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Extended session command support to cover COM_CHANGE_USER, and COM_INIT_DB.

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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).
This commit is contained in:
VilhoRaatikka
2014-03-14 13:25:37 +02:00
parent cb6a976555
commit a3f7eebdc9
8 changed files with 233 additions and 293 deletions
Download Patch File Download Diff File Expand all files Collapse all files

353
server/modules/routing/readwritesplit/readwritesplit.c
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@ -98,6 +98,7 @@ static void mysql_sescmd_done(
static mysql_sescmd_t* mysql_sescmd_init (
rses_property_t* rses_prop,
GWBUF* sescmd_buf,
unsigned char packet_type,
ROUTER_CLIENT_SES* rses);
static rses_property_t* mysql_sescmd_get_property(
@ -590,9 +591,7 @@ static int routeQuery(
}
else
{
/**
* Lock router client session for secure read of DCBs
*/
/*< Lock router client session for secure read of DCBs */
rses_is_closed =
!(rses_begin_locked_router_action(router_cli_ses));
}
@ -678,6 +677,43 @@ static int routeQuery(
switch (qtype) {
case QUERY_TYPE_WRITE:
#if 0
/**
* Running this block cause deadlock because read mutex is
* on hold. This doesn't serialize subsequent session commands
* and queries if there are multiple session commands and other
* backend starts to lag behind. vraa : 14.3.13
*/
/**
* Wait until master has executed all its session commands.
* TODO: if master fails it needs to be detected in the loop.
*/
if (!rses_begin_locked_router_action(router_cli_ses))
{
goto return_ret;
}
while (sescmd_cursor_is_active(rses_get_sescmd_cursor(
router_cli_ses,
BE_MASTER)))
{
rses_end_locked_router_action(router_cli_ses);
LOGIF(LD, (skygw_log_write(
LOGFILE_DEBUG,
"%lu [routeQuery:rwsplit] Session command is "
"active in MASTER. Waiting in loop.",
pthread_self())));
usleep(10);
if (!rses_begin_locked_router_action(router_cli_ses))
{
goto return_ret;
}
}
rses_end_locked_router_action(router_cli_ses);
#endif
LOGIF(LT, (skygw_log_write(
LOGFILE_TRACE,
"%lu [routeQuery:rwsplit] Query type\t%s, "
@ -702,84 +738,65 @@ static int routeQuery(
"%lu [routeQuery:rwsplit] Query type\t%s, "
"routing to Slave.",
pthread_self(),
STRQTYPE(qtype))));
/** Lock router session */
if (!rses_begin_locked_router_action(router_cli_ses))
STRQTYPE(qtype))));
while (true)
{
/** Log error to debug */
goto return_ret;
}
/**
* If session command is being executed in slave
* route to master
*/
if (sescmd_cursor_is_active(rses_get_sescmd_cursor(
router_cli_ses,
BE_SLAVE)))
{
LOGIF(LT, tracelog_routed_query(router_cli_ses,
"routeQuery",
master_dcb,
gwbuf_clone(querybuf)));
ret = master_dcb->func.write(master_dcb, querybuf);
atomic_add(&inst->stats.n_master, 1);
}
else
{
LOGIF(LT, tracelog_routed_query(router_cli_ses,
"routeQuery",
slave_dcb,
gwbuf_clone(querybuf)));
ret = slave_dcb->func.write(slave_dcb, querybuf);
atomic_add(&inst->stats.n_slave, 1);
}
rses_end_locked_router_action(router_cli_ses);
if (!rses_begin_locked_router_action(router_cli_ses))
{
goto return_ret;
}
/**
* If session command is being executed in slave
* route to master.
*/
if (!sescmd_cursor_is_active(rses_get_sescmd_cursor(
router_cli_ses,
BE_SLAVE)))
{
rses_end_locked_router_action(router_cli_ses);
LOGIF(LT, tracelog_routed_query(router_cli_ses,
"routeQuery",
slave_dcb,
gwbuf_clone(querybuf)));
ret = slave_dcb->func.write(slave_dcb, querybuf);
atomic_add(&inst->stats.n_slave, 1);
break;
}
else if (!sescmd_cursor_is_active(rses_get_sescmd_cursor(
router_cli_ses,
BE_MASTER)))
{
rses_end_locked_router_action(router_cli_ses);
LOGIF(LT, tracelog_routed_query(router_cli_ses,
"routeQuery",
master_dcb,
gwbuf_clone(querybuf)));
ret = slave_dcb->func.write(master_dcb, querybuf);
atomic_add(&inst->stats.n_master, 1);
break;
}
rses_end_locked_router_action(router_cli_ses);
} /*< while (true) */
goto return_ret;
break;
case QUERY_TYPE_SESSION_WRITE:
/**
* Execute in backends used by current router session.
