Correct multiplexing

hub/connection_list.go

@@ -0,0 +1,70 @@
+package hub
+
+import (
+	"fmt"
+	"sort"
+)
+
+const connectionListMaxClientsPerConnection = 2
+
+type connectionList struct {
+	connections []*connection
+}
+
+func (c *connectionList) Get(conn *ProxyConn) (*connection, error) {
+	if len(c.connections) > 0 {
+		c.gc()
+	}
+
+	if len(c.connections) > 0 && c.connections[0].Len() < connectionListMaxClientsPerConnection {
+		if err := c.connections[0].Attach(conn); err == nil {
+			return c.connections[0], nil
+		}
+	}
+
+	newConn, err := newConnection(conn.req)
+	if err != nil {
+		return nil, fmt.Errorf("cannot allocate a new connection: %w", err)
+	}
+
+	if err = newConn.Attach(conn); err != nil {
+		newConn.Close()
+		return nil, fmt.Errorf("cannot attach to the newly created connection: %w", err)
+	}
+
+	c.connections = append(c.connections, newConn)
+	lastIndex := len(c.connections) - 1
+	c.connections[0], c.connections[lastIndex] = c.connections[lastIndex], c.connections[0]
+
+	return newConn, nil
+}
+
+func (c *connectionList) gc() {
+	prevLen := len(c.connections)
+
+	for i := len(c.connections) - 1; i >= 0; i-- {
+		lastIndex := len(c.connections) - 1
+
+		if c.connections[i].Done() {
+			c.connections[i].Close()
+
+			if len(c.connections)-1 == i {
+				c.connections = c.connections[:lastIndex]
+			} else {
+				c.connections[i], c.connections[lastIndex] = c.connections[lastIndex], c.connections[i]
+			}
+		}
+	}
+
+	if prevLen != len(c.connections) {
+		c.sort()
+	}
+}
+
+func (c *connectionList) sort() {
+	if len(c.connections) > 1 {
+		sort.Slice(c.connections, func(i, j int) bool {
+			return c.connections[i].Len() < c.connections[j].Len()
+		})
+	}
+}