The slave connection I/O-tread stays running if replication credentials are
wrong when connecting to master. This causes a switchover/failover timeout.
When this happens, print the error in the slave connection status as this
clarifies the problem to the user.
If one slave is executing a query while another one is executing a session
command and the one that is executing the session command fails, the
ongoing query would get retried even though the server that failed was not
executing it. If the server was executing a session command, nothing needs
to be done.
If a resultset is followed by an ERR packet that is not expected
(e.g. server is shutting down), the packet must not be sent to the
client. This allows readwritesplit to replace the failing connection with
a new one thus hiding server shutdowns from clients.
RWBackend did not expect that a resultset and an unexpected ERR packet
could be stored in the same buffer. This can happen for example if a
server shuts down immediately after the resultset is sent.
If a packet with a KILL query was followed with another packet in the same
network buffer, the code wouldn't work as it expected to receive only one
packet at a time.
The name of the object (i.e. the section name from the configuration
file), is now stored in the configuration object for that object.
That way, more contextual and hence morfe user friendly errors and
warnings can be generated.
If the server (a real one or a service exposed as a server) is
on the same machine as MaxScale, then for performance reasons
a Unix domain socket and not a TCP/IP socket should be used.
Rename config::Configuration::configure() to
config::Configuration::post_configure(). Latter name makes it
unambiguously clear at what point the function is called.
As an error returned by the server is now stored inside RWBackend,
irrespective of whether it is returned solely or e.g. last after
a result set, there is no need to examine the GWBUF in rws, but
we can use the information that exists.
This is the base for Smart Router. Review and TODO comments are in the
code. This commit will be squashed several times so don't pay attention to this
specific commit message. I will add and remove TODO's in the code, rather
than save them in git commits. RBCommons will contain the history.
By iterating over the servers and sending the master's charset we are
guaranteed a "known good" charset. This also solves the problem where a
deactivated server reference would be used as the charset and server
version source.
If the execution of a session command fails on a master, it is retried
again. If the master is not available, the response will be returned from
one of the slaves.
The retrying of a read on a slave should only be done when the failing
server is waiting for a result and it was the last server from which a
result was expected.
If the master fails when a session command is being executed with
delayed_retry enabled, a null query would get placed into the query
queue. This change simply prevents the crash and closes the session even
though the query could be retried.
A query should not be queued if no responses are expected. The code that
executes queued queries should be dead code and this assertion would catch
it.
