0, fmt.Errorf("error completing upload: %v", err)
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}
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log.Printf("completed upload, key = %s, bytesUploaded = %d", u.key, uploadedBytes)
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return uploadedBytes, nil
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}
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// Abort aborts the upload process, cancelling the upload on S3. It accepts a
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// separate context to the associated writer in case it is called during
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// cleanup after the original context was killed.
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func (u *multipartUploadWriter) Abort(ctx context.Context) error {
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input := s3.AbortMultipartUploadInput{
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Bucket: aws.String(u.bucket),
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Key: aws.String(u.key),
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UploadId: aws.String(u.uploadID),
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}
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_, err := u.s3.AbortMultipartUpload(ctx, &input)
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if err != nil {
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return fmt.Errorf("error aborting upload: %v", err)
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}
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log.Printf("aborted upload, key = %s", u.key)
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return nil
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}
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