gotosocial/vendor/codeberg.org/gruf/go-cache/v3/ttl/ttl.go

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package ttl
import (
"sync"
"time"
"codeberg.org/gruf/go-maps"
)
// Entry represents an item in the cache, with it's currently calculated Expiry time.
type Entry[Key comparable, Value any] struct {
Key Key
Value Value
Expiry time.Time
}
// Cache is the underlying Cache implementation, providing both the base Cache interface and unsafe access to underlying map to allow flexibility in building your own.
type Cache[Key comparable, Value any] struct {
// TTL is the cache item TTL.
TTL time.Duration
// Evict is the hook that is called when an item is evicted from the cache.
Evict func(*Entry[Key, Value])
// Invalid is the hook that is called when an item's data in the cache is invalidated, includes Add/Set.
Invalid func(*Entry[Key, Value])
// Cache is the underlying hashmap used for this cache.
Cache maps.LRUMap[Key, *Entry[Key, Value]]
// stop is the eviction routine cancel func.
stop func()
// pool is a memory pool of entry objects.
pool []*Entry[Key, Value]
// Embedded mutex.
sync.Mutex
}
// New returns a new initialized Cache with given initial length, maximum capacity and item TTL.
func New[K comparable, V any](len, cap int, ttl time.Duration) *Cache[K, V] {
c := new(Cache[K, V])
c.Init(len, cap, ttl)
return c
}
// Init will initialize this cache with given initial length, maximum capacity and item TTL.
func (c *Cache[K, V]) Init(len, cap int, ttl time.Duration) {
if ttl <= 0 {
// Default duration
ttl = time.Second * 5
}
c.TTL = ttl
c.SetEvictionCallback(nil)
c.SetInvalidateCallback(nil)
c.Cache.Init(len, cap)
}
// Start: implements cache.Cache's Start().
func (c *Cache[K, V]) Start(freq time.Duration) (ok bool) {
// Nothing to start
if freq <= 0 {
return false
}
// Safely start
c.Lock()
if ok = c.stop == nil; ok {
// Not yet running, schedule us
c.stop = schedule(c.Sweep, freq)
}
// Done with lock
c.Unlock()
return
}
// Stop: implements cache.Cache's Stop().
func (c *Cache[K, V]) Stop() (ok bool) {
// Safely stop
c.Lock()
if ok = c.stop != nil; ok {
// We're running, cancel evicts
c.stop()
c.stop = nil
}
// Done with lock
c.Unlock()
return
}
// Sweep attempts to evict expired items (with callback!) from cache.
func (c *Cache[K, V]) Sweep(now time.Time) {
var after int
// Sweep within lock
c.Lock()
defer c.Unlock()
// Sentinel value
after = -1
// The cache will be ordered by expiry date, we iterate until we reach the index of
// the youngest item that hsa expired, as all succeeding items will also be expired.
c.Cache.RangeIf(0, c.Cache.Len(), func(i int, _ K, item *Entry[K, V]) bool {
if now.After(item.Expiry) {
after = i
// All older than this (including) can be dropped
return false
}
// Continue looping
return true
})
if after == -1 {
// No Truncation needed
return
}
// Truncate items, calling eviction hook
c.truncate(c.Cache.Len()-after, c.Evict)
}
// SetEvictionCallback: implements cache.Cache's SetEvictionCallback().
func (c *Cache[K, V]) SetEvictionCallback(hook func(*Entry[K, V])) {
// Ensure non-nil hook
if hook == nil {
hook = func(*Entry[K, V]) {}
}
// Update within lock
c.Lock()
defer c.Unlock()
// Update hook
c.Evict = hook
}
// SetInvalidateCallback: implements cache.Cache's SetInvalidateCallback().
func (c *Cache[K, V]) SetInvalidateCallback(hook func(*Entry[K, V])) {
// Ensure non-nil hook
if hook == nil {
hook = func(*Entry[K, V]) {}
}
// Update within lock
c.Lock()
defer c.Unlock()
// Update hook
c.Invalid = hook
}
// SetTTL: implements cache.Cache's SetTTL().
func (c *Cache[K, V]) SetTTL(ttl time.Duration, update bool) {
if ttl < 0 {
panic("ttl must be greater than zero")
}
// Update within lock
c.Lock()
defer c.Unlock()
// Set updated TTL
diff := ttl - c.TTL
c.TTL = ttl
if update {
// Update existing cache entries with new expiry time
c.Cache.Range(0, c.Cache.Len(), func(i int, _ K, item *Entry[K, V]) {
item.Expiry = item.Expiry.Add(diff)
})
}
}
// Get: implements cache.Cache's Get().
func (c *Cache[K, V]) Get(key K) (V, bool) {
// Read within lock
c.Lock()
defer c.Unlock()
// Check for item in cache
item, ok := c.Cache.Get(key)
if !ok {
var value V
return value, false
}
// Update item expiry and return
item.Expiry = time.Now().Add(c.TTL)
return item.Value, true
}
// Add: implements cache.Cache's Add().
