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.
Keeping the parser state internal to a subclass makes the code more
readable and allows the removal of most parameters. It also removes the
need to return iterator ranges from the tokenization function thus making
the Token class obsolete.
Unit testing benefits from this as well as it more closely resembles usage
in the wild as more of the code can be run without a live system.
The tokenization is somewhat crude but given the small amount of token
types it is acceptably efficient while still maintaining readability. The
parsing is quite simple to implement as a sort of a recursive descent
parser and is a lot more readable that the old state machine
implementation.
Extended the unit test to check that all supported hint types are parsed
correctly. The stack mechanism isn't fully covered by the unit test and it
needs to be added once the stack mechanism uses STL containers.
The code extracts comments from a query. All three comment types are
supported and the double dash comments properly handle invalid input
(fixes MXS-2289).
The code uses iterators to access to the query and returns a list of
iterator pairs as start and end markers to comments. This makes testing
easier as the input and output can be passed as an std::string.
Since the current node id can be obtained using the function gtmnid()
the queries for finding out whether a node is in the quorum and whether
it is softfailed can be made simpler.
When a softfailed node is finally revoked, it will appear as the
single node in a functioning Clustrix cluster. To ensure that the
Clustrix monitor will not stick to that node, if the node that is
used as hub is softfailed, it is immediately replaced with another
node.
Session log files are now regularly checked for existence. If the log file
does not exist (likely because it has been rotated), a new log file is created.
Worker::STOPPED -> MONITOR_STATE_STOPPED
Worker::POLLING -> MONITOR_STATE_RUNNING
Worker::PROCESSING -> MONITOR_STATE_RUNNING
By defining the monitor state from the worker state there is
no risk they will ever get out of sync. And there is one thing
less to maintain.
When the servers of a service are defined by a monitor, then
at startup all servers of the monitor should be added to relevant
services. Likewise, when a server is added to or removed from a
monitor at runtime, those changes should affect services as well.
However, whether that should happen or not depends upon the monitor.
In the case of the Clustrix monitor this should not happen as it
adds and removes servers depending on the runtime state of the
Clustrix cluster.