The initialization and starting of the housekeeper is now done
separately. This allows housekeeper tasks to be created when the services
are being created while still preventing the execution of the task before
the startup is complete.
The two-part shutdown procedure for the housekeeper was not needed and
caused problems if SIGINT wasn't raised. Since the main thread returns to
the main function, a single shutdown function is all that the housekeeper
needs to function.
Moved all the shutdown related code into Housekeeper::stop to remove the
waiting for the thread in the destructor.
The tasks themselves now control whether they are executed again. To
compare it to the old system, oneshot tasks now return `false` and
repeating tasks return `true`.
Letting the housekeeper remove the tasks makes the code simpler and
removes the possibility of the task being removed while it is being
executed. It does introduce a deadlock possibility if a housekeeper
function is called inside a housekeeper task.
The class now does all of the work and the API wraps the calls to the
member methods. Using an STL container makes the list management a lot
more convenient.
The old hkheartbeat variable was changed to the mxs_clock() function that
simply wraps an atomic load of the variable. This allows it to be
correctly read by MaxScale as well as opening up the possibility of
converting the value load to a relaxed memory order read.
Renamed the header and associated macros. Removed inclusion of the
heartbeat header from the housekeeper header and added it to the files
that were missing it.
It is now possible to specify the thread stack size to be used,
when a new thread is created. This will subsequently be used
for allowing the stack size to be specified for worker threads.
When MaxScale is started, a separate thread for the administrative
interface is started. This allows the worker threads to handle client
requests while the administrative thread handles the lower priority
administrative requests.
The administrative interface responds to all request with a 200 OK HTTP
response. This allows the administrative interface itself to be tested.
