The query classifier stores information about the statement carried
by a GWBUF in the GWBUF itself. We need to be able to store that
object out side the lifetime of the GWBUF. So, we require that a
query classifier is capable of duplicating references to that object.
Minor cleanup:
- Unit variables places in anonymous namespace.
- Unit variables accessed via this_unit struct.
This is the first commit of many where the mapping from canonical
statement to query classification result is introduced.
The mapping is placed above the actual query classifier, so that all
query classifiers will benefit from it.
The mapping will be maintained by thread so that there will not be
any synchronization issues. Further, initially a simple map without
upper boundary will be used; if this is found to provide measurable
benefits, the map will then be replaced with an LRU mechanism so
that it becomes possible to specify just how much memory the mapping
may use.
The evq_length file held the returned number of descriptors from
the last epoll_wait() call. As such it is highly temporal and not
particularly meaningful.
That has now been removed and the instead the average number of
returned descriptors is maintained. That information changes slowly
and thus carries some meaning.
It is now possible to prevent the masking filter from rejecting
statements using functions in conjunction with fields to be
masked. So now it is possible to not use the blanket rejection
of the masking filter and replace it with more detailed firewall
rules.
The masking filter works only on the result-set. However, if
functions are used, the column names will not be available in
the result-set, and hence masking will not take place.
Now, the statement is checked and if functions are used in
conjunction with columns that should be masked, the statement
is rejected. Thus, functions can no longer be used for bypassing
the masking. That was possible earlier as well, but required
manually setting up the firewall filter.
Before the state of the backend servers is checked, MaxScale needs to be
stopped to prevent the automated failover from interfering in the start-up
process.
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.
The log manager is the only one that uses the mlist_t versioned list. The
counter that keeps track of the version number was not modified using
atomic operations meaning that the compiler is free to optimize away parts
of the lock-free versioning mechanism that uses it.
To prevent this optimization, the variable is declared volatile. A rewrite
is direly needed but it cannot be done in 2.2.
Displaying the MaxScale version helps identify which package the
executable was bundled with. As the MaxCtrl source is a part of MaxScale,
there's no need for separate versioning.
Empty databases were not mapped to ServerMap because they had no tables
to map. Modified the query to also include empty databases making it
possible to also connect to empty databases through schemarouter.
Removed the excessive comments in favor of a simplified description. Use
stack-allocated TestConnections and simplify assertions.
The main change is the different SQL used to update the user with the old
password. Direct modification of the `mysql`.`user` database isn't very
neat but it guarantees that the value is updated.
The test should stop MaxScale at the start unless the manual debug flag is
given on the command line. This fixes the connection failure of mxs1719
but reveals a problem with the filter itself.
Due to the skewed accept distribution without SO_REUSEPORT, we use
round-robin assignment of workers for new client connections. This
provides better performance as work is more likely to be evenly
distributed across all threads.
Using a least-busy-worker algorithm would provide a more stable result but
this is not trivially simple to implement. For this reason, the
round-robin based approach was chosen for 2.2.
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 test is checking the status of the nodes, the output is relatively
verbose.
Also changed dropping of users to use the IF EXISTS syntax. This will
remove the errors if the users do not exist.
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.
If only one server is used, the amount of requests can be reduced from a
minimum of two to a minimum of one. In most cases this cuts down the
response time in half.
If two or more session commands contain identical buffers, the buffer of
the first session command is shared between the others. This reduces the
amount of memory used to store repeated executions of session commands.
The purging of session command history in readwritesplit was replaced with
session command de-duplication. This was done to prevent problems that
could arise when the order of session commands plays a significant role.
