Previously, runtime monitor modifications could directly alter monitor fields,
which could leave the text-form parameters and reality out-of-sync. Also,
the configure-function was not called for the entire monitor-object, only the
module-implementation.
Now, all modifications go through the overridden configure-function, which calls the
base-class function. As most configuration changes are given in text-form, this
removes the need for specific setters. The only exceptions are the server add/remove
operations, which must modify the text-form serverlist.
Was deprecated in 2.3. Similar features are in MariaDB-Monitor.
One system test was modified to use MariaDB-Monitor instead. Some parts
of the test are disabled for now to make it pass.
Queries in the query queue need to be explicitly parsed since they are
stored in a single buffer and thus share the query classification
information. In the next major version this should be changed into an
array of individual buffers instead of a shared buffer.
Always storing runtime configuration changes prevents problems when the
change causes another parameter to change. One example of this is
transaction_replay that implicitly enables other parameters.
If a DCB was closed and a hangup event was sent to it via
dcb_hangup_foreach shortly after it was closed, the DCB would still
receive it even if it was closed. To prevent this, events must only be
delivered to DCBs if they haven't been closed.
If a session command is executed when lazy_connect is enabled and no
connections have been created, a connection must be made. This makes sure
that the session isn't closed and that the client receives a response.
The lazy connection creation reduces the burden that short sessions place
on the backend servers. This also prevents the problems caused by early
disconnections that happen when only one server is used but multiple
connections are created. This does not solve the problem (MXS-619) but it
does mitigate it to acceptable levels.
This commit also adds a change to the weighting algorithm that prefers
existing connections over unopened ones. This helps avoid the
flip-flopping that happens when the absolute scores are very similar. The
hard-coded value might need to be tuned once testing is done.
The protocol should not track the session state as the parsing is quite
expensive with the current code. This change is a workaround that enables
the parsing only when required. A proper way to handle this would be to do
all the response processing in one place thus avoiding the duplication of
work.
Given the fact that there exist only three possible categories, the map
can be replaced with a static array that needs no memory
allocations. Making this array thread-local allows it to be reused which
places an upper limit on the number of memory allocations.
The monitor now continuously updates a list of enabled server events. When
promoting a new master in failover/switchover, only events that were enabled
on the previous master are enabled on the new. This avoids enabling events
that may have been disabled on the master yet stayed in the SLAVESIDE_DISABLED-
state on the slave.
In the case of reset-replication command, events on the new master are only
enabled if the monitor had a master when the command was launched. Otherwise
all events remain disabled.
It is frequently used when using self-signed certificates so making it
shorther makes life easier. Also added the missing --tls-passphrase into
the TLS options group.
