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Merged
toddbaert merged 3 commits into from
Apr 1, 2026
Merged

feat!: fractional bucketing improvements #1909

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1e7175b
feat: high precision and nested fractional
toddbaert Feb 23, 2026
8d04a4f
fixup: update flagd-schemas to json-schema-v0.2.14
toddbaert Mar 30, 2026
5ac713a
fixup: update schema and fix clamping impl
toddbaert Mar 31, 2026
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5 changes: 3 additions & 2 deletions Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -52,8 +52,9 @@ flagd-benchmark-test:
flagd-integration-test-harness:
# target used to start a locally built flagd with the e2e flags
cd flagd; go run main.go start -f file:../test-harness/flags/testing-flags.json -f file:../test-harness/flags/custom-ops.json -f file:../test-harness/flags/evaluator-refs.json -f file:../test-harness/flags/zero-flags.json -f file:../test-harness/flags/edge-case-flags.json
flagd-integration-test: # dependent on flagd-e2e-test-harness if not running in github actions
go test -count=1 -cover ./test/integration $(ARGS)
flagd-integration-test: workspace-clean
# this is a intentionally an "orphaned" module so that it effectively does e2e testing independently of the rest of the code
cd test/integration && go test -count=1 -cover $(ARGS)
run: # default to flagd
make run-flagd
run-flagd:
Expand Down
2 changes: 1 addition & 1 deletion core/go.mod
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Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,7 @@ require (
buf.build/gen/go/open-feature/flagd/protocolbuffers/go v1.36.11-20260217192757-1388a552fc3c.1
connectrpc.com/connect v1.19.1
connectrpc.com/otelconnect v0.7.2
github.com/diegoholiveira/jsonlogic/v3 v3.8.4
github.com/diegoholiveira/jsonlogic/v3 v3.9.0
github.com/fsnotify/fsnotify v1.9.0
github.com/google/go-cmp v0.7.0
github.com/google/uuid v1.6.0
Expand Down
46 changes: 4 additions & 42 deletions core/go.sum
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Original file line number Diff line number Diff line change
Expand Up @@ -117,8 +117,8 @@ github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc h1:U9qPSI2PIWSS1
github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f h1:lO4WD4F/rVNCu3HqELle0jiPLLBs70cWOduZpkS1E78=
github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f/go.mod h1:cuUVRXasLTGF7a8hSLbxyZXjz+1KgoB3wDUb6vlszIc=
github.com/diegoholiveira/jsonlogic/v3 v3.8.4 h1:IVVU/VLz2hn10ImbmibjiUkdVsSFIB1vfDaOVsaipH4=
