privacy-on-beam/pbeam/sum.go - third_party/github.com/google/differential-privacy - Git at Google

 //
 // Copyright 2020 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //      http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
 //

 package pbeam

 import (
 	"bytes"
 	"fmt"
 	"reflect"

 	log "github.com/golang/glog"
 	"github.com/google/differential-privacy/go/v3/checks"
 	"github.com/google/differential-privacy/go/v3/dpagg"
 	"github.com/google/differential-privacy/go/v3/noise"
 	"github.com/google/differential-privacy/privacy-on-beam/v3/internal/kv"
 	"github.com/apache/beam/sdks/v2/go/pkg/beam"
 	"github.com/apache/beam/sdks/v2/go/pkg/beam/core/typex"
 	"github.com/apache/beam/sdks/v2/go/pkg/beam/register"
 	"github.com/apache/beam/sdks/v2/go/pkg/beam/transforms/stats"
 )

 func init() {
 	register.DoFn2x3[beam.W, kv.Pair, kv.Pair, beam.V, error](&prepareSumFn{})
 	register.DoFn2x3[beam.X, int64, beam.X, int64, error](&addNoiseToEmptyPublicPartitionsInt64Fn{})
 	register.DoFn2x3[beam.X, float64, beam.X, float64, error](&addNoiseToEmptyPublicPartitionsFloat64Fn{})
 }

 // SumParams specifies the parameters associated with a Sum aggregation.
 type SumParams struct {
 	// Noise type (which is either LaplaceNoise{} or GaussianNoise{}).
 	//
 	// Defaults to LaplaceNoise{}.
 	NoiseKind NoiseKind
 	// Differential privacy budget consumed by this aggregation. If there is
 	// only one aggregation, both epsilon and delta can be left 0; in that case
 	// the entire budget reserved for aggregation in the PrivacySpec is consumed.
 	AggregationEpsilon, AggregationDelta float64
 	// Differential privacy budget consumed by partition selection of this
 	// aggregation.
 	//
 	// If PublicPartitions are specified, this needs to be left unset.
 	//
 	// If there is only one aggregation, this can be left unset; in that case
 	// the entire budget reserved for partition selection in the PrivacySpec
 	// is consumed.
 	//
 	// Optional.
 	PartitionSelectionParams PartitionSelectionParams
 	// You can input the list of partitions present in the output if you know
 	// them in advance. When you specify partitions, partition selection /
 	// thresholding will be disabled and partitions will appear in the output
 	// if and only if they appear in the set of public partitions.
 	//
 	// You should not derive the list of partitions non-privately from private
 	// data. You should only use this in either of the following cases:
 	// 	1. The list of partitions is data-independent. For example, if you are
 	// 	aggregating a metric by hour, you could provide a list of all possible
 	// 	hourly period.
 	// 	2. You use a differentially private operation to come up with the list of
 	// 	partitions. For example, you could use the output of a SelectPartitions
 	//  operation or the keys of a DistinctPrivacyID operation as the list of
 	//  public partitions.
 	//
 	// PublicPartitions needs to be a beam.PCollection, slice, or array. The
 	// underlying type needs to match the partition type of the PrivatePCollection.
 	//
 	// Prefer slices or arrays if the list of public partitions is small and
 	// can fit into memory (e.g., up to a million). Prefer beam.PCollection
 	// otherwise.
 	//
 	// If PartitionSelectionParams are specified, this needs to be left unset.
 	//
 	// Optional.
 	PublicPartitions any
 	// The maximum number of distinct values that a given privacy identifier
 	// can influence. There is an inherent trade-off when choosing this
 	// parameter: a larger MaxPartitionsContributed leads to less data loss due
 	// to contribution bounding, but since the noise added in aggregations is
 	// scaled according to maxPartitionsContributed, it also means that more
 	// noise is added to each count.
 	//
 	// Required.
 	MaxPartitionsContributed int64
 	// The total contribution of a given privacy identifier to partition can be
 	// at at least MinValue, and at most MaxValue; otherwise it will be clamped
 	// to these bounds. For example, if a privacy identifier is associated with
 	// the key-value pairs [("a", -5), ("a", 2), ("b", 7), ("c", 3)] and the
 	// (MinValue, MaxValue) bounds are (0, 5), the contribution for "a" will be
 	// clamped up to 0, the contribution for "b" will be clamped down to 5, and
 	// the contribution for "c" will be untouched. There is an inherent
 	// trade-off when choosing MinValue and MaxValue: a small MinValue and a
 	// large MaxValue means that less records will be clamped, but that more
 	// noise will be added.
 	//
 	// Required.
 	MinValue, MaxValue float64
 }

 // SumPerKey sums the values associated with each key in a
 // PrivatePCollection<K,V>, adding differentially private noise to the sums and
 // doing pre-aggregation thresholding to remove sums with a low number of
 // distinct privacy identifiers. Client can also specify a PCollection of partitions.
 //
 // It is also possible to manually specify the list of partitions
 // present in the output, in which case the partition selection/thresholding
 // step is skipped.
 //
 // SumPerKey transforms a PrivatePCollection<K,V> either into a
 // PCollection<K,int64> or a PCollection<K,float64>, depending on whether its
 // input is an integer type or a float type.
 //
 // Note: Do not use when your results may cause overflows for int64 and float64
 // values. This aggregation is not hardened for such applications yet.
 func SumPerKey(s beam.Scope, pcol PrivatePCollection, params SumParams) beam.PCollection {
 	s = s.Scope("pbeam.SumPerKey")
 	// Obtain & validate type information from the underlying PCollection<K,V>.
 	idT, kvT := beam.ValidateKVType(pcol.col)
 	if kvT.Type() != reflect.TypeOf(kv.Pair{}) {
 		log.Fatalf("SumPerKey must be used on a PrivatePCollection of type <K,V>, got type %v instead", kvT)
 	}
 	if pcol.codec == nil {
 		log.Fatalf("SumPerKey: no codec found for the input PrivatePCollection.")
 	}

