use go 1.12

Signed-off-by: hongming <talonwan@yunify.com>

vendor/github.com/lucas-clemente/quic-go/multiplexer.go

@@ -0,0 +1,63 @@
+package quic
+
+import (
+	"fmt"
+	"net"
+	"sync"
+
+	"github.com/lucas-clemente/quic-go/internal/utils"
+)
+
+var (
+	connMuxerOnce sync.Once
+	connMuxer     multiplexer
+)
+
+type multiplexer interface {
+	AddConn(net.PacketConn, int) (packetHandlerManager, error)
+}
+
+type connManager struct {
+	connIDLen int
+	manager   packetHandlerManager
+}
+
+// The connMultiplexer listens on multiple net.PacketConns and dispatches
+// incoming packets to the session handler.
+type connMultiplexer struct {
+	mutex sync.Mutex
+
+	conns                   map[net.PacketConn]connManager
+	newPacketHandlerManager func(net.PacketConn, int, utils.Logger) packetHandlerManager // so it can be replaced in the tests
+
+	logger utils.Logger
+}
+
+var _ multiplexer = &connMultiplexer{}
+
+func getMultiplexer() multiplexer {
+	connMuxerOnce.Do(func() {
+		connMuxer = &connMultiplexer{
+			conns:                   make(map[net.PacketConn]connManager),
+			logger:                  utils.DefaultLogger.WithPrefix("muxer"),
+			newPacketHandlerManager: newPacketHandlerMap,
+		}
+	})
+	return connMuxer
+}
+
+func (m *connMultiplexer) AddConn(c net.PacketConn, connIDLen int) (packetHandlerManager, error) {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+
+	p, ok := m.conns[c]
+	if !ok {
+		manager := m.newPacketHandlerManager(c, connIDLen, m.logger)
+		p = connManager{connIDLen: connIDLen, manager: manager}
+		m.conns[c] = p
+	}
+	if p.connIDLen != connIDLen {
+		return nil, fmt.Errorf("cannot use %d byte connection IDs on a connection that is already using %d byte connction IDs", connIDLen, p.connIDLen)
+	}
+	return p.manager, nil
+}