github.com/diegoholiveira/jsonlogic/v3 v3.8.4/go.mod h1:OYRb6FSTVmMM+MNQ7ElmMsczyNSepw+OU4Z8emDSi4w=
github.com/diegoholiveira/jsonlogic/v3 v3.9.0 h1:ZYx6tM8+1NRo0RwFpBmVxtmJnXs/f3rtIZo9t9dCk3Y=
github.com/diegoholiveira/jsonlogic/v3 v3.9.0/go.mod h1:OYRb6FSTVmMM+MNQ7ElmMsczyNSepw+OU4Z8emDSi4w=
github.com/dlclark/regexp2 v1.11.0 h1:G/nrcoOa7ZXlpoa/91N3X7mM3r8eIlMBBJZvsz/mxKI=
github.com/dlclark/regexp2 v1.11.0/go.mod h1:DHkYz0B9wPfa6wondMfaivmHpzrQ3v9q8cnmRbL6yW8=
github.com/emicklei/go-restful/v3 v3.12.0 h1:y2DdzBAURM29NFF94q6RaY4vjIH1rtwDapwQtU84iWk=
Expand Down Expand Up @@ -336,78 +336,42 @@ go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.6
go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.60.0/go.mod h1:rg+RlpR5dKwaS95IyyZqj5Wd4E13lk/msnTS0Xl9lJM=
go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.62.0 h1:Hf9xI/XLML9ElpiHVDNwvqI0hIFlzV8dgIr35kV1kRU=
go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.62.0/go.mod h1:NfchwuyNoMcZ5MLHwPrODwUF1HWCXWrL31s8gSAdIKY=
go.opentelemetry.io/otel v1.40.0 h1:oA5YeOcpRTXq6NN7frwmwFR0Cn3RhTVZvXsP4duvCms=
go.opentelemetry.io/otel v1.40.0/go.mod h1:IMb+uXZUKkMXdPddhwAHm6UfOwJyh4ct1ybIlV14J0g=
go.opentelemetry.io/otel v1.42.0 h1:lSQGzTgVR3+sgJDAU/7/ZMjN9Z+vUip7leaqBKy4sho=
go.opentelemetry.io/otel v1.42.0/go.mod h1:lJNsdRMxCUIWuMlVJWzecSMuNjE7dOYyWlqOXWkdqCc=
go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc v0.14.0 h1:OMqPldHt79PqWKOMYIAQs3CxAi7RLgPxwfFSwr4ZxtM=
go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc v0.14.0/go.mod h1:1biG4qiqTxKiUCtoWDPpL3fB3KxVwCiGw81j3nKMuHE=
go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc v0.18.0 h1:deI9UQMoGFgrg5iLPgzueqFPHevDl+28YKfSpPTI6rY=
go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc v0.18.0/go.mod h1:PFx9NgpNUKXdf7J4Q3agRxMs3Y07QhTCVipKmLsMKnU=
go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploghttp v0.14.0 h1:QQqYw3lkrzwVsoEX0w//EhH/TCnpRdEenKBOOEIMjWc=
go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploghttp v0.14.0/go.mod h1:gSVQcr17jk2ig4jqJ2DX30IdWH251JcNAecvrqTxH1s=
go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploghttp v0.18.0 h1:icqq3Z34UrEFk2u+HMhTtRsvo7Ues+eiJVjaJt62njs=
go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploghttp v0.18.0/go.mod h1:W2m8P+d5Wn5kipj4/xmbt9uMqezEKfBjzVJadfABSBE=
go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc v1.40.0 h1:NOyNnS19BF2SUDApbOKbDtWZ0IK7b8FJ2uAGdIWOGb0=
go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc v1.40.0/go.mod h1:VL6EgVikRLcJa9ftukrHu/ZkkhFBSo1lzvdBC9CF1ss=