 	// Get privacy parameters.
 	spec := pcol.privacySpec
 	var err error
 	params.AggregationEpsilon, params.AggregationDelta, err = spec.aggregationBudget.get(params.AggregationEpsilon, params.AggregationDelta)
 	if err != nil {
 		log.Fatalf("Couldn't consume aggregation budget for SumPerKey: %v", err)
 	}
 	if params.PublicPartitions == nil {
 		params.PartitionSelectionParams.Epsilon, params.PartitionSelectionParams.Delta, err = spec.partitionSelectionBudget.get(params.PartitionSelectionParams.Epsilon, params.PartitionSelectionParams.Delta)
 		if err != nil {
 			log.Fatalf("Couldn't consume partition selection budget for SumPerKey: %v", err)
 		}
 	}

 	var noiseKind noise.Kind
 	if params.NoiseKind == nil {
 		noiseKind = noise.LaplaceNoise
 		log.Infof("No NoiseKind specified, using Laplace Noise by default.")
 	} else {
 		noiseKind = params.NoiseKind.toNoiseKind()
 	}

 	err = checkSumPerKeyParams(params, noiseKind, pcol.codec.KType.T)
 	if err != nil {
 		log.Fatalf("pbeam.SumPerKey: %v", err)
 	}

 	// Drop non-public partitions, if public partitions are specified.
 	pcol.col, err = dropNonPublicPartitions(s, pcol, params.PublicPartitions, pcol.codec.KType.T)
 	if err != nil {
 		log.Fatalf("Couldn't drop non-public partitions for SumPerKey: %v", err)
 	}
 	// First, group together the privacy ID and the partition ID, and sum the
 	// values per-privacy unit and per-partition.
 	decoded := beam.ParDo(s,
 		newPrepareSumFn(idT, pcol.codec),
 		pcol.col,
 		beam.TypeDefinition{Var: beam.VType, T: pcol.codec.VType.T})
 	summed := stats.SumPerKey(s, decoded)
 	// Second, convert the sum to int64 or float64, and re-key.
 	_, sumT := beam.ValidateKVType(summed)
 	convertFn, err := findConvertFn(sumT)
 	if err != nil {
 		log.Fatalf("Couldn't get convertFn for SumPerKey: %v", err)
 	}
 	vKind, err := getKind(convertFn)
 	if err != nil {
 		log.Fatalf("Couldn't get vKind for SumPerKey: %v", err)
 	}
 	converted := beam.ParDo(s, convertFn, summed)
 	rekeyFn, err := findRekeyFn(vKind)
 	if err != nil {
 		log.Fatalf("Couldn't get rekeyFn for SumPerKey: %v", err)
 	}
 	rekeyed := beam.ParDo(s, rekeyFn, converted)
 	// Second, do cross-partition contribution bounding if not in test mode without contribution bounding.
 	if spec.testMode != TestModeWithoutContributionBounding {
 		rekeyed = boundContributions(s, rekeyed, params.MaxPartitionsContributed)
 	}
 	// Fourth, now that contribution bounding is done, remove the privacy keys,
 	// decode the value, and do a DP sum with all the partial sums.
 	partialSumPairs := beam.DropKey(s, rekeyed)
 	partitionT := pcol.codec.KType.T
 	decodePairFn, err := newDecodePairFn(partitionT, vKind)
 	if err != nil {
 		log.Fatalf("Couldn't get decodePairFn for SumPerKey: %v", err)
 	}
 	partialSumKV := beam.ParDo(s,
 		decodePairFn,
 		partialSumPairs,
 		beam.TypeDefinition{Var: beam.WType, T: partitionT})

 	var result beam.PCollection
 	// Add public partitions and return the aggregation output, if public partitions are specified.
 	if params.PublicPartitions != nil {
 		result = addPublicPartitionsForSum(s, *spec, params, noiseKind, vKind, partialSumKV)
 	} else {
 		boundedSumFn, err := newBoundedSumFn(*spec, params, noiseKind, vKind, false)
 		if err != nil {
 			log.Fatalf("Couldn't get boundedSumFn for SumPerKey: %v", err)
 		}
 		sums := beam.CombinePerKey(s,
 			boundedSumFn,
 			partialSumKV)
 		// Drop thresholded partitions.
 		dropThresholdedPartitionsFn, err := findDropThresholdedPartitionsFn(vKind)
 		if err != nil {
 			log.Fatalf("Couldn't get dropThresholdedPartitionsFn for SumPerKey: %v", err)
 		}
 		result = beam.ParDo(s, dropThresholdedPartitionsFn, sums)
 	}

