This prevents empty or failed reads from updating the last_read flag which
in turn gives us the correct connection idle time when network errors
occur.
The code registered both client and backend callbacks for backend
DCBs. This caused the whole connection to hang if backend side throtting
was ever triggered.
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 FakeEventTask called the actual DCB handler with a fake task but it
didn't set the fake event flag. This caused KILL queries to be treated as
if they were network errors.
The hangup and error handlers now have unique messages. Although the
behavior in the handlers is practically the same in both cases, the cause
of the error is not the same.
If a socket error is present, it is added to the error message. If an
error is present, it should clearly show the reason why the TCP socket was
closed.
The is_fake_event boolean helps distinguish fake events from real
ones. This makes figuring out the real source of hangup events easier.
When fake hangup events are delivered via DCBs, the current DCB would not
be updated. This would cause error messages without a session ID which
makes failure analysis harder.
SSLContext is now used everywhere except the binlogrouter which still
allocates the contexts itself. Fixing the binlogrouter's misuse of
internal structures is a rather large undertaking and for this reason the
SSLContext will be taken into use there in a separate commit.
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.
