const mongoc_topology_description_t * mongoc_apm_topology_changed_get_previous_description ( const mongoc_apm_topology_changed_t *event);
Returns this event's previous description. The data is only valid in the scope of the callback that receives this event; copy it if it will be accessed after the callback returns.
- event: A mongoc_apm_topology_changed_t.
A mongoc_topology_description_t that should not be modified or freed.
Introduction to Application Performance Monitoring
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