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.
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
Declared program_invocation_name, and program_invocation_short_name. They are used as identifier strings in syslog logging in cases where log_manager is not initialized explicitly and/or the caller hasn't specified program name as one of the arguments in arguments array.
Fixed memory corruption. Length of sequence number of file name was calculated to as one too short and one byte was written to unallocated memory.
Freed also the linkpath in cases where at least one of the log files is written to shm and a symlink is added to log directory.
mysql_client.c
Added debug check for protocol pointer because of memory issues in mysql_client.c
Added new argument '-s' which takes additional argument composed of list of logfile identifiers. Logfiles listed with '-s' will be written on main memory instead of disk. In practice, the log file in question will be written in /dev/shm but corresponding symlink is added to log directory. In the case of name conflicts with log files and links, a differentiating sequence number is included in hte name of the file. This, however, is done only when existing file is not writable or is of different type (symlink <> file).
Added new logfile LOGFILE_DEBUG whose contents will be largerly what was included up to date in trace log.
Disabled feature which spreads writes to log files to others because of bug (#338) in the way block buffers are managed.
Changed log manager parameters to match with the current implementation. List of arguments:
"-h - help\n"
"-a <debug prefix> ............(\"skygw_debug\")\n"
"-b <debug suffix> ............(\".log\")\n"
"-c <trace prefix> ............(\"skygw_trace\")\n"
"-d <trace suffix> ............(\".log\")\n"
"-e <message prefix> ............(\"skygw_msg\")\n"
"-f <message suffix> ............(\".log\")\n"
"-g <error prefix> ............(\"skygw_err\")\n"
"-i <error suffix> ............(\".log\")\n"
"-j <log path> ............(\"/tmp\")\n"
"-s <shmem log file ids> ........(no default)\n";
dcb.c
dcb_add_to_zombieslist, add dcb to the front of zombies list instead of inserting to the end of it.
gateway.c
Renamed shutdown_gateway to shutdown_server (Bug #131)
Call skygw_logmanager_init so that trace and debug logs are written to shared memory.
poll.c
dcb.h
Removed some dead code and references to unneeded mutexes.
debugcmd.c
Added enable/disable log command for debug log.
skygw_utils.cc
skygw_file_init now takes optional symlink name as a second argument. Symlink is created to point to the file being created.
resolve_query_type, added GSYSVAR_FUNC type for functions that read system variables and can be executed in Maxscale instead of backend server.
dcb.c
dcb_read, if read returns value <= 0 and if error is EAGAIN/EWOULDBLOCK so there was nothing to read in sthe socket, that is not an error because some other thread may have read the data that was expected to be available.
mysql_backend.c
gw_read_backend_event, used dcb->authlock to ensure that dcb's protocol state is read and modified serially. This removes issues with false authentication failures which may happen when two threads modify and read the state without any control.
mysql_client.c
removed dead code.
readconnroute.c, readwritesplit.c
removed invalid assert which assumed that spinlock can not have larger value than one when itis locked.
poll.c
Removed mutex from epoll_wait.
Removed read and write mutexes from poll_waitevents.
session.c
If session_alloc fails, instead of calling directly free(session), call session_free, which decreases refcounter and only frees session when there are no references left.
Added session_unlink_dcb function which removes link from session and optionally sets the dcb->session pointer to NULL.
readconnection.h, readwritesplit.h
Added check fields to ROUTER_CLIENT_SES strct as well as lock, version number (not used yet) and closed flag.
mysql_backend.c
gw_read_backend_event: if backend_protocol->state was set to MYSQL_AUTH_RECV, function returned, which was unnecessary. If mysql state became MYSQL_AUTH_FAILED, router client session was closed. Removed unnecessary NULL checks because rsession is not allowed to be NULL. Similarly, removed other NULL checks and replaced them with asserts checking that router client session is not NULL at any phase.
mysql_client.c
Removed unused code blocks. Polished log commands. Replaced router client sessions NULL checks with asserts.
mysql_common.c
mysql_send_custom_error: if called with dcb == NULL, return.
readconnroute.c
Replaced malloc with calloc. Added functions rses_begin_router_action and rses_exit_router_action. If router client session is not closed, they take a lock and release it, respectively. Those functions are used for protecting all operations which modify the contents of router client session struct.
readwritesplit.c
Identical changes than in readconnroute.c
skygw_debug.h
Added check number and - macro for ROUTER_CLIENT_SES, and added COM_QUIT to STRPACKETTYPE.
the delay queue is now consumed when backend_protocol->state == MYSQL_AUTH_FAILED.