 	// Clamp negative counts to zero when MinValue is non-negative.
 	if params.MinValue >= 0 {
 		clampNegativePartitionsFn, err := findClampNegativePartitionsFn(vKind)
 		if err != nil {
 			log.Fatalf("Couldn't get clampNegativePartitionsFn for SumPerKey: %v", err)
 		}
 		result = beam.ParDo(s, clampNegativePartitionsFn, result)
 	}

 	return result
 }

 func addPublicPartitionsForSum(s beam.Scope, spec PrivacySpec, params SumParams, noiseKind noise.Kind, vKind reflect.Kind, partialSumKV beam.PCollection) beam.PCollection {
 	// Calculate sums with empty public partitions added. Result is PCollection<partition, vKind>, where vKind is either int64 or float64.
 	// First, add zero values to all public partitions.
 	addZeroValuesToPublicPartitions, err := newAddZeroValuesToPublicPartitionsFn(vKind)
 	if err != nil {
 		log.Fatalf("Couldn't get addZeroValuesToPublicPartitions for SumPerKey: %v", err)
 	}
 	publicPartitions, isPCollection := params.PublicPartitions.(beam.PCollection)
 	if !isPCollection {
 		publicPartitions = beam.Reshuffle(s, beam.CreateList(s, params.PublicPartitions))
 	}
 	publicPartitionsWithZeroValues := beam.ParDo(s, addZeroValuesToPublicPartitions, publicPartitions)
 	// Second, add noise to all public partitions (all of which are zero-valued).
 	boundedSumFn, err := newBoundedSumFn(spec, params, noiseKind, vKind, true)
 	if err != nil {
 		log.Fatalf("Couldn't get boundedSumFn for SumPerKey: %v", err)
 	}
 	noisyEmptyPublicPartitions := beam.CombinePerKey(s, boundedSumFn, publicPartitionsWithZeroValues)
 	// Third, compute noisy sums for partitions in the actual data.
 	sums := beam.CombinePerKey(s, boundedSumFn, partialSumKV)
 	// Fourth, co-group by actual noisy sums with noisy public partitions, emit noisy zero value for public partitions not found in data.
 	actualNoisySumsWithPublicPartitions := beam.CoGroupByKey(s, sums, noisyEmptyPublicPartitions)
 	sums = beam.ParDo(s, mergeResultWithEmptyPublicPartitionsFn, actualNoisySumsWithPublicPartitions)
 	// Fifth, dereference *int64/*float64 results and return.
 	dereferenceValueFn, err := findDereferenceValueFn(vKind)
 	if err != nil {
 		log.Fatalf("Couldn't get dereferenceValueFn for SumPerKey: %v", err)
 	}
 	return beam.ParDo(s, dereferenceValueFn, sums)
 }

 func checkSumPerKeyParams(params SumParams, noiseKind noise.Kind, partitionType reflect.Type) error {
 	err := checkPublicPartitions(params.PublicPartitions, partitionType)
 	if err != nil {
 		return err
 	}
 	err = checkAggregationEpsilon(params.AggregationEpsilon)
 	if err != nil {
 		return err
 	}
 	err = checkAggregationDelta(params.AggregationDelta, noiseKind)
 	if err != nil {
 		return err
 	}
 	err = checkPartitionSelectionEpsilon(params.PartitionSelectionParams.Epsilon, params.PublicPartitions)
 	if err != nil {
 		return err
 	}
 	err = checkPartitionSelectionDelta(params.PartitionSelectionParams.Delta, params.PublicPartitions)
 	if err != nil {
 		return err
 	}
 	err = checkMaxPartitionsContributedPartitionSelection(params.PartitionSelectionParams.MaxPartitionsContributed)
 	if err != nil {
 		return err
 	}
 	err = checks.CheckBoundsFloat64(params.MinValue, params.MaxValue)
 	if err != nil {
 		return err
 	}
 	return checkMaxPartitionsContributed(params.MaxPartitionsContributed)
 }

 // prepareSumFn takes a PCollection<ID,kv.Pair{K,V}> as input, and returns a
 // PCollection<kv.Pair{ID,K},V>; where ID has been coded, and V has been
 // decoded.
 type prepareSumFn struct {
 	IDType         beam.EncodedType
 	idEnc          beam.ElementEncoder
 	InputPairCodec *kv.Codec
 }

 func newPrepareSumFn(idType typex.FullType, kvCodec *kv.Codec) *prepareSumFn {
 	return &prepareSumFn{
 		IDType:         beam.EncodedType{idType.Type()},
 		InputPairCodec: kvCodec,
 	}
 }

 func (fn *prepareSumFn) Setup() error {
 	fn.idEnc = beam.NewElementEncoder(fn.IDType.T)
 	return fn.InputPairCodec.Setup()
 }

 func (fn *prepareSumFn) ProcessElement(id beam.W, pair kv.Pair) (kv.Pair, beam.V, error) {
 	var idBuf bytes.Buffer
 	if err := fn.idEnc.Encode(id, &idBuf); err != nil {
 		return kv.Pair{}, nil, fmt.Errorf("pbeam.prepareSumFn.ProcessElement: couldn't encode ID %v: %w", id, err)
 	}
 	_, v, err := fn.InputPairCodec.Decode(pair)
 	return kv.Pair{idBuf.Bytes(), pair.K}, v, err
 }

 // findConvertFn gets the correct conversion to int64 or float64 function.
 func findConvertFn(t typex.FullType) (any, error) {
 	switch t.Type().String() {
 	case "int", "int8", "int16", "int32", "int64":
 		return convertToInt64Fn, nil
 	case "uint", "uint8", "uint16", "uint32", "uint64":
 		return convertToInt64Fn, nil
 	case "float32", "float64":
 		return convertToFloat64Fn, nil
 	default:
 		return nil, fmt.Errorf("unexpected value type of %v", t)
 	}
 }

