hcq/MaxScale
hcq/MaxScale
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Do error handling in one big locked action

Browse Source 
This is not the optimal way to do error handling but it should solve all
problems that could rise from the multi-threaded model of MaxScale.

By taking a lock at the start of handleError, we'll be able to modify the
dcb error handling flag in a thread-safe manner. This should prevent
double error handling for all DCBs.
This commit is contained in:
Markus Makela 2016-11-28 13:13:17 +02:00
parent f8f400bdfd
commit 0bc68742a6
1 changed files with 39 additions and 51 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

90
server/modules/routing/readwritesplit/readwritesplit.c
View File

@ -69,7 +69,15 @@ MODULE_INFO info =
* @endverbatim
*/
#define RW_CHK_DCB(bref, dcb) do{if(dcb->state == DCB_STATE_DISCONNECTED){MXS_NOTICE("DCB was closed on line %d and another attempt to close it is made on line %d." , (bref) ? (bref)->closed_at : -1, __LINE__);}}while(false)
#define RW_CHK_DCB(bref, dcb) \
do{ \
if(dcb->state == DCB_STATE_DISCONNECTED){ \
MXS_NOTICE("DCB was closed on line %d and another attempt to close it is made on line %d." , \
(bref) ? (bref)->closed_at : -1, __LINE__); \
} \
}while (false)
#define RW_CLOSE_BREF(b) do{ if (bref){ bref->closed_at = __LINE__; } } while (false)
static char *version_str = "V1.1.0";
@ -956,7 +964,7 @@ static void closeSession(ROUTER *instance, void *router_session)
*/
RW_CHK_DCB(bref, dcb);
dcb_close(dcb);
bref->closed_at = __LINE__;
RW_CLOSE_BREF(bref);
/** decrease server current connection counters */
atomic_add(&bref->bref_backend->backend_conn_count, -1);
}
@ -3001,7 +3009,7 @@ bool connect_server(backend_ref_t *bref, SESSION *session, bool execute_history)
bref->bref_backend->backend_server->port);
RW_CHK_DCB(bref, bref->bref_dcb);
dcb_close(bref->bref_dcb);
bref->closed_at = __LINE__;
RW_CLOSE_BREF(bref);
bref->bref_dcb = NULL;
}
}
@ -3318,7 +3326,7 @@ static bool select_connect_backend_servers(backend_ref_t **p_master_ref,
atomic_add(&backend_ref[i].bref_backend->backend_conn_count, -1);
RW_CHK_DCB(&backend_ref[i], backend_ref[i].bref_dcb);
dcb_close(backend_ref[i].bref_dcb);
backend_ref[i].closed_at = __LINE__;
RW_CLOSE_BREF(&backend_ref[i]);
}
}
}
@ -3562,7 +3570,7 @@ static GWBUF *sescmd_cursor_process_replies(GWBUF *replybuf,
{
RW_CHK_DCB(bref, bref->bref_dcