a12f493bd3
Prevents the copy method from calling discard on the writer when the reader is not seekable. Instead, the copy method will discard up to the offset. Truncate is a more expensive operation since any bytes that are truncated already have their hash calculated and are stored on disk in the backend. Re-writing bytes which were truncated requires transfering the data over GRPC again and re-computing the hash up to the point of truncation. Signed-off-by: Derek McGowan <derek@mcgstyle.net>
113 lines
2.4 KiB
Go
113 lines
2.4 KiB
Go
package content
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import (
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"bytes"
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"context"
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"io"
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"strings"
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"testing"
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"github.com/containerd/containerd/errdefs"
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"github.com/opencontainers/go-digest"
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"github.com/stretchr/testify/assert"
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"github.com/stretchr/testify/require"
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)
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type copySource struct {
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reader io.Reader
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size int64
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digest digest.Digest
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}
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func TestCopy(t *testing.T) {
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defaultSource := newCopySource("this is the source to copy")
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var testcases = []struct {
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name string
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source copySource
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writer fakeWriter
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expected string
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}{
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{
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name: "copy no offset",
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source: defaultSource,
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writer: fakeWriter{},
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expected: "this is the source to copy",
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},
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{
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name: "copy with offset from seeker",
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source: defaultSource,
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writer: fakeWriter{status: Status{Offset: 8}},
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expected: "the source to copy",
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},
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{
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name: "copy with offset from unseekable source",
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source: copySource{reader: bytes.NewBufferString("foobar"), size: 6},
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writer: fakeWriter{status: Status{Offset: 3}},
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expected: "bar",
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},
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{
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name: "commit already exists",
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source: defaultSource,
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writer: fakeWriter{commitFunc: func() error {
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return errdefs.ErrAlreadyExists
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}},
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},
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}
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for _, testcase := range testcases {
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t.Run(testcase.name, func(t *testing.T) {
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err := Copy(context.Background(),
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&testcase.writer,
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testcase.source.reader,
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testcase.source.size,
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testcase.source.digest)
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require.NoError(t, err)
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assert.Equal(t, testcase.source.digest, testcase.writer.commitedDigest)
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assert.Equal(t, testcase.expected, testcase.writer.String())
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})
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}
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}
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func newCopySource(raw string) copySource {
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return copySource{
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reader: strings.NewReader(raw),
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size: int64(len(raw)),
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digest: digest.FromBytes([]byte(raw)),
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}
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}
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type fakeWriter struct {
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bytes.Buffer
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commitedDigest digest.Digest
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status Status
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commitFunc func() error
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}
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func (f *fakeWriter) Close() error {
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f.Buffer.Reset()
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return nil
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}
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func (f *fakeWriter) Commit(ctx context.Context, size int64, expected digest.Digest, opts ...Opt) error {
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f.commitedDigest = expected
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if f.commitFunc == nil {
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return nil
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}
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return f.commitFunc()
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}
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func (f *fakeWriter) Digest() digest.Digest {
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return f.commitedDigest
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}
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func (f *fakeWriter) Status() (Status, error) {
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return f.status, nil
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}
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func (f *fakeWriter) Truncate(size int64) error {
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f.Buffer.Truncate(int(size))
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return nil
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}
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