Files
hatchet/internal/cache/cache.go

131 lines
2.9 KiB
Go

package cache
import (
"sync"
"time"
)
// item represents a cache item with a value and an expiration time.
type item[V any] struct {
value V
expiry time.Time
}
// isExpired checks if the cache item has expired.
func (i item[V]) isExpired() bool {
return time.Now().After(i.expiry)
}
// TTLCache is a generic cache implementation with support for time-to-live
// (TTL) expiration.
type TTLCache[K comparable, V any] struct {
items map[K]item[V] // The map storing cache items.
mu sync.Mutex // Mutex for controlling concurrent access to the cache.
stop chan interface{} // Channel to stop the goroutine that removes expired items.
}
// NewTTL creates a new TTLCache instance and starts a goroutine to periodically
// remove expired items every 5 seconds.
func NewTTL[K comparable, V any]() *TTLCache[K, V] {
c := &TTLCache[K, V]{
items: make(map[K]item[V]),
stop: make(chan interface{}),
}
go func() {
// Create a new ticker to remove expired items every 5 seconds.
ticker := time.NewTicker(5 * time.Second)
defer ticker.Stop()
for {
select {
case <-c.stop:
return
case <-ticker.C:
c.mu.Lock()
// Iterate over the cache items and delete expired ones.
for key, item := range c.items {
if item.isExpired() {
delete(c.items, key)
}
}
c.mu.Unlock()
}
}
}()
return c
}
func (c *TTLCache[K, V]) Stop() {
close(c.stop)
}
// Set adds a new item to the cache with the specified key, value, and
// time-to-live (TTL).
func (c *TTLCache[K, V]) Set(key K, value V, ttl time.Duration) {
c.mu.Lock()
defer c.mu.Unlock()
c.items[key] = item[V]{
value: value,
expiry: time.Now().Add(ttl),
}
}
// Get retrieves the value associated with the given key from the cache.
func (c *TTLCache[K, V]) Get(key K) (V, bool) {
c.mu.Lock()
defer c.mu.Unlock()
item, found := c.items[key]
if !found {
// If the key is not found, return the zero value for V and false.
return item.value, false
}
if item.isExpired() {
// If the item has expired, remove it from the cache and return the
// value and false.
delete(c.items, key)
return item.value, false
}
// Otherwise return the value and true.
return item.value, true
}
// Remove removes the item with the specified key from the cache.
func (c *TTLCache[K, V]) Remove(key K) {
c.mu.Lock()
defer c.mu.Unlock()
// Delete the item with the given key from the cache.
delete(c.items, key)
}
// Pop removes and returns the item with the specified key from the cache.
func (c *TTLCache[K, V]) Pop(key K) (V, bool) {
c.mu.Lock()
defer c.mu.Unlock()
item, found := c.items[key]
if !found {
// If the key is not found, return the zero value for V and false.
return item.value, false
}
// If the key is found, delete the item from the cache.
delete(c.items, key)
if item.isExpired() {
// If the item has expired, return the value and false.
return item.value, false
}
// Otherwise return the value and true.
return item.value, true
}