The process of appending to a std::string always includes a size check in
case the internal storage needs to expand. Given that we know a
canonicalized version of a query string is never larger than the original
string and that we pre-allocate enough memory to cope with the worst-case
scenario, the extra logic in std::string::push_back is unnecessary and an
extra cost. Writing directly into the string avoids this cost and improves
the performance.
Switched from default character type functions to ones that use lookup
tables. Eliminated the internal state and replaced with in-place iteration
of the query. Added code to allow single-lookup detection of normal
characters.
The log message should now contain enough information to more easily debug
any configuration issues that result from updating the main config file
after runtime changes have been done.
Also fixed the theoretical race condition in detection of persisted
configuration files by only checking for their existence once.
By storing the server statistics object in side the session, the lookup
involved in getting a worker-local value is avoided. Since the lookup is
done multiple times for a single query, it is beneficial to store it in
the session.
As the worker-local value is never deleted, it is safe to store a
reference to it in the session. It is also never updated concurrently so
no atomic operations are necessary.
The code now only checks the need for a keepalive ping once every
keepalive interval. Reduced the number of mxs_clock calls to one so that
all servers use the same value.
All global parameters are now handled by the runtime configuration
modification code. The parameters that are trivial to update can now be
updated at runtime. All other global parameters cause a new error message
to be returned stating that the parameter in question cannot be modified
at runtime.
Also updated the list of modifiable parameters in MaxCtrl. This list
should not be stored in MaxCtrl and should be created by MaxScale at
runtime.
The prefix was always added even when the original version would've been
acceptable. For example, a version string of 5.5.40 would get converted to
5.5.5-5.5.40 which is quite confusing for older client applications.
Due to MDEV-15556 and MDEV-15840 recursive CTEs can't be reliably used
with older 10.2 versions. To prevent problems, only use the query that
extracts composite roles with newer versions.
DCBs can now have a null session pointer and if they do, they are in the
persistent pool. The no-null-session assertions are no longer valid but
with a reorganization of the pooling code to only use file descriptors,
the assertions can be added back.
The old behavior is to not start MaxScale if any listeners fail to
bind. This behavior is convenient when there are conflicts with other
applications so it should remain. This change prevents the internal
service restarts from functioning which might have already been broken.
The "restarting" of services after a failure to bind to an interface is
somewhat questionable. Almost no transient errors are expected at startup
with the exception of running out of sockets. This should probably be the
only case when the internal service restart is done and in other cases it
causes more harm than good.
Since we know the worst-case size of a canonical statement is the size of
the query string, we can reduce the number of memory allocations to one in
the get_canonical function.
Minor renaming of the session state enum values. Also exposed the session
state stringification function in the public header and removed the
stringification macro.
The error flag was set before the function was called which caused the
function to never be used. As the core should handle the filtering of
multiple errors on the same DCB, the protocol modules should not check it.
When an attempt to accept a client DCB fails, the session should only be
deleted directly if the allocation of the client DCB fails. Otherwise the
closing of the DCB triggers the session deletion.
