mongoc_client_select_server man page
mongoc_client_select_server — mongoc_client_select_server()
mongoc_server_description_t * mongoc_client_select_server (mongoc_client_t *client, bool for_writes, const mongoc_read_prefs_t *prefs, bson_error_t *error);
Choose a server for an operation, according to the logic described in the Server Selection Spec.
Use this function only for building a language driver that wraps the C Driver. When writing applications in C, higher-level functions automatically select a suitable server.
client: A mongoc_client_t.
for_writes: Whether to choose a server suitable for writes or reads.
prefs: An optional mongoc_read_prefs_t. If for_writes is true, prefs must be NULL. Otherwise, use prefs to customize server selection, or pass NULL to use the read preference configured on the client.
error: An optional location for a bson_error_t or NULL.
A mongoc_server_description_t that must be freed with mongoc_server_description_destroy. If no suitable server is found, returns NULL and error is filled out.
2017, MongoDB, Inc