[ISSUE 50] Adding in an example for multipart upload

examples/walkthrough/main.go

@@ -18,30 +18,41 @@ import (
 
 const defaultExpiration = 7 * 24 * time.Hour
 
-// UploadAndDownloadData uploads the specified data to the specified key in the
-// specified bucket, using the specified Satellite, API key, and passphrase.
-func UploadAndDownloadData(ctx context.Context,
-	accessGrant, bucketName, uploadKey string, dataToUpload []byte) error {
-
+func CreateProjectAndConfirmBucket(ctx context.Context, accessGrant, bucketName string) (*uplink.Project, error) {
 	// Parse access grant, which contains necessary credentials and permissions.
 	access, err := uplink.ParseAccess(accessGrant)
 	if err != nil {
-		return fmt.Errorf("could not request access grant: %v", err)
+		return nil, fmt.Errorf("could not request access grant: %v", err)
 	}
 
 	// Open up the Project we will be working with.
 	project, err := uplink.OpenProject(ctx, access)
 	if err != nil {
-		return fmt.Errorf("could not open project: %v", err)
+		return nil, fmt.Errorf("could not open project: %v", err)
 	}
-	defer project.Close()
 
 	// Ensure the desired Bucket within the Project is created.
 	_, err = project.EnsureBucket(ctx, bucketName)
 	if err != nil {
-		return fmt.Errorf("could not ensure bucket: %v", err)
+		_ = project.Close()
+		return nil, fmt.Errorf("could not ensure bucket: %v", err)
 	}
 
+	return project, nil
+}
+
+// UploadAndDownloadData uploads the specified data to the specified key in the
+// specified bucket, using the specified Satellite, API key, and passphrase.
+func UploadAndDownloadData(ctx context.Context,
+	accessGrant, bucketName, uploadKey string, dataToUpload []byte) error {
+
+	// Open up the Project we will be working with.
+	project, err := CreateProjectAndConfirmBucket(ctx, accessGrant, bucketName)
+	if err != nil {
+		return fmt.Errorf("could not create project: %v", err)
+	}
+	defer project.Close()
+
 	// Intitiate the upload of our Object to the specified bucket and key.
 	upload, err := project.UploadObject(ctx, bucketName, uploadKey, &uplink.UploadOptions{
 		// It's possible to set an expiration date for data.
@@ -129,6 +140,114 @@ func CreatePublicSharedLink(ctx context.Context, accessGrant, bucketName, object
 	return url, nil
 }
 
+func MultipartUpload(ctx context.Context, accessGrant, bucketName, objectKey string, contents1, contents2 []byte) error {
+	// Create the project and ensure the bucket exists
+	project, err := CreateProjectAndConfirmBucket(ctx, accessGrant, bucketName)
+	if err != nil {
+		return fmt.Errorf("could not create project: %v", err)
+	}
+	defer project.Close()
+
+	// Create multipart upload
+	uploadInfo, err := project.BeginUpload(ctx, bucketName, objectKey, &uplink.UploadOptions{
+		// It's possible to set an expiration date for data.
+		Expires: time.Now().Add(defaultExpiration),
+	})
+
+	if err != nil {
+		return fmt.Errorf("unable to begin multipart upload: %v", err)
+	}
+
+	// Start the upload of part 1
+	part1, err := project.UploadPart(ctx, bucketName, objectKey, uploadInfo.UploadID, 1)
+	if err != nil {
+		return fmt.Errorf("unable to upload part 1: %v", err)
+	}
+
+	// Write the contents to part 1 upload
+	_, err = part1.Write(contents1)
+	if err != nil {
+		return fmt.Errorf("unable to write to part 1: %v", err)
+	}
+
+	// Commit part 1 upload
+	err = part1.Commit()
+	if err != nil {
+		return fmt.Errorf("unable to commit to part 1: %v", err)
+	}
+
+	// Start the upload of part 2
+	part2, err := project.UploadPart(ctx, bucketName, objectKey, uploadInfo.UploadID, 2)
+	if err != nil {
+		return fmt.Errorf("unable to upload part 2: %v", err)
+	}
+
+	// Write the contents to part 2 upload
+	_, err = part2.Write(contents2)
+	if err != nil {
+		return fmt.Errorf("unable to write to part 2: %v", err)
+	}
+
+	// Commit part 2 upload
+	err = part2.Commit()
+	if err != nil {
+		return fmt.Errorf("unable to commit to part 2: %v", err)
+	}
+
+	// Complete the multipart upload
+	multipartObject, err := project.CommitUpload(ctx, bucketName, objectKey, uploadInfo.UploadID, nil)
+	if err != nil {
+		return fmt.Errorf("unable to complete the upload: %v", err)
+	}
+
+	// Initiate a download of the same object again
+	download, err := project.DownloadObject(ctx, bucketName, objectKey, nil)
+	if err != nil {
+		return fmt.Errorf("could not open multipart object: %v", err)
+	}
+	defer download.Close()
+
+	// Read everything from the download stream
+	receivedContents, err := io.ReadAll(download)
+	if err != nil {
+		return fmt.Errorf("could not read multipart data: %v", err)
+	}
+
+	// Check that the downloaded data is the same as the uploaded data.
+	uploadedData := append(contents1, contents2...)
+	if !bytes.Equal(receivedContents, uploadedData) {
+		return fmt.Errorf("got different multipart object back: %q != %q", uploadedData, receivedContents)
+	}
+
+	fmt.Fprintln(os.Stderr, "success!")
+	fmt.Fprintln(os.Stderr, "completed multipart upload:", multipartObject.Key)
+
+	return nil
+}
+
+func createMultipartData() (contents1, contents2 []byte) {
+	const minimumUploadSize = 5 * 1024 * 1024 // 5 MiB
+
+	// The first contents is the alphabet on repeat
+	alphabet := "abcdefghijklmnopqrstuvwxyz"
+
+	contents1 = make([]byte, minimumUploadSize)
+	alphabetLength := len(alphabet)
+	for i := 0; i < minimumUploadSize; i++ {
+		contents1[i] = alphabet[i%alphabetLength]
+	}
+
+	// The second contents is numbers on repeat
+	numbers := "1234567890"
+	numbersLength := len(numbers)
+	contents2 = make([]byte, minimumUploadSize)
+	for i := 0; i < minimumUploadSize; i++ {
+		contents2[i] = numbers[i%numbersLength]
+	}
+
+	return contents1, contents2
+}
+
 func main() {
 	ctx := context.Background()
 	accessGrant := flag.String("access", os.Getenv("ACCESS_GRANT"), "access grant from satellite")
@@ -151,4 +270,14 @@ func main() {
 
 	fmt.Println("success!")
 	fmt.Println("public link:", url)
+
+	largeObjectKey := "foo/bar/large"
+
+	largeContents1, largeContents2 := createMultipartData()
+
+	err = MultipartUpload(ctx, *accessGrant, bucketName, largeObjectKey, largeContents1, largeContents2)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, "creating mulipart upload failed:", err)
+		os.Exit(1)
+	}
 }