If a session command produces a different result on the slave than it did
on the master, a warning is logged. This warning now also logs the query
that was being executed to make investigation of the problem easier.
When a BEGIN statement is prepared using the binary protocol, it returns a
single OK packet. Due to a bug in the code that deals with multi-statement
results and EOF packets, the response was never sent to the client.
Also added back the error messages of failed session commands to the INFO
level. This way it's still possible to see why a session command fails but
the log isn't flooded by them in normal usage.
The responses of slaves that arrived before the master were always
compared to the empty value of 0x00. If the slave connection replied after
the master, the comparison was correct.
This commit introduces a map of slaves and their responses that
are handled once the master's response arrives.
Removed false error message about failed session commands. An error in
response to a session command is a perfectly valid result.
Also added the explicit commands that the master and slave return to the
warning that is logged when the results differ.
If a prepared statement fails to execute on a backend server, no prepared
statement ID is returned. As the connection to the slave backend will be
closed when the result of a session command differs from the master's
response, there's no need to even attempt extracting the response.
This change avoids the triggering of a false positive in
mxs_mysql_extract_ps_response when an attempt to extract a
COM_STMT_PREPARE response is made on a response that isn't a
COM_STMT_PREPARE response.
If a prepared statement sends large amounts of data, the target server
where the data is sent will be tracked. The tracked target was not reset
after a multi-packet query was completed and the target itself was used to
check whether the session was processing a multi-packet query.
Changed the check to use the boolean variable instead of the target and
added a reset of the tracked target after a multi-packet query was
completed.
The enums exposed by the connector are not intended to be used by the
users of the library. The fact that the protocol, and other, modules used
it was in violation of how the library is intended to be used.
Adding an internal mapping into MaxScale also removes some of the
dependencies that the core has on the connector.
Providing helper functions for the commonly used parts of the server makes
code easier to read. It also removes any possibility for formatting
problems by moving the URI and name string handling inside the Backend
class.
Renamed variables to better represent the types of variables they
represent. Reordered some of the functions so that the functions don't
need to be declared before they are used.
Readwritesplit now uses the SessionCommand class as a "master list" of
executed session commands. This allows the session commands to be easily
copied over to slaves that are taken into use after session commands have
already been executed.
Currently, the code doesn't execute the session command history when a
mid-session reconnection occurs. A method to cleanly copy the session
commands needs to be exposed by the Backend class.
The session commands are now duplicated as SessionCommand objects This
allows for an easier migration from the old session command implementation
to the new one.
