lib/mongo/operation/shared/sessions_supported.rb
# Adds causal consistency document to the selector, if one can be
# constructed and the selector is for a startTransaction command.
#
# When operations are performed in a transaction, only the first
# operation (the one which starts the transaction via startTransaction)
# is allowed to have a read concern, and with it the causal consistency
# document, specified.
Adds causal consistency document to the selector, if one can be
constructed and the selector is for a startTransaction command.

When operations are performed in a transaction, only the first
operation (the one which starts the transaction via startTransaction)
is allowed to have a read concern, and with it the causal consistency
document, specified.
Adds causal consistency document to the selector if one can be constructed and the selector is for a startTransaction command . When operations are performed in a transaction only the first operation ( the one which starts the transaction via startTransaction ) is allowed to have a read concern and with it the causal consistency document specified .
def apply_causal_consistency!(selector, connection)
        return unless selector[:startTransaction]
        apply_causal_consistency_if_possible(selector, connection)
      end
def apply_causal_consistency! ( selector , connection ) return unless selector [ :startTransaction ] apply_causal_consistency_if_possible ( selector , connection ) end
Adds causal consistency document to the selector, if one can be
constructed and the selector is for a startTransaction command.
Adds causal consistency document to the selector if one can be constructed and the selector is for a startTransaction command .
selector
<not_specific>
connection
<not_specific>