Add quantile trees and deprecate order statistics in C++

C++:
- Add an interface for multiple quantiles, supported by Quantile
Trees
- Mark OrderStatistics as deprecated in favor of the new quantile implementation

Go & Privacy on Beam:
- Various fixes and improvements for CI with the `go` tool

Privacy on Beam:
- Improve instructions for depending on the library with Bazel
- Fix typos in DistinctPerKey tests

Accounting:
- Add a function to conveniently create PLD for Discrete Laplace,
Discrete Gaussian and Gaussian Mechanisms

GitOrigin-RevId: 958acb2199902126d3d333dd8d1da150fa281911
Change-Id: I89de361be98dcc6da9675d5730f5b06bb7c59a31

.github/workflows/go.yml

@@ -0,0 +1,47 @@
+name: Go
+
+on:
+  push:
+    branches-ignore:
+    # Version 1.0 does not work with the "go" tool properly.
+    - "1.0"
+  pull_request:
+    branches-ignore:
+    # Version 1.0 does not work with the "go" tool properly.
+    - "1.0"
+  schedule:
+    # Every Thursday at 1PM UTC
+    - cron: "0 13 * * 4"
+
+jobs:
+
+  build:
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Set up Go
+      uses: actions/setup-go@v2
+      with:
+        go-version: 1.16
+
+    - name: Build go
+      run: go build -mod=mod -v ./...
+      working-directory: ./go
+
+    - name: Test go
+      run: go test -mod=mod -v ./...
+      working-directory: ./go
+
+    - name: Build examples/go
+      run: go build -mod=mod -v ./...
+      working-directory: ./examples/go
+
+    - name: Build privacy-on-beam
+      run: go build -mod=mod -v ./...
+      working-directory: ./privacy-on-beam
+
+    - name: Test privacy-on-beam
+      run: go test -mod=mod -v ./...
+      working-directory: ./privacy-on-beam

README.md

@@ -28,8 +28,8 @@ Currently, the DP building block libraries support the following algorithms:
 | Count                            | Supported | Supported | Supported |
 | Sum                              | Supported | Supported | Supported |
 | Mean                             | Supported | Supported | Supported |
-| Variance                         | Supported | Planned   | Planned   |
-| Standard deviation               | Supported | Planned   | Planned   |
+| Variance                         | Supported | Supported | Planned   |
+| Standard deviation               | Supported | Supported | Planned   |
 | Quantiles                        | Supported | Supported | Supported |
 | Automatic bounds approximation   | Supported | Planned   | Planned   |
 | Truncated geometric thresholding | Supported | Supported | Supported |

cc/accounting/BUILD

@@ -47,6 +47,7 @@ cc_library(
         "@com_google_absl//absl/container:flat_hash_map",
         "@com_google_absl//absl/status",
         "@com_google_absl//absl/strings:str_format",
+        "@com_google_absl//absl/types:optional",
         "@com_google_cc_differential_privacy//base:status",
         "@com_google_cc_differential_privacy//base:statusor",
     ],
@@ -81,6 +82,7 @@ cc_test(
         "//accounting/common:test_util",
         "@com_google_differential_privacy//proto/accounting:privacy_loss_distribution_cc_proto",
         "@com_google_absl//absl/status",
+        "@com_google_absl//absl/types:optional",
         "@com_google_cc_differential_privacy//base:statusor",
     ],
 )

cc/accounting/privacy_loss_distribution.cc

@@ -22,6 +22,7 @@
 #include "absl/strings/str_format.h"
 #include "accounting/common/common.h"
 #include "accounting/convolution.h"
+#include "accounting/privacy_loss_mechanism.h"
 #include "proto/accounting/privacy-loss-distribution.pb.h"
 #include "base/status_macros.h"
 
@@ -204,6 +205,39 @@ PrivacyLossDistribution::CreateForLaplaceMechanism(
                                 discretization_interval);
 }
 
+base::StatusOr<std::unique_ptr<PrivacyLossDistribution>>
+PrivacyLossDistribution::CreateForDiscreteLaplaceMechanism(
+    double parameter, int sensitivity, EstimateType estimate_type,
+    double discretization_interval) {
+  ASSIGN_OR_RETURN(std::unique_ptr<DiscreteLaplacePrivacyLoss> privacy_loss,
+                   DiscreteLaplacePrivacyLoss::Create(parameter, sensitivity));
+  return CreateForAdditiveNoise(*privacy_loss, estimate_type,
+                                discretization_interval);
+}
+
+base::StatusOr<std::unique_ptr<PrivacyLossDistribution>>
+PrivacyLossDistribution::CreateForGaussianMechanism(
+    double standard_deviation, double sensitivity, EstimateType estimate_type,
+    double discretization_interval, double mass_truncation_bound) {
+  ASSIGN_OR_RETURN(
+      std::unique_ptr<GaussianPrivacyLoss> privacy_loss,
+      GaussianPrivacyLoss::Create(standard_deviation, sensitivity,
+                                  estimate_type, mass_truncation_bound));
+  return CreateForAdditiveNoise(*privacy_loss, estimate_type,
+                                discretization_interval);
+}
+
+base::StatusOr<std::unique_ptr<PrivacyLossDistribution>>
+PrivacyLossDistribution::CreateForDiscreteGaussianMechanism(
+    double sigma, int sensitivity, EstimateType estimate_type,
+    double discretization_interval, absl::optional<int> truncation_bound) {
+  ASSIGN_OR_RETURN(std::unique_ptr<DiscreteGaussianPrivacyLoss> privacy_loss,
+                   DiscreteGaussianPrivacyLoss::Create(sigma, sensitivity,
+                                                       truncation_bound));
+  return CreateForAdditiveNoise(*privacy_loss, estimate_type,
+                                discretization_interval);
+}
+
 std::unique_ptr<PrivacyLossDistribution>
 PrivacyLossDistribution::CreateForPrivacyParameters(
     EpsilonDelta epsilon_delta, double discretization_interval) {

