At the end of the chapter, let's try to create a different Daemon plugin. This plugin, called
sys_status, does not start any threads and does not do anything in the background. It uses the status variables to provide access to the
getrusage() statistics. The
getrusage() system call returns information about the process resource usage such as number of page faults, number of signals received, and number of context switches. How could we let MySQL users see this information?
As we remember, status variables are defined in terms of pointers to data. That is,
SHOW STATUS takes the
st_mysql_show_var structure and shows the data pointed to by its
value member. It works well when a value to show is stored in a variable; ...