Remove unused factory pattern code from sampling strategy packages (#7705)

- [x] Verify that flagged functions are unused outside tests
- [x] Remove unused functions from adaptive/factory.go (entire file
deleted)
- [x] Remove unused functions from adaptive/options.go (AddFlags,
InitFromViper)
- [x] Remove unused functions from
adaptive/calculationstrategy/interface.go (CalculateFunc type)
- [x] Remove unused functions from file/factory.go (entire file deleted)
- [x] Remove unused functions from file/options.go (AddFlags,
InitFromViper)
- [x] Remove unused functions from file/provider.go (deepCopy)
- [x] Remove unused functions from metafactory/factory.go (entire
directory deleted)
- [x] Remove unused functions from metafactory/factory_config.go (entire
directory deleted)
- [x] Clean up unused imports after deletions
- [x] Remove metafactory references from cmd/internal/env/command.go
- [x] Remove test files that only tested deleted functions
- [x] Update remaining tests to not use deleted functions
- [x] Fix formatting issues
- [x] Remove unused defaultResourceName constant
- [x] Remove viper imports and constants no longer needed
- [x] Inline default constants into DefaultOptions()
- [x] Add unit test for DefaultOptions()
- [x] Build all binaries successfully (jaeger, remote-storage, and
others)
- [x] Run all tests successfully (sampling strategy, extension,
processor tests pass)
- [x] Lint passes with 0 issues

## Summary
Successfully removed all 25 unused functions flagged by the deadcode
detector plus additional cleanup:
- Deleted entire factory.go files from adaptive, file, and metafactory
packages
- Removed AddFlags and InitFromViper functions from options.go files
- Removed deepCopy function from file/provider.go
- Removed CalculateFunc type from interface.go
- Updated tests to use documented mock implementations
- Removed metafactory references from cmd/internal/env/command.go
- Removed viper imports and viper key constants that were only used by
deleted functions
- Inlined default constants directly into DefaultOptions() to reduce
mental overhead
- Added unit test for DefaultOptions() to provide test coverage
- All binaries build successfully
- All tests pass
- Linter passes with 0 issues

<!-- START COPILOT CODING AGENT SUFFIX -->



<!-- START COPILOT ORIGINAL PROMPT -->



<details>

<summary>Original prompt</summary>

> Deadcode detector tool flags the following functions as unused. Verify
that they are indeed not used outside of their internal unit tests and
delete them. Make sure all binaries build via `make build-binaries` and
all tests pass via `make tests`.
> 
> ```
> internal/sampling/samplingstrategy/adaptive/factory.go:37:6:
unreachable func: NewFactory
> internal/sampling/samplingstrategy/adaptive/factory.go:47:17:
unreachable func: Factory.AddFlags
> internal/sampling/samplingstrategy/adaptive/factory.go:52:19:
unreachable func: Factory.InitFromViper
> internal/sampling/samplingstrategy/adaptive/factory.go:57:19:
unreachable func: Factory.Initialize
> internal/sampling/samplingstrategy/adaptive/factory.go:83:19:
unreachable func: Factory.CreateStrategyProvider
> internal/sampling/samplingstrategy/adaptive/factory.go:97:19:
unreachable func: Factory.Close
> internal/sampling/samplingstrategy/adaptive/options.go:122:6:
unreachable func: AddFlags
>
internal/sampling/samplingstrategy/adaptive/calculationstrategy/interface.go:15:24:
unreachable func: CalculateFunc.Calculate
> internal/sampling/samplingstrategy/file/factory.go:26:6: unreachable
func: NewFactory
> internal/sampling/samplingstrategy/file/factory.go:34:17: unreachable
func: Factory.AddFlags
> internal/sampling/samplingstrategy/file/factory.go:39:19: unreachable
func: Factory.InitFromViper
> internal/sampling/samplingstrategy/file/factory.go:44:19: unreachable
func: Factory.Initialize
> internal/sampling/samplingstrategy/file/factory.go:50:19: unreachable
func: Factory.CreateStrategyProvider
> internal/sampling/samplingstrategy/file/factory.go:60:17: unreachable
func: Factory.Close
> internal/sampling/samplingstrategy/file/options.go:31:6: unreachable
func: AddFlags
> internal/sampling/samplingstrategy/file/provider.go:324:6: unreachable
func: deepCopy
> internal/sampling/samplingstrategy/metafactory/factory.go:45:6:
unreachable func: NewFactory
> internal/sampling/samplingstrategy/metafactory/factory.go:61:17:
unreachable func: Factory.getFactoryOfType
> internal/sampling/samplingstrategy/metafactory/factory.go:73:19:
unreachable func: Factory.AddFlags
> internal/sampling/samplingstrategy/metafactory/factory.go:82:19:
unreachable func: Factory.InitFromViper
> internal/sampling/samplingstrategy/metafactory/factory.go:91:19:
unreachable func: Factory.Initialize
> internal/sampling/samplingstrategy/metafactory/factory.go:101:19:
unreachable func: Factory.CreateStrategyProvider
> internal/sampling/samplingstrategy/metafactory/factory.go:110:19:
unreachable func: Factory.Close
> internal/sampling/samplingstrategy/metafactory/factory_config.go:24:6:
unreachable func: FactoryConfigFromEnv
> internal/sampling/samplingstrategy/metafactory/factory_config.go:36:6:
unreachable func: getStrategyStoreTypeFromEnv
> ```


