The MODULE_INFO is now the main object which is used by modules to convey
information to the MaxScale core. The MXS_MODULE name is more apt as it
now contains the actual module definition.
The old MODULES structure was moved into load_utils.c as an internal
implementation and was renamed so that it is not confused with the new
MODULE structure.
The modules are now declared with a common macro. This allows future
additions to the module loading process while also making the loaded
symbol name a constant.
This allows modules to only expose one entry point with a consistent
signature. In the future, this could be used to implement declarations of
module parameters.
It is possible that a session is in the dummy state (a transient state)
when a backend write occurs. The check for the client protocol NULL-ness
should extend to the client DCB itself.
The backend MySQL protocol module now supports a new routing capability
which allows result sets to be gathered into one buffer before they are
routed onward. This should not be used by modules that expect large
result sets as the result set is buffered in memory.
Adding a limit on how large of a result set could be buffered would allow
relatively safe use of this routing capability without compromising the
stability of the system.
Doing batch inserts though readwritesplit would stall due to the fact that
pending session commands were stored instead of executed immediately.
Session command responses that weren't complete also discarded the partial
event instead of storing it for later use.
When a session command was received, any trailing data was lost even
though an attempt to split is was made.
With this change, each session command reply will be routed individually
and any trailing data is routed separately.
The routing capabilities now define the type of output the reply
processing chain expects. Currently, this only consists of two
capabilities; complete packet output and contiguous buffer output. The
latter implies the former.
The MySQLBackend protocol now only checks for complete packets if the
service requires statement based routing. This should remove unnecessary
processing when data is only streamed from the backend to the client.
The packet was generated with the wrong number of elements due to usage of
sizeof on an integer where the correct type was an uint8_t.
This only fixes the malformed packets but does not fix the root cause of
the problem. The affected rows and last insert ID are length encoded
integers which should be handled. The current code treats them as one byte
fields.
When persistent connections were used, it was possible that the injection
of COM_CHANGE_USER statements caused a crash when a DCB in the wrong state
was accessed.
For MySQL protocol modules, the `data` member of the client DCB points to
the shared session data, a MYSQL_session struct, but for sessions in the
persistent pool, it points to NULL. The boolean, `was_persistent`, tells
whether a DCB was just taken from the pool or it has been in use.
The `was_persistent` status wasn't properly reset for connections that
were put into the pool which caused a COM_CHANGE_USER statement to be
injected for stale connections in the pool which caused a crash when the
NULL `data` member was accessed.
When a persistent connection is taken from the pool, the state is reset
with a COM_CHANGE_USER on the next write. This allows reuse of persistent
connections without having to worry about the state of the MySQL session.
The transaction state only reflects explicitly started transactions.
Thus, by looking at the autocommit mode and the transaction state a
component can figure out whether the current statement will be committed
or not.
The transaction state must be updated after a buffer has been split
into buffer containing individual packets.
NOTE: The actual updating of the transaction state and the autocommit
mode is currently wrong, but will be updated in a subsequent change.
This tracks only what is explicitly set. That is, if autocommit
has been set true then, even if a transaction is started, autocommit
will not be set false.
That is, a user of the session autocommit and transaction states
need to be aware of their semantics. If a transaction is active,
then the state of autocommit is irrelevant.
When a MySQL SSL connection is made, the first packet from the client will
contain the SSLRequest packet. This packet is a truncated normal auth
packet and the real auth packet will be sent after SSL has been
established.
The MySQLClient protocol should read the client information for SSL
connections after SSL has been established.
When a client without SSL connected to a listener which requires SSL, the
error message always used the package sequence number 3 even if the
response was the second packet.
Also fixed debug assertions which failed when non-SSL connections were
created to SSL listeners.
- Since the capabilities are a bitmask, it is better if an unsigned
integral type is used.
- Since the function is part of an ABI, it is better if an explicit
size is used.
- 64-bits so that there also is room for independent filter
capabilities.
The client protocol module now extracts the information that is relevant
for all modules. Currently this information consists of the client
capabilities, character set, username and default database.
In a subsequent change, the includes of server/core/*.c will be
cleaned up, and if there is a common set of include files, needed
by most, then a server/core/maxscale/core.h that includes those
will be introduced.
The general purpose stuff in skygw_utils.h was moved to utils.h
and the corresponding implementation from skygw_utils.cc to utils.c.
Includes updated accordingly.
Skygw_utils.h is now only used by log_manager and by mlist, which
is only used by log_manager. Consequently, skygw_utils.h was moved
to server/maxscale.
Utils.h needs a separate overhaul.
Made the packet sequence number handling automatic so that it always uses
the correct one.
All functions now have documentation in them. Cleaned up code and added
comments to GSSAPI code.
- STRERROR_BUFLEN moved to cdefs.h and renamed to MXS_STRERROR_BUFLEN.
Better would be to provide a 'const char* mxs_strerror(int errno)'
that would have a thread specific buffer for the error message.
- MIN and MAX also moved to defs.h as MXS_MIN and MXS_MAX.
- Now only mlist.h of the headers depend upon skygw_utils.h.
- Headers now to be included as <maxscale/xyz.h>
- First step, no cleanup of headers has been made. Only moving
from one place to another + necessary modifications.
The GSSAPI backend authentication is based on tokens. The server first
sends the service principal name which is used for token generation. The
client then retrieves a token from the GSSAPI server which it sends to the
backend server. If the server can verify the authenticity of the token,
authentication is successful.
This module can be used with both GSSAPIAuth and MySQLAuth modules.
Moving the sending of the final OK packet of the authentication process to
the client protocol plugin makes the authentication plugins simpler.
By reading the client's sequence and incrementing that by one, the client
protocol module will always send the correct sequence byte in the final OK
packet.
The first message exchange between the server and the client will almost
always contain the same data. If the server is going to change
authentication methods, it will send an AuthSwitchRequest packet instead
of the OK/ERR packet that it would normally send. Only after this point
the authenticator modules actually need to do something.
In the case of the default 'mysql_native_password' plugin, the only thing
that the plugin needs to do is to check whether the server responded with
an OK packet.
The MySQLCommon library contains functions used by both the protocol and
authenticator modules. The contents of the modutil.c file could also be
moved to this file if the functions in that file are only used by modules
and not the core.
