If the startup of the listeners requires communication with all of the
workers, the workers must be up and running for that to happen.
Due to the fact that the main thread is still a worker thread, the
initialization code is not extra straightforward. By queuing an event to
the main worker, the startup of all listeners is done at a fully
operational state with all workers fully functional.
The service initialization code was also flawed in the sense that it would
cause a deadlock if any of the threads would have to check for the user
permissions. This is mainly a problem with the authenticator modules but
the benefits of the per service pre-loading of users is most likely
superficial. In theory startup will be faster as each thread now queries
the users in parallel.
Replaced the DCB with a single file descriptor that the listener listens
on and which is added to all of the workers. The Listener also extends the
MXB_POLL_DATA which allows it to handle epoll events.
Moved the code that creates the listening socket into listener.cc where it
belongs and did a minor cleanup of it.
By storing the reference in the DCB, the two-way dependency between the
listeners and services is severed. Now the services have no direct link to
listeners and after the destruction of a listener it will be freed once
all connections through it have closed.
Due to the fact that a listener itself has a DCB that must point to a
valid listener, a self-reference is stored in the listener DCB. This is
extremely confusing and is only here to keep the code functional until the
DCB part of the listener can be factored out.
By storing a shared pointer to the listeners in the services, they will be
available as long as the service using them exists. This enables clean
destruction of listeners that still have open sessions.
The listener creation code now separately creates the listener and links
it to the service. Also replaced relevant parts of the related code with
the listener implemented versions of it.
The iteration of listeners is now done via the global list of
listeners. This removes the need to have a service before a listener is
accessed which also reflects how the actual configuration is laid out. It
also guarantees that any results returned by the find functions will be
valid as long as the results are used.
The class is still mostly the same as the old C version but it now uses
std::string instead of char pointers. Changed configuration default values
so that the parameters passed to the listener allocation are always valid.
Fetching the users may potentially take longer than the watchdog
timeout. To ensure that MaxScale is not killed by systemd, we must
ensure that the notifications are generated also when MaxScale
synchronously is fetching the users.
The servers with a zero weight would be always used over ones that have a
weight. This means that the behavior was inverted and caused the
mxs2054_hybrid_cluster test to fail in 2.3.
Also fixed a typo in the deprecation message.
Even though directly closing the socket is not very neat in the
architectural sense of things, it allows the best of both worlds: the
socket is instantly closed and is open for reuse while the listener struct
is still available as a reference.
This change needs to be revised when the listeners are refactored into
separate objects.
Updated documentation to reflect the change in behavior.
See script directory for method. The script to run in the top level
MaxScale directory is called maxscale-uncrustify.sh, which uses
another script, list-src, from the same directory (so you need to set
your PATH). The uncrustify version was 0.66.
The math becomes simpler when the weight is inverted, i.e. a simple multiplication
to get the (inverse) score. Inverse weights are normalized to the range [0..1] where a lower
number is a higher weight,
The enum select_criteria_t is used to provide a std::function that takes the backends
as vector (rather than the prior pairwise compares) and returns the best backend.
Given that worker.hh was public, it made sense to make routingworker.hh
public as well. This removes the need to include private headers in
modules and allows C++ constructs to be used in C++ code when previously
only the C API was available.
The maxscale_is_shutting_down function is used to detect when MaxScale
should stop. This fixes a race condition in the code where the workers has
not yet been initialized but a termination signal has been received. It
also replaces the misuse of the service_should_stop variable with a proper
function.
Services, monitors and filters all use the parameters for object
serialization. This means that when the object is created, the module
parameter must be in the parameter list.
The services, monitors and filters now construct the JSON format
parameters from the configuration parameters. This reduces the need for
the amount of explicit operations and makes adding new parameters easier.
The runtime modification of servers, services and monitors now validates
the parameters before starting the update process. This guarantees that
the set of parameters is valid before it is processed.
After the validation, the parameters are now also stored in the list of
configuration parameters. This will simplify the serialization process by
removing the need to explicitly serialize all common object parameters.
Putting the file descriptor first keeps it in line with dprintf.
Making the parameter set an initializer list allows matching against
multiple sets of parameters in one function call. This will compact the
parameter serialization by using the same code for the common service
parameters and the module parameters.
The service configuration serialization now uses the helper functions from
config.hh. This fixes the failing test mxs1731_old_persisted_config and
improves the readability of persisted configuration files.
Converted parameters into booleans that were used like booleans. This
forced the removal of the automatic enabling of
localhost_match_wildcard_host but since it has been enable by default,
this change should have no practical effects.
In addition to the clarification of the persisted configurations, this
change will limit the negative side-effects of changing a configuration
value in the main configuration file after a runtime modification has been
made. If a value has not been modified at runtime, changes to it in the
main configuration will take effect.
Previously, a runtime modification prevented all further manual changes to
the configuration file. Although in theory this sounds good, in practice
this does very little to improve the situation: The only reliable way to
change a parameter after a runtime modification is to do it via the REST
API (or MaxAdmin).