* Save session variable commands to router session property
* struct. Thus, they
* can be replayed in backends which are started and joined later.
*
* Suppress OK packets sent to MaxScale by slaves.
*
* DOES THIS ALL APPLY TO COM_QUIT AS WELL??
*
*/
/**
* Update connections which are used in this session.
*
* For each connection updated, add a flag which indicates that
* OK Packet must arrive for this command before server
* in question is allowed to be used by router. That is,
* maintain a queue of pending OK packets and remove item
* from queue by FIFO.
*
* Return when the master responds OK Packet. Send that
* OK packet back to client.
*
* Suppress OK packets sent to MaxScale by slaves.
*
* Open questions:
* How to handle interleaving session write
* and queries? It would be simple if OK must be received
* from all/both servers before continuing query execution.
* How to maintain the order of operations? Execution queue
* would solve the problem. In the queue some things must be
* executed in serialized manner while some could be executed
* in parallel. Queries mostly.
*
* Instead of waiting for the OK packet from the master, the
* first OK packet could also be sent to client. TBD.
* vraa 9.12.13
*
*/
* Execute in backends used by current router session.
* Save session variable commands to router session property
* struct. Thus, they can be replayed in backends which are
* started and joined later.
*
* Suppress redundant OK packets sent by backends.
*
* DOES THIS ALL APPLY TO COM_QUIT AS WELL??
*
* The first OK packet is replied to the client.
*
*/
LOGIF(LT, (skygw_log_write(
LOGFILE_TRACE,
"%lu [routeQuery:rwsplit] DCB M:%p s:%p, "
@ -791,106 +808,45 @@ static int routeQuery(
STRQTYPE(qtype),
STRPACKETTYPE(packet_type))));
switch(packet_type) {
case COM_CHANGE_USER:
LOGIF(LT, tracelog_routed_query(
router_cli_ses,
"routeQuery",
master_dcb,
gwbuf_clone(querybuf)));
master_dcb->func.auth(
master_dcb,
NULL,
master_dcb->session,
gwbuf_clone(querybuf));
LOGIF(LT, tracelog_routed_query(
router_cli_ses,
"routeQuery",
slave_dcb,
gwbuf_clone(querybuf)));
slave_dcb->func.auth(
slave_dcb,
NULL,
master_dcb->session,
querybuf);
break;
case COM_QUIT:
case COM_QUERY:
/**
* 1. Create new property of type RSES_PROP_TYPE_SESCMD.
* 2. Add property to the ROUTER_CLIENT_SES struct of
* this router session.
* 3. For each backend, and for each non-executed
* sescmd:
* call execution of current sescmd in
* all backends as long as both have executed
* them all.
* Execution call is dcb->func.session.
* All sescmds are executed when its return value is
* NULL, otherwise it is a pointer to next property.
*/
prop = rses_property_init(RSES_PROP_TYPE_SESCMD);
/**
* Additional reference is created to querybuf to
* prevent it from being released before properties
* are cleaned up as a part of router sessionclean-up.
*/
mysql_sescmd_init(prop, querybuf, router_cli_ses);
/** Lock router session */
if (!rses_begin_locked_router_action(router_cli_ses))
{
rses_property_done(prop);
goto return_ret;
}
/** Add sescmd property to router client session */
rses_property_add(router_cli_ses, prop);
/** Execute session command in master */
if (execute_sescmd_in_backend(router_cli_ses, BE_MASTER))
{
ret = 1;
}
else
{
/** Log error */
}
/** Execute session command in slave */
if (execute_sescmd_in_backend(router_cli_ses, BE_SLAVE))
{
ret = 1;
}
else
{
/** Log error */
}
/** Unlock router session */
rses_end_locked_router_action(router_cli_ses);
break;
default:
LOGIF(LT, tracelog_routed_query(router_cli_ses,
"routeQuery",
master_dcb,
gwbuf_clone(querybuf)));
ret = master_dcb->func.write(master_dcb,
(void *)gwbuf_clone(querybuf));
LOGIF(LT, tracelog_routed_query(router_cli_ses,
"routeQuery",
slave_dcb,
gwbuf_clone(querybuf)));
slave_dcb->func.write(slave_dcb, (void *)querybuf);
break;
} /**< switch by packet type */
prop = rses_property_init(RSES_PROP_TYPE_SESCMD);
/**
* Additional reference is created to querybuf to
* prevent it from being released before properties
* are cleaned up as a part of router sessionclean-up.
