. That means that (at least) the first packet in the message is response to session command. Then if the response is alread
y forwarded to client it is discarded. Otherwise it is routed to client and the command is marked as responded so that the o
ther backend knows to discard its duplicate response.
For each session command a sescmd property is created and added to the end of list of session commands. List is owned by router client session and it includes all session commands from the beginning of router session.
Router maintains an individual session command cursor for each backend. A cursor refers to the first session command which the corresponding backend server haven't yet responded yet.
When response message arrives at any time from backend, first it is checked whether backend's cursor is active. Cursor is active if a session command is routed to backend and the backend haven't responded to it yet. If cursor is active, next it is checked whether the current session command property has been responded by other backend. If both are true, then response message is sent to client as is. If session command response is routed to client already, the arrived response is discarded.
This implementation doesn't guarantee execution order between session commands and queries
if other backend server lags behind in session command execution.
In poll.c : moved processing of EPOLLERR and EPOLLHUP after processing of EPOLLIN and EPOLLOUT.
This ensures that COM_QUIT messages are read and routed forward before signals arrive (from local client/backend).
nection router stream is used and with read/write split router individual statements are passed to router.
Added new function to ROUTER_OBJECT : uint8_t (*getCapabilities)(ROUTER *instance, void* router_session); which is implemented in every route
r.
Added support for multi-statement packets in rwsplit router. In other words, if network packet includes multiple mysql statements, they are separated and passed to router one by one.
Multi-packet statements (those which exceeds network packet boundaries) are _not_ supported yet.
Added support for multi-statement packets.
This is an intermediate commit to save work. Code is not cleaned and there are debug prints and prototypes to be removed.
Session commands are identified by query clasisfier, and added to the session command property list in router client session object.
Session commands are then executed in existing backend servers but only one of them will reply to client.
dcb.c:dcb_write accept also dcb state DCB_STATE_NOPOLLING since it only means that dcb has been removed from epoll set but it is still possible to write to it.
Bug #384http://bugs.skysql.com/show_bug.cgi?id=384
session.h:added new state for SESSION, SESSION_STATE_ROUTER_READY which follows SESSION_STATE_READY. The difference is that ROUTER_READY is set only after router session is successfully created while READY means that session still lacks router.
session.c:set SESSION_STATE_ROUTER_READY when router is created.
mysql_backend.c:gw_read_backend_event, added SESSION_STATE_ROUTER_READY check before router session is closed. Changed chec kso that it doesn't block in infinite loop (although it shouldn't be possible anyway).
mysql_backend.c:gw_error_backend_event, added similar check before session is closed.
If backend authentication fails, wait until session has created router_client_session before reading the session->router_session pointer value. There should only be one case where this situation occurs : when session is being initialized concurrently with authentication. Only consequence is to close router_client_session immediately after session initialization is completed.
if ioctl() return 0 bytes, recv(..., MSG_PEEK) is called, reading 1 byte.
if recv returns 0 or -1 the socket is closed and dcb->func.close(dcb) is called.
Client, session and backend connections will be closed
Tested with 4 MaxScale running threads
