63 lines
1.5 KiB
Go
63 lines
1.5 KiB
Go
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// Package uidstore provides a concurrency-safe two-way mapping between UIDs
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// used by the UI and arbitrary string keys as used by different mail backends.
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//
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// Multiple Store instances can safely be created and the UIDs that they
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// generate will be globally unique.
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package uidstore
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import (
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"sync"
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"sync/atomic"
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)
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var nextUID uint32 = 1
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// Store holds a mapping between application keys and globally-unique UIDs.
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type Store struct {
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keyByUID map[uint32]string
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uidByKey map[string]uint32
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m sync.Mutex
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}
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// NewStore creates a new, empty Store.
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func NewStore() *Store {
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return &Store{
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keyByUID: make(map[uint32]string),
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uidByKey: make(map[string]uint32),
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}
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}
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// GetOrInsert returns the UID for the provided key. If the key was already
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// present in the store, the same UID value is returned. Otherwise, the key is
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// inserted and the newly generated UID is returned.
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func (s *Store) GetOrInsert(key string) uint32 {
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s.m.Lock()
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defer s.m.Unlock()
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if uid, ok := s.uidByKey[key]; ok {
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return uid
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}
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uid := atomic.AddUint32(&nextUID, 1)
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s.keyByUID[uid] = key
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s.uidByKey[key] = uid
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return uid
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}
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// GetKey returns the key for the provided UID, if available.
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func (s *Store) GetKey(uid uint32) (string, bool) {
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s.m.Lock()
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defer s.m.Unlock()
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key, ok := s.keyByUID[uid]
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return key, ok
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}
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// RemoveUID removes the specified UID from the store.
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func (s *Store) RemoveUID(uid uint32) {
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s.m.Lock()
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defer s.m.Unlock()
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key, ok := s.keyByUID[uid]
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if ok {
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delete(s.uidByKey, key)
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}
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delete(s.keyByUID, uid)
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}
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