When pre-parsing the configuration file, the existence of environment
variables is only done for the [maxscale] section. For other sections
a nicer error message is obtained if the comlplaint is made when the
configuration file is actually loaded.
Mechanism for providing custom error message from the pre-parsing
function added.
With this variables set to true, if $VAR is used as a value in the
configuration file, then `$VAR` will be replaced with the value of
the environment variable VAR.
The GLIBC backtrace functionality doesn't generate file names and line
numbers in the generated stacktrace. This can to be done manually by
executing a set of system commands.
Conceptually doing non-signal-safe operations in a signal handler is very
wrong but as stacktraces are only printed when something has gone horribly
wrong, there is no real need to worry about making things worse.
As a safeguard for fatal errors while the stacktrace is being generated,
it is first dumped into the standard error output of the process. This
will function even if malloc is corrupted.
The GLIBC backtrace functionality doesn't generate file names and line
numbers in the generated stacktrace. This can to be done manually by
executing a set of system commands.
Conceptually doing non-signal-safe operations in a signal handler is very
wrong but as stacktraces are only printed when something has gone horribly
wrong, there is no real need to worry about making things worse.
As a safeguard for fatal errors while the stacktrace is being generated,
it is first dumped into the standard error output of the process. This
will function even if malloc is corrupted.
The stack traces weren't logged as the LOG_ALERT priority wasn't enabled
by default. As an alert is intended to be something that must leave a
trace somewhere, and as such, it must not be possible to disable it. For
this reason, it is acceptable to always log the message if the priority is
LOG_ALERT.
Added the -rdynamic linker flag so that all symbols are exported when
linking MaxScale.
As the stack trace is printed in a signal handler, the first attempt
should be to print the stack trace to the standard output. This way the
output is printed before an attempt to use malloc is made when it is
logged to the logfile.
The `passive` parameter can be given in the configuration file or on the
command line. It is displayed in the diagnostic output and changes to it
are persisted.
The variable itself does nothing.
The original process should use _exit if the forking of the child process
is successful. This makes sure that the exit handlers are called only when
the daemon process exits.
The workers need to be destroyed only after services have been
to ensure that they are around in case the destruction of services
involves the closing of dcbs.
The default interface for the admin interface is the IPv6 address '::'
which corresponds to the IPv4 address '0.0.0.0'. If the system doesn't
support IPv6, then an attempt to bind on IPv4 should be made.
Added a debug option that allows stdout and stderr to be redirected to a
file. This helps with the use of ASAN which prints all of its findings to
stderr.
It is now possible to specify the thread stack size to be used,
when a new thread is created. This will subsequently be used
for allowing the stack size to be specified for worker threads.
OpenSSL 1.1 supports most of the native threading libraries, including
pthread. This means that only versions before 1.1 need the thread handling
code.
MXS-1282. The flags "-g=arglist" or "--debug=arglist" activate
the debug settings specified in the comma-separated list arglist.
Currently, the setting "disable-module-unloading", which prevents
modules (.so-files) from being unloaded at exit, is supported. This
allows Valgrind to produce line numbers for leak reports when the
memory was allocated in a module. The setting "enable-module-unloading"
is also available, but this is activated by default.
The debug arguments and their actions are defined in a structure
array, so adding more is straightforward.
The /users/ resource shows all user accounts that can be used with
MaxScale. This resource is further split into two resource collections,
/users/inet and /users/unix, which contain the network users and Linux
accounts respectively.
When MaxScale is started, a separate thread for the administrative
interface is started. This allows the worker threads to handle client
requests while the administrative thread handles the lower priority
administrative requests.
The administrative interface responds to all request with a 200 OK HTTP
response. This allows the administrative interface itself to be tested.
The shutdown is now performed so that a shutdown message is
sent to all workers. When the workers receive that message, they
turn on a shutdown flag, which subsequently is checked in the poll
loop.
MXS_WORKER is an abstraction of a worker aka worker thread.
It has a pipe whose read descriptor is added to the worker/thread
specific poll set and a write descriptor used for sending messages
to the worker.
The worker exposes a function mxs_worker_post_message using which
messages can be sent to the worker. These messages can be sent from
any thread but will be delivered on the thread dedicated for the
worker.
To illustrate how it works, maxadmin has been provided with a new
command "ping workers" that sends a message to every worker, which
then logs a message to the log.
Additional refactoring are needed, since there currently are overlaps
and undesirable interactions between the poll mechanism, the thread
mechanism and the worker mechanism.
This is visible currently, for instance, by it not being possible to
shut down MaxScale. The reason is that the workers should be shut down
first, then the poll mechanism and finally the threads. The shutdown
need to be arranged so that a shutdown message is sent to the workers
who then cause the polling loop to exit, which will cause the threads
to exit.
That can be arranged cleanly by making poll_waitevents() a "method"
of the worker, which implies that the poll set becomes a "member
variable" of the worker.
To be continued.
