Include content length in the response of Get and GetRange

CHANGELOG.md

@@ -10,6 +10,7 @@ We use *breaking :warning:* to mark changes that are not backward compatible (re
 
 ## Unreleased
 - [#38](https://github.com/thanos-io/objstore/pull/38) GCS: Upgrade cloud.google.com/go/storage version to `v1.43.0`.
+- [#145](https://github.com/thanos-io/objstore/pull/145) Include content length in the response of Get and GetRange.
 
 ### Fixed
 - [#117](https://github.com/thanos-io/objstore/pull/117) Metrics: Fix `objstore_bucket_operation_failures_total` incorrectly incremented if context is cancelled while reading object contents.

inmem.go

@@ -119,7 +119,12 @@ func (b *InMemBucket) Get(_ context.Context, name string) (io.ReadCloser, error)
 		return nil, errNotFound
 	}
 
-	return io.NopCloser(bytes.NewReader(file)), nil
+	return ObjectSizerReadCloser{
+		ReadCloser: io.NopCloser(bytes.NewReader(file)),
+		Size: func() (int64, error) {
+			return int64(len(file)), nil
+		},
+	}, nil
 }
 
 // GetRange returns a new range reader for the given object name and range.
@@ -136,23 +141,40 @@ func (b *InMemBucket) GetRange(_ context.Context, name string, off, length int64
 	}
 
 	if int64(len(file)) < off {
-		return io.NopCloser(bytes.NewReader(nil)), nil
+		return ObjectSizerReadCloser{
+			ReadCloser: io.NopCloser(bytes.NewReader(nil)),
+			Size:       func() (int64, error) { return 0, nil },
+		}, nil
 	}
 
 	if length == -1 {
-		return io.NopCloser(bytes.NewReader(file[off:])), nil
+		return ObjectSizerReadCloser{
+			ReadCloser: io.NopCloser(bytes.NewReader(file[off:])),
+			Size: func() (int64, error) {
+				return int64(len(file[off:])), nil
+			},
+		}, nil
 	}
 
 	if length <= 0 {
-		return io.NopCloser(bytes.NewReader(nil)), errors.New("length cannot be smaller or equal 0")
+		// wrap with ObjectSizerReadCloser to return 0 size.
+		return ObjectSizerReadCloser{
+			ReadCloser: io.NopCloser(bytes.NewReader(nil)),
+			Size:       func() (int64, error) { return 0, nil },
+		}, errors.New("length cannot be smaller or equal 0")
 	}
 
 	if int64(len(file)) <= off+length {
 		// Just return maximum of what we have.
 		length = int64(len(file)) - off
 	}
 
-	return io.NopCloser(bytes.NewReader(file[off : off+length])), nil
+	return ObjectSizerReadCloser{
+		ReadCloser: io.NopCloser(bytes.NewReader(file[off : off+length])),
+		Size: func() (int64, error) {
+			return length, nil
+		},
+	}, nil
 }
 
 // Exists checks if the given directory exists in memory.

objstore.go

@@ -829,3 +829,17 @@ func (t *timingReaderWriterTo) WriteTo(w io.Writer) (n int64, err error) {
 	t.timingReader.updateMetrics(int(n), err)
 	return n, err
 }
+
+type ObjectSizerReadCloser struct {
+	io.ReadCloser
+	Size func() (int64, error)
+}
+
+// ObjectSize implement ObjectSizer.
+func (o ObjectSizerReadCloser) ObjectSize() (int64, error) {
+	if o.Size == nil {
+		return 0, errors.New("unknown size")
+	}
+
+	return o.Size()
+}

providers/azure/azure.go

@@ -273,7 +273,13 @@ func (b *Bucket) getBlobReader(ctx context.Context, name string, httpRange blob.
 		return nil, errors.Wrapf(err, "cannot download blob, address: %s", blobClient.URL())
 	}
 	retryOpts := azblob.RetryReaderOptions{MaxRetries: int32(b.readerMaxRetries)}
-	return resp.NewRetryReader(ctx, &retryOpts), nil
+
+	return objstore.ObjectSizerReadCloser{
+		ReadCloser: resp.NewRetryReader(ctx, &retryOpts),
+		Size: func() (int64, error) {
+			return *resp.ContentLength, nil
+		},
+	}, nil
 }
 
 // Get returns a reader for the given object name.

providers/bos/bos.go

@@ -308,7 +308,12 @@ func (b *Bucket) getRange(_ context.Context, bucketName, objectKey string, off,
 		return nil, err
 	}
 