go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc v1.42.0 h1:MdKucPl/HbzckWWEisiNqMPhRrAOQX8r4jTuGr636gk=
go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc v1.42.0/go.mod h1:RolT8tWtfHcjajEH5wFIZ4Dgh5jpPdFXYV9pTAk/qjc=
go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp v1.40.0 h1:9y5sHvAxWzft1WQ4BwqcvA+IFVUJ1Ya75mSAUnFEVwE=
go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp v1.40.0/go.mod h1:eQqT90eR3X5Dbs1g9YSM30RavwLF725Ris5/XSXWvqE=
go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp v1.42.0 h1:H7O6RlGOMTizyl3R08Kn5pdM06bnH8oscSj7o11tmLA=
go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp v1.42.0/go.mod h1:mBFWu/WOVDkWWsR7Tx7h6EpQB8wsv7P0Yrh0Pb7othc=
go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.40.0 h1:QKdN8ly8zEMrByybbQgv8cWBcdAarwmIPZ6FThrWXJs=
go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.40.0/go.mod h1:bTdK1nhqF76qiPoCCdyFIV+N/sRHYXYCTQc+3VCi3MI=
go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.42.0 h1:THuZiwpQZuHPul65w4WcwEnkX2QIuMT+UFoOrygtoJw=
go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.42.0/go.mod h1:J2pvYM5NGHofZ2/Ru6zw/TNWnEQp5crgyDeSrYpXkAw=
go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.40.0 h1:DvJDOPmSWQHWywQS6lKL+pb8s3gBLOZUtw4N+mavW1I=
go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.40.0/go.mod h1:EtekO9DEJb4/jRyN4v4Qjc2yA7AtfCBuz2FynRUWTXs=
go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.42.0 h1:zWWrB1U6nqhS/k6zYB74CjRpuiitRtLLi68VcgmOEto=
go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.42.0/go.mod h1:2qXPNBX1OVRC0IwOnfo1ljoid+RD0QK3443EaqVlsOU=
go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.40.0 h1:wVZXIWjQSeSmMoxF74LzAnpVQOAFDo3pPji9Y4SOFKc=
go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.40.0/go.mod h1:khvBS2IggMFNwZK/6lEeHg/W57h/IX6J4URh57fuI40=
go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.42.0 h1:uLXP+3mghfMf7XmV4PkGfFhFKuNWoCvvx5wP/wOXo0o=
go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.42.0/go.mod h1:v0Tj04armyT59mnURNUJf7RCKcKzq+lgJs6QSjHjaTc=
go.opentelemetry.io/otel/exporters/prometheus v0.60.0 h1:cGtQxGvZbnrWdC2GyjZi0PDKVSLWP/Jocix3QWfXtbo=
go.opentelemetry.io/otel/exporters/prometheus v0.60.0/go.mod h1:hkd1EekxNo69PTV4OWFGZcKQiIqg0RfuWExcPKFvepk=
go.opentelemetry.io/otel/exporters/prometheus v0.64.0 h1:g0LRDXMX/G1SEZtK8zl8Chm4K6GBwRkjPKE36LxiTYs=
go.opentelemetry.io/otel/exporters/prometheus v0.64.0/go.mod h1:UrgcjnarfdlBDP3GjDIJWe6HTprwSazNjwsI+Ru6hro=
