question: private boolean handleHostsAvailabilityError ( Throwable e , int attempt , String msg ) { if ( attempt >= CQL_EXECUTION_ATTEMPTS_COUNT ) { log . error ( "Host availability problem detected. " + "Number of CQL execution attempts reached maximum " + CQL_EXECUTION_ATTEMPTS_COUNT + ", exception will be thrown to upper execution layer." , e ) ; throw msg == null ? new IgniteException ( e ) : new IgniteException ( msg , e ) ; } if ( attempt == CQL_EXECUTION_ATTEMPTS_COUNT / 4 || attempt == CQL_EXECUTION_ATTEMPTS_COUNT / 2 || attempt == CQL_EXECUTION_ATTEMPTS_COUNT / 2 + CQL_EXECUTION_ATTEMPTS_COUNT / 4 || attempt == CQL_EXECUTION_ATTEMPTS_COUNT - 1 ) { log . warning ( "Host availability problem detected, CQL execution attempt  " + ( attempt + 1 ) + ", " + "refreshing Cassandra session" , e ) ; refresh ( ) ; log . warning ( "Cassandra session refreshed" ) ; return true ; } log . warning ( "Host availability problem detected, CQL execution attempt " + ( attempt + 1 ) + ", " + "sleeping extra " + CQL_EXECUTION_ATTEMPT_MAX_TIMEOUT + " milliseconds" , e ) ; try { Thread . sleep ( CQL_EXECUTION_ATTEMPT_MAX_TIMEOUT ) ; } catch ( InterruptedException ignored ) { } log . warning ( "Sleep completed" ) ; return false ; }
target:  Handles situation when Cassandra host which is responsible for CQL query execution became unavailable.