func (c *Cache[K, V]) Add(key K, value V) bool {
// Write within lock
c.Lock()
defer c.Unlock()
// Check if already exists
item, ok := c.Cache.Get(key)
if ok {
return false
}
// Alloc new item
item = c.alloc()
item.Key = key
item.Value = value
item.Expiry = time.Now().Add(c.TTL)
var hook func(K, *Entry[K, V])
if c.Evict != nil {
// Pass evicted entry to user hook
hook = func(_ K, item *Entry[K, V]) {
c.Evict(item)
}
}
// Place new item in the map with hook
c.Cache.SetWithHook(key, item, hook)
if c.Invalid != nil {
// invalidate old
c.Invalid(item)
}
return true
}
// Set: implements cache.Cache's Set().
func (c *Cache[K, V]) Set(key K, value V) {
// Write within lock
c.Lock()
defer c.Unlock()
// Check if already exists
item, ok := c.Cache.Get(key)
if !ok {
var hook func(K, *Entry[K, V])
// Allocate new item
item = c.alloc()
item.Key = key
if c.Evict != nil {
// Pass evicted entry to user hook
hook = func(_ K, item *Entry[K, V]) {
c.Evict(item)
}
}
// Place new item in the map with hook
c.Cache.SetWithHook(key, item, hook)
}
if c.Invalid != nil {
// invalidate old
c.Invalid(item)
}
// Update the item value + expiry
item.Expiry = time.Now().Add(c.TTL)
item.Value = value
}
// CAS: implements cache.Cache's CAS().
func (c *Cache[K, V]) CAS(key K, old V, new V, cmp func(V, V) bool) bool {
// CAS within lock
c.Lock()
defer c.Unlock()
// Check for item in cache
item, ok := c.Cache.Get(key)
if !ok || !cmp(item.Value, old) {
return false
}
if c.Invalid != nil {
// invalidate old
c.Invalid(item)
}
// Update item + Expiry
item.Value = new
item.Expiry = time.Now().Add(c.TTL)
return ok
}
// Swap: implements cache.Cache's Swap().
func (c *Cache[K, V]) Swap(key K, swp V) V {
// Swap within lock
c.Lock()
defer c.Unlock()
// Check for item in cache
item, ok := c.Cache.Get(key)
if !ok {
var value V
return value
}
if c.Invalid != nil {
// invalidate old
c.Invalid(item)
}
old := item.Value
// update item + Expiry
item.Value = swp
item.Expiry = time.Now().Add(c.TTL)
return old
}
// Has: implements cache.Cache's Has().
func (c *Cache[K, V]) Has(key K) bool {
c.Lock()
ok := c.Cache.Has(key)
c.Unlock()
return ok
}
// Invalidate: implements cache.Cache's Invalidate().
func (c *Cache[K, V]) Invalidate(key K) bool {
// Delete within lock
c.Lock()
defer c.Unlock()
// Check if we have item with key
item, ok := c.Cache.Get(key)
if !ok {
return false
}
// Remove from cache map
_ = c.Cache.Delete(key)
if c.Invalid != nil {
// Invalidate item
c.Invalid(item)
}
// Return item to pool
c.free(item)
return true
}
// Clear: implements cache.Cache's Clear().
func (c *Cache[K, V]) Clear() {
c.Lock()
defer c.Unlock()
c.truncate(c.Cache.Len(), c.Invalid)
}
// Len: implements cache.Cache's Len().
func (c *Cache[K, V]) Len() int {
c.Lock()
l := c.Cache.Len()
c.Unlock()
return l
}
// Cap: implements cache.Cache's Cap().
func (c *Cache[K, V]) Cap() int {
c.Lock()
l := c.Cache.Cap()
c.Unlock()
return l
}
// truncate will call Cache.Truncate(sz), and if provided a hook will temporarily store deleted items before passing them to the hook. This is required in order to prevent cache writes during .Truncate().
func (c *Cache[K, V]) truncate(sz int, hook func(*Entry[K, V])) {
if hook == nil {
// No hook was provided, we can simply truncate and free items immediately.
c.Cache.Truncate(sz, func(_ K, item *Entry[K, V]) { c.free(item) })
return
}
// Store list of deleted items for later callbacks
deleted := make([]*Entry[K, V], 0, sz)
// Truncate and store list of deleted items
c.Cache.Truncate(sz, func(_ K, item *Entry[K, V]) {
deleted = append(deleted, item)
})
// Pass each deleted to hook, then free
for _, item := range deleted {
hook(item)
c.free(item)
}
}
// alloc will acquire cache entry from pool, or allocate new.
func (c *Cache[K, V]) alloc() *Entry[K, V] {
if len(c.pool) == 0 {
return &Entry[K, V]{}
}
idx := len(c.pool) - 1
e := c.pool[idx]
c.pool = c.pool[:idx]
return e
}
// free will reset entry fields and place back in pool.
func (c *Cache[K, V]) free(e *Entry[K, V]) {
var (
zk K
zv V
)
e.Key = zk
e.Value = zv
e.Expiry = time.Time{}
c.pool = append(c.pool, e)
}