</details>



<!-- START COPILOT CODING AGENT TIPS -->
---

💬 We'd love your input! Share your thoughts on Copilot coding agent in
our [2 minute survey](https://gh.io/copilot-coding-agent-survey).

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: yurishkuro <[email protected]>
Co-authored-by: Yuri Shkuro <[email protected]>

Author: Copilot

cmd/internal/env/command.go

@@ -10,7 +10,6 @@ import (
 	"github.com/spf13/cobra"
 	"github.com/spf13/pflag"
 
-	ss "github.com/jaegertracing/jaeger/internal/sampling/samplingstrategy/metafactory"
 	"github.com/jaegertracing/jaeger/internal/storage/metricstore"
 	storage "github.com/jaegertracing/jaeger/internal/storage/v1/factory"
 )
@@ -33,15 +32,6 @@ Multiple backends can be specified as comma-separated list, e.g. "cassandra,elas
 (currently only for writing spans). Note that "kafka" is only valid in jaeger-collector;
 it is not a replacement for a proper storage backend, and only used as a buffer for spans
 when Jaeger is deployed in the collector+ingester configuration.
-`
-
-	samplingTypeDescription = `The method [%s] used for determining the sampling rates served
-to clients configured with remote sampling enabled. "file" uses a periodically reloaded file and
-"adaptive" dynamically adjusts sampling rates based on current traffic.
-`
-
-	samplingStorageTypeDescription = `The type of backend [%s] used for adaptive sampling storage
-when adaptive sampling is enabled via %s.
 `
 
 	metricsStorageTypeDescription = `The type of backend [%s] used as a metrics store with
@@ -65,23 +55,6 @@ func Command() *cobra.Command {
 		"${SPAN_STORAGE_TYPE}",
 		"The type of backend used for service dependencies storage.",
 	)
-	fs.String(
-		ss.SamplingTypeEnvVar,
-		"file",
-		fmt.Sprintf(
-			strings.ReplaceAll(samplingTypeDescription, "\n", " "),
-			strings.Join(ss.AllSamplingTypes, ", "),
-		),
-	)
-	fs.String(
-		storage.SamplingStorageTypeEnvVar,
-		"",
-		fmt.Sprintf(
-			strings.ReplaceAll(samplingStorageTypeDescription, "\n", " "),
-			strings.Join(storage.AllSamplingStorageTypes(), ", "),
-			ss.SamplingTypeEnvVar,
-		),
-	)
 	fs.String(
 		metricstore.StorageTypeEnvVar,
 		"",

