Due to the fact that both client connections and listeners use sessions in
2.3, the client_count tracking must be done inside the client DCB. In
addition to this, the max_connections check didn't take the current
pending connection into account which caused an off-by-one error.
This commit fixes the connection_limit test failure that was introduced by
commit 6306519e5e75575ba083ee2f0edfe7e624da5d26.
By incrementing the counters when the session is created, we know that the
counter will always be decremented correctly. This does cause the listener
session to be counted as an actual session but this is already present in
the statistics calculations and is something we have to live with in 2.3
This change also makes it possible to overshoot the connection count
limitation as the session creation is delayed until authentication
fails. Both of these problems are fixed in 2.4.
The number of sessions wasn't always incremented but it was always
decremented. This happened primarily when authentication failed. By making
the management of the counters a part of the object lifecycle, this
problem goes away.
The number of sessions wasn't always incremented but it was always
decremented. This happened primarily when authentication failed. By making
the management of the counters a part of the object lifecycle, this
problem goes away.
When matching hostnames between MaxScale server configuration and the
SHOW SLAVE STATUS-output, use DNS-resolution if a simple string comparison
doesn't find an answer. Results of the resolution are saved to avoid
repeating the operation for the same address.
Formatted with nl_func_type_name and related options set to ignore. This
keeps the formatting intact for long return types in declarations and
definitions.
The code that selects which worker to assign the DCB to is now completely
in the Listener class. This removes the need to change the ownership of a
DCB after it has been allocated.
Storing all the runtime errors makes it possible to return all of them
them via the REST API. MaxAdmin will still only show the latest error but
MaxCtrl will now show all errors if more than one error occurs.
Minor renaming of the session state enum values. Also exposed the session
state stringification function in the public header and removed the
stringification macro.
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.
Whenever a client DCB is accepted, a session for it is allocated. This
simplifies the handling of shared data between DCBs by allowing it to be
placed inside the session object. Currently, the data is stashed away in
the client DCB.
The session allocation now has two distinct parts: the initialization of
the session itself and the creation of the router and filter
sessions. This allows sessions to be allocated the moment a client DCB is
created instead of only after the authentication is complete. With this
change, the need for the dummy session is removed.
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.
