question: private void updateRegistrations ( ) { synchronized ( updateLock ) { int j = 0 ; while ( j < updateCount ) { int fd = updateDescriptors [ j ] ; short events = getUpdateEvents ( fd ) ; boolean isRegistered = registered . get ( fd ) ; int opcode = 0 ; if ( events != KILLED ) { if ( isRegistered ) { opcode = ( events != 0 ) ? EPOLL_CTL_MOD : EPOLL_CTL_DEL ; } else { opcode = ( events != 0 ) ? EPOLL_CTL_ADD : 0 ; } if ( opcode != 0 ) { epollCtl ( epfd , opcode , fd , events ) ; if ( opcode == EPOLL_CTL_ADD ) { registered . set ( fd ) ; } else if ( opcode == EPOLL_CTL_DEL ) { registered . clear ( fd ) ; } } } j ++ ; } updateCount = 0 ; } }
target:  Update the pending registrations.