[feature] add per-uri dereferencer locks (#2291)

vendor/codeberg.org/gruf/go-iotools/read.go

@@ -12,6 +12,14 @@ func (r ReaderFunc) Read(b []byte) (int, error) {
 	return r(b)
 }
 
+// ReaderFromFunc is a function signature which allows
+// a function to implement the io.ReaderFrom type.
+type ReaderFromFunc func(io.Reader) (int64, error)
+
+func (rf ReaderFromFunc) ReadFrom(r io.Reader) (int64, error) {
+	return rf(r)
+}
+
 // ReadCloser wraps an io.Reader and io.Closer in order to implement io.ReadCloser.
 func ReadCloser(r io.Reader, c io.Closer) io.ReadCloser {
 	return &struct {