 // getKind gets the return kind of the convertFn function.
 func getKind(fn any) (reflect.Kind, error) {
 	if fn == nil {
 		return reflect.Invalid, fmt.Errorf("convertFn is nil")
 	}
 	if reflect.TypeOf(fn).Kind() != reflect.Func {
 		return reflect.Invalid, fmt.Errorf("convertFn is %v, should be a function", reflect.TypeOf(fn).Kind())
 	}
 	if reflect.TypeOf(fn).NumOut() < 2 {
 		return reflect.Invalid, fmt.Errorf("convertFn has %v outputs, expected at least 2", reflect.TypeOf(fn).NumOut())
 	}
 	return reflect.TypeOf(fn).Out(1).Kind(), nil
 }

 func newAddNoiseToEmptyPublicPartitionsFn(epsilon, delta float64, maxPartitionsContributed int64, lower, upper float64, noiseKind noise.Kind, vKind reflect.Kind, testMode TestMode) (any, error) {
 	var err error
 	var bsFn any

 	switch vKind {
 	case reflect.Int64:
 		err = checks.CheckBoundsFloat64AsInt64(lower, upper)
 		bsFn = newAddNoiseToEmptyPublicPartitionsInt64Fn(epsilon, delta, maxPartitionsContributed, int64(lower), int64(upper), noiseKind, testMode)
 	case reflect.Float64:
 		err = checks.CheckBoundsFloat64(lower, upper)
 		bsFn = newAddNoiseToEmptyPublicPartitionsFloat64Fn(epsilon, delta, maxPartitionsContributed, lower, upper, noiseKind, testMode)
 	default:
 		err = fmt.Errorf("vKind(%v) should be int64 or float64", vKind)
 	}

 	return bsFn, err
 }

 // addNoiseToEmptyPublicPartitionsInt64Fn adds integer noise to empty partitions.
 type addNoiseToEmptyPublicPartitionsInt64Fn struct {
 	// Privacy spec parameters (set during initial construction).
 	NoiseEpsilon             float64
 	NoiseDelta               float64
 	MaxPartitionsContributed int64
 	Lower                    int64
 	Upper                    int64
 	NoiseKind                noise.Kind
 	noise                    noise.Noise // Set during Setup phase according to NoiseKind.
 	TestMode                 TestMode
 }

 // newAddNoiseToEmptyPublicPartitionsInt64Fn returns a addNoiseToEmptyPublicPartitionsInt64Fn with the given budget and parameters.
 func newAddNoiseToEmptyPublicPartitionsInt64Fn(epsilon, delta float64, maxPartitionsContributed, lower, upper int64, noiseKind noise.Kind, testMode TestMode) *addNoiseToEmptyPublicPartitionsInt64Fn {
 	return &addNoiseToEmptyPublicPartitionsInt64Fn{
 		NoiseEpsilon:             epsilon,
 		NoiseDelta:               delta,
 		MaxPartitionsContributed: maxPartitionsContributed,
 		Lower:                    lower,
 		Upper:                    upper,
 		NoiseKind:                noiseKind,
 		TestMode:                 testMode,
 	}
 }

 func (fn *addNoiseToEmptyPublicPartitionsInt64Fn) Setup() {
 	fn.noise = noise.ToNoise(fn.NoiseKind)
 	if fn.TestMode.isEnabled() {
 		fn.noise = noNoise{}
 	}
 }

 func (fn *addNoiseToEmptyPublicPartitionsInt64Fn) ProcessElement(partitionKey beam.X, _ int64) (beam.X, int64, error) {
 	bs, err := dpagg.NewBoundedSumInt64(&dpagg.BoundedSumInt64Options{
 		Epsilon:                  fn.NoiseEpsilon,
 		Delta:                    fn.NoiseDelta,
 		MaxPartitionsContributed: fn.MaxPartitionsContributed,
 		Lower:                    fn.Lower,
 		Upper:                    fn.Upper,
 		Noise:                    fn.noise,
 	})
 	if err != nil {
 		return partitionKey, 0, err
 	}
 	noisedValue, err := bs.Result()
 	return partitionKey, noisedValue, err
 }

 // addNoiseToEmptyPublicPartitionsFloat64Fn adds integer noise to empty partitions.
 type addNoiseToEmptyPublicPartitionsFloat64Fn struct {
 	// Privacy spec parameters (set during initial construction).
 	NoiseEpsilon             float64
 	NoiseDelta               float64
 	MaxPartitionsContributed int64
 	Lower                    float64
 	Upper                    float64
 	NoiseKind                noise.Kind
 	noise                    noise.Noise // Set during Setup phase according to NoiseKind.
 	TestMode                 TestMode
 }

 // newAddNoiseToEmptyPublicPartitionsFloat64Fn returns a addNoiseToEmptyPublicPartitionsFloat64Fn with the given budget and parameters.
 func newAddNoiseToEmptyPublicPartitionsFloat64Fn(epsilon, delta float64, maxPartitionsContributed int64, lower, upper float64, noiseKind noise.Kind, testMode TestMode) *addNoiseToEmptyPublicPartitionsFloat64Fn {
 	return &addNoiseToEmptyPublicPartitionsFloat64Fn{
 		NoiseEpsilon:             epsilon,
 		NoiseDelta:               delta,
 		MaxPartitionsContributed: maxPartitionsContributed,
 		Lower:                    lower,
 		Upper:                    upper,
 		NoiseKind:                noiseKind,
 		TestMode:                 testMode,
 	}
 }

 func (fn *addNoiseToEmptyPublicPartitionsFloat64Fn) Setup() {
 	fn.noise = noise.ToNoise(fn.NoiseKind)
 	if fn.TestMode.isEnabled() {
 		fn.noise = noNoise{}
 	}
 }

