The driver’s logging system uses stderr by default and the log level CASS_LOG_WARN. Both of these settings can be changed using the driver’s cass_log_*() configuration functions.

Important: Logging configuration must be done before calling any other driver function.

Log Level

To update the log level use cass_log_set_level().


/* Create cluster and connect session */

Custom Logging Callback

The use of a logging callback allows an application to log messages to a file, syslog, or any other logging mechanism. This callback must be thread-safe because it is possible for it to be called from multiple threads concurrently. The data parameter allows custom resources to be passed to the logging callback.

void on_log(const CassLogMessage* message, void* data) {
  /* Handle logging */


void* log_data = /* Custom log resource */;
cass_log_set_callback(on_log, log_data);

/* Create cluster and connect session */

Logging Cleanup

Resources passed to a custom logging callback should be cleaned up after a call to cass_log_cleanup(). This shuts down the logging system and ensures that the custom callback will no longer be called.

/* Close any sessions */


/* Free custom logging resources */