Since the listmanager code isn't used, the debug assertions will always
fail. They should be disabled until the listmanager code can converted to
the per-thread model.
Because each thread has their own epoll file descriptor and only one
thread can process a DCB, it makes sense to move to a per thread zombie
queue. This removes one of the last restrictions on scalability.
The thread-specific spinlock needs to be acquired before a fake event is
inserted from a non-polling thread. The usual situation is when a monitor
thread inserts a hangup event for a DCB.
Other, less common cases are when session timeouts have been enabled and
the DCB needs to be closed. Here it is better to insert a fake hangup
event instead of directly closing the DCB from an external thread.
Having a unique epoll instance for each thread allows a lot of the locking
from poll.c to be removed. The downside to this is that each session can
have only one thread processing events for it which might reduce
performance with very low client counts.
The service header in include/maxscale/ contains the public part of the
service API. These functions can be safely used by the modules.
The internal header located in service/core/maxscale/ is used by the core
to initialize MaxScale at startup or to provide other services in a more
controlled way (the config_runtime, for example).
The listeners aren't really destroyed and are only stopped. Further
changes are required so that they won't be started again once they have
been destroyed.
The created listeners are now stored to disk like created servers
are. This allows them to be used even after a restart.
Currently, the listeners cannot be deleted and need to be manually
removed.
The server test used the wrong name.
MySQL users test loaded multiple modules in one function call and wasn't
appropriate for an internal test suite test as it requires a working
installation.
The cache filter didn't set the library paths before trying to load
modules.
The binlogrouter was missing a NULL check which caused a crash.
If the SSL configuration of a server was altered successfully, it would
overwrite an existing configuration leading to a true memory
leak. Converting the SSL_LISTENER structure to a list allows it to store
the old configurations without leaking the memory.
This has no functional benefits apart from storing references which could
aid in debugging. In the future, the discarded configurations could be
freed once all connections that use it are closed.
The config_runtime.h header contains functions that can be used to
manipulate the running configuration. Currently the header contains the
function to create, add, remove and destroy servers.
MXS-843. When a monitor executes an external script in response to
a server event, the execution is logged to the MaxScale main log.
Previously, the log message only contained the script name as given
in the configuration file. Now, the message contains the script name
and argument values as given to the execvp-call.
DCBs and SESSIONs can be passed either as raw pointers or as the string
representations of them.
The preferred way to pass them is to use the raw pointer types. This
removes the need to convert the pointer to string form and back.
The modulecmd_foreach function allows commands to be iterated without having
to manage the locking of the system. This allows the commands to be easily
iterated and gathered into filtered lists without having to build it into
the module command system itself.
The modules can now return human-readable error messages to the caller of
the function. The internals of the modulecmd system also use this to
return errors to the users.
The error messages can be retrieved with a common error function which
should make it easy to use in various clients.
A module can register a function to a domain. These function can then be
called by external actors enabling the modules to expand their
functionality beyond the module API. Each module should use its own domain
e.g the library name.
Currently, the functions do not return results. The possible next step
would be to alter the function entry point to return a result set of
sorts. This would allow the modules to convey structured information to
the client information which would handle the formatting of the result.
Although this sounds good, it is not required for the implementation of
MXS-929.
When C and C++ are mixed in a project, main() should be compiled
as C++ to ensure that all C++ static initializations are performed
properly. That may not be strictly true anymore, depending on the
used compiler and environment, but better to do that to be on the
safe side.
The code that checked whether a server was added to a service did not
check whether the server reference was active. This caused problems when
an old server was added again to a service that once had used it.
If a master once had slaves and is in the stale status, it will not retain
this status after a restart. Without storing on-disk information, the
stale master status cannot be deduced by looking at the master
alone. Because of this, the user should be able to manually enable the
stale master status.
The listen() backlog is now set to INT_MAX which should guarantee that the
internal limit is always higher than the system limit. This means that the
length of the queue always follows /proc/sys/net/ipv4/tcp_max_syn_backlog.
When a service is added or removed from a service, a supplementary
configuration file is created. This allows MaxScale to survive restars and
unexpected downtime even if runtime changes to the servers of a service
have been made.
With these changes, it is possible to start MaxScale without any servers,
create servers, add the created servers to services and monitors and
restart Maxscale without losing the runtime configuration changes.
When a server is added to a monitor, an supplementary configuration file
is generated to persist this information. This will allow dynamic
modifications to server lists which will survive restarts and unexpected
downtime.
The monitor will only add new servers to its list of monitored
servers. This prevents duplicate entries in the list and makes it safe to
persist all used servers to the supplementary configuration file instead of only the ones that are not listed in the main configuration.
Servers created at runtime can now be configured to use SSL. The
configuration is only possible if the server is not in use.
The `alter server` command in maxadmin now takes a list of `key=value`
strings. This allows the user to define multiple alter operations with one
command.
The functions allow simple operations on configuration context
objects. This makes it easier to understand what the code does and allows
reuse of the configuration processing code.