go.mod

@@ -157,8 +157,6 @@ require (
 require (
 	github.com/IBM/sarama v1.46.3 // indirect
 	github.com/alecthomas/participle/v2 v2.1.4 // indirect
-	github.com/alecthomas/units v0.0.0-20240927000941-0f3dac36c52b // indirect
-	github.com/andybalholm/brotli v1.2.0 // indirect
 	github.com/antchfx/xmlquery v1.5.0 // indirect
 	github.com/antchfx/xpath v1.3.5 // indirect
 	github.com/aws/aws-msk-iam-sasl-signer-go v1.0.4 // indirect
@@ -171,7 +169,6 @@ require (
 	github.com/aws/aws-sdk-go-v2/internal/ini v1.8.4 // indirect
 	github.com/aws/aws-sdk-go-v2/service/internal/accept-encoding v1.13.3 // indirect
 	github.com/aws/aws-sdk-go-v2/service/internal/presigned-url v1.13.14 // indirect
-	github.com/aws/aws-sdk-go-v2/service/signin v1.0.1 // indirect
 	github.com/aws/aws-sdk-go-v2/service/sso v1.30.4 // indirect
 	github.com/aws/aws-sdk-go-v2/service/ssooidc v1.35.9 // indirect
 	github.com/aws/aws-sdk-go-v2/service/sts v1.41.1 // indirect
@@ -182,7 +179,6 @@ require (
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/cpuguy83/go-md2man/v2 v2.0.6 // indirect
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
-	github.com/dennwc/varint v1.0.0 // indirect
 	github.com/dgraph-io/ristretto/v2 v2.2.0 // indirect
 	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/eapache/go-resiliency v1.7.0 // indirect
@@ -204,16 +200,11 @@ require (
 	github.com/gobwas/glob v0.2.3 // indirect
 	github.com/goccy/go-json v0.10.5 // indirect
 	github.com/gogo/googleapis v1.4.1 // indirect
-	github.com/golang-jwt/jwt/v5 v5.3.0 // indirect
 	github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da // indirect
 	github.com/golang/snappy v1.0.0 // indirect
 	github.com/google/flatbuffers v25.2.10+incompatible // indirect
 	github.com/google/go-tpm v0.9.7 // indirect
-	github.com/google/s2a-go v0.1.9 // indirect
 	github.com/google/uuid v1.6.0 // indirect
-	github.com/googleapis/enterprise-certificate-proxy v0.3.6 // indirect
-	github.com/googleapis/gax-go/v2 v2.15.0 // indirect
-	github.com/grafana/regexp v0.0.0-20250905093917-f7b3be9d1853 // indirect
 	github.com/grpc-ecosystem/grpc-gateway/v2 v2.27.2 // indirect
 	github.com/hailocab/go-hostpool v0.0.0-20160125115350-e80d13ce29ed // indirect
 	github.com/hashicorp/go-uuid v1.0.3 // indirect
@@ -229,15 +220,12 @@ require (
 	github.com/jcmturner/rpc/v2 v2.0.3 // indirect
 	github.com/jonboulle/clockwork v0.5.0 // indirect
 	github.com/josharian/intern v1.0.0 // indirect
-	github.com/jpillora/backoff v1.0.0 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect
 	github.com/klauspost/compress v1.18.1 // indirect
-	github.com/klauspost/cpuid/v2 v2.0.9 // indirect
 	github.com/knadh/koanf/maps v0.1.2 // indirect
 	github.com/knadh/koanf/providers/confmap v1.0.0 // indirect
 	github.com/knadh/koanf/v2 v2.3.0 // indirect
 	github.com/kr/text v0.2.0 // indirect
-	github.com/kylelemons/godebug v1.1.0 // indirect
 	github.com/lightstep/go-expohisto v1.0.0 // indirect
 	github.com/lufia/plan9stats v0.0.0-20220913051719-115f729f3c8c // indirect
 	github.com/magefile/mage v1.15.0 // indirect
@@ -251,7 +239,6 @@ require (
 	github.com/open-telemetry/opentelemetry-collector-contrib/internal/common v0.141.0 // indirect
 	github.com/open-telemetry/opentelemetry-collector-contrib/internal/coreinternal v0.141.0 // indirect
 	github.com/open-telemetry/opentelemetry-collector-contrib/internal/filter v0.141.0 // indirect
-	github.com/open-telemetry/opentelemetry-collector-contrib/internal/healthcheck v0.141.0 // indirect
 	github.com/open-telemetry/opentelemetry-collector-contrib/internal/kafka v0.141.0 // indirect
 	github.com/open-telemetry/opentelemetry-collector-contrib/internal/pdatautil v0.141.0 // indirect
 	github.com/open-telemetry/opentelemetry-collector-contrib/pkg/batchpersignal v0.141.0 // indirect
@@ -270,14 +257,10 @@ require (
 	github.com/paulmach/orb v0.11.1 // indirect
 	github.com/pelletier/go-toml/v2 v2.2.4 // indirect
 	github.com/pierrec/lz4/v4 v4.1.22 // indirect