cc/accounting/privacy_loss_distribution.h

@@ -22,6 +22,7 @@
 
 #include "absl/container/flat_hash_map.h"
 #include "base/statusor.h"
+#include "absl/types/optional.h"
 #include "accounting/common/common.h"
 #include "accounting/privacy_loss_mechanism.h"
 #include "proto/accounting/privacy-loss-distribution.pb.h"
@@ -122,12 +123,80 @@ class PrivacyLossDistribution {
   // estimate_type: kPessimistic denoting that the rounding is done in such a
   //   way that the resulting epsilon-hockey stick divergence computation gives
   //   an upper estimate to the real value.
+  // discretization_interval: the length of the dicretization interval for the
+  //   privacy loss distribution. The values will be rounded up/down to be
+  //   integer multiples of this number.
   static base::StatusOr<std::unique_ptr<PrivacyLossDistribution>>
   CreateForLaplaceMechanism(
       double parameter, double sensitivity = 1,
       EstimateType estimate_type = EstimateType::kPessimistic,
       double discretization_interval = 1e-4);
 
+  // Creates {@link PrivacyLossDistribution} for the Discrete Laplace mechanism.
+  //
+  // parameter: the parameter of the Discrete Laplace distribution.
+  // sensitivity: the sensitivity of function f. (i.e. the maximum absolute
+  //   change in f when an input to a single user changes.)
+  // estimate_type: kPessimistic denoting that the rounding is done in such a
+  //   way that the resulting epsilon-hockey stick divergence computation gives
+  //   an upper estimate to the real value.
+  // discretization_interval: the length of the dicretization interval for the
+  //   privacy loss distribution. The values will be rounded up/down to be
+  //   integer multiples of this number.
+  static base::StatusOr<std::unique_ptr<PrivacyLossDistribution>>
+  CreateForDiscreteLaplaceMechanism(
+      double parameter, int sensitivity = 1,
+      EstimateType estimate_type = EstimateType::kPessimistic,
+      double discretization_interval = 1e-4);
+
+  // Creates {@link PrivacyLossDistribution} for the Gaussian mechanism.
+  //
+  // standard_deviation: the standard_deviation of the Gaussian distribution.
+  // sensitivity: the sensitivity of function f. (i.e. the maximum absolute
+  //   change in f when an input to a single user changes.)
+  // estimate_type: kPessimistic denoting that the rounding is done in such a
+  //   way that the resulting epsilon-hockey stick divergence computation gives
+  //   an upper estimate to the real value.
+  // discretization_interval: the length of the dicretization interval for the
+  //   privacy loss distribution. The values will be rounded up/down to be
+  //   integer multiples of this number.
+  // mass_truncation_bound: the natural log of the probability mass that might
+  //   be discarded from the noise distribution. The larger this number, the
+  //   more error it may introduce in divergence calculations.
+  static base::StatusOr<std::unique_ptr<PrivacyLossDistribution>>
+  CreateForGaussianMechanism(
+      double standard_deviation, double sensitivity = 1,
+      EstimateType estimate_type = EstimateType::kPessimistic,
+      double discretization_interval = 1e-4,
+      double mass_truncation_bound = -50);
+
+  // Creates {@link PrivacyLossDistribution} for the Gaussian mechanism.
+  //
+  // sigma: he parameter of the discrete Gaussian distribution. Note that unlike
+  //   the (continuous) Gaussian distribution this is not equal to the standard
+  //   deviation of the noise.
+  // sensitivity: the sensitivity of function f. (i.e. the maximum absolute
+  //   change in f when an input to a single user changes.)
+  // estimate_type: kPessimistic denoting that the rounding is done in such a
+  //   way that the resulting epsilon-hockey stick divergence computation gives
+  //   an upper estimate to the real value.
+  // discretization_interval: the length of the dicretization interval for the
+  //   privacy loss distribution. The values will be rounded up/down to be
+  //   integer multiples of this number.
+  // mass_truncation_bound: the natural log of the probability mass that might
+  //   be discarded from the noise distribution. The larger this number, the
+  //   more error it may introduce in divergence calculations.
+  // truncation_bound: bound for truncating the noise, i.e. the noise will only
+  //   have a support in [-truncation_bound, truncation_bound]. When not set,
+  //   truncation_bound will be chosen in such a way that the mass of the noise
+  //   outside of this range is at most 1e-30.
+  static base::StatusOr<std::unique_ptr<PrivacyLossDistribution>>
+  CreateForDiscreteGaussianMechanism(
+      double sigma, int sensitivity = 1,
+      EstimateType estimate_type = EstimateType::kPessimistic,
+      double discretization_interval = 1e-4,
+      absl::optional<int> truncation_bound = absl::nullopt);
+
   // Creates {@link PrivacyLossDistribution} from epsilon and delta parameters.
   //
   // When the mechanism is (epsilon, delta)-differentially private, the