Update differential_privacy module to convert DP events to and from…

… `NamedTuple`s.

PiperOrigin-RevId: 525517433

tensorflow_privacy/privacy/dp_query/tree_aggregation.py

@@ -21,11 +21,11 @@
 as helper functions for `tree_aggregation_query`. This module and helper
 functions are publicly accessible.
 """
+
 import abc
 import collections
-from typing import Any, Callable, Collection, Optional, Tuple, Union
+from typing import Any, Callable, Collection, NamedTuple, Optional, Tuple, Union
 
-import attr
 import tensorflow as tf
 
 # TODO(b/192464750): find a proper place for the helper functions, privatize
@@ -170,8 +170,7 @@ def next(self, state):
     return self.value_fn(), state
 
 
-@attr.s(eq=False, frozen=True, slots=True)
-class TreeState(object):
+class TreeState(NamedTuple):
   """Class defining state of the tree.
 
   Attributes:
@@ -183,9 +182,9 @@ class TreeState(object):
       for the most recent leaf node.
    value_generator_state: State of a stateful `ValueGenerator` for tree node.
   """
-  level_buffer = attr.ib(type=tf.Tensor)
-  level_buffer_idx = attr.ib(type=tf.Tensor)
-  value_generator_state = attr.ib(type=Any)
+  level_buffer: tf.Tensor
+  level_buffer_idx: tf.Tensor
+  value_generator_state: Any
 
 
 # TODO(b/192464750): move `get_step_idx` to be a property of `TreeState`.

tensorflow_privacy/privacy/dp_query/tree_aggregation_query.py

@@ -33,9 +33,11 @@
   eps = rdp_accountant.get_privacy_spent(orders, rdp, target_delta)[0]
 """
 
-import attr
+from typing import Any, NamedTuple
+
 import dp_accounting
 import tensorflow as tf
+
 from tensorflow_privacy.privacy.dp_query import dp_query
 from tensorflow_privacy.privacy.dp_query import tree_aggregation
 
@@ -84,8 +86,7 @@ class TreeCumulativeSumQuery(dp_query.SumAggregationDPQuery):
       O(clip_norm*log(T)/eps) to guarantee eps-DP.
   """
 
-  @attr.s(frozen=True)
-  class GlobalState(object):
+  class GlobalState(NamedTuple):
     """Class defining global state for Tree sum queries.
 
     Attributes:
@@ -94,9 +95,9 @@ class GlobalState(object):
       clip_value: The clipping value to be passed to clip_fn.
       samples_cumulative_sum: Noiseless cumulative sum of samples over time.
     """
-    tree_state = attr.ib()
-    clip_value = attr.ib()
-    samples_cumulative_sum = attr.ib()
+    tree_state: Any
+    clip_value: Any
+    samples_cumulative_sum: Any
 
   def __init__(self,
                record_specs,
@@ -182,10 +183,11 @@ def get_noised_result(self, sample_state, global_state):
         global_state.tree_state)
     noised_cumulative_sum = tf.nest.map_structure(tf.add, new_cumulative_sum,
                                                   cumulative_sum_noise)
-    new_global_state = attr.evolve(
-        global_state,
+    new_global_state = TreeCumulativeSumQuery.GlobalState(
+        tree_state=new_tree_state,
+        clip_value=global_state.clip_value,
         samples_cumulative_sum=new_cumulative_sum,
-        tree_state=new_tree_state)
+    )
     event = dp_accounting.UnsupportedDpEvent()
     return noised_cumulative_sum, new_global_state, event
 
@@ -206,10 +208,11 @@ def reset_state(self, noised_results, global_state):
         state for the next cumulative sum.
     """
     new_tree_state = self._tree_aggregator.reset_state(global_state.tree_state)
-    return attr.evolve(
-        global_state,
+    return TreeCumulativeSumQuery.GlobalState(
+        tree_state=new_tree_state,
+        clip_value=global_state.clip_value,
         samples_cumulative_sum=noised_results,
-        tree_state=new_tree_state)
+    )
 
   @classmethod
   def build_l2_gaussian_query(cls,
@@ -312,8 +315,7 @@ class TreeResidualSumQuery(dp_query.SumAggregationDPQuery):
       O(clip_norm*log(T)/eps) to guarantee eps-DP.
   """
 
-  @attr.s(frozen=True)
-  class GlobalState(object):
+  class GlobalState(NamedTuple):
     """Class defining global state for Tree sum queries.
 
