Add DPEvent to the state in DifferentiallyPrivateFactory's next_fn. This requires implementing initial_sample_state in TreeRangeSumQuery for tests to pass.

tensorflow_privacy/privacy/dp_query/dp_query.py

@@ -268,10 +268,11 @@ def derive_metrics(self, global_state):
 
 def _zeros_like(arg):
   """A `zeros_like` function that also works for `tf.TensorSpec`s."""
-  try:
-    arg = tf.convert_to_tensor(value=arg)
-  except TypeError:
-    pass
+  if not isinstance(arg, tf.TensorSpec):
+    try:
+      arg = tf.convert_to_tensor(value=arg)
+    except TypeError:
+      pass
   return tf.zeros(arg.shape, arg.dtype)
 
 

tensorflow_privacy/privacy/dp_query/tree_range_query.py

@@ -18,7 +18,7 @@
 
 import distutils
 import math
-from typing import Optional
+from typing import Any, Optional
 
 import attr
 import dp_accounting
@@ -136,6 +136,12 @@ def initial_global_state(self):
         arity=self._arity,
         inner_query_state=self._inner_query.initial_global_state())
 
+  def initial_sample_state(self, template: Optional[Any] = None):
+    """Implements `tensorflow_privacy.DPQuery.initial_sample_state`."""
+    return self.preprocess_record(
+        self.derive_sample_params(self.initial_global_state()),
+        super().initial_sample_state(template))
+
   def derive_sample_params(self, global_state):
     """Implements `tensorflow_privacy.DPQuery.derive_sample_params`."""
     return (global_state.arity,