VictoriaMetrics/vendor/go.opentelemetry.io/collector/featuregate/registry.go

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2024-01-26 21:56:37 +00:00
// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
package featuregate // import "go.opentelemetry.io/collector/featuregate"
import (
"fmt"
"net/url"
"regexp"
"sort"
"sync"
"sync/atomic"
"github.com/hashicorp/go-version"
)
var (
globalRegistry = NewRegistry()
// idRegexp is used to validate the ID of a Gate.
// IDs' characters must be alphanumeric or dots.
idRegexp = regexp.MustCompile(`^[0-9a-zA-Z\.]*$`)
)
// GlobalRegistry returns the global Registry.
func GlobalRegistry() *Registry {
return globalRegistry
}
type Registry struct {
gates sync.Map
}
// NewRegistry returns a new empty Registry.
func NewRegistry() *Registry {
return &Registry{}
}
// RegisterOption allows to configure additional information about a Gate during registration.
type RegisterOption interface {
apply(g *Gate) error
}
type registerOptionFunc func(g *Gate) error
func (ro registerOptionFunc) apply(g *Gate) error {
return ro(g)
}
// WithRegisterDescription adds description for the Gate.
func WithRegisterDescription(description string) RegisterOption {
return registerOptionFunc(func(g *Gate) error {
g.description = description
return nil
})
}
// WithRegisterReferenceURL adds a URL that has all the contextual information about the Gate.
// referenceURL must be a valid URL as defined by `net/url.Parse`.
func WithRegisterReferenceURL(referenceURL string) RegisterOption {
return registerOptionFunc(func(g *Gate) error {
if _, err := url.Parse(referenceURL); err != nil {
return fmt.Errorf("WithRegisterReferenceURL: invalid reference URL %q: %w", referenceURL, err)
}
g.referenceURL = referenceURL
return nil
})
}
// WithRegisterFromVersion is used to set the Gate "FromVersion".
// The "FromVersion" contains the Collector release when a feature is introduced.
// fromVersion must be a valid version string: it may start with 'v' and must be in the format Major.Minor.Patch[-PreRelease].
// PreRelease is optional and may have dashes, tildes and ASCII alphanumeric characters.
func WithRegisterFromVersion(fromVersion string) RegisterOption {
return registerOptionFunc(func(g *Gate) error {
from, err := version.NewVersion(fromVersion)
if err != nil {
return fmt.Errorf("WithRegisterFromVersion: invalid version %q: %w", fromVersion, err)
}
g.fromVersion = from
return nil
})
}
// WithRegisterToVersion is used to set the Gate "ToVersion".
// The "ToVersion", if not empty, contains the last Collector release in which you can still use a feature gate.
// If the feature stage is either "Deprecated" or "Stable", the "ToVersion" is the Collector release when the feature is removed.
// toVersion must be a valid version string: it may start with 'v' and must be in the format Major.Minor.Patch[-PreRelease].
// PreRelease is optional and may have dashes, tildes and ASCII alphanumeric characters.
func WithRegisterToVersion(toVersion string) RegisterOption {
return registerOptionFunc(func(g *Gate) error {
to, err := version.NewVersion(toVersion)
if err != nil {
return fmt.Errorf("WithRegisterToVersion: invalid version %q: %w", toVersion, err)
}
g.toVersion = to
return nil
})
}
// MustRegister like Register but panics if an invalid ID or gate options are provided.
func (r *Registry) MustRegister(id string, stage Stage, opts ...RegisterOption) *Gate {
g, err := r.Register(id, stage, opts...)
if err != nil {
panic(err)
}
return g
}
func validateID(id string) error {
if id == "" {
return fmt.Errorf("empty ID")
}
if !idRegexp.MatchString(id) {
return fmt.Errorf("invalid character(s) in ID")
}
return nil
}
// Register a Gate and return it. The returned Gate can be used to check if is enabled or not.
// id must be an ASCII alphanumeric nonempty string. Dots are allowed for namespacing.
func (r *Registry) Register(id string, stage Stage, opts ...RegisterOption) (*Gate, error) {
if err := validateID(id); err != nil {
return nil, fmt.Errorf("invalid ID %q: %w", id, err)
}
g := &Gate{
id: id,
stage: stage,
}
for _, opt := range opts {
err := opt.apply(g)
if err != nil {
return nil, fmt.Errorf("failed to apply option: %w", err)
}
}
switch g.stage {
case StageAlpha, StageDeprecated:
g.enabled = &atomic.Bool{}
case StageBeta, StageStable:
enabled := &atomic.Bool{}
enabled.Store(true)
g.enabled = enabled
default:
return nil, fmt.Errorf("unknown stage value %q for gate %q", stage, id)
}
if (g.stage == StageStable || g.stage == StageDeprecated) && g.toVersion == nil {
return nil, fmt.Errorf("no removal version set for %v gate %q", g.stage.String(), id)
}
if g.fromVersion != nil && g.toVersion != nil && g.toVersion.LessThan(g.fromVersion) {
return nil, fmt.Errorf("toVersion %q is before fromVersion %q", g.toVersion, g.fromVersion)
}
if _, loaded := r.gates.LoadOrStore(id, g); loaded {
return nil, fmt.Errorf("attempted to add pre-existing gate %q", id)
}
return g, nil
}
// Set the enabled valued for a Gate identified by the given id.
func (r *Registry) Set(id string, enabled bool) error {
v, ok := r.gates.Load(id)
if !ok {
validGates := []string{}
r.VisitAll(func(g *Gate) {
validGates = append(validGates, g.ID())
})
return fmt.Errorf("no such feature gate %q. valid gates: %v", id, validGates)
}
g := v.(*Gate)
switch g.stage {
case StageStable:
if !enabled {
return fmt.Errorf("feature gate %q is stable, can not be disabled", id)
}
fmt.Printf("Feature gate %q is stable and already enabled. It will be removed in version %v and continued use of the gate after version %v will result in an error.\n", id, g.toVersion, g.toVersion)
case StageDeprecated:
if enabled {
return fmt.Errorf("feature gate %q is deprecated, can not be enabled", id)
}
fmt.Printf("Feature gate %q is deprecated and already disabled. It will be removed in version %v and continued use of the gate after version %v will result in an error.\n", id, g.toVersion, g.toVersion)
default:
g.enabled.Store(enabled)
}
return nil
}
// VisitAll visits all the gates in lexicographical order, calling fn for each.
func (r *Registry) VisitAll(fn func(*Gate)) {
var gates []*Gate
r.gates.Range(func(key, value any) bool {
gates = append(gates, value.(*Gate))
return true
})
sort.Slice(gates, func(i, j int) bool {
return gates[i].ID() < gates[j].ID()
})
for i := range gates {
fn(gates[i])
}
}