Uses mostly the status functions for reading the flags. Strickly
speaking this breaks the REST API since in some cases (status combinations)
the printed string is different from what was printed before.
The monitor can now differentiate between slaves with a running
series of slave connections to the master from slaves with broken
links. Both still get the SERVER_SLAVE-flag if 'detect_stale_slave'
is on.
Also, relay servers must be running.
If auto_failover is disabled and an alternative master exists, the
monitor will swap the master. This may break replication, but the
situation requires that the dba has set up a cluster with multiple
masters.
The relay master status was assigned to a server based on the last known
replication status of the slaves that have at some point replicated from
it. This can cause false positives and the relay master status is assigned
to servers that have never been observed to act as relay masters.
The master validity check now checks if the master is down. This requires
that the slave status is assigned even if no master is available.
The failover precondition is also fulfilled as long as one valid promotion
candidate is found. Previously a slave that didn't use GTID replication
appeared to prevent failover.
The auto_failover is a more reliable solution and should be used instead. Several
unused parameters were removed, although they can still be defined in the config
file. Updated documentation on the relevant parts.
In previously the status bits were assigned only for running servers. Due
to the changes done in the monitoring algorithm, the slave and master
status bits are assigned to servers that are down. This change broke a
number of tests and deviates from previous behavior.
To keep the old behavior and to fix the test, the status bits are not
assigned to servers that are down.
The command is saved in a function object which is read by the monitor
thread. This way, manual and automatic cluster modification commands are
ran in the same step of a monitor cycle.
This update required several modifications in related code.
The monitor now detects when a server has changed such that a replication
graph rebuild is needed and only then rebuilds the graph and detects
cycles and master.
Also, some old code is no longer called in the monitor cycle. It will be
removed in later commits. Refactored some of the related functions.
Not yet used, as more is needed to replace the old code. The
algorithm is based on counting the total number of slave nodes
a server has, possibly in multiple layers and/or cycles.
This makes the code clearer and reduces race conditions, as the monitor
could be writing SERVER->status while a router is reading it. Also,
the time during which the SERVER struct is locked drops to a fraction.
The master down verification through slaves won't work with this commit. It needs to be
redesigned to handle multiple slave connections or removed. Also, only the first row of
slave status data is used by the monitor, so multiple slave connections are still
incorrectly handled.
5.1 to 5.3 are officially not supported anymore, so support can be removed from
the monitor. This allows removing the config parameter "mysql51_replication".
Also, the QueryResult integer reading method now only reads non-negative integers
since the server rarely returns negative values. This frees negative values for
indicating parsing error(s).
Gtid-class was moved back to utility.hh/.cc because the QueryResult-class requires it.
Renamed to MariaDBServer. The objects have a pointer to the underlying
MXS_MONITORED_SERVER. The purpose is to have the monitor mainly use
MariaDBServer instead of the current mix of MXS_MONITORED_SERVER* and
MySqlServerInfo and to simplify the mapping between the two. Also,
many methods can be moved to the MariaDBServer class later on.
Some functions have been converted from MXS_MONITORED_SERVER* to
MariaDBServer.
1. Move some remaining class data private.
2. Linebreak long lines.
3. Move current master autoselection inside class method.
4. Remove single-use constant #defines.
5. Monitor status is only written inside loop.