go.opentelemetry.io/otel/exporters/stdout/stdoutlog v0.14.0 h1:B/g+qde6Mkzxbry5ZZag0l7QrQBCtVm7lVjaLgmpje8=
go.opentelemetry.io/otel/exporters/stdout/stdoutlog v0.14.0/go.mod h1:mOJK8eMmgW6ocDJn6Bn11CcZ05gi3P8GylBXEkZtbgA=
go.opentelemetry.io/otel/exporters/stdout/stdoutlog v0.18.0 h1:KJVjPD3rcPb98rIs3HznyJlrfx9ge5oJvxxlGR+P/7s=
go.opentelemetry.io/otel/exporters/stdout/stdoutlog v0.18.0/go.mod h1:K3kRa2ckmHWQaTWQdPRHc7qGXASuVuoEQXzrvlA98Ws=
go.opentelemetry.io/otel/exporters/stdout/stdoutmetric v1.40.0 h1:ZrPRak/kS4xI3AVXy8F7pipuDXmDsrO8Lg+yQjBLjw0=
go.opentelemetry.io/otel/exporters/stdout/stdoutmetric v1.40.0/go.mod h1:3y6kQCWztq6hyW8Z9YxQDDm0Je9AJoFar2G0yDcmhRk=
go.opentelemetry.io/otel/exporters/stdout/stdoutmetric v1.42.0 h1:lSZHgNHfbmQTPfuTmWVkEu8J8qXaQwuV30pjCcAUvP8=
go.opentelemetry.io/otel/exporters/stdout/stdoutmetric v1.42.0/go.mod h1:so9ounLcuoRDu033MW/E0AD4hhUjVqswrMF5FoZlBcw=
go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.40.0 h1:MzfofMZN8ulNqobCmCAVbqVL5syHw+eB2qPRkCMA/fQ=
go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.40.0/go.mod h1:E73G9UFtKRXrxhBsHtG00TB5WxX57lpsQzogDkqBTz8=
go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.42.0 h1:s/1iRkCKDfhlh1JF26knRneorus8aOwVIDhvYx9WoDw=
go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.42.0/go.mod h1:UI3wi0FXg1Pofb8ZBiBLhtMzgoTm1TYkMvn71fAqDzs=
go.opentelemetry.io/otel/log v0.14.0 h1:2rzJ+pOAZ8qmZ3DDHg73NEKzSZkhkGIua9gXtxNGgrM=
go.opentelemetry.io/otel/log v0.14.0/go.mod h1:5jRG92fEAgx0SU/vFPxmJvhIuDU9E1SUnEQrMlJpOno=
go.opentelemetry.io/otel/log v0.18.0 h1:XgeQIIBjZZrliksMEbcwMZefoOSMI1hdjiLEiiB0bAg=
go.opentelemetry.io/otel/log v0.18.0/go.mod h1:KEV1kad0NofR3ycsiDH4Yjcoj0+8206I6Ox2QYFSNgI=
go.opentelemetry.io/otel/metric v1.40.0 h1:rcZe317KPftE2rstWIBitCdVp89A2HqjkxR3c11+p9g=
go.opentelemetry.io/otel/metric v1.40.0/go.mod h1:ib/crwQH7N3r5kfiBZQbwrTge743UDc7DTFVZrrXnqc=
go.opentelemetry.io/otel/metric v1.42.0 h1:2jXG+3oZLNXEPfNmnpxKDeZsFI5o4J+nz6xUlaFdF/4=
go.opentelemetry.io/otel/metric v1.42.0/go.mod h1:RlUN/7vTU7Ao/diDkEpQpnz3/92J9ko05BIwxYa2SSI=
go.opentelemetry.io/otel/sdk v1.40.0 h1:KHW/jUzgo6wsPh9At46+h4upjtccTmuZCFAc9OJ71f8=
go.opentelemetry.io/otel/sdk v1.40.0/go.mod h1:Ph7EFdYvxq72Y8Li9q8KebuYUr2KoeyHx0DRMKrYBUE=
go.opentelemetry.io/otel/sdk v1.42.0 h1:LyC8+jqk6UJwdrI/8VydAq/hvkFKNHZVIWuslJXYsDo=
go.opentelemetry.io/otel/sdk v1.42.0/go.mod h1:rGHCAxd9DAph0joO4W6OPwxjNTYWghRWmkHuGbayMts=
go.opentelemetry.io/otel/sdk/log v0.14.0 h1:JU/U3O7N6fsAXj0+CXz21Czg532dW2V4gG1HE/e8Zrg=
