Add db-connect, a SQL over HTTPS server

vendor/github.com/kshvakov/clickhouse/clickhouse_ping.go

@@ -0,0 +1,28 @@
+package clickhouse
+
+import (
+	"context"
+	"database/sql/driver"
+
+	"github.com/kshvakov/clickhouse/lib/protocol"
+)
+
+func (ch *clickhouse) Ping(ctx context.Context) error {
+	return ch.ping(ctx)
+}
+
+func (ch *clickhouse) ping(ctx context.Context) error {
+	if ch.conn.closed {
+		return driver.ErrBadConn
+	}
+	ch.logf("-> ping")
+	finish := ch.watchCancel(ctx)
+	defer finish()
+	if err := ch.encoder.Uvarint(protocol.ClientPing); err != nil {
+		return err
+	}
+	if err := ch.encoder.Flush(); err != nil {
+		return err
+	}
+	return ch.process()
+}