add keepAlive option for udp Listener

common/net/udp/pool.go

@@ -0,0 +1,100 @@
+package udp
+
+import (
+	"sync"
+	"time"
+
+	"github.com/go-gost/core/logger"
+)
+
+type connPool struct {
+	m      sync.Map
+	ttl    time.Duration
+	closed chan struct{}
+	logger logger.Logger
+}
+
+func newConnPool(ttl time.Duration) *connPool {
+	p := &connPool{
+		ttl:    ttl,
+		closed: make(chan struct{}),
+	}
+	go p.idleCheck()
+	return p
+}
+
+func (p *connPool) WithLogger(logger logger.Logger) *connPool {
+	p.logger = logger
+	return p
+}
+
+func (p *connPool) Get(key any) (c *conn, ok bool) {
+	v, ok := p.m.Load(key)
+	if ok {
+		c, ok = v.(*conn)
+	}
+	return
+}
+
+func (p *connPool) Set(key any, c *conn) {
+	p.m.Store(key, c)
+}
+
+func (p *connPool) Delete(key any) {
+	p.m.Delete(key)
+}
+
+func (p *connPool) Close() {
+	select {
+	case <-p.closed:
+		return
+	default:
+	}
+
+	close(p.closed)
+
+	p.m.Range(func(k, v any) bool {
+		if c, ok := v.(*conn); ok && c != nil {
+			c.Close()
+		}
+		return true
+	})
+}
+
+func (p *connPool) idleCheck() {
+	ticker := time.NewTicker(p.ttl)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ticker.C:
+			size := 0
+			idles := 0
+			p.m.Range(func(key, value any) bool {
+				c, ok := value.(*conn)
+				if !ok || c == nil {
+					p.Delete(key)
+					return true
+				}
+				size++
+
+				if c.IsIdle() {
+					idles++
+					p.Delete(key)
+					c.Close()
+					return true
+				}
+
+				c.SetIdle(true)
+
+				return true
+			})
+
+			if idles > 0 {
+				p.logger.Debugf("connection pool: size=%d, idle=%d", size, idles)
+			}
+		case <-p.closed:
+			return
+		}
+	}
+}