Add prometheus endpoint for getting metrics (#33)

vendor/github.com/go-redis/redis/internal/pool/pool_single.go

@@ -0,0 +1,53 @@
+package pool
+
+type SingleConnPool struct {
+	cn *Conn
+}
+
+var _ Pooler = (*SingleConnPool)(nil)
+
+func NewSingleConnPool(cn *Conn) *SingleConnPool {
+	return &SingleConnPool{
+		cn: cn,
+	}
+}
+
+func (p *SingleConnPool) NewConn() (*Conn, error) {
+	panic("not implemented")
+}
+
+func (p *SingleConnPool) CloseConn(*Conn) error {
+	panic("not implemented")
+}
+
+func (p *SingleConnPool) Get() (*Conn, error) {
+	return p.cn, nil
+}
+
+func (p *SingleConnPool) Put(cn *Conn) {
+	if p.cn != cn {
+		panic("p.cn != cn")
+	}
+}
+
+func (p *SingleConnPool) Remove(cn *Conn) {
+	if p.cn != cn {
+		panic("p.cn != cn")
+	}
+}
+
+func (p *SingleConnPool) Len() int {
+	return 1
+}
+
+func (p *SingleConnPool) IdleLen() int {
+	return 0
+}
+
+func (p *SingleConnPool) Stats() *Stats {
+	return nil
+}
+
+func (p *SingleConnPool) Close() error {
+	return nil
+}