-	return obj.Body, nil
+	return objstore.ObjectSizerReadCloser{
+		ReadCloser: obj.Body,
+		Size: func() (int64, error) {
+			return obj.ContentLength, nil
+		},
+	}, err
 }
 
 func configFromEnv() Config {

providers/cos/cos.go

@@ -320,18 +320,12 @@ func (b *Bucket) getRange(ctx context.Context, name string, off, length int64) (
 		return nil, err
 	}
 	// Add size info into reader to pass it to Upload function.
-	r := objectSizerReadCloser{ReadCloser: resp.Body, size: resp.ContentLength}
-	return r, nil
-}
-
-type objectSizerReadCloser struct {
-	io.ReadCloser
-	size int64
-}
-
-// ObjectSize implement objstore.ObjectSizer.
-func (o objectSizerReadCloser) ObjectSize() (int64, error) {
-	return o.size, nil
+	return objstore.ObjectSizerReadCloser{
+		ReadCloser: resp.Body,
+		Size: func() (int64, error) {
+			return resp.ContentLength, nil
+		},
+	}, nil
 }
 
 // Get returns a reader for the given object name.

providers/filesystem/filesystem.go

@@ -150,8 +150,12 @@ func (b *Bucket) GetRange(ctx context.Context, name string, off, length int64) (
 		return nil, errors.New("object name is empty")
 	}
 
-	file := filepath.Join(b.rootDir, name)
-	if _, err := os.Stat(file); err != nil {
+	var (
+		file = filepath.Join(b.rootDir, name)
+		stat os.FileInfo
+		err  error
+	)
+	if stat, err = os.Stat(file); err != nil {
 		return nil, errors.Wrapf(err, "stat %s", file)
 	}
 
@@ -160,18 +164,33 @@ func (b *Bucket) GetRange(ctx context.Context, name string, off, length int64) (
 		return nil, err
 	}
 
+	var newOffset int64
 	if off > 0 {
-		_, err := f.Seek(off, 0)
+		newOffset, err = f.Seek(off, 0)
 		if err != nil {
 			return nil, errors.Wrapf(err, "seek %v", off)
 		}
 	}
 
+	size := stat.Size() - newOffset
 	if length == -1 {
-		return f, nil
+		return objstore.ObjectSizerReadCloser{
+			ReadCloser: f,
+			Size: func() (int64, error) {
+				return size, nil
+			},
+		}, nil
 	}
 
-	return &rangeReaderCloser{Reader: io.LimitReader(f, length), f: f}, nil
+	return objstore.ObjectSizerReadCloser{
+		ReadCloser: &rangeReaderCloser{
+			Reader: io.LimitReader(f, length),
+			f:      f,
+		},
+		Size: func() (int64, error) {
+			return min(length, size), nil
+		},
+	}, nil
 }
 
 // Exists checks if the given directory exists in memory.

providers/gcs/gcs.go

@@ -226,12 +226,33 @@ func (b *Bucket) Iter(ctx context.Context, dir string, f func(string) error, opt
 
 // Get returns a reader for the given object name.
 func (b *Bucket) Get(ctx context.Context, name string) (io.ReadCloser, error) {
-	return b.bkt.Object(name).NewReader(ctx)
+	r, err := b.bkt.Object(name).NewReader(ctx)
+	if err != nil {
+		return r, err
+	}
+
+	return objstore.ObjectSizerReadCloser{
+		ReadCloser: r,
+		Size: func() (int64, error) {
+			return r.Attrs.Size, nil
+		},
+	}, nil
 }
 
 // GetRange returns a new range reader for the given object name and range.
 func (b *Bucket) GetRange(ctx context.Context, name string, off, length int64) (io.ReadCloser, error) {
-	return b.bkt.Object(name).NewRangeReader(ctx, off, length)
+	r, err := b.bkt.Object(name).NewRangeReader(ctx, off, length)
+	if err != nil {
+		return r, err
+	}
+
+	sz := r.Remain()
+	return objstore.ObjectSizerReadCloser{
+		ReadCloser: r,
+		Size: func() (int64, error) {
+			return sz, nil
+		},
+	}, nil
 }
 
 // Attributes returns information about the specified object.

providers/obs/obs.go

@@ -299,7 +299,12 @@ func (b *Bucket) getRange(_ context.Context, name string, off, length int64) (io
 	if err != nil {
 		return nil, errors.Wrap(err, "failed to get object")
 	}
-	return output.Body, nil
+	return objstore.ObjectSizerReadCloser{
+		ReadCloser: output.Body,
+		Size: func() (int64, error) {
+			return output.ContentLength, nil
+		},
+	}, nil
 }
 
 // Exists checks if the given object exists in the bucket.

providers/oci/oci.go

@@ -134,7 +134,12 @@ func (b *Bucket) Get(ctx context.Context, name string) (io.ReadCloser, error) {
 	if err != nil {
 		return nil, err
 	}
-	return response.Content, nil
+	return objstore.ObjectSizerReadCloser{
+		ReadCloser: response.Content,
+		Size: func() (int64, error) {
+			return *response.ContentLength, nil
+		},
+	}, nil
 }
 
 // GetRange returns a new range reader for the given object name and range.
@@ -164,7 +169,11 @@ func (b *Bucket) GetRange(ctx context.Context, name string, offset, length int64
 	if err != nil {
 		return nil, err
 	}
-	return response.Content, nil
+	return objstore.ObjectSizerReadCloser{ReadCloser: response.Content,
+		Size: func() (int64, error) {
+			return *response.ContentLength, nil
+		},
+	}, nil
 }
 