-	github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c // indirect
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
 	github.com/power-devops/perfstat v0.0.0-20240221224432-82ca36839d55 // indirect
-	github.com/prometheus/otlptranslator v1.0.0 // indirect
 	github.com/prometheus/procfs v0.17.0 // indirect
-	github.com/prometheus/prometheus v0.307.3 // indirect
-	github.com/prometheus/sigv4 v0.2.1 // indirect
 	github.com/rcrowley/go-metrics v0.0.0-20250401214520-65e299d6c5c9 // indirect
 	github.com/relvacode/iso8601 v1.7.0 // indirect
 	github.com/rogpeppe/go-internal v1.14.1 // indirect
@@ -292,22 +275,18 @@ require (
 	github.com/spf13/cast v1.10.0 // indirect
 	github.com/stretchr/objx v0.5.2 // indirect
 	github.com/subosito/gotenv v1.6.0 // indirect
-	github.com/tg123/go-htpasswd v1.2.4 // indirect
 	github.com/tklauser/go-sysconf v0.3.15 // indirect
 	github.com/tklauser/numcpus v0.10.0 // indirect
 	github.com/twmb/franz-go v1.20.5 // indirect
-	github.com/twmb/franz-go/pkg/kadm v1.17.1 // indirect
 	github.com/twmb/franz-go/pkg/kmsg v1.12.0 // indirect
 	github.com/twmb/franz-go/pkg/sasl/kerberos v1.1.0 // indirect
 	github.com/twmb/franz-go/plugin/kzap v1.1.2 // indirect
 	github.com/twmb/murmur3 v1.1.8 // indirect
 	github.com/ua-parser/uap-go v0.0.0-20240611065828-3a4781585db6 // indirect
 	github.com/uber/jaeger-lib v2.4.1+incompatible // indirect
 	github.com/xdg-go/pbkdf2 v1.0.0 // indirect
-	github.com/xdg-go/scram v1.2.0 // indirect
 	github.com/xdg-go/stringprep v1.0.4 // indirect
 	github.com/yusufpapurcu/wmi v1.2.4 // indirect
-	github.com/zeebo/xxh3 v1.0.2 // indirect
 	go.opentelemetry.io/auto/sdk v1.2.1 // indirect
 	go.opentelemetry.io/collector v0.141.0 // indirect
 	go.opentelemetry.io/collector/config/configcompression v1.47.0 // indirect
@@ -339,7 +318,6 @@ require (
 	go.opentelemetry.io/collector/receiver/receiverhelper v0.141.0 // indirect
 	go.opentelemetry.io/collector/receiver/receivertest v0.141.0 // indirect
 	go.opentelemetry.io/collector/receiver/xreceiver v0.141.0 // indirect
-	go.opentelemetry.io/collector/semconv v0.128.1-0.20250610090210-188191247685 // indirect
 	go.opentelemetry.io/collector/service v0.141.0
 	go.opentelemetry.io/collector/service/hostcapabilities v0.141.0 // indirect
 	go.opentelemetry.io/contrib/bridges/otelzap v0.13.0 // indirect
@@ -357,22 +335,13 @@ require (
 	go.opentelemetry.io/proto/otlp v1.9.0 // indirect
 	go.uber.org/atomic v1.11.0 // indirect
 	go.uber.org/multierr v1.11.0 // indirect
-	go.yaml.in/yaml/v2 v2.4.3 // indirect
 	go.yaml.in/yaml/v3 v3.0.4
 	golang.org/x/crypto v0.45.0 // indirect
 	golang.org/x/exp v0.0.0-20251009144603-d2f985daa21b
-	golang.org/x/oauth2 v0.32.0 // indirect
 	golang.org/x/text v0.31.0 // indirect
-	golang.org/x/time v0.13.0 // indirect
 	gonum.org/v1/gonum v0.16.0 // indirect
-	google.golang.org/api v0.250.0 // indirect
 	google.golang.org/genproto/googleapis/api v0.0.0-20251022142026-3a174f9686a8 // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20251022142026-3a174f9686a8 // indirect
 	gopkg.in/inf.v0 v0.9.1 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
-	gopkg.in/yaml.v3 v3.0.1 // indirect
-	k8s.io/apimachinery v0.34.1 // indirect
-	k8s.io/client-go v0.34.1 // indirect
-	k8s.io/klog/v2 v2.130.1 // indirect
-	k8s.io/utils v0.0.0-20250604170112-4c0f3b243397 // indirect
 )

internal/sampling/samplingstrategy/adaptive/calculationstrategy/interface.go

@@ -7,11 +7,3 @@ package calculationstrategy
 type ProbabilityCalculator interface {
 	Calculate(targetQPS, curQPS, prevProbability float64) (newProbability float64)
 }
-
-// CalculateFunc wraps a function of appropriate signature and makes a ProbabilityCalculator from it.
-type CalculateFunc func(targetQPS, curQPS, prevProbability float64) (newProbability float64)
-
-// Calculate implements Calculator interface.
-func (c CalculateFunc) Calculate(targetQPS, curQPS, prevProbability float64) float64 {
-	return c(targetQPS, curQPS, prevProbability)
-}