The Driver Sessions Spec requires all functions that communicate with the server to accept a session parameter. We'll do this in the C Driver by accepting an arbitrary BSON document called "opts" that can include a variety of options, including a session.

Details:

Users create sessions with mongoc_client_start_session and bind the session to an opts document. A new function mongoc_client_session_append (mongoc_client_session_t *, bson_t *) appends an opaque integer id to the opts document, with the field name "sessionId".

When the driver executes a command with opts, the driver checks the opts for a "sessionId", retrieves the mongoc_client_session_t from a list of them in the mongoc_client_t, and adds the session's lsid and (if causally consistent) its clusterTime to the command it sends to the server.

Make a list of every public function in the driver that does not end with "_with_opts". Remove from the list any functions that have a "_with_opts" equivalent. Remove any that don't communicate with the server. For all remaining functions, add a "_with_opts" equivalent and test it in test-mongoc-client-session.c.

Done: Remove some workarounds from test-mongoc-client-session.c, like the direct call to the "insert" command (works around the current lack of mongoc_collection_insert_with_opts) and the "suspend_monitoring" field used in tests.

• Done: mongoc_client_find_databases_with_opts
• Done: mongoc_client_get_database_names_with_opts
• Done: mongoc_collection_create_bulk_operation_with_opts
• Done: mongoc_collection_find_indexes_with_opts
• Done: mongoc_collection_insert_one_with_opts
• Done: mongoc_database_find_collections_with_opts
• Done: mongoc_database_get_collection_names_with_opts
• Done: Rename the CDRIVER-2205 functions mongoc_collection_update_one/many_with_opts and mongoc_collection_replace_one_with_opts: remove "_with_opts".
• mongoc_collection_insert_many, delete_one, delete_many

The generic command function is split out into CDRIVER-2207, GridFS work is split out in CDRIVER-2332 and delayed for a future version.

Don't do mongoc_database_create_user_with_opts, mongoc_database_remove_all_users_with_opts, or mongoc_database_remove_user_with_opts. Same justification as when we cancelled CDRIVER-326: this is not a libmongoc priority.