When the setting up of filters for a session fails, the DCB is closed and
the client DCB's session pointer is set to NULL. This needs to be checked
in the schemarouter before the `m_client->session` pointer is used.
The act of setting the session pointer to NULL should not be necessary as
the session is freed once the reference count drops down to zero. Due to
the fact that changing this would require moderate changes in session code
means that it should not be done in a patch release as the risks are too
high.
This is somewhat questionable, as the slaves won't be able to really
replicate from the new master. However, not doing this causes the wrong
master to be selected after failover unless the new master has a majority
of slaves under it.
Added support for composite roles for 10.2 and newer versions. As
recursive CTEs are required to extract the role mappings, composite roles
aren't supported on 10.1.
By storing the data gathere by readwritesplit inside the session, the
protocol will be aware of the state of the LOAD DATA LOCAL INFILE
execution. This prevents misinterpretation of the data which previously
led to closed connections, effectively rendering LOAD DATA LOCAL INFILE
unusable.
This change is a temporary solution to a problem that needs to be solved
at the protocol level. The changes required to implement this are too big
to add into a bug fix release.
If a large packet is received, the stack would overflow when the username
size was determined from the packet size. The code must not assume
anything about the size of the packet being read.
The offsets in the events were wrong if MaxScale was restarted in the
middle of a binlog. This was caused by the fact that the FDE event
contains information on binlog checksums which is required for a correct
interpretation of the binlog. The FDE event was only read when the binlog
was first opened when it needs to be read every time the binlog is opened.
As a JSON object can never start with the ERR prefix, it is safe to check
it for all requests. Also fixed the missing newline in the avrorouter
error message.
When the query queue does not contain a complete packet
(i.e. modutil_get_next_MySQL_packet return NULL), an informative dump of
how many bytes and what is stored is logged.
The LocalClient micro-client required a reference to the session that was
valid at construction time. This is the reason why the previous
implementation used dcb_foreach to first gather the targets and then
execute queries on them. By replacing this reference with pointers to the
raw data it requires, we lift the requirement of the orignating session
being alive at construction time.
Now that the LocalClient no longer holds a reference to the session, the
killing of the connection does not have to be done on the same thread that
started the process. This prevents the deadlock that occurred when
concurrect dcb_foreach calls were made.
Replaced the unused dcb_foreach_parallel with a version of dcb_foreach
that allows iteration of DCBs local to this worker. The dcb_foreach_local
is the basis upon which all DCB access outside of administrative tasks
should be built on.
This change will introduce a regression in functionality: The client will
no longer receive an error if no connections match the KILL query
criteria. This is done to avoid having to synchronize the workers after
they have performed the killing of their own connections.
If a client is executing a COM_CHANGE_USER command and the
reauthentication of the client fails, no error message would be logged
about the failure of the reauthentication process and only a routing
failure message would be logged.
The protocol could leak memory in rare cases where several commands were
queued at the same time. Readwritesplit also didn't free the memory it
acquired via qc_get_table_names.
If a service has no active servers and users are injected, a warning would
be logged. This is a misleading warning if the service has no servers and
should only be logged if the failure to load any users is an unexpected
situation.
Parameters that accept whitespace-only values need to have their default
values quoted if they contain only whitespace characters. In 2.2 the
qlafilter is the only module that did not do this.
When a valid target was not found, no error message was logged by the
router. This would cause the "Routing the query failed. Session will be
closed." message to be logged with no explanation as to why the routing
failed.
In addition to the above-mentioned case, no message would be logged if the
target for a COM_STMT_FETCH was not in use.
If the authentication failure was due to a missing database, this extra
information can be logged. This will help cases where users are using
databases that do not exist.
Also change the following defaults:
- "selects": Was "verify_cacheable", is now "assume_cacheable"
- "cached_data": Was "shared", is now "thread_specific"
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.
Backend::execute_session_command would use the overridden write method
instead of the Backend::write method that it intended to use. This caused
session commands that did not expect a response to be in a state that
expected a result.
Also fixed RWBackend::write pass the response_type value to
Backend::write.
If the service user does not have adequate grants to the mysql tables, the
legacy query is used. This prevents an upgrade failure when the user was
lacking the new privileges.
The cache filter walks through the resultset in order to detect
when the resultset ends. That is, it reads each packet header as
they arrive.
In case the resultset is large, the cache will have to read several
packet headers. That it does using gwbuf_copy_data(). However, as that
was done using the first received GWBUF as the starting point, it meant
that in gwbuf_copy_data() the buffer chain was walked over and over
and over again, with a significant performance hit as the result.
Now we separetely store the last buffer received, and the the starting
offset of it. That way there will be no buffer chain walking.
As this is a common problem, GWBUF could cache the offset of the tail,
thus removing the performance penalty if you read from an offset that
happens to be in the tail. However, it's better to do that as a part
of a general overhaul of GWBUF.
If the server sends a server shutdown error, it is safe for readwritesplit
to ignore it. When the TCP connection is closed, the router error handling
will discard the connection, optionally replacing it.
