Support to read chunk id in stream object.

python/vineyard/io/stream.py

@@ -28,13 +28,13 @@
 from vineyard._C import ObjectID
 from vineyard._C import ObjectMeta
 from vineyard._C import StreamDrainedException
 from vineyard.core.driver import registerize
 from vineyard.core.resolver import resolver_context
 
 logger = logging.getLogger('vineyard')
 
 
 @registerize
 def read(
     path,
     *args,
@@ -114,7 +114,7 @@
         raise ValueError("No IO driver registered for %s" % path)
 
 
 @registerize
 def write(
     path, stream, *args, handlers=None, chunk_hook: Optional[Callable] = None, **kwargs
 ):
@@ -264,6 +264,12 @@
             self._resolver = resolver
             self._client.open_stream(stream, 'r')
 
+        def next_chunk_id(self) -> ObjectID:
+            try:
+                return self._client.next_chunk_id(self._stream)
+            except StreamDrainedException as e:
+                raise StopIteration('No more chunks') from e
+
         def next(self) -> object:
             try:
                 chunk = self._client.next_chunk(self._stream)
@@ -418,7 +424,7 @@
         return self._meta
 
     @property
     def isglobal(self):
         return self._global
 
     @property