*/
mysql_sescmd_init(prop, querybuf, packet_type, router_cli_ses);
/** Lock router session */
if (!rses_begin_locked_router_action(router_cli_ses))
{
rses_property_done(prop);
goto return_ret;
}
/** Add sescmd property to router client session */
rses_property_add(router_cli_ses, prop);
/** Execute session command in master */
if (execute_sescmd_in_backend(router_cli_ses, BE_MASTER))
{
ret = 1;
}
else
{
/** Log error */
}
/** Execute session command in slave */
if (execute_sescmd_in_backend(router_cli_ses, BE_SLAVE))
{
ret = 1;
}
else
{
/** Log error */
}
/** Unlock router session */
rses_end_locked_router_action(router_cli_ses);
atomic_add(&inst->stats.n_all, 1);
goto return_ret;
break;
@ -1066,8 +1022,9 @@ static void clientReply(
*/
if (!rses_begin_locked_router_action(router_cli_ses))
{
/** is this needed ??*/
gwbuf_consume(writebuf, gwbuf_length(writebuf));
while ((writebuf = gwbuf_consume(
writebuf,
GWBUF_LENGTH(writebuf))) != NULL);
goto lock_failed;
}
master_dcb = router_cli_ses->rses_dcb[BE_MASTER];
@ -1091,7 +1048,9 @@ static void clientReply(
*/
if (client_dcb == NULL)
{
gwbuf_consume(writebuf, gwbuf_length(writebuf));
while ((writebuf = gwbuf_consume(
writebuf,
GWBUF_LENGTH(writebuf))) != NULL);
/** Log that client was closed before reply */
return;
}
@ -1111,7 +1070,7 @@ static void clientReply(
goto lock_failed;
}
scur = rses_get_sescmd_cursor(router_cli_ses, be_type);
/**
/**
* Active cursor means that reply is from session command
* execution.
*/
@ -1134,6 +1093,7 @@ static void clientReply(
}
/** Set cursor passive. */
sescmd_cursor_set_active(scur, false);
ss_dassert(!sescmd_cursor_is_active(scur));
/** Unlock router session */
rses_end_locked_router_action(router_cli_ses);
@ -1142,6 +1102,7 @@ static void clientReply(
{
/** Write reply to client DCB */
client_dcb->func.write(client_dcb, writebuf);
ss_dassert(!sescmd_cursor_is_active(scur));
/** Unlock router session */
rses_end_locked_router_action(router_cli_ses);
LOGIF(LT, (skygw_log_write_flush(
@ -1150,12 +1111,10 @@ static void clientReply(
"backend dcb %p. End of normal reply.",
pthread_self(),
client_dcb,
backend_dcb)));
backend_dcb)));
}
return; /*< succeed */
lock_failed:
/** log that router session couldn't be locked */
return;
return;
}
/**
@ -1443,6 +1402,7 @@ static void rses_end_locked_property_action(
static mysql_sescmd_t* mysql_sescmd_init (
rses_property_t* rses_prop,
GWBUF* sescmd_buf,
unsigned char packet_type,
ROUTER_CLIENT_SES* rses)
{
mysql_sescmd_t* sescmd;
@ -1453,11 +1413,12 @@ static mysql_sescmd_t* mysql_sescmd_init (
sescmd->my_sescmd_prop = rses_prop; /*< reference to owning property */
// sescmd->my_sescmd_rsession = rses;
#if defined(SS_DEBUG)
sescmd->my_sescmd_chk_top = CHK_NUM_MY_SESCMD;
sescmd->my_sescmd_chk_top = CHK_NUM_MY_SESCMD;
sescmd->my_sescmd_chk_tail = CHK_NUM_MY_SESCMD;
#endif
/** Set session command buffer */
sescmd->my_sescmd_buf = sescmd_buf;
sescmd->my_sescmd_buf = sescmd_buf;
sescmd->my_sescmd_packet_type = packet_type;
return sescmd;
}
@ -1624,8 +1585,25 @@ static bool execute_sescmd_in_backend(
"execute_sescmd_in_backend",
dcb,
sescmd_cursor_clone_querybuf(scur)));
rc = dcb->func.write(dcb, sescmd_cursor_clone_querybuf(scur));
switch (scur->scmd_cur_cmd->my_sescmd_packet_type) {
case COM_CHANGE_USER:
rc = dcb->func.auth(
dcb,
NULL,
dcb->session,
sescmd_cursor_clone_querybuf(scur));
break;
case COM_QUIT:
case COM_QUERY:
case COM_INIT_DB:
default:
rc = dcb->func.write(
dcb,
sescmd_cursor_clone_querybuf(scur));
break;
}
if (rc != 1)
{
succp = false;
@ -1685,7 +1663,6 @@ static bool cont_exec_sescmd_in_backend(
dcb,
sescmd_cursor_clone_querybuf(scur)));
// rc = dcb->func.session(dcb, sescmd_cursor_clone_querybuf(scur));
rc = dcb->func.write(dcb, sescmd_cursor_clone_querybuf(scur));
if (rc != 1)
{