This will avoid sending more times the custom error in the threaded configuration.
mysql_client.c:gw_MySQLWrite_client is simply return dcb_write(dcb, queue);
The return codes are not the same of the code replaced, but they are not checked in the caller routines.
dcb_write, if write failed, gwbuf wasn't freed.
mysql_backend.c
gw_MySQLWrite_backend, if dcb wasn'r in POLLING state then write was skpiped but gwbuf wasn't freed.
mysql_client.c
gw_MySQLWrite_client, disabled the use of dcb_write because it returns different values than the code it replaced. Also removed erroneous call of gwbuf_consume.
mysql_common.c
mysql_send_custom_error, removed erroneous call of gwbuf_free.
changed gw_receive_backend_auth declaration to return int instead of boolean.
mysql_backend.c:
gw_read_backend_event calls gw_receive_backend_auth which either fails (== -1), succeeds with nothing to read (== 0) or succeeds (== 1). For each case there is handling. If dcb_read succeeds without read bytes, return asap.
mysql_client.c:
gw_error_client_event, gw_client_close, gw_client_hangup_event : all close client dcb but now they also close backend dcb.
mysql_common.c:
gw_receive_backend_auth, return -1, 0, or 1 if read from backend failed, was empty, or succeed, respectively.:
State update for filewriter was missing and that caused Maxscale to fail if opening of any log file failed.
dcb.c:
Added EAGAIN and EWOULDBLOCK handling to dcb_read. If dcb_close is called for freshly created dcb, dcb is only freed.
gateway.c:
Added file_write_footer and write_footer of which the latter is called at exit time. It simply draws a line to screen.
gw_utils.c:
Some macros for helping comparison between gw_read_gwbuff and dcb_read, which overlap.
poll.c:
Some macros to help enable/disable mutexing in poll_waitevents
service.c:
Check return value of listen and session_alloc and behave accordingly.
mysql_client.c:
If ioctl returned successfully with b==0 it earlier caused closing the client and backend dcbs. Since that doesn't reliably indicate that client has closed socket on its side, Maxscale doesn't close its sockets either.
mysql_common.c:
In gw_receive_backend_auth, if dcb_read returns n==0, it is not considered as an error anymore. The implemented behavior is not yet complete and correct. Result should be successful but the protocol state shouldn't change to MYSQL_IDLE before backend return is received.
In gw_send_authentication_to_backend protocol state was always set to MYSQL_AUTH_RECV even if gw_rwite had failed. Now, return value is read and state is set in caller's context basen on the return value.
skygw_utils.cc:
Removed ss_dassert from skyge_file_init because it prevented from returning meaningful error meassage to the client.:
tuned error printing and log writing output format
dcb.c :
dcb_connect, check return value of poll_add_dcb and behave accordingly.
dcb_write, in case of SIFPIPE, only write to trace log.
dcb_close, dassert with incorrect dcb states.
gateway.c :
added file_write_header to print header similar than in logs to stderr.
main, add signal handler for SIGPIPE
poll.c :
poll_remove_dcb, don't fail if dcb is in NOPOLLING or in ZOMBIE states.
poll_waitevents, write EPOLLHUPs to trace log, don't even attempt to write to closed socket.
readconnection.h :
shortened comment.
readwritesplit.h :
replaced generic names with more specific ones.
httpd.c :
Check listen return value and behave accordingly.
mysql_backend.c :
Tiny clean up.
mysql_client.c :
gw_MySQLListener, Check listen return value and behave accordingly.
mysql_common.c :
Shortened a header.
telnetd.c :
telnetd_listen, check listen return value and behave accordingly.
readconnroute.c :
Tuned log writing format.
readwritesplit.c :
Added function search_backend_servers, which chooses suitable backend and master server among those known by Maxscale. Fixed clean-up routines. Not ready yet but works somehow.
testroute.c :
Cleanup.
skygw_utils.cc :
Log writing clean up.