go.opentelemetry.io/otel/sdk/log v0.14.0/go.mod h1:imQvII+0ZylXfKU7/wtOND8Hn4OpT3YUoIgqJVksUkM=
go.opentelemetry.io/otel/sdk/log v0.18.0 h1:n8OyZr7t7otkeTnPTbDNom6rW16TBYGtvyy2Gk6buQw=
go.opentelemetry.io/otel/sdk/log v0.18.0/go.mod h1:C0+wxkTwKpOCZLrlJ3pewPiiQwpzycPI/u6W0Z9fuYk=
go.opentelemetry.io/otel/sdk/log/logtest v0.14.0 h1:Ijbtz+JKXl8T2MngiwqBlPaHqc4YCaP/i13Qrow6gAM=
go.opentelemetry.io/otel/sdk/log/logtest v0.14.0/go.mod h1:dCU8aEL6q+L9cYTqcVOk8rM9Tp8WdnHOPLiBgp0SGOA=
go.opentelemetry.io/otel/sdk/metric v1.40.0 h1:mtmdVqgQkeRxHgRv4qhyJduP3fYJRMX4AtAlbuWdCYw=
go.opentelemetry.io/otel/sdk/metric v1.40.0/go.mod h1:4Z2bGMf0KSK3uRjlczMOeMhKU2rhUqdWNoKcYrtcBPg=
go.opentelemetry.io/otel/sdk/log/logtest v0.18.0 h1:l3mYuPsuBx6UKE47BVcPrZoZ0q/KER57vbj2qkgDLXA=
go.opentelemetry.io/otel/sdk/log/logtest v0.18.0/go.mod h1:7cHtiVJpZebB3wybTa4NG+FUo5NPe3PROz1FqB0+qdw=
go.opentelemetry.io/otel/sdk/metric v1.42.0 h1:D/1QR46Clz6ajyZ3G8SgNlTJKBdGp84q9RKCAZ3YGuA=
go.opentelemetry.io/otel/sdk/metric v1.42.0/go.mod h1:Ua6AAlDKdZ7tdvaQKfSmnFTdHx37+J4ba8MwVCYM5hc=
go.opentelemetry.io/otel/trace v1.40.0 h1:WA4etStDttCSYuhwvEa8OP8I5EWu24lkOzp+ZYblVjw=
go.opentelemetry.io/otel/trace v1.40.0/go.mod h1:zeAhriXecNGP/s2SEG3+Y8X9ujcJOTqQ5RgdEJcawiA=
go.opentelemetry.io/otel/trace v1.42.0 h1:OUCgIPt+mzOnaUTpOQcBiM/PLQ/Op7oq6g4LenLmOYY=
go.opentelemetry.io/otel/trace v1.42.0/go.mod h1:f3K9S+IFqnumBkKhRJMeaZeNk9epyhnCmQh/EysQCdc=
go.opentelemetry.io/proto/otlp v1.9.0 h1:l706jCMITVouPOqEnii2fIAuO3IVGBRPV5ICjceRb/A=
Expand Down Expand Up @@ -553,8 +517,6 @@ google.golang.org/grpc v1.23.0/go.mod h1:Y5yQAOtifL1yxbo5wqy6BxZv8vAUGQwXBOALyac
google.golang.org/grpc v1.25.1/go.mod h1:c3i+UQWmh7LiEpx4sFZnkU36qjEYZ0imhYfXVyQciAY=
google.golang.org/grpc v1.27.0/go.mod h1:qbnxyOmOxrQa7FizSgH+ReBfzJrCY1pSN7KXBS8abTk=
google.golang.org/grpc v1.33.2/go.mod h1:JMHMWHQWaTccqQQlmk3MJZS+GWXOdAesneDmEnv2fbc=
google.golang.org/grpc v1.79.2 h1:fRMD94s2tITpyJGtBBn7MkMseNpOZU8ZxgC3MMBaXRU=
google.golang.org/grpc v1.79.2/go.mod h1:KmT0Kjez+0dde/v2j9vzwoAScgEPx/Bw1CYChhHLrHQ=
google.golang.org/grpc v1.79.3 h1:sybAEdRIEtvcD68Gx7dmnwjZKlyfuc61Dyo9pGXXkKE=
google.golang.org/grpc v1.79.3/go.mod h1:KmT0Kjez+0dde/v2j9vzwoAScgEPx/Bw1CYChhHLrHQ=
google.golang.org/protobuf v0.0.0-20200109180630-ec00e32a8dfd/go.mod h1:DFci5gLYBciE7Vtevhsrf46CRTquxDuWsQurQQe4oz8=
Expand Down
118 changes: 86 additions & 32 deletions core/pkg/evaluator/fractional.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -9,23 +9,27 @@
"github.com/twmb/murmur3"
)

