Upgrade flatbuffers version to 1.10.0. (#3559)

* Upgrade flatbuffers version to 1.10.0.

* Temporarily change ray.utils.decode for backwards compatibility.

python/ray/experimental/state.py

@@ -366,12 +366,14 @@ class GlobalState(object):
             node_info[client_id] = {
                 "ClientID": client_id,
                 "IsInsertion": client.IsInsertion(),
-                "NodeManagerAddress": decode(client.NodeManagerAddress()),
+                "NodeManagerAddress": decode(
+                    client.NodeManagerAddress(), allow_none=True),
                 "NodeManagerPort": client.NodeManagerPort(),
                 "ObjectManagerPort": client.ObjectManagerPort(),
                 "ObjectStoreSocketName": decode(
-                    client.ObjectStoreSocketName()),
-                "RayletSocketName": decode(client.RayletSocketName()),
+                    client.ObjectStoreSocketName(), allow_none=True),
+                "RayletSocketName": decode(
+                    client.RayletSocketName(), allow_none=True),
                 "Resources": resources
             }
         return list(node_info.values())
@@ -433,7 +435,8 @@ class GlobalState(object):
 
             component_type = decode(profile_table_message.ComponentType())
             component_id = binary_to_hex(profile_table_message.ComponentId())
-            node_ip_address = decode(profile_table_message.NodeIpAddress())
+            node_ip_address = decode(
+                profile_table_message.NodeIpAddress(), allow_none=True)
 
             for j in range(profile_table_message.ProfileEventsLength()):
                 profile_event_message = profile_table_message.ProfileEvents(j)

python/ray/utils.py

@@ -165,10 +165,24 @@ def random_string():
     return random_id
 
 
-def decode(byte_str):
-    """Make this unicode in Python 3, otherwise leave it as bytes."""
+def decode(byte_str, allow_none=False):
+    """Make this unicode in Python 3, otherwise leave it as bytes.
+
+    Args:
+        byte_str: The byte string to decode.
+        allow_none: If true, then we will allow byte_str to be None in which
+            case we will return an empty string. TODO(rkn): Remove this flag.
+            This is only here to simplify upgrading to flatbuffers 1.10.0.
+
+    Returns:
+        A byte string in Python 2 and a unicode string in Python 3.
+    """
+    if byte_str is None and allow_none:
+        return ""
+
     if not isinstance(byte_str, bytes):
-        raise ValueError("The argument must be a bytes object.")
+        raise ValueError(
+            "The argument {} must be a bytes object.".format(byte_str))
     if sys.version_info >= (3, 0):
         return byte_str.decode("ascii")
     else: