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aliases.go
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aliases.go
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// Copyright (C) 2019-2023, Ava Labs, Inc. All rights reserved.
// See the file LICENSE for licensing terms.
package ids
import (
"errors"
"fmt"
"sync"
)
var (
ErrNoIDWithAlias = errors.New("there is no ID with alias")
errNoAliasForID = errors.New("there is no alias for ID")
errAliasAlreadyMapped = errors.New("alias already mapped to an ID")
)
// AliaserReader allows one to lookup the aliases given to an ID.
type AliaserReader interface {
// Lookup returns the ID associated with alias
Lookup(alias string) (ID, error)
// PrimaryAlias returns the first alias of [id]
PrimaryAlias(id ID) (string, error)
// Aliases returns the aliases of an ID
Aliases(id ID) ([]string, error)
}
// AliaserWriter allows one to give an ID aliases. An ID can have arbitrarily
// many aliases; two IDs may not have the same alias.
type AliaserWriter interface {
// Alias gives [id] the alias [alias]
Alias(id ID, alias string) error
// RemoveAliases of the provided ID
RemoveAliases(id ID)
}
// Aliaser allows one to give an ID aliases and lookup the aliases given to an
// ID.
type Aliaser interface {
AliaserReader
AliaserWriter
// PrimaryAliasOrDefault returns the first alias of [id], or ID string as a
// default if no alias exists
PrimaryAliasOrDefault(id ID) string
}
type aliaser struct {
lock sync.RWMutex
dealias map[string]ID
aliases map[ID][]string
}
func NewAliaser() Aliaser {
return &aliaser{
dealias: make(map[string]ID),
aliases: make(map[ID][]string),
}
}
func (a *aliaser) Lookup(alias string) (ID, error) {
a.lock.RLock()
defer a.lock.RUnlock()
if id, ok := a.dealias[alias]; ok {
return id, nil
}
return ID{}, fmt.Errorf("%w: %s", ErrNoIDWithAlias, alias)
}
func (a *aliaser) PrimaryAlias(id ID) (string, error) {
a.lock.RLock()
defer a.lock.RUnlock()
aliases := a.aliases[id]
if len(aliases) == 0 {
return "", fmt.Errorf("%w: %s", errNoAliasForID, id)
}
return aliases[0], nil
}
func (a *aliaser) PrimaryAliasOrDefault(id ID) string {
alias, err := a.PrimaryAlias(id)
if err != nil {
return id.String()
}
return alias
}
func (a *aliaser) Aliases(id ID) ([]string, error) {
a.lock.RLock()
defer a.lock.RUnlock()
return a.aliases[id], nil
}
func (a *aliaser) Alias(id ID, alias string) error {
a.lock.Lock()
defer a.lock.Unlock()
if _, exists := a.dealias[alias]; exists {
return fmt.Errorf("%w: %s", errAliasAlreadyMapped, alias)
}
a.dealias[alias] = id
a.aliases[id] = append(a.aliases[id], alias)
return nil
}
func (a *aliaser) RemoveAliases(id ID) {
a.lock.Lock()
defer a.lock.Unlock()
aliases := a.aliases[id]
delete(a.aliases, id)
for _, alias := range aliases {
delete(a.dealias, alias)
}
}
// GetRelevantAliases returns the aliases with the redundant identity alias
// removed (each id is aliased to at least itself).
func GetRelevantAliases(aliaser Aliaser, ids []ID) (map[ID][]string, error) {
result := make(map[ID][]string, len(ids))
for _, id := range ids {
aliases, err := aliaser.Aliases(id)
if err != nil {
return nil, err
}
// remove the redundant alias where alias = id.
relevantAliases := make([]string, 0, len(aliases)-1)
for _, alias := range aliases {
if alias != id.String() {
relevantAliases = append(relevantAliases, alias)
}
}
result[id] = relevantAliases
}
return result, nil
}