const maxWeightSum = math.MaxInt32 // 2,147,483,647

const FractionEvaluationName = "fractional"

type Fractional struct {
Logger *logger.Logger
}

type fractionalEvaluationDistribution struct {
totalWeight int
totalWeight int32
weightedVariants []fractionalEvaluationVariant
data any
logger *logger.Logger
}

type fractionalEvaluationVariant struct {
variant string
weight int
variant any // string, bool, number or nil
weight int32
}

func (v fractionalEvaluationVariant) getPercentage(totalWeight int) float64 {
func (v fractionalEvaluationVariant) getPercentage(totalWeight int32) float64 {
if totalWeight == 0 {
return 0
}
Expand All @@ -38,16 +42,17 @@
}

func (fe *Fractional) Evaluate(values, data any) any {
valueToDistribute, feDistributions, err := parseFractionalEvaluationData(values, data)
valueToDistribute, feDistributions, err := parseFractionalEvaluationData(values, data, fe.Logger)
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@gemini-code-assist gemini-code-assist bot Mar 20, 2026

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medium

The fe.Logger is passed as an argument to parseFractionalEvaluationData. This is good for testability and dependency injection.

if err != nil {
fe.Logger.Warn(fmt.Sprintf("parse fractional evaluation data: %v", err))
return nil
}

return distributeValue(valueToDistribute, feDistributions)
hashValue := uint32(murmur3.StringSum32(valueToDistribute))
return distributeValue(hashValue, feDistributions)
Comment on lines +51 to +52
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medium

The hashing of the valueToDistribute is now done in the Evaluate function rather than in the distributeValue function. This centralizes the hashing logic and makes the distributeValue function more focused on its core task.

}

func parseFractionalEvaluationData(values, data any) (string, *fractionalEvaluationDistribution, error) {
func parseFractionalEvaluationData(values, data any, logger *logger.Logger) (string, *fractionalEvaluationDistribution, error) {
valuesArray, ok := values.([]any)
if !ok {
return "", nil, errors.New("fractional evaluation data is not an array")
Expand All @@ -61,9 +66,8 @@
return "", nil, errors.New("data isn't of type map[string]any")
}

// Ignore the error as we can't really do anything if the properties are
// somehow missing.
properties, _ := getFlagdProperties(dataMap)
flagKey := properties.FlagKey

bucketBy, ok := valuesArray[0].(string)
if ok {
Expand All @@ -76,73 +80,123 @@

targetingKey, ok := dataMap[targetingKeyKey].(string)
if !ok {
return "", nil, errors.New("bucketing value not supplied and no targetingKey in context")
return "", nil, fmt.Errorf("flag %q: bucketing value not supplied and no targetingKey in context", flagKey)
}

bucketBy = fmt.Sprintf("%s%s", properties.FlagKey, targetingKey)
}

feDistributions, err := parseFractionalEvaluationDistributions(valuesArray)
feDistributions, err := parseFractionalEvaluationDistributions(valuesArray, data, logger, flagKey)
if err != nil {
return "", nil, err
}

return bucketBy, feDistributions, nil
}

func parseFractionalEvaluationDistributions(values []any) (*fractionalEvaluationDistribution, error) {
func parseFractionalEvaluationDistributions(values []any, data any, logger *logger.Logger, flagKey string) (*fractionalEvaluationDistribution, error) {

Check failure on line 97 in core/pkg/evaluator/fractional.go

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SonarQubeCloud / SonarCloud Code Analysis

Refactor this method to reduce its Cognitive Complexity from 27 to the 15 allowed. 


See more on https://sonarcloud.io/project/issues?id=open-feature_flagd&issues=AZ0MscyArpT77nGxkKX3&open=AZ0MscyArpT77nGxkKX3&pullRequest=1909
feDistributions := &fractionalEvaluationDistribution{
totalWeight: 0,
weightedVariants: make([]fractionalEvaluationVariant, len(values)),
data: data,
logger: logger,
}

// parse all weights first to validate the sum
var totalWeightInt64 int64 = 0

for i := 0; i < len(values); i++ {
distributionArray, ok := values[i].([]any)
if !ok {
return nil, errors.New("distribution elements aren't of type []any. " +
"please check your rule in flag definition")
return nil, fmt.Errorf("flag %q: distribution elements aren't of type []any. "+
"please check your rule in flag definition", flagKey)
}

if len(distributionArray) == 0 {
return nil, errors.New("distribution element needs at least one element")
return nil, fmt.Errorf("flag %q: distribution element needs at least one element", flagKey)
}

