The filter implementation is now fully hidden. Also converted it to a C++
struct allocated with new and stored the filters in a global list instead
of embedding the list in the object itself.
The causal read queries were performed also when the target server was the
master. The extra functionality of the causal reads is only needed on
slaves.
Adjusted the test case to require GTID replication.
The configuration used the wrong parameter name. The test also did not
explicitly enable tracking of the last_gtid variable which caused it to
fail if it wasn't already on.
The test failed because router instances are now created when the service
is allocated. In addition to this, a debug assertion was hit when a
service was freed if the router instance creation failed.
Add support for binary protocol prepared statements for schemarouter.
This implementation doesn't yet attempt to handle all the edge cases.
Prepared statements are routed to the server that contains the affected
tables, the internal id from the server is then mapped to the session
command id that is inceremented for each prepared statement. This unique
session command id is returned to the client because internal id given
by server might be same around different servers and this way it is
possible to keep track of them and route them to the right servers when
executed.
When the query queue does not contain a complete packet
(i.e. modutil_get_next_MySQL_packet return NULL), an informative dump of
how many bytes and what is stored is logged.
With the removal of the old session command implementation, the code that
used it can be removed or replaced with newer constructs. As a result, the
backend protocol no longer does any session command processing.
The three buffer types, GWBUF_TYPE_SESCMD_RESPONSE,
GWBUF_TYPE_RESPONSE_END and GWBUF_TYPE_SESCMD as well as their related
macros are no longer used and can be removed.
The test cases allocated servers in a way that doesn't comfortably suit
the way the servers are now allocated. Adding a helper C++ class to load
module defaults makes it easier to do explicit server initialization in
tests.
The binlogrouter was also fixed in this commit as it uses servers much
like a test would use.
The configuration system that modules use allows the SSL parameter
validation to be simplified. It should also provide more consistent error
messages for similar types of errors.
The SSL_LISTENER initialization is now done in one step. There was no good
reason to do it in two separate steps for listeners but in one step for
servers.
The `ssl` parameter now also accepts boolean values. As the parameter
behaves like a boolean and looks like a boolean, it ought to be a
boolean. It still accepts the custom `required` and `disabled` values
simply for backwards compatibility.
Also added the missing freeing functions for the SSL_LISTENER type. This
prevents failed SSL_LISTENER creations from leaking memory.
The same mechanism that is used for modules can be used for the
configuration of the core objects. This removes the need for the redundant
code that validates various values that is already present in the code
that modules use.
The protocol could leak memory in rare cases where several commands were
queued at the same time. Readwritesplit also didn't free the memory it
acquired via qc_get_table_names.
Relaced router_options with configuration parameters in the createInstance
router entry point. The same needs to be done for the filter API as barely
any filters use the feature.
Some routers (binlogrouter) still support router_options but using it is
deprecated. This had to be done as their use wasn't deprecated in 2.2.
To prepare the router's for the eventual removal of the router_options
parameter, the API option arguments should not be used. The parameters can
be substituted by tokenizing the value of the parameter that is still
stored as a part of the service.
The schemarouter now also uses versioned configurations implemented by
shared pointers to configuration objects. Moved all the configuration
management into the Config class. Removed router options from
schemarouter.
Readconnroute can now be configured at runtime. The changes to
configuration processing allow the removal of router_options now that the
parameters are parsed inside the router.
The transaction migration in the case of a changed master never worked as
transaction replay would only be triggered when the master fails. To cover
this case, the transaction replay just needs to be started when the need
for a transaction migration is detected.
To help diagnose the behavior, the Trx class no longer logs a message when
a transaction is closed. This is now done by readwritesplit which has more
knowledge of the context in which the transaction is closed.
Moved transaction statistics calculations into a member function and
placed all target type specific processing into their respective
functions.
Also inverted the connection keepalive check to also cover hinted queries.
The parameter accepts both counts and percentages which requires special
handling in the router. This needs to be done when the configuration is
updated.
If a transaction is replayed, queued commands must not be processed. The
exception to this rule is when pending session commands are executed
before the first statement in the replayed transaction is executed.
If transaction replaying was enabled and a result was returned in more
than one call to clientReply, a NULL value would be added to the statement
which in turn would trigger a debug assertion.
Similarly any following statements in the transaction would be executed
regardless of whether the result was complete.
Renamed the statement execution function to better describe what it does.
Extended the basic functional test case to cover this.
Added a new router API entry point that allows configuration changes after
the instance has been created. This makes alterations to most service
parameters at runtime possible.
An option to reconfiguration would have been the creation of a new
service and the eventual destruction of the old one. This would be a more
complicated and costly method but from an architectural point of view it
is interesting.
The actual implementation of the configuration change is left to the
router. Currently, only readwritesplit performs reconfiguration as
implementing it with versioned configurations is very easy.
Versioned configurations can be considered an adequate first step but it
is not an optimal solution as it causes a bottleneck in the reference
counting of the shared configuration. Thread-specific configuration
definitions would make for a more efficient solution but the
implementation is more complex.
By using a shared pointer instead of a plain object, we can replace the
router configuration without it affecting existing sessions. This is a
change that is required to enable runtime reconfiguration of
readwritesplit.
The evq_length file held the returned number of descriptors from
the last epoll_wait() call. As such it is highly temporal and not
particularly meaningful.
That has now been removed and the instead the average number of
returned descriptors is maintained. That information changes slowly
and thus carries some meaning.
Empty databases were not mapped to ServerMap because they had no tables
to map. Modified the query to also include empty databases making it
possible to also connect to empty databases through schemarouter.
When a valid target was not found, no error message was logged by the
router. This would cause the "Routing the query failed. Session will be
closed." message to be logged with no explanation as to why the routing
failed.
In addition to the above-mentioned case, no message would be logged if the
target for a COM_STMT_FETCH was not in use.
If two or more session commands contain identical buffers, the buffer of
the first session command is shared between the others. This reduces the
amount of memory used to store repeated executions of session commands.
The purging of session command history in readwritesplit was replaced with
session command de-duplication. This was done to prevent problems that
could arise when the order of session commands plays a significant role.
The assertion that was added to RWSplitSession::handle_slave_is_target
failed when delayed_retry was enabled or when slave reconnection
occurred. In 2.3, targets returned by the target selection functions do
not need to be in use but they must be valid connection targets.
All executed session commands were logged in the RWSplitSession
destructor. This is not really necessary and shouldn't have been placed
there in the first place.
When the `optimistic_trx` mode is enabled, all transactions are started on
a slave server. If the client executes a query inside the transaction that
is not of a read-only nature, the transaction is rolled back and replayed
on the master.
