When providing pointer to instance and pointer to member function
of the class of the instance, the pointer to the member function
should be first and the pointer to the instance second.
The interface for canceling calls is now geared towards the needs
of sessions. Basically the idea is as follows:
class MyFilterSession : public maxscale::FilterSession
{
...
int MyFilterSession::routeQuery(GWBUF* pPacket)
{
...
if (needs_to_be_delayed())
{
Worker* pWorker = Worker::current();
void* pTag = this;
pWorker->delayed_call(5000, pTag, this,
&MyFilterSession::delayed_routeQuery,
pPacket);
return 1;
}
...
}
bool MyFilterSession::delayed_routeQuery(Worker::Call:action_t action,
GWBUF* pPacket)
{
if (action == Worker::Call::EXECUTE)
{
routeQuery(pPacket);
}
else
{
ss_dassert(action == Worker::Call::CANCEL);
gwbuf_free(pPacket);
}
return false;
}
~MyFilterSession()
{
void* pTag = this;
Worker::current()->cancel_delayed_calls(pTag);
}
}
The alternative, returning some key that the caller must keep
around seems more cumbersome for the general case.
It's now possible to provide Worker with a function to call
at a later time. It's possible to provide a function or a
member function (with the object), taking zero or one argument
of any kind. The argument must be copyable.
There's currently no way to cancel a call, which must be added
as typically the delayed calling is associated with a session
and if the session is closed before the delayed call is made,
bad things are likely to happen.
