74 lines
1.2 KiB
Go
74 lines
1.2 KiB
Go
package utils
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import (
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"sync"
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"time"
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)
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func zilch[T any]() T {
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var zero T
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return zero
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}
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type DecayMap[K comparable, V any] struct {
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data map[K]DecayMapEntry[V]
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lock sync.RWMutex
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}
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type DecayMapEntry[V any] struct {
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Value V
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expiry time.Time
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}
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func NewDecayMap[K comparable, V any]() *DecayMap[K, V] {
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return &DecayMap[K, V]{
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data: make(map[K]DecayMapEntry[V]),
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}
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}
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func (m *DecayMap[K, V]) Get(key K) (V, bool) {
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m.lock.RLock()
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value, ok := m.data[key]
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m.lock.RUnlock()
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if !ok {
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return zilch[V](), false
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}
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if time.Now().After(value.expiry) {
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m.lock.Lock()
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// Since previously reading m.data[key], the value may have been updated.
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// Delete the entry only if the expiry time is still the same.
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if m.data[key].expiry == value.expiry {
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delete(m.data, key)
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}
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m.lock.Unlock()
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return zilch[V](), false
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}
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return value.Value, true
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}
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func (m *DecayMap[K, V]) Set(key K, value V, ttl time.Duration) {
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m.lock.Lock()
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defer m.lock.Unlock()
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m.data[key] = DecayMapEntry[V]{
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Value: value,
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expiry: time.Now().Add(ttl),
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}
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}
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func (m *DecayMap[K, V]) Decay() {
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m.lock.Lock()
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defer m.lock.Unlock()
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now := time.Now()
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for key, entry := range m.data {
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if now.After(entry.expiry) {
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delete(m.data, key)
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}
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}
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}
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