 // Upload the contents of the reader as an object into the bucket.

providers/oss/oss.go

@@ -16,6 +16,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/aliyun/aliyun-oss-go-sdk/oss"
 	alioss "github.com/aliyun/aliyun-oss-go-sdk/oss"
 	"github.com/go-kit/log"
 	"github.com/pkg/errors"
@@ -342,12 +343,22 @@ func (b *Bucket) getRange(_ context.Context, name string, off, length int64) (io
 		opts = append(opts, opt)
 	}
 
-	resp, err := b.bucket.GetObject(name, opts...)
+	resp, err := b.bucket.DoGetObject(&oss.GetObjectRequest{ObjectKey: name}, opts)
 	if err != nil {
 		return nil, err
 	}
 
-	return resp, nil
+	size, err := clientutil.ParseContentLength(resp.Response.Headers)
+	if err == nil {
+		return objstore.ObjectSizerReadCloser{
+			ReadCloser: resp.Response,
+			Size: func() (int64, error) {
+				return size, nil
+			},
+		}, nil
+	}
+
+	return resp.Response, nil
 }
 
 // Get returns a reader for the given object name.

providers/s3/s3.go

@@ -452,7 +452,17 @@ func (b *Bucket) getRange(ctx context.Context, name string, off, length int64) (
 		return nil, err
 	}
 
-	return r, nil
+	return objstore.ObjectSizerReadCloser{
+		ReadCloser: r,
+		Size: func() (int64, error) {
+			stat, err := r.Stat()
+			if err != nil {
+				return 0, err
+			}
+
+			return stat.Size, nil
+		},
+	}, nil
 }
 
 // Get returns a reader for the given object name.

providers/swift/swift.go

@@ -262,7 +262,11 @@ func (c *Container) get(name string, headers swift.Headers, checkHash bool) (io.
 	if err != nil {
 		return nil, errors.Wrap(err, "open object")
 	}
-	return file, err
+
+	return objstore.ObjectSizerReadCloser{
+		ReadCloser: file,
+		Size:       file.Length,
+	}, nil
 }
 
 // Get returns a reader for the given object name.

testing.go

@@ -106,6 +106,11 @@ func AcceptanceTest(t *testing.T, bkt Bucket) {
 	rc1, err := bkt.Get(ctx, "id1/obj_1.some")
 	testutil.Ok(t, err)
 	defer func() { testutil.Ok(t, rc1.Close()) }()
+
+	sz, err := TryToGetSize(rc1)
+	testutil.Ok(t, err)
+	testutil.Equals(t, int64(11), sz, "expected size to be equal to 11")
+
 	content, err := io.ReadAll(rc1)
 	testutil.Ok(t, err)
 	testutil.Equals(t, "@test-data@", string(content))
@@ -118,6 +123,11 @@ func AcceptanceTest(t *testing.T, bkt Bucket) {
 	rc2, err := bkt.GetRange(ctx, "id1/obj_1.some", 1, 3)
 	testutil.Ok(t, err)
 	defer func() { testutil.Ok(t, rc2.Close()) }()
+
+	sz, err = TryToGetSize(rc2)
+	testutil.Ok(t, err)
+	testutil.Equals(t, int64(3), sz, "expected size to be equal to 3")
+
 	content, err = io.ReadAll(rc2)
 	testutil.Ok(t, err)
 	testutil.Equals(t, "tes", string(content))
@@ -126,6 +136,11 @@ func AcceptanceTest(t *testing.T, bkt Bucket) {
 	rcUnspecifiedLen, err := bkt.GetRange(ctx, "id1/obj_1.some", 1, -1)
 	testutil.Ok(t, err)
 	defer func() { testutil.Ok(t, rcUnspecifiedLen.Close()) }()
+
+	sz, err = TryToGetSize(rcUnspecifiedLen)
+	testutil.Ok(t, err)
+	testutil.Equals(t, int64(10), sz, "expected size to be equal to 10")
+
 	content, err = io.ReadAll(rcUnspecifiedLen)
 	testutil.Ok(t, err)
 	testutil.Equals(t, "test-data@", string(content))
@@ -141,6 +156,11 @@ func AcceptanceTest(t *testing.T, bkt Bucket) {
 	rcLength, err := bkt.GetRange(ctx, "id1/obj_1.some", 3, 9999)
 	testutil.Ok(t, err)
 	defer func() { testutil.Ok(t, rcLength.Close()) }()
+
+	sz, err = TryToGetSize(rcLength)
+	testutil.Ok(t, err)
+	testutil.Equals(t, int64(8), sz, "expected size to be equal to 8")
+
 	content, err = io.ReadAll(rcLength)
 	testutil.Ok(t, err)
 	testutil.Equals(t, "st-data@", string(content))