1 files changed, 208 insertions, 0 deletions
diff --git a/modules/cache/cache_twoqueue.go b/modules/cache/cache_twoqueue.go
new file mode 100644
index 0000000..c15ed52
--- /dev/null
+++ b/modules/cache/cache_twoqueue.go
@@ -0,0 +1,208 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package cache
+
+import (
+	"strconv"
+	"sync"
+	"time"
+
+	"code.gitea.io/gitea/modules/json"
+
+	mc "code.forgejo.org/go-chi/cache"
+	lru "github.com/hashicorp/golang-lru/v2"
+)
+
+// TwoQueueCache represents a LRU 2Q cache adapter implementation
+type TwoQueueCache struct {
+	lock     sync.Mutex
+	cache    *lru.TwoQueueCache[string, any]
+	interval int
+}
+
+// TwoQueueCacheConfig describes the configuration for TwoQueueCache
+type TwoQueueCacheConfig struct {
+	Size        int     `ini:"SIZE" json:"size"`
+	RecentRatio float64 `ini:"RECENT_RATIO" json:"recent_ratio"`
+	GhostRatio  float64 `ini:"GHOST_RATIO" json:"ghost_ratio"`
+}
+
+// MemoryItem represents a memory cache item.
+type MemoryItem struct {
+	Val     any
+	Created int64
+	Timeout int64
+}
+
+func (item *MemoryItem) hasExpired() bool {
+	return item.Timeout > 0 &&
+		(time.Now().Unix()-item.Created) >= item.Timeout
+}
+
+var _ mc.Cache = &TwoQueueCache{}
+
+// Put puts value into cache with key and expire time.
+func (c *TwoQueueCache) Put(key string, val any, timeout int64) error {
+	item := &MemoryItem{
+		Val:     val,
+		Created: time.Now().Unix(),
+		Timeout: timeout,
+	}
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	c.cache.Add(key, item)
+	return nil
+}
+
+// Get gets cached value by given key.
+func (c *TwoQueueCache) Get(key string) any {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	cached, ok := c.cache.Get(key)
+	if !ok {
+		return nil
+	}
+	item, ok := cached.(*MemoryItem)
+
+	if !ok || item.hasExpired() {
+		c.cache.Remove(key)
+		return nil
+	}
+
+	return item.Val
+}
+
+// Delete deletes cached value by given key.
+func (c *TwoQueueCache) Delete(key string) error {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	c.cache.Remove(key)
+	return nil
+}
+
+// Incr increases cached int-type value by given key as a counter.
+func (c *TwoQueueCache) Incr(key string) error {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	cached, ok := c.cache.Get(key)
+	if !ok {
+		return nil
+	}
+	item, ok := cached.(*MemoryItem)
+
+	if !ok || item.hasExpired() {
+		c.cache.Remove(key)
+		return nil
+	}
+
+	var err error
+	item.Val, err = mc.Incr(item.Val)
+	return err
+}
+
+// Decr decreases cached int-type value by given key as a counter.
+func (c *TwoQueueCache) Decr(key string) error {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	cached, ok := c.cache.Get(key)
+	if !ok {
+		return nil
+	}
+	item, ok := cached.(*MemoryItem)
+
+	if !ok || item.hasExpired() {
+		c.cache.Remove(key)
+		return nil
+	}
+
+	var err error
+	item.Val, err = mc.Decr(item.Val)
+	return err
+}
+
+// IsExist returns true if cached value exists.
+func (c *TwoQueueCache) IsExist(key string) bool {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	cached, ok := c.cache.Peek(key)
+	if !ok {
+		return false
+	}
+	item, ok := cached.(*MemoryItem)
+	if !ok || item.hasExpired() {
+		c.cache.Remove(key)
+		return false
+	}
+
+	return true
+}
+
+// Flush deletes all cached data.
+func (c *TwoQueueCache) Flush() error {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	c.cache.Purge()
+	return nil
+}
+
+func (c *TwoQueueCache) checkAndInvalidate(key string) {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	cached, ok := c.cache.Peek(key)
+	if !ok {
+		return
+	}
+	item, ok := cached.(*MemoryItem)
+	if !ok || item.hasExpired() {
+		c.cache.Remove(key)
+	}
+}
+
+func (c *TwoQueueCache) startGC() {
+	if c.interval < 0 {
+		return
+	}
+	for _, key := range c.cache.Keys() {
+		c.checkAndInvalidate(key)
+	}
+	time.AfterFunc(time.Duration(c.interval)*time.Second, c.startGC)
+}
+
+// StartAndGC starts GC routine based on config string settings.
+func (c *TwoQueueCache) StartAndGC(opts mc.Options) error {
+	var err error
+	size := 50000
+	if opts.AdapterConfig != "" {
+		size, err = strconv.Atoi(opts.AdapterConfig)
+	}
+	if err != nil {
+		if !json.Valid([]byte(opts.AdapterConfig)) {
+			return err
+		}
+
+		cfg := &TwoQueueCacheConfig{
+			Size:        50000,
+			RecentRatio: lru.Default2QRecentRatio,
+			GhostRatio:  lru.Default2QGhostEntries,
+		}
+		_ = json.Unmarshal([]byte(opts.AdapterConfig), cfg)
+		c.cache, err = lru.New2QParams[string, any](cfg.Size, cfg.RecentRatio, cfg.GhostRatio)
+	} else {
+		c.cache, err = lru.New2Q[string, any](size)
+	}
+	c.interval = opts.Interval
+	if c.interval > 0 {
+		go c.startGC()
+	}
+	return err
+}
+
+// Ping tests if the cache is alive.
+func (c *TwoQueueCache) Ping() error {
+	return mc.GenericPing(c)
+}
+
+func init() {
+	mc.Register("twoqueue", &TwoQueueCache{})
+}