variant, ok := distributionArray[0].(string)
if !ok {
return nil, errors.New("first element of distribution element isn't string")
// JSONLogic pre-evaluates all arguments before they reach fractional.
// Pre-evaluated operators become primitive values (strings, numbers, etc.), never map[string]any nodes.
var variant any
switch v := distributionArray[0].(type) {
case string:
variant = v
case bool:
variant = v
case float64:
variant = v
case nil:
variant = nil
default:
return nil, fmt.Errorf("flag %q: first element of distribution element must be a string, bool, number, or nil", flagKey)
}

weight := 1.0
weight := int64(1)
if len(distributionArray) >= 2 {
// parse as float64 first since that's what JSON gives us
distributionWeight, ok := distributionArray[1].(float64)
if !ok && distributionArray[1] != nil {
return nil, fmt.Errorf("flag %q: weight must be a number", flagKey)
}
if ok {
// default the weight to 1 if not specified explicitly
weight = distributionWeight
weight = int64(distributionWeight)
}
}

// validate weight is a whole number
if len(distributionArray) >= 2 {
distributionWeight, ok := distributionArray[1].(float64)
if ok && distributionWeight != float64(int64(distributionWeight)) {
return nil, fmt.Errorf("flag %q: weights must be integers", flagKey)
}
}

feDistributions.totalWeight += int(weight)
// validate individual weight doesn't exceed int32
if weight > math.MaxInt32 {
return nil, fmt.Errorf("flag %q: weight %d exceeds maximum allowed value %d", flagKey, weight, math.MaxInt32)
}

// clamp negative weights to 0
if weight < 0 {
// negative weights can be the result of rollout calculations, so we log and clamp to 0 rather than returning an error
logger.Debug(fmt.Sprintf("flag %q: negative weight %d clamped to 0", flagKey, weight))
weight = 0
}

totalWeightInt64 += weight
feDistributions.weightedVariants[i] = fractionalEvaluationVariant{
variant: variant,
weight: int(weight),
weight: int32(weight),
}
}

// validate total weight doesn't exceed MaxInt32
if totalWeightInt64 > int64(maxWeightSum) {
return nil, fmt.Errorf("flag %q: sum of all weights (%d) exceeds maximum allowed value (%d)", flagKey, totalWeightInt64, maxWeightSum)
}

feDistributions.totalWeight = int32(totalWeightInt64)
return feDistributions, nil
}

// distributeValue calculate hash for given hash key and find the bucket distributions belongs to
func distributeValue(value string, feDistribution *fractionalEvaluationDistribution) string {
hashValue := int32(murmur3.StringSum32(value))
hashRatio := math.Abs(float64(hashValue)) / math.MaxInt32
bucket := hashRatio * 100 // in range [0, 100]
// distributeValue accepts a pre-computed 32-bit hash value and distributes it to a variant using high-precision integer arithmetic.
// It maps a 32-bit hash to the range [0, totalWeight) and finds the variant bucket that contains that value.
func distributeValue(hashValue uint32, feDistribution *fractionalEvaluationDistribution) any {
if feDistribution.totalWeight == 0 {
return ""
}

bucket := (uint64(hashValue) * uint64(feDistribution.totalWeight)) >> 32
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@gemini-code-assist gemini-code-assist bot Mar 20, 2026

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medium

This calculation is the core of the high-precision fractional bucketing. It uses integer arithmetic to map the hash value to a bucket within the range [0, totalWeight).

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@toddbaert toddbaert Mar 20, 2026

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Weird that gemini seems to just be making a lot of these observational comment lately.


rangeEnd := float64(0)
for _, weightedVariant := range feDistribution.weightedVariants {
rangeEnd += weightedVariant.getPercentage(feDistribution.totalWeight)
var rangeEnd uint64 = 0
for _, variant := range feDistribution.weightedVariants {
rangeEnd += uint64(variant.weight)
if bucket < rangeEnd {
return weightedVariant.variant
return variant.variant
}
}

// unreachable given validation
return ""
}
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