All prepare commands are executed in every backend server currently connected.
All executes are routed to master. If stmt type was recorded in prepare phase in rwsplit router, read-only stmts could be routed to slaves.
COM_STMT_PREPARE gets arbitrary number of response packets from backend database. Since statements are prepared in every backend server and only one multi-packet response can be replied to client, redundant multi-packet responses are discarded. This is done in router. Mechanisms from session command handling are utilized with little changes: router must identify when response consists of multiple packets so that it knows to calculate the number of packets in response and that it is able to discard correct number of packets.
Information to the reply-handling router is provided by backend protocol, which includes a ordered list of commands of commands sent to protocol-owning backend server. A command is stored to protocol struct in mysql_backend.c:gw_MySQLWrite_backend if the statement buffer's type has GWBUF_TYPE_SINGLE_STMT set in mysql_client.c:route_by_statement. GWBUF_TYPE_SINGLE_STATEMENT indicates that there is single statement in the buffer, as opposite to Read Connection router, which accepts streaming input from client.
New rules for selecting Master/Slaves are based on MySQL depth in the
replication tree.
The only Master is the root server with SERVER_MASTER bit set
All other servers even with both SLAVE and MASTER bit will be selected
as slaves
Conflicts:
server/core/session.c
server/modules/protocol/mysql_backend.c
server/modules/routing/readwritesplit/readwritesplit.c
Resolved.
Addition of user in topfilter report and general tidyup
Rwsplit handles ERRACT_NEW_CONNECTION by clearing backend reference, removing callbacks and associating backend reference with new backend server. If it succeeds and the router session can continue, handleError returns true. Otherwise false. When ever false is returned it means that session must be closed.
Rwsplit now tolerates backend failures in a way that it searches new backends when monitor, backend, or client operation fails due to backend failure.
Added flags to those backend references which have sent something to backend which causes the backend to send results or reply back. Didn't add removal of the flag since there's currently no way to tell whether response from backend contains anything else than session command reply - which aren't counted when BREF_WAITING_RESULT is set and cleared.
dcb.h: define ERRHAND temporarily since changes are still behind that macro
Defined two error handling actions in router.h: ERRACT_NEW_COMMECTION and ERRACT_REPLY_CLIENT.
Failed database is logged at expanding frequence to error and to message log due changes in mysql_mon.c. Added two new members in MONITOR_SERVERS: mon_err_count, and mon_prev_status so that each backend can be treated individually.
Error handling: if mysql_backend.c:dcb_read fails, router's handleError is called instead of closing session.
If mysql_client.c:SESSION_ROUTE_QUERY fails router's handleError is called instead of sending error to client.
readwritesplit.c:select_connect_backend_servers is modified so that in can be called during active router session. When called, it attempts to find one master and maximum number of configured slaves in correct state if necessary.
When handleError needs to replace failed unit it now calls select_connect_backend_servers.
Added a lot of logging to error, trace and message logs which should help the user to handle errors which can't be automatically resolved, like attempt to use nonexisting database.
monitors used mysql_ping without MYSQL_OPT_READ_TIMEOUT which caused read to block. Fixed in mysql and galera monitor.
Added log writing per each status change of each server and repeatedly if server is not running.
Removed SERVER_IS_JOINED checks from rwsplit router.
Maintenance mode prevents a server from having new connections made
to it and stops MaxScale from monitoring a server. It is designed
to allow a server to be taken out of an active cluster for maintenance.
It prevents new connections and allowsg existing connections to
drain away prior to performaing maintenance on the server.
be extracted from the modules.
This gives a way to verify the API that the module provides as well
as the version of that API. The hope is that this will make it possible
for MaxScale to detect out of date plugins and either adapt to use them
or reject loading them.
Also added the ability to set a release state on a per module basis.
This allows for production ready and non-production ready plugins to
be identified.
Only downstream filters are supported currently, i.e. no result
set filtering can be done.
A crude QLA (Query Log All) filter is included as a test harness only
