improve cache handler, embracing #2210 too

cache/entry/pool.go

@@ -0,0 +1,69 @@
+package entry
+
+import (
+	"sync"
+	"time"
+
+	"github.com/kataras/iris/v12/cache/cfg"
+	"github.com/kataras/iris/v12/core/memstore"
+)
+
+// Pool is the context pool, it's used inside router and the framework by itself.
+type Pool struct {
+	pool *sync.Pool
+}
+
+// NewPool creates and returns a new context pool.
+func NewPool() *Pool {
+	return &Pool{pool: &sync.Pool{New: func() any { return &Entry{} }}}
+}
+
+// func NewPool(newFunc func() any) *Pool {
+// 	return &Pool{pool: &sync.Pool{New: newFunc}}
+// }
+
+// Acquire returns an Entry from pool.
+// See Release.
+func (c *Pool) Acquire(lifeDuration time.Duration, r *Response, onExpire func()) *Entry {
+	// If the given duration is not <=0 (which means finds from the headers)
+	// then we should check for the MinimumCacheDuration here
+	if lifeDuration >= 0 && lifeDuration < cfg.MinimumCacheDuration {
+		lifeDuration = cfg.MinimumCacheDuration
+	}
+
+	e := c.pool.Get().(*Entry)
+
+	lt := memstore.NewLifeTime()
+	lt.Begin(lifeDuration, func() {
+		onExpire()
+		c.release(e)
+	})
+
+	e.reset(lt, r)
+	return e
+}
+
+// Release puts an Entry back to its pull, this function releases its resources.
+// See Acquire.
+func (c *Pool) release(e *Entry) {
+	e.response.body = nil
+	e.response.headers = nil
+	e.response.statusCode = 0
+	e.response = nil
+
+	// do not call it, it contains a lock too, release is controlled only inside the Acquire itself when the entry is expired.
+	// if e.lifeTime != nil {
+	// 	e.lifeTime.ExpireNow() // stop any opening timers if force released.
+	// }
+
+	c.pool.Put(e)
+}
+
+// Release can be called by custom stores to release an entry.
+func (c *Pool) Release(e *Entry) {
+	if e.lifeTime != nil {
+		e.lifeTime.ExpireNow() // stop any opening timers if force released.
+	}
+
+	c.release(e)
+}