(mongodb >=1.17.0)
Classes implementing this interface may be registered as a subscriber and receive log messages from the extension. This is similar to stream-based debug logging (i.e. mongodb.debug) except that trace-level log messages are not received.
As with stream-based logging, it is only possible to register a logger globally using MongoDB\Driver\Monitoring\addSubscriber(). The extension is not able to distinguish log messages for individual MongoDB\Driver\Manager objects.
MongoDB\Driver\Monitoring\LogSubscriber::LEVEL_ERRORMongoDB\Driver\Monitoring\LogSubscriber::LEVEL_CRITICALMongoDB\Driver\Monitoring\LogSubscriber::LEVEL_WARNINGMongoDB\Driver\Monitoring\LogSubscriber::LEVEL_MESSAGEMongoDB\Driver\Monitoring\LogSubscriber::LEVEL_INFOMongoDB\Driver\Monitoring\LogSubscriber::LEVEL_DEBUG