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.
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.
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.
Reproduce #217 by connecting with telnet to debug client interface and execute command:
fail accept 23
and try to execute read query, for example, with
mysql -h 127.0.0.1 -P 4008 -u maxuser -pmaxpwd -e 'select current_user(), @@server_id'
dcb_final_free: Router session is not closed anymore when dcb is closed. Router session is shared among all dcbs and is closed and freed with session.
dcb_connect: dcb's state must be switched fro DCB_STATE_ALLOC to DCB_STATE_DISCONNECTED before dcb_final_free can be called for it.
dcb_close: poll_remove_dcb encapsulates dcb's state transition in the same way as poll_add_dcb. Removed state modification from dcb_close. Read return value of poll_remove_dcb and log accordingly.
dcb_set state: remove dassert if dcb_set_state_nomutex returned false. False can be returned indicating that intented change didn't occur but the end state, for example, may be acceptable. Failures in state transitions are asserted in dcb_Set_state_nomutex.
poll.c
poll_add_dcb: dcb state is now set here to either DCB_STATE_LISTENING or to DCB_STATE_POLLING according to dcb's role. Failures in state setting and in epoll_ctl are detected, logged and handled.
poll_remove_dcb: Failures in state setting and epoll_ctl are detected, logged, and handled.
mysql_client_server_protocol.h
Removed macros MYSQL_FAILED_AUTHENTICATION & MYSQL_SUCCESFUL_AUTHENTICATION as they were not necessary and used with constant values 0 and 1 depending on the case.
Renamed variable 'conn' to 'protocol' in cases where it meant protocol.
mysql_backend.c
gw_read_backend_event: In case when there was nothing to read or read failed, backend dcb is closed because situation is assumed to be such that backend server closed its side of the socket. Removed macros MYSQL_FAILED/SUCCESFUL_AUTHENTICATION
gw_create_backend_connection: Assigned protocol with fd which is connected to backend.
backend_write_delayqueue: In case where dcb_write fails to write anything, close backend dcb to avoid it getting hanging.
mysql_client.c
gw_read_client_event: Read return value of routeQuery and if it isn't == 1, call mysql_send_custom_error with client dcb and set client's protocol state to MYSQL_IDLE instead of MYSQL_ROUTING.
gw_MySQLAccept: Static reply counter was erroneously used as a criteria for jumping to return point where return value was constantly 'success' (=0). Replaced static reply counter with private. Fixed return value in different cases.
mysql_common.c
gw_receive_backend_auth: Changed to return boolean values indicating of success or failue. Used integers which were assigned to macroed values on the caller side. Added length check before accessing buffer.
readconnroute.c
Cut too long lines and removed statements with side effects.
skygw_debug.h
Added macro STRPROTOCOLSTATE(s) to produce string representation of a given protocol state.
If backend connection can't be created, backend_dcb is not create, router client session is not created and what already is created in session_alloc, is freed.
mysql_client.c : gw_read_client_event
If session creation failed, then - instead of sending ok to client, "failed to create new session" is sent and client dcb is closed.
: gw_MySQLAccept
removed loop where accept was called again and again. With single thread looping forever is not possible because there's no one to free previously allocated resources.
If accept fails ten times in a row, then return without new client dcb.
: dcb_alloc switched malloc to calloc, dcb->fd is initialized to -1.
: dcb_process_zombies return value of close(fd) is checked. Closed fds are stored to conn_open array.
: dcb_connect assigns new fd only if backend connection succeeds. Dcb is added to poll set in the same way, only if connect succeed.
gateway.c : conn_open array is initialized in main. For each created socket, a true is set to corresponding slot. Max. number of slots is 1024.
mysql_client_server_protocol.h : gw_do_connect_to declaration
mysql_backend.c : gw_create_backend_connection returns rv >= 0 and a protocol which is assigned to backend_dcb. In error, -1 is returned and fd is not set.
mysql_client.c : conn_open array is kept up-to-date and protocol pointer is assigned also to dcb outside mysql_protocol_init.
mysql_common.c : gw_do_connect_to_backend 3rd argument is pointer to fd, not protocol. dcb is added to poll set later in dcb_connect.
skygw_debug.h : define conn_open[1024] array where open connections can be marked in debug build.
-------
Removed DCB states DCB_STATE_IDLE, and DCB_STATE_PROCESSING.
Added DCB_STATE_UNDEFINED for initial content for state variable which doesn't have any specific value set, and DCB_STATE_NOPOLLING to indicate that dcb has been removed from poll set.
Added following dcb roles: DCB_ROLE_SERVICE_LISTENER for listeners of services, and DCB_ROLE_REQUEST_HANDLER for client/backend dcbs. Listeners may have state DCB_STATE_LISTENING, but not DCB_STATE_POLLING. Request handlers may have DCB_STATE_POLLING but not DCB_STATE_LISTENING. Role is passed as an argument to dcb.c:dcb_alloc.
From now on, struct check numbers of DCB are included and checked in DEBUG build only.
Added dcb_role_t dcb_role-member to DCB as well as SPINLOCK dcb_initlock, which protects state changes.
Removed extern keyword from function declarations because functions are by default externally visible if they are declared in header.
dcb.b
------
Function dcb_set_state, and dcb_set_state_nomutex provide functions for changing dcb states. Latter implements a state machine for dcb.
Function dcb_add_to_zombieslist replaces dcb_free. It adds in atomic step dcb to zombieslist and changes state to DCB_STATE_ZOMBIE.
Function dcb_final_free removes dcb from allDCBs list, terminates router and client sessions, and frees dcb and related memory.
Function dcb_process_zombies removes executing thread from dcb's bitmask, and it there are no further thread bits, moves dcb to a victim list, and finally, for each dcb on victim list, closes fd and sets state to DCB_STATE_DISCONNECTED.
Function dcb_close sets dcb state to DCB_STATE_NOPOLLIN, removes dcb from poll set and sets bit to bitmask for each server thread in an atomic step.
poll.c
------
Function poll_add_dcb sets either DCB_STATE_LISTENING or DCB_STATE_POLLING state for newly created dcb, depending whether the role of dcb is DCB_ROLE_SERVICE_LISTENER, or DCB_ROLE_REQUEST_HANDLER, respectively. Then dcb is set to poll set.
poll_waitevents : commented out code which skipped event if dcb was added to zombieslist or if fd was closed. Added state checks.
service.c : Minor changes.
httpd.c : Removed dcb state changes. They are done in core.
mysql_backend.c : Added checks, removed dcb state changes.
mysql_client.c : Removed dcb state changes. Added checks.
mysql_common.c : Minor changes
telnetd.c : Removed state changes. Replaced some typecasts and pointer references with local variable reads.
skygw_debug.h : Removed two states, and added two to state printing macro.
reworked the reference count mechanism on the session. Introduced a
FREE state for the session and alter the session destruction flow so
that we only remove the session when all the DCB's have singled they
have finished processing events for the DCB rather than when the first
thread decides to clsoe the DCB.
routeQuery()
(dcb->func).close(dcb);
This will prevent setting again dcb->sate = DCB_STATE_POLLING in return_rc label.
The log entry for
[gw_read_client_event] ioctl FIONREAD for fd 21 failed. errno 9, Bad file descriptor. dcb->state = 3
now is not present anymore.
