(mongodb >=1.6.0)
MongoDB\Driver\Session::getServer — Returns the server to which this session is pinned
Returns the MongoDB\Driver\Server to which this
session is pinned. If the session is not pinned to a server, null will be
returned.
Session pinning is primarily used for sharded transactions, as all commands within a sharded transaction must be sent to the same mongos instance. This method is intended to be used by libraries built atop the extension to allow use of a pinned server instead of invoking server selection.
此函数没有参数。
Returns the MongoDB\Driver\Server to which this
session is pinned, or null if the session is not pinned to any server.