Comparing two fixed std::strings would have equal C strings but comparing
with operator== they would be different. This was a result of the string
modification done by fix_object_name.
Converted the internal header into a C++ header, added std::string
overload and fixed use of the function.
There exists a dependency on the configuration for the workers: the total
number of worker thread is defined by the `threads` parameter. This means
that the global configuration section must be read before workers are
started.
Commit 411b70e25656317909e54f748f8012593120041f broke MaxScale and turned
it into a single threaded application as the default configuration value
of one worker was used.
MaxScale can now be started with an empty configuration file and services
can be created at runtime. Filters cannot yet be created at runtime so
complete runtime creation of configurations is not yet possible.
By reading the configuration as late as possible, we allow the objects to
be created in an environment which is nearly identical to the environment
that is present at runtime.
This change makes it possible to execute worker tasks in the instance
creation functions of various modules. The avrorouter in particular
depended on being able to queue worker tasks on startup.
The initialization and starting of the housekeeper is now done
separately. This allows housekeeper tasks to be created when the services
are being created while still preventing the execution of the task before
the startup is complete.
The runtime configuration of a MaxScale can now be exported to a single
file. This allows modifications made via runtime configuration commands to
be "committed" for later use.
With the global configuration parameter 'query_classifier_cache'
the query classification cache can be turned on. At the moment it
does not matter what value it has; its presence simply enables the
caching.
Eventually you will be able to specify how much memory the cache
is allowed to consume.
Now takes a structure that, if present, enables the query
classification caching and specifies the properties of the
cache.
For the time being no actual properties are yet available.
The core library now contains the maxscale_shutdown() command. This makes
it possible to resolve all symbols at link time even for administrative
modules.
Backported the minimal set of changes required to build 2.1 with GCC
8. The format-truncation and format-overflow warnings are disabled instead
of fixed in 2.1 to remove duplication of effort that was already done in
2.2 (the commit doesn't cherry-pick cleanly).
The two-part shutdown procedure for the housekeeper was not needed and
caused problems if SIGINT wasn't raised. Since the main thread returns to
the main function, a single shutdown function is all that the housekeeper
needs to function.
Moved all the shutdown related code into Housekeeper::stop to remove the
waiting for the thread in the destructor.
Worker is now the base class of all workers. It has a message
queue and can be run in a thread of its own, or in the calling
thread. Worker can not be used as such, but a concrete worker
class must be derived from it. Currently there is only one
concrete class RoutingWorker.
There is some overlapping in functionality between Worker and
RoutingWorker, as there is e.g. a need for broadcasting a
message to all routing workers, but not to other workers.
Currently other workers can not be created as the array for
holding the pointers to the workers is exactly as large as
there will be RoutingWorkers. That will be changed so that
the maximum number of threads is hardwired to some ridiculous
value such as 128. That's the first step in the path towards
a situation where the number of worker threads can be changed
at runtime.
A new class mxs::Worker will be introduced and mxs::RoutingWorker
will be inherited from that. mxs::Worker will basically only be a
thread with a message-loop.
Once available, all current non-worker threads (but the one
implicitly created by microhttpd) can be creating by inheriting
from that; in practice that means the housekeeping thread, all
monitor threads and possibly the logging thread.
The benefit of this arrangement is that there then will be a general
mechanism for cross thread communication without having to use any
shared data structures.
From a practical perspective it makes no relevant difference
whether you have to add an entry to the config file and restart
maxscale or if you have to restart maxscale and provide a specific
command line, so better to provide just either possiblity.
More important would be to provide a way for turning this feature
on and off at runtime.
With the configuration entry
dump_last_statements=[never|on_close|on_error]
you can now specify when and if to dump the last statements
of of a session.
With the configuration entry
retain_last_statements=<unsigned>
or the debug flag '--debug=retain-last-statements=<unsigned>',
MaxScale will store the specified number of last statements
for each session. By calling
session_dump_statements(session);
MaxScale will dump the last statements as NOTICE messages.
For debugging purposes.
With the flag --debug=enable-statement-logging it is now possible
to instruct MaxScale to log all SQL statements it sends to the
servers.
The format of the logged string looks like:
notice : SQL(127.0.0.1): 0, "SELECT ..."
First the fixed string "SQL", followed by the server address in
parenthesis followed by the actual return value of mysql_query(),
followed by the statement itself.
The "SQL" string makes the lines easy to grep for and having the
return value before the statement makes it easier to spot since
the length of the return value string does not wary much, but the
length of the statements do wary a lot.
According to customer reports collecting the statistics has a significant
impact on the performance. As we don't need that information we can just
as well turn off that.
Further, since maxscale-common now links to the sqlite3-library, no
module needs to do that explicitly.
The internal header directory conflicted with in-source builds causing a
build failure. This is fixed by renaming the internal header directory to
something other than maxscale.
The renaming pointed out a few problems in a couple of source files that
appeared to include internal headers when the headers were in fact public
headers.
Fixed maxctrl in-source builds by making the copying of the sources
optional.
With "--daemon" or "-n" MaxScale can now be told to run in daemon
mode, that is, it forks and the parent exits. This is the default
behaviour, but a flag to this effect is needed if the default
behaviour is changed.
MaxScale now refuses to run as root. However, it is possible to
start MaxScale as root, as long as a user to run MaxScale as is
provided as a command line argument.
It is possible to run as root by invoking MaxScale as root and
by specifying the MaxScale user to be root.