 func (fn *addNoiseToEmptyPublicPartitionsFloat64Fn) ProcessElement(partitionKey beam.X, _ float64) (beam.X, float64, error) {
 	bs, err := dpagg.NewBoundedSumFloat64(&dpagg.BoundedSumFloat64Options{
 		Epsilon:                  fn.NoiseEpsilon,
 		Delta:                    fn.NoiseDelta,
 		MaxPartitionsContributed: fn.MaxPartitionsContributed,
 		Lower:                    fn.Lower,
 		Upper:                    fn.Upper,
 		Noise:                    fn.noise,
 	})
 	if err != nil {
 		return partitionKey, 0, err
 	}
 	noisedValue, err := bs.Result()
 	return partitionKey, noisedValue, err
 }
	//
	// Copyright 2020 Google LLC
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.
	//

	package pbeam

	import (
	"bytes"
	"fmt"
	"reflect"

	log "github.com/golang/glog"
	"github.com/google/differential-privacy/go/v3/checks"
	"github.com/google/differential-privacy/go/v3/dpagg"
	"github.com/google/differential-privacy/go/v3/noise"
	"github.com/google/differential-privacy/privacy-on-beam/v3/internal/kv"
	"github.com/apache/beam/sdks/v2/go/pkg/beam"
	"github.com/apache/beam/sdks/v2/go/pkg/beam/core/typex"
	"github.com/apache/beam/sdks/v2/go/pkg/beam/register"
	"github.com/apache/beam/sdks/v2/go/pkg/beam/transforms/stats"
	)

	func init() {
	register.DoFn2x3[beam.W, kv.Pair, kv.Pair, beam.V, error](&prepareSumFn{})
	register.DoFn2x3[beam.X, int64, beam.X, int64, error](&addNoiseToEmptyPublicPartitionsInt64Fn{})
	register.DoFn2x3[beam.X, float64, beam.X, float64, error](&addNoiseToEmptyPublicPartitionsFloat64Fn{})
	}

	// SumParams specifies the parameters associated with a Sum aggregation.
	type SumParams struct {
	// Noise type (which is either LaplaceNoise{} or GaussianNoise{}).
	//
	// Defaults to LaplaceNoise{}.
	NoiseKind NoiseKind
	// Differential privacy budget consumed by this aggregation. If there is
	// only one aggregation, both epsilon and delta can be left 0; in that case
	// the entire budget reserved for aggregation in the PrivacySpec is consumed.
	AggregationEpsilon, AggregationDelta float64
	// Differential privacy budget consumed by partition selection of this
	// aggregation.
	//
	// If PublicPartitions are specified, this needs to be left unset.
	//
	// If there is only one aggregation, this can be left unset; in that case
	// the entire budget reserved for partition selection in the PrivacySpec
	// is consumed.
	//
	// Optional.
	PartitionSelectionParams PartitionSelectionParams
	// You can input the list of partitions present in the output if you know
	// them in advance. When you specify partitions, partition selection /
	// thresholding will be disabled and partitions will appear in the output
	// if and only if they appear in the set of public partitions.
	//
	// You should not derive the list of partitions non-privately from private
	// data. You should only use this in either of the following cases:
	// 1. The list of partitions is data-independent. For example, if you are
	// aggregating a metric by hour, you could provide a list of all possible
	// hourly period.
	// 2. You use a differentially private operation to come up with the list of
	// partitions. For example, you could use the output of a SelectPartitions
	// operation or the keys of a DistinctPrivacyID operation as the list of
	// public partitions.
	//
	// PublicPartitions needs to be a beam.PCollection, slice, or array. The
	// underlying type needs to match the partition type of the PrivatePCollection.
	//
	// Prefer slices or arrays if the list of public partitions is small and
	// can fit into memory (e.g., up to a million). Prefer beam.PCollection
	// otherwise.
	//
	// If PartitionSelectionParams are specified, this needs to be left unset.
	//
	// Optional.
	PublicPartitions any
	// The maximum number of distinct values that a given privacy identifier
	// can influence. There is an inherent trade-off when choosing this
	// parameter: a larger MaxPartitionsContributed leads to less data loss due
	// to contribution bounding, but since the noise added in aggregations is
	// scaled according to maxPartitionsContributed, it also means that more
	// noise is added to each count.
	//
	// Required.
	MaxPartitionsContributed int64
	// The total contribution of a given privacy identifier to partition can be
	// at at least MinValue, and at most MaxValue; otherwise it will be clamped
	// to these bounds. For example, if a privacy identifier is associated with
	// the key-value pairs [("a", -5), ("a", 2), ("b", 7), ("c", 3)] and the
	// (MinValue, MaxValue) bounds are (0, 5), the contribution for "a" will be
	// clamped up to 0, the contribution for "b" will be clamped down to 5, and
	// the contribution for "c" will be untouched. There is an inherent
	// trade-off when choosing MinValue and MaxValue: a small MinValue and a
	// large MaxValue means that less records will be clamped, but that more
	// noise will be added.
	//
	// Required.
	MinValue, MaxValue float64
	}

	// SumPerKey sums the values associated with each key in a
	// PrivatePCollection<K,V>, adding differentially private noise to the sums and
	// doing pre-aggregation thresholding to remove sums with a low number of
	// distinct privacy identifiers. Client can also specify a PCollection of partitions.
	//
	// It is also possible to manually specify the list of partitions
	// present in the output, in which case the partition selection/thresholding
	// step is skipped.
	//
	// SumPerKey transforms a PrivatePCollection<K,V> either into a
	// PCollection<K,int64> or a PCollection<K,float64>, depending on whether its
	// input is an integer type or a float type.
	//
	// Note: Do not use when your results may cause overflows for int64 and float64
	// values. This aggregation is not hardened for such applications yet.
	func SumPerKey(s beam.Scope, pcol PrivatePCollection, params SumParams) beam.PCollection {
	s = s.Scope("pbeam.SumPerKey")
	// Obtain & validate type information from the underlying PCollection<K,V>.
	idT, kvT := beam.ValidateKVType(pcol.col)
	if kvT.Type() != reflect.TypeOf(kv.Pair{}) {
	log.Fatalf("SumPerKey must be used on a PrivatePCollection of type <K,V>, got type %v instead", kvT)
	}
	if pcol.codec == nil {
	log.Fatalf("SumPerKey: no codec found for the input PrivatePCollection.")
	}

