The `master_reconnection` parameter now controls both the reconnection of
the master server as well as the migration of the master server to another
server. Although these two cases appear to be different, the end result
from readwritesplit's point of view is the same and are thus controlled
with the same parameter.
The RWBackend class now resets its internal state when it is closed. This
allows readwritesplit to handle the case when a result was expected from
the master but the master died before the result was returned. The same
code should also handle slave connection failures mid-result, allowing
Backend reuse.
Added a test case that verifies the new functionality when combined with
`master_failure_mode=error_on_write`.
Moved session command execution into the Backend class itself as the
session commands are defined as a related part of it. This allows all
connections to execute session commands if some are available.
Removed explicit SERVER_REF usage in the readwritesplit connection
creation code and replaced it with SRWBackend. This allows the removal of
the get_root_master_backend function which duplicated the functionality in
get_root_master.
Disabled the reconnection in clientReply prior to moving the connection
creation code into routeQuery. This allows new connections to be made when
they are needed.
Provides a clearer separation between what deals with query
classification and what deals with query routing.
Functions have only been moved. No other cleanup has been
done.
When a multi-statement query consisting completely of UPDATE statements is
received, the packets can be received in two separate buffers. To cope
with this situation, the state change into REPLY_STATE_RSET_COLDEF must
only be done if the buffer contains more than a single packet.
When a multi-statement query consisting completely of UPDATE statements is
received, the packets can be received in two separate buffers. To cope
with this situation, the state change into REPLY_STATE_RSET_COLDEF must
only be done if the buffer contains more than a single packet.
By making it conditional, we prevent the problems that arise when the
replication protocol is used in combination with the session state change
tracking. In addition to this, it prevents unnecessary work for routers
and filters that don't need it.
When the master changes mid-session, the temporary tables are inevitably
lost. This could be avoided by routing temporary table creation to all
servers.
If the connection to the backend where a read-only transaction is being
performed fails, the Backend object should be closed for it. This fixes a
debug assertion in readwritesplit.cc:check_and_log_backend_state which
asserts that the failed connection must not be in use after the error
handling is done.
Also reordered the failing assertion and the accompanying error message so
that the error is logged first.
With the `allow_master_change` parameter enabled, sessions can start using
a different master node if one is available. This will not prevent
sessions from closing if a write query is received while no master
replacement is available.
When readwritesplit receives a reply from a backend, an info level log
message is now logged. This allows easier debugging of situations where
replies aren't properly returned by the router.
After a temporary table is created, readwritesplit will check whether a
query drops or targets that temporary table. The check for query type was
missing from the table dropping part of the code. The temporary table read
part was checking that the query is a text form query.
Added a debug assertion to the query parsing function in qc_sqlite to
catch this type of interface misuse.
When a BEGIN statement is prepared using the binary protocol, it returns a
single OK packet. Due to a bug in the code that deals with multi-statement
results and EOF packets, the response was never sent to the client.
Also added back the error messages of failed session commands to the INFO
level. This way it's still possible to see why a session command fails but
the log isn't flooded by them in normal usage.
The responses of slaves that arrived before the master were always
compared to the empty value of 0x00. If the slave connection replied after
the master, the comparison was correct.
This commit introduces a map of slaves and their responses that
are handled once the master's response arrives.
Removed false error message about failed session commands. An error in
response to a session command is a perfectly valid result.
Also added the explicit commands that the master and slave return to the
warning that is logged when the results differ.
The debug assertion wasn't well placed as it is perfectly possible that a
master connnection exists but it is not in use. This can be further
checked by asserting that the master is indeed closed and not in use.
Moved the original debug assertion into a separate branch that should
catch any errors in the routing logic.
* MXS-199: Support Causal Read in Read Write Splitting
* move most causal read logic into rwsplit router and get server type from monitor
* misc fix: remove new line
* refactor, move config to right place, replace ltrim with gwbuf_consume
* refacter a little for previous commit
* fix code style
As chages to the transaction state are detected by the protocol level
mini-parser, there's no need to fully classify queries inside read-only
transactions. This should be a good performance boost for loads that
heavily use read-only transactions.
Make all modules lowercase and make module loading case
insensitive. Further, make command invocation case insensitive,
as far as the module name is conserned.
The default value for strict_multi_stmt prevents compound statements and
atomic multi-statement commands from being executed without completely
disabling load balancing. As the new default value will have no practical
effect on all correct uses of readwritesplit, this is a relatively safe
thing to change.
When binary data was processed, it was possible that the values were
misinterpreted as OK packets which caused debug assertions to trigger.
In addition to this, readwritesplit did not handle the case when all
packets were routed individually.
A multi-statements can return multiple resultsets in one response. To
accommodate for this, both the readwritesplit and modutil code must be
altered.
By ignoring complete resultsets in readwritesplit, the code can deduce
whether a result is complete or not.
When LEAST_BEHIND_MASTER routing criteria was used, the info level logging
function would fall through to the default case. In debug builds, this
would trigger a debug assertion.
Returning the results of a query as a set of packets is currently more
efficient. This is mainly due to the fact that each individual packet for
single packet routing is allocated from the heap which causes a
significant loss in performance.
Took the new capability into use in readwritesplit and modified the
reply_is_complete function to work with non-contiguous results.
