The services whose servers are defined using a monitor, will
now be populated from the monitor.
Note, no consideration has yet been given to runtime changes.
The manipulation functions are currently static so that the container can be initialized
if required. This will be fixed later.
The new functions are taken into use in monitor management.
Replaces uses of config_get_param() in modules either with contains()
or get_string(). The config_get_param() is moved to internal headers,
as it allows seeing inside a config setting.
Since the settings are now protected fields, all related functions were
moved inside the monitor class. mon_ping_or_connect_to_db() is now a method
of MXS_MONITORED_SERVER. The connection settings class is defined inside the
server since that is the class actually using the settings.
When the connection state is reset by executing a COM_CHANGE_USER or
COM_RESET_CONNECTION, readwritesplit does not need to store the session
command history that was executed before it. With this, pooled connections
will effectively behave like normal connections if the pooling mechanism
is smart enough to reset the connection. This also prevents unwanted
visibility into the session states of other connections.
If the routing of a session command fails due to problems with the backend
connections, a more verbose error message is logged. The added status
information in the Backend class makes tracking the original cause of the
problem a lot easier due to knowing where, when and why the connection was
closed.
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.
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 class MonitorManager contains monitor-related functions that should not
be called from modules. MonitorManager can access private fields and methods
of the monitor.
Both the replication lag and the message printing state are saved in SERVER,
although the values are mostly used by readwritesplit. A log message is printed
both when a server goes over the limit and when it comes back below.
Because of concurrency issues, a message may be printed multiple times before
different threads detect the new message state.
Documentation updated to explain the change.
