Session log files are now regularly checked for existence. If the log file
does not exist (likely because it has been rotated), a new log file is created.
Replaces uses of config_get_param() in modules either with contains()
or get_string(). The config_get_param() is moved to internal headers,
as it allows seeing inside a config setting.
If the session doesn't match the required username or remote address, the
match data is not allocated. This also doubles as a replacement of the
active member variable.
The code used a rather questionable method for parsing SQL statements
instead of using the query classifier for detecting transaction start and
stop events.
Minor renaming of the session state enum values. Also exposed the session
state stringification function in the public header and removed the
stringification macro.
Fixed the use of DCBs and sessions in the mock testing framework and
adapted them to the changes done to the objects in question. Extended the
testing utility functions to allow preloading modules as well as making it
possible to only partially initialize the query classifier.
Allocating the session before a DCB guarantees that at no point will a DCB
have a null session. This further clarifies the concept of the session and
also allows the listener reference to be moved there.
Ideally, the session itself would allocate and assign the client DCB but
since the Listener is the only one who does it, it's acceptable for now.
As each connection now immediately gets a session the dummy session is no
longer required. The next step would be to combine parts of the session
and the client DCB into one entity. This would prevent the possibility of
a client DCB with no associated session. Backend DCBs are different as
they can move from one session to another when the persistent connection
pool is in use.
Allocating DCB with new allows the use of C++ objects in the DCB
struct. Also the explicit poll field can be replaced by inheriting from
MXB_POLL_DATA.