     Attributes:
@@ -323,9 +325,9 @@ class GlobalState(object):
       previous_tree_noise: Cumulative noise by tree aggregation from the
         previous time the query is called on a sample.
     """
-    tree_state = attr.ib()
-    clip_value = attr.ib()
-    previous_tree_noise = attr.ib()
+    tree_state: Any
+    clip_value: Any
+    previous_tree_noise: Any
 
   def __init__(self,
                record_specs,
@@ -426,8 +428,11 @@ def get_noised_result(self, sample_state, global_state):
     noised_sample = tf.nest.map_structure(lambda a, b, c: a + b - c,
                                           sample_state, tree_noise,
                                           global_state.previous_tree_noise)
-    new_global_state = attr.evolve(
-        global_state, previous_tree_noise=tree_noise, tree_state=new_tree_state)
+    new_global_state = TreeResidualSumQuery.GlobalState(
+        tree_state=new_tree_state,
+        clip_value=global_state.clip_value,
+        previous_tree_noise=tree_noise,
+    )
     event = dp_accounting.UnsupportedDpEvent()
     return noised_sample, new_global_state, event
 
@@ -448,21 +453,28 @@ def reset_state(self, noised_results, global_state):
     """
     del noised_results
     new_tree_state = self._tree_aggregator.reset_state(global_state.tree_state)
-    return attr.evolve(
-        global_state,
+    return TreeResidualSumQuery.GlobalState(
+        tree_state=new_tree_state,
+        clip_value=global_state.clip_value,
         previous_tree_noise=self._zero_initial_noise(),
-        tree_state=new_tree_state)
+    )
 
   def reset_l2_clip_gaussian_noise(self, global_state, clip_norm, stddev):
     noise_generator_state = global_state.tree_state.value_generator_state
     assert isinstance(self._tree_aggregator.value_generator,
                       tree_aggregation.GaussianNoiseGenerator)
     noise_generator_state = self._tree_aggregator.value_generator.make_state(
         noise_generator_state.seeds, stddev)
-    new_tree_state = attr.evolve(
-        global_state.tree_state, value_generator_state=noise_generator_state)
-    return attr.evolve(
-        global_state, clip_value=clip_norm, tree_state=new_tree_state)
+    new_tree_state = tree_aggregation.TreeState(
+        level_buffer=global_state.tree_state.level_buffer,
+        level_buffer_idx=global_state.tree_state.level_buffer_idx,
+        value_generator_state=noise_generator_state,
+    )
+    return TreeResidualSumQuery.GlobalState(
+        tree_state=new_tree_state,
+        clip_value=clip_norm,
+        previous_tree_noise=global_state.previous_tree_noise,
+    )
 
   @classmethod
   def build_l2_gaussian_query(cls,

tensorflow_privacy/privacy/dp_query/tree_range_query.py

@@ -18,9 +18,8 @@
 
 import distutils
 import math
-from typing import Optional
+from typing import Any, NamedTuple, Optional
 
-import attr
 import dp_accounting
 import tensorflow as tf
 from tensorflow_privacy.privacy.dp_query import distributed_discrete_gaussian_query
@@ -102,17 +101,16 @@ class TreeRangeSumQuery(dp_query.SumAggregationDPQuery):
   Improves efficiency and reduces noise scale.
   """
 
-  @attr.s(frozen=True)
-  class GlobalState(object):
+  class GlobalState(NamedTuple):
     """Class defining global state for TreeRangeSumQuery.
 
     Attributes:
       arity: The branching factor of the tree (i.e. the number of children each
         internal node has).
       inner_query_state: The global state of the inner query.
     """
-    arity = attr.ib()
-    inner_query_state = attr.ib()
+    arity: Any
+    inner_query_state: Any
 
   def __init__(self,
                inner_query: dp_query.SumAggregationDPQuery,