Method NewBatchObjectIter

git/batch_obj_iter.go:33–124

NewBatchObjectIter returns a `*BatchObjectIterator` and an `io.WriteCloser`. The iterator iterates over objects whose names are fed into the `io.WriteCloser`, one per line. The `io.WriteCloser` should normally be closed and the iterator's output drained before `Close()` is called.

(ctx context.Context)

// `io.WriteCloser` should normally be closed and the iterator's
// output drained before `Close()` is called.
func (repo *Repository) NewBatchObjectIter(ctx context.Context) (*BatchObjectIter, error) {
	iter := BatchObjectIter{
		ctx:   ctx,
		p:     pipe.New(),
		oidCh: make(chan OID),
		objCh: make(chan ObjectRecord),
		errCh: make(chan error),
	}

	iter.p.Add(
		// Read OIDs from `iter.oidCh` and write them to `git
		// cat-file`:
		pipe.Function(
			"request-objects",
			func(ctx context.Context, _ pipe.Env, _ io.Reader, stdout io.Writer) error {
				out := bufio.NewWriter(stdout)

				for {
					select {
					case oid, ok := <-iter.oidCh:
						if !ok {
							return out.Flush()
						}
						if _, err := fmt.Fprintln(out, oid.String()); err != nil {
							return fmt.Errorf("writing to 'git cat-file': %w", err)
						}
					case <-ctx.Done():
						return ctx.Err()
					}
				}
			},
		),

		// Read OIDs from `stdin` and output a header line followed by
		// the contents of the corresponding Git objects:
		pipe.CommandStage(
			"git-cat-file",
			repo.GitCommand("cat-file", "--batch", "--buffer"),
		),

		// Parse the object headers and read the object contents, and
		// shove both into `objCh`:
		pipe.Function(
			"object-reader",
			func(ctx context.Context, _ pipe.Env, stdin io.Reader, _ io.Writer) error {
				defer close(iter.objCh)

				f := bufio.NewReader(stdin)

				for {
					header, err := f.ReadString('\n')
					if err != nil {
						if err == io.EOF {
							return nil
						}
						return fmt.Errorf("reading from 'git cat-file': %w", err)
					}
					batchHeader, err := ParseBatchHeader("", header)