	// Get privacy parameters.
	spec := pcol.privacySpec
	var err error
	params.AggregationEpsilon, params.AggregationDelta, err = spec.aggregationBudget.get(params.AggregationEpsilon, params.AggregationDelta)
	if err != nil {
	log.Fatalf("Couldn't consume aggregation budget for SumPerKey: %v", err)
	}
	if params.PublicPartitions == nil {
	params.PartitionSelectionParams.Epsilon, params.PartitionSelectionParams.Delta, err = spec.partitionSelectionBudget.get(params.PartitionSelectionParams.Epsilon, params.PartitionSelectionParams.Delta)
	if err != nil {
	log.Fatalf("Couldn't consume partition selection budget for SumPerKey: %v", err)
	}
	}

	var noiseKind noise.Kind
	if params.NoiseKind == nil {
	noiseKind = noise.LaplaceNoise
	log.Infof("No NoiseKind specified, using Laplace Noise by default.")
	} else {
	noiseKind = params.NoiseKind.toNoiseKind()
	}

	err = checkSumPerKeyParams(params, noiseKind, pcol.codec.KType.T)
	if err != nil {
	log.Fatalf("pbeam.SumPerKey: %v", err)
	}

	// Drop non-public partitions, if public partitions are specified.
	pcol.col, err = dropNonPublicPartitions(s, pcol, params.PublicPartitions, pcol.codec.KType.T)
	if err != nil {
	log.Fatalf("Couldn't drop non-public partitions for SumPerKey: %v", err)
	}
	// First, group together the privacy ID and the partition ID, and sum the
	// values per-privacy unit and per-partition.
	decoded := beam.ParDo(s,
	newPrepareSumFn(idT, pcol.codec),
	pcol.col,
	beam.TypeDefinition{Var: beam.VType, T: pcol.codec.VType.T})
	summed := stats.SumPerKey(s, decoded)
	// Second, convert the sum to int64 or float64, and re-key.
	_, sumT := beam.ValidateKVType(summed)
	convertFn, err := findConvertFn(sumT)
	if err != nil {
	log.Fatalf("Couldn't get convertFn for SumPerKey: %v", err)
	}
	vKind, err := getKind(convertFn)
	if err != nil {
	log.Fatalf("Couldn't get vKind for SumPerKey: %v", err)
	}
	converted := beam.ParDo(s, convertFn, summed)
	rekeyFn, err := findRekeyFn(vKind)
	if err != nil {
	log.Fatalf("Couldn't get rekeyFn for SumPerKey: %v", err)
	}
	rekeyed := beam.ParDo(s, rekeyFn, converted)
	// Second, do cross-partition contribution bounding if not in test mode without contribution bounding.
	if spec.testMode != TestModeWithoutContributionBounding {
	rekeyed = boundContributions(s, rekeyed, params.MaxPartitionsContributed)
	}
	// Fourth, now that contribution bounding is done, remove the privacy keys,
	// decode the value, and do a DP sum with all the partial sums.
	partialSumPairs := beam.DropKey(s, rekeyed)
	partitionT := pcol.codec.KType.T
	decodePairFn, err := newDecodePairFn(partitionT, vKind)
	if err != nil {
	log.Fatalf("Couldn't get decodePairFn for SumPerKey: %v", err)
	}
	partialSumKV := beam.ParDo(s,
	decodePairFn,
	partialSumPairs,
	beam.TypeDefinition{Var: beam.WType, T: partitionT})

	var result beam.PCollection
	// Add public partitions and return the aggregation output, if public partitions are specified.
	if params.PublicPartitions != nil {
	result = addPublicPartitionsForSum(s, *spec, params, noiseKind, vKind, partialSumKV)
	} else {
	boundedSumFn, err := newBoundedSumFn(*spec, params, noiseKind, vKind, false)
	if err != nil {
	log.Fatalf("Couldn't get boundedSumFn for SumPerKey: %v", err)
	}
	sums := beam.CombinePerKey(s,
	boundedSumFn,
	partialSumKV)
	// Drop thresholded partitions.
	dropThresholdedPartitionsFn, err := findDropThresholdedPartitionsFn(vKind)
	if err != nil {
	log.Fatalf("Couldn't get dropThresholdedPartitionsFn for SumPerKey: %v", err)
	}
	result = beam.ParDo(s, dropThresholdedPartitionsFn, sums)
	}

	// Clamp negative counts to zero when MinValue is non-negative.
	if params.MinValue >= 0 {
	clampNegativePartitionsFn, err := findClampNegativePartitionsFn(vKind)
	if err != nil {
	log.Fatalf("Couldn't get clampNegativePartitionsFn for SumPerKey: %v", err)
	}
	result = beam.ParDo(s, clampNegativePartitionsFn, result)
	}

	return result
	}

	func addPublicPartitionsForSum(s beam.Scope, spec PrivacySpec, params SumParams, noiseKind noise.Kind, vKind reflect.Kind, partialSumKV beam.PCollection) beam.PCollection {
	// Calculate sums with empty public partitions added. Result is PCollection<partition, vKind>, where vKind is either int64 or float64.
	// First, add zero values to all public partitions.
	addZeroValuesToPublicPartitions, err := newAddZeroValuesToPublicPartitionsFn(vKind)
	if err != nil {
	log.Fatalf("Couldn't get addZeroValuesToPublicPartitions for SumPerKey: %v", err)
	}
	publicPartitions, isPCollection := params.PublicPartitions.(beam.PCollection)
	if !isPCollection {
	publicPartitions = beam.Reshuffle(s, beam.CreateList(s, params.PublicPartitions))
	}
	publicPartitionsWithZeroValues := beam.ParDo(s, addZeroValuesToPublicPartitions, publicPartitions)
	// Second, add noise to all public partitions (all of which are zero-valued).
	boundedSumFn, err := newBoundedSumFn(spec, params, noiseKind, vKind, true)
	if err != nil {
	log.Fatalf("Couldn't get boundedSumFn for SumPerKey: %v", err)
	}
	noisyEmptyPublicPartitions := beam.CombinePerKey(s, boundedSumFn, publicPartitionsWithZeroValues)
	// Third, compute noisy sums for partitions in the actual data.
	sums := beam.CombinePerKey(s, boundedSumFn, partialSumKV)
	// Fourth, co-group by actual noisy sums with noisy public partitions, emit noisy zero value for public partitions not found in data.
	actualNoisySumsWithPublicPartitions := beam.CoGroupByKey(s, sums, noisyEmptyPublicPartitions)
	sums = beam.ParDo(s, mergeResultWithEmptyPublicPartitionsFn, actualNoisySumsWithPublicPartitions)
	// Fifth, dereference int64/float64 results and return.
	dereferenceValueFn, err := findDereferenceValueFn(vKind)
	if err != nil {
	log.Fatalf("Couldn't get dereferenceValueFn for SumPerKey: %v", err)
	}
	return beam.ParDo(s, dereferenceValueFn, sums)
	}

	func checkSumPerKeyParams(params SumParams, noiseKind noise.Kind, partitionType reflect.Type) error {
	err := checkPublicPartitions(params.PublicPartitions, partitionType)
	if err != nil {
	return err
	}
	err = checkAggregationEpsilon(params.AggregationEpsilon)
	if err != nil {
	return err
	}
	err = checkAggregationDelta(params.AggregationDelta, noiseKind)
	if err != nil {
	return err
	}
	err = checkPartitionSelectionEpsilon(params.PartitionSelectionParams.Epsilon, params.PublicPartitions)
	if err != nil {
	return err
	}
	err = checkPartitionSelectionDelta(params.PartitionSelectionParams.Delta, params.PublicPartitions)
	if err != nil {
	return err
	}
	err = checkMaxPartitionsContributedPartitionSelection(params.PartitionSelectionParams.MaxPartitionsContributed)
	if err != nil {
	return err
	}
	err = checks.CheckBoundsFloat64(params.MinValue, params.MaxValue)
	if err != nil {
	return err
	}
	return checkMaxPartitionsContributed(params.MaxPartitionsContributed)
	}

	// prepareSumFn takes a PCollection<ID,kv.Pair{K,V}> as input, and returns a
	// PCollection<kv.Pair{ID,K},V>; where ID has been coded, and V has been
	// decoded.
	type prepareSumFn struct {
	IDType beam.EncodedType
	idEnc beam.ElementEncoder
	InputPairCodec *kv.Codec
	}

	func newPrepareSumFn(idType typex.FullType, kvCodec kv.Codec) prepareSumFn {
	return &prepareSumFn{
	IDType: beam.EncodedType{idType.Type()},
	InputPairCodec: kvCodec,
	}
	}

	func (fn *prepareSumFn) Setup() error {
	fn.idEnc = beam.NewElementEncoder(fn.IDType.T)
	return fn.InputPairCodec.Setup()
	}

	func (fn *prepareSumFn) ProcessElement(id beam.W, pair kv.Pair) (kv.Pair, beam.V, error) {
	var idBuf bytes.Buffer
	if err := fn.idEnc.Encode(id, &idBuf); err != nil {
	return kv.Pair{}, nil, fmt.Errorf("pbeam.prepareSumFn.ProcessElement: couldn't encode ID %v: %w", id, err)
	}
	_, v, err := fn.InputPairCodec.Decode(pair)
	return kv.Pair{idBuf.Bytes(), pair.K}, v, err
	}

	// findConvertFn gets the correct conversion to int64 or float64 function.
	func findConvertFn(t typex.FullType) (any, error) {
	switch t.Type().String() {
	case "int", "int8", "int16", "int32", "int64":
	return convertToInt64Fn, nil
	case "uint", "uint8", "uint16", "uint32", "uint64":
	return convertToInt64Fn, nil
	case "float32", "float64":
	return convertToFloat64Fn, nil
	default:
	return nil, fmt.Errorf("unexpected value type of %v", t)
	}
	}

