This way the state is encapsulated in the object and the required changes
are done in one place. This makes the code reusable across all functions
making it easier to implement better monitor alteration code.
Queries such as SHOW TABLES FROM db1 are now routed to the backend with db1.
This gives the correct result as long as db1 is not sharded to multiple
backends.
Increasing counter sizes from int to long for averages.
Rename random functions to end with _co instead of _exclusive to
indicate range [close, open[, and to allow future suffixes oc, cc and oo.
The code only handled the basic version of the command, returning incorrect
results if modifiers were used. The code is now removed, causing the command
to be routed to the backend of the current database. This will give correct
results as long as that backend contains all the tables of the database e.g.
no table sharding.
When default parameters are loaded, the type and module name are
added. This helps object serialization and allows all the code to expect
that all the parameters needed to create an object are always present.
Adding the same task twice isn't allowed. The API of the housekeeper tasks
might have to be changed in a way that makes it possible for the caller to
know whether a task has been added.
By passing strings instead of const char pointers to the task control
functions, we can safely make copies of them knowing that the contents
won't disappear.
The cluster check can only be made after the monitor has been
started. If done when monitor is configured it will at startup
be done when services are not yet available and hence they will
not be populated with the dynamically discovered servers.
The last server wasn't removed as the set of relationships was empty. In
addition to this, changes to relationships via the relations endpoint
wasn't reflected by the monitor parameters.
If a monitor was created at runtime, it was missing some parameters that
were assumed to be always present. In addition to that, the parameters
weren't validated against the list of common and module parameters.
Since the monitors always reconstruct the server list, the new servers can
be stored as a parameter. To make this possible, the
server_relationship_to_parameter helper function is needed.
This commit fixes the MaxCtrl test suite failures but does not fix the
failures in the REST API test suite.
Reactivating monitors shouldn't be done as it's simpler to actually
destroy and create a new one. The performance of reactivation is
insignificant compared to the possible inconsistency problems it allows.
Storing all the runtime errors makes it possible to return all of them
them via the REST API. MaxAdmin will still only show the latest error but
MaxCtrl will now show all errors if more than one error occurs.
The connections to servers being drained should not be closed like they
should be for servers in maintenance mode. The change in functionality
between 2.3 and develop caused the connections to be discarded if the
server was in either maintenance or drain mode.
By using a std::vector to store the keys, the cost of key lookup goes down
in comparison with std::unordered_map. The downside is the increase in
memory use in certain situations but given the fact that the intended
purpose of worker-local data is to store global data, this is unlikely to
have observable negative side-effects. Depending on the implementations of
std::vector and std::unordered_map, the use of std::vector could even
result in a smaller memory footprint.
