Single spot where an existing hint ptr was overwritten. Removed gwbuf_add_hint()
because it was adding hints at the opposite end compared to functions in hint.h.
Added hint_splice() to replace.
The MariaDB implementation allows the last GTID to be tracked with the
`last_gtid` variable. To do this, the configuration option
`session_track_system_variables=last_gtid` must be used or it must be
enabled at runtime.
The protocol now allows protocol modules to return JSON formatted
information about the protocol module internals. Currently this is only
implemented by the mariadbbackend module and it returns the current
connection ID on the backend server.
Removed unused and properly documented all entry points in the protocol
module API. As the removal of the `session` entry point is an backwards
incompatible change, the protocol API version was updated.
The connections that relate to a particular session are now a part of the
sessions resource. Currently, only the generic information is stored for
each connection (id and server name).
By storing a link to the backend DCBs in the session object itself, we can
reach all related objects from the session. This removes the need to
iterate over all DCBs to find the set of related DCBs.
The fact that a client dcb was immediately added to the epoll-
instance of the relevant worker (possible, since that is thread-
safe), but was added to the book-keeping via the message mechanism
(necessary, since that is not thread-safe), meant that if the
connection was closed before the message was delivered, the handling
of the message then caused an access error.
Now the fd is also added to the epoll-instance via the messaging
mechanism, so the problem can no longer occur. The only fds this
affects are connections made to maxadmin or maxinfo as they are
always handled by the main thread due to deadlock issues.
Since we need to call mysql_thread_init(), which can fail, in
the monitor thread, we need to wait for the outcome of that
before we can return from start().
The configuring of the monitor instance is now performed in a
separate function. That is in preparation for the moving of the
start function to maxscale::MonitorInstance.
- All monitors (but MariaDBMon for the time being) inherit
from that.
- All common member variables moved to that class. Still
manipulated in derived classes.
In subsequent commits common functionality will be moved to
that class.
By relying on the server to tell us that it is requesting the loading of a
local infile, we can remove one state from the state machine that governs
the loading of local files. It also removes the need to handle error and
success cases separately.
A side-effect of this change is that execution of multi-statement LOAD
DATA LOCAL INFILE no longer hangs. This is done by checking whether the
completion of one command initiates a new load.
The current code recursively checks the reply state and clones the
buffers. Neither of these are required nor should they be done but
refactoring the code is to be done in a separate commit.
Added two helper functions that are used to detect requests for local
infiles and to extract the total packet length from a non-contiguous
GWBUF.
From 10.1.32, 10.2.14 and 10.3.6 onwards, there is an
information_schema plugin called DISKS using which information
about the disk space situation on the server can be obtained.
Subsequent commits will add configuration options for specifying
limits and take the functionality in use in monitors where it makes
sense.
The parameter extraction caused a recursive lock of the server
spinlock. To work around this, an unlocked version of server_get_parameter
is needed.
Ideally, a lock-free setup would be used but due to this being a bug fix,
it will have to be done later on.
The purpose of this template class is to provide the
implementation of the monitor C-api. It's to be instantiated
with the class that actually provides the monitor behaviour.
A separate class maxscale::MonitorInstance will be provided
that then in turn implements the behaviour common to most
monitors. So, the structure will be like:
class SomeMonitor : public maxscale::MonitorInstance {...}
extern "C" MXS_MODULE* MXS_CREATE_MODULE()
{
static MXS_MODULE info =
{
...
&maxscale::MonitorApi<SomeMonitor>::s_api,
...
};
return &info;
}
StartMonitor() now takes a MXS_MONITOR_INSTANCE and returns
true, if the monitor could be started and false otherwise.
So, the setup is such that in createInstance(), the instance
data is created and then using startMonitor() and stopMonitor()
the monitor is started/stopped. Finally in destroyInstance(),
the actual instance data is deleted.
The following type name changes
MXS_MONITOR_OBJECT -> MXS_MONITOR_API
MXS_SPECIFIC_MONITOR -> MXS_MONITOR_INSTANCE
Further, the 'handle' instance variable of what used to be
called MXS_MONITOR_OBJECT has been renamed to 'api'.
An example, what used to look like
mon->module->stopMonitor(mon->handle);
now looks like
mon->api->stopMonitor(mon->instance);
which makes it more obvious what is going on.
CreateInstance() (renamed from initMonitor()) and destroyInstance()
(renamed from finishMonitor()) have now tentatively been
implemented for all monitors.
Next step is to
1) change the prototype of startMonitor() to
bool (*startMonitor)(MXS_SPECIFIC_MONITOR*,
const MXS_MONITOR_PARAMETER*);
and assume that mon->handle will always contain the
instance,
2) not delete any data in stopMonitor(),
3) add monitorCreateAll() that calls createInstance() for all
monitors (and call that in main()), and
4) add monitorDestroyAll() that calls destroyInstance() for
all monitors (and call that in main()).
Now, all monitor functions but startMonitor takes a
MXS_SPECIFIC_MONITOR instead of MXS_MONITOR. That is, startMonitor
is now like a static factory member returning a new specific
monitor instance and the other functions are like member functions
of that instance.
Instead of using void there's now a MXS_SPECIFIC_MONITOR struct
from which monitor specific types can be derived. This change
does not bring about other benefits than a bit of clarity but
this is the first step in clearing up the monitor API.