	// getKind gets the return kind of the convertFn function.
	func getKind(fn any) (reflect.Kind, error) {
	if fn == nil {
	return reflect.Invalid, fmt.Errorf("convertFn is nil")
	}
	if reflect.TypeOf(fn).Kind() != reflect.Func {
	return reflect.Invalid, fmt.Errorf("convertFn is %v, should be a function", reflect.TypeOf(fn).Kind())
	}
	if reflect.TypeOf(fn).NumOut() < 2 {
	return reflect.Invalid, fmt.Errorf("convertFn has %v outputs, expected at least 2", reflect.TypeOf(fn).NumOut())
	}
	return reflect.TypeOf(fn).Out(1).Kind(), nil
	}

	func newAddNoiseToEmptyPublicPartitionsFn(epsilon, delta float64, maxPartitionsContributed int64, lower, upper float64, noiseKind noise.Kind, vKind reflect.Kind, testMode TestMode) (any, error) {
	var err error
	var bsFn any

	switch vKind {
	case reflect.Int64:
	err = checks.CheckBoundsFloat64AsInt64(lower, upper)
	bsFn = newAddNoiseToEmptyPublicPartitionsInt64Fn(epsilon, delta, maxPartitionsContributed, int64(lower), int64(upper), noiseKind, testMode)
	case reflect.Float64:
	err = checks.CheckBoundsFloat64(lower, upper)
	bsFn = newAddNoiseToEmptyPublicPartitionsFloat64Fn(epsilon, delta, maxPartitionsContributed, lower, upper, noiseKind, testMode)
	default:
	err = fmt.Errorf("vKind(%v) should be int64 or float64", vKind)
	}

	return bsFn, err
	}

	// addNoiseToEmptyPublicPartitionsInt64Fn adds integer noise to empty partitions.
	type addNoiseToEmptyPublicPartitionsInt64Fn struct {
	// Privacy spec parameters (set during initial construction).
	NoiseEpsilon float64
	NoiseDelta float64
	MaxPartitionsContributed int64
	Lower int64
	Upper int64
	NoiseKind noise.Kind
	noise noise.Noise // Set during Setup phase according to NoiseKind.
	TestMode TestMode
	}

	// newAddNoiseToEmptyPublicPartitionsInt64Fn returns a addNoiseToEmptyPublicPartitionsInt64Fn with the given budget and parameters.
	func newAddNoiseToEmptyPublicPartitionsInt64Fn(epsilon, delta float64, maxPartitionsContributed, lower, upper int64, noiseKind noise.Kind, testMode TestMode) *addNoiseToEmptyPublicPartitionsInt64Fn {
	return &addNoiseToEmptyPublicPartitionsInt64Fn{
	NoiseEpsilon: epsilon,
	NoiseDelta: delta,
	MaxPartitionsContributed: maxPartitionsContributed,
	Lower: lower,
	Upper: upper,
	NoiseKind: noiseKind,
	TestMode: testMode,
	}
	}

	func (fn *addNoiseToEmptyPublicPartitionsInt64Fn) Setup() {
	fn.noise = noise.ToNoise(fn.NoiseKind)
	if fn.TestMode.isEnabled() {
	fn.noise = noNoise{}
	}
	}

	func (fn *addNoiseToEmptyPublicPartitionsInt64Fn) ProcessElement(partitionKey beam.X, _ int64) (beam.X, int64, error) {
	bs, err := dpagg.NewBoundedSumInt64(&dpagg.BoundedSumInt64Options{
	Epsilon: fn.NoiseEpsilon,
	Delta: fn.NoiseDelta,
	MaxPartitionsContributed: fn.MaxPartitionsContributed,
	Lower: fn.Lower,
	Upper: fn.Upper,
	Noise: fn.noise,
	})
	if err != nil {
	return partitionKey, 0, err
	}
	noisedValue, err := bs.Result()
	return partitionKey, noisedValue, err
	}

	// addNoiseToEmptyPublicPartitionsFloat64Fn adds integer noise to empty partitions.
	type addNoiseToEmptyPublicPartitionsFloat64Fn struct {
	// Privacy spec parameters (set during initial construction).
	NoiseEpsilon float64
	NoiseDelta float64
	MaxPartitionsContributed int64
	Lower float64
	Upper float64
	NoiseKind noise.Kind
	noise noise.Noise // Set during Setup phase according to NoiseKind.
	TestMode TestMode
	}

	// newAddNoiseToEmptyPublicPartitionsFloat64Fn returns a addNoiseToEmptyPublicPartitionsFloat64Fn with the given budget and parameters.
	func newAddNoiseToEmptyPublicPartitionsFloat64Fn(epsilon, delta float64, maxPartitionsContributed int64, lower, upper float64, noiseKind noise.Kind, testMode TestMode) *addNoiseToEmptyPublicPartitionsFloat64Fn {
	return &addNoiseToEmptyPublicPartitionsFloat64Fn{
	NoiseEpsilon: epsilon,
	NoiseDelta: delta,
	MaxPartitionsContributed: maxPartitionsContributed,
	Lower: lower,
	Upper: upper,
	NoiseKind: noiseKind,
	TestMode: testMode,
	}
	}

	func (fn *addNoiseToEmptyPublicPartitionsFloat64Fn) Setup() {
	fn.noise = noise.ToNoise(fn.NoiseKind)
	if fn.TestMode.isEnabled() {
	fn.noise = noNoise{}
	}
	}

	func (fn *addNoiseToEmptyPublicPartitionsFloat64Fn) ProcessElement(partitionKey beam.X, _ float64) (beam.X, float64, error) {
	bs, err := dpagg.NewBoundedSumFloat64(&dpagg.BoundedSumFloat64Options{
	Epsilon: fn.NoiseEpsilon,
	Delta: fn.NoiseDelta,
	MaxPartitionsContributed: fn.MaxPartitionsContributed,
	Lower: fn.Lower,
	Upper: fn.Upper,
	Noise: fn.noise,
	})
	if err != nil {
	return partitionKey, 0, err
	}
	noisedValue, err := bs.Result()
	return partitionKey, noisedValue, err
	}