This keeps the behavior the same but allows the heartbeat to be used as a crude timer
without including everything the housekeeper.h header includes.
Moved the protocol level updates on the DCBs last_read value into dcb_read.
This keeps the implementation nice and compact.
mysql_backend.c:gw_change_user: instead of setting flags directly to replybuffer, set server command to backend's protocol object and reply the message directly to backend where flags are set and it is replied back to client.
RWSplit router handles query processing errors that happened in router by sending parse error reply to client. routeQuery fails only when backend has failed.
query_classifier.cc: set_query_type lost previous query type if the new was more restrictive. Problem was that if query is both READ and SESSION_WRITE and configuration parameter use_sql_variables_in=all was set, routing target became ambiguous. Replaced call to set_query_type with simply adding new type to type (=bit field) and checking unsupported combinations in readwritesplit.c:get_route_target. If such a case is met, a detailed error is written to error log in readwritesplit.c. mysql_client.c sees the error code and sends an error to client. Then mysql_client.c calls router's handleError which ensures that there are enough backend servers so that the session can continue.
tee.c:routeQuery cloned partial MySQL packets to be routed to child router. Problems were due to the use of gwbuf_clone and modutil_MySQL_query which clone/examine only the first buffer from the buffer list which composes GWBUF.
modutil.c: Added function modutil_MySQL_query_len which calculates MySQL packet length and the missing bytecount
http://bugs.skysql.com/show_bug.cgi?id=665http://bugs.skysql.com/show_bug.cgi?id=664http://bugs.skysql.com/show_bug.cgi?id=649
dcb.c:dcb_final_free: (665):set dcb->session->client pointer to NULL so that it won't be read anymore and other threads won't try to close it.
dcb_final_free:(664):don't free dcb->data, it is either freed in session_alloc if session creation fails or in session_free only.
session.c:if session creation fails, free dcb->data and remove links between client DCB and session.
mysql_backend.c:(665):gw_backend_close:check that session->client isn't NULL and that client DCB's state is still polling before calling dcb_close for it.
mysql_client.c:gw_mysql_do_authentication:if anything fails, and session_alloc won't be called, free dcb->data.
mysql_common.c:gw_send_authentication_to_backend:if session is already closing then return with error.
readwritesplit.h:Removed invalid macros which assumed that ROUTER_CLIENT_SES->rses_backend_ref always pointed to valid and used backend reference and thus included potential risk of NULL-pointer refernce.
mysql_backend.c and mysql_client.c:avoid executing CHK_PROTOCOL(p) after original DCB has been released the memory.
readwritesplit.c:Replaced RSES_CLEINT_DCB macro with a function which returns client DCB for a given router client session.
session.c:session_free:if session is child of another service (tee in this case), it is the parent which releases child's allocated memory back to the system. This now also includes the child router session.
dcb.h: Added DCB_IS_CLONE macro
tee.c:freeSession:if parent session triggered closing of tee, then child session may not be closed yet. In that case free the child session first and only then free child router session and release child session's memory back to system.
tee.c:routeQuery: only route if child session is ready for routing. Log if session is not ready for routing and set tee session inactive
mysql_client.c:gw_client_close:if DCB is cloned one don't close the protocol because they it is shared with the original DCB.
dcb.c:dcb_clone: set same close function than in the original DCB so that routing session will become closed when client DCB is closed.
session.h:introduce a new state which indicates that SESSION structure can be freed next, SESSION_STATE_TO_BE_FREED. State is needed to separate the state before and after memory free. Memory is freed in different situation depending on whether the session is parent or child session. Child sessions are freed in their parent.
Also introduce a new member in SESSION struct, ses_is_child, to indicate whether SESSION has a parent session which is responsible for releasing the memory of it.
session.c:session_unlink_dcb:when last session reference is removed set SESSION->state=SESSION_STATE_TO_BE_FREED
session.c:session_free:only free the memory if session is not child session. If it is child, session is left to be freed by the parent (in tee filter's freeSession, for example).
tee.c:newSession:mark branch session to child.
tee.c:freeSession:if child session memory is ready to be freed, free it.
mysql_mon.c:monitorMain:when backend server's status changes so that it is not running anymore or doesn't have any of the states - master, slave, ndb, joined - call for each DCB the callback-function DCB_REASON_NOT_RESPONDING if specified. Earlier callbacks were called if there was any change in the state of the server being monitored.
