rpc/client: add Close method

Allow to close unused network connections and use it during RPC broadcaster
shutdown, because otherwise we leak them.

pkg/rpc/client/client.go

@@ -167,6 +167,11 @@ func (c *Client) Init() error {
 	return nil
 }
 
+// Close closes unused underlying networks connections.
+func (c *Client) Close() {
+	c.cli.CloseIdleConnections()
+}
+
 func (c *Client) performRequest(method string, p request.RawParams, v interface{}) error {
 	var r = request.Raw{
 		JSONRPC:   request.JSONRPCVersion,

pkg/services/helpers/rpcbroadcaster/client.go

@@ -66,6 +66,7 @@ run:
 			}
 		}
 	}
+	c.client.Close()
 drain:
 	for {
 		select {