TODO: This much explanation in the release notes is a bit too
much, the beef should be moved somewhere else and the release
notes simply refer to that.
When looking for a master, if it does exist it should be found
even if it is not connectible. The fact that it is not connectible
should be dealt with when a connection is created.
If a master is found but it is being drained, the connection attempt
is rejected if the master failure mode is fail_instantly.
In that case the logged message makes it plain that it is the draining
that is the reason for the connection attempt to fail.
The schema router now deals with the being drained bit the same way
it deals with the maintenance bit, that is, a server being drained will
simply be ignored.
TODO: This behaviour needs to be document.
TODO: It seems the schema router simply ignores the maintenance bit
once a connection has been establisdhed.
Currently the bit is set so that is may be overwritten by the monitor
if the setting of the bit takes place while the monitor is performing
its monitor loop.
With this bit set, existing connections to a server should not be
closed, but no new connections should be created to the server.
The bits have also slight been rearranged.
- Bits 0 - 15 are now reserved for bits applicable to all servers
- Bits 16 - 31 are monitor specific
Further, the cases whether a server can be connected to and whether
it can be used, but be separated.
Once the monitor has been able to connect to a clustrix node
and obtain the clustrix nodes, it'll primarily use those nodes
when looking for a Clustrix node to be used as the "hub".
With this change it is sufficient (but perhaps unwise) to provide
a single node boostrap node in the configuration file.
Some other rearrangements and renamings of functions has also been
made.
Whitespace in section names have been deprecated since 2.2 and will
be rejected in 2.4. Consequently, the configuration files of the
system tests must be updated.
Convention needs to be that the runtime object creating other objects
needs to incorporate its own name in the name of any object created.
Together with the '@@' prefix that ensures that the created name will
be reasonably globally unique.
Names starting with '@@' can now longer be used in configuration files.
Subsequent commits will prevent such names from being used when objects
are created dynamically.
The QueryResult-object remembers if a conversion failed. This makes checking
for errors more convenient, as just one check per row is required. The conversion
functions always return a valid value.
The class MonitorManager contains monitor-related functions that should not
be called from modules. MonitorManager can access private fields and methods
of the monitor.
If a server cannot be used, close the associated MYSQL connection.
Further, when an existing connection is used, verify that the server
is still part of the quorum.
From system.membership we can find out what server exist in the
cluster while system.nodeinfo contains information about those
servers. If a node goes down, it will disappear from system.nodeinfo,
but not from system.membership. Consequently, we must start from
system.membership and then fetch more information from system.nodeinfo.
Incidentally, a query like
SELECT ms.nid, ni.iface_ip
FROM system.membership AS ms
LEFT JOIN system.nodeinfo AS ni ON ms.nid=ni.nodeid;
should provide all information in one go, but it seems that such joins
are not supported on the system tables.
The node infos of the Clustrix servers are now kept around and
and updated based upon changing conditions instead of regularly
being re-created.
Further, the server is now looked up by name only right after
having been created (and that only due to runtime_create_server()
currently being used).
The state of the dynamically created server is now updated directly
as a result of the health-check ping, while the state of the bootstrap
servers is updated during the tick()-call according to the monitor
"protocol".
