Add no-op close() and flush() methods to PackedObjectReader, CallbackStreamWrapper, and ZlibLikeBaseStreamDecompresser (#205)

When the packed object are returned they still should support close() and flush(), because in aiida-core TextIOWrapper is used as a context manager, its __exit__ calls close(), which propagates to the underlying stream. 

The methods are intentionally no-ops because these readers don't own the underlying file handles they read from.

Author: khsrali

disk_objectstore/utils.py

@@ -548,6 +548,12 @@ def writable() -> bool:
     def closed(self) -> bool:
         return self._fhandle.closed
 
+    def close(self) -> None:
+        """Close the reader. Does not close the underlying file handle since it is shared."""
+
+    def flush(self) -> None:
+        """Flush is a no-op for a read-only stream."""
+
     @staticmethod
     def seekable() -> bool:
         """Return whether object supports random access."""
@@ -683,6 +689,12 @@ def writable() -> bool:
     def closed(self) -> bool:
         return self._stream.closed
 
+    def close(self) -> None:
+        """Close the wrapper. Does not close the underlying stream."""
+
+    def flush(self) -> None:
+        """Flush is a no-op for a read-only stream."""
+
     def seekable(self) -> bool:
         """Return whether object supports random access."""
         return self._stream.seekable()
@@ -834,6 +846,12 @@ def closed(self) -> bool:
             self._lazy_uncompressed_stream is None or self._lazy_uncompressed_stream.closed
         )
 
+    def close(self) -> None:
+        """Close the decompresser. Does not close the underlying compressed stream."""
+
+    def flush(self) -> None:
+        """Flush is a no-op for a read-only stream."""
+
     def read(self, size: int = -1) -> bytes:
         """
         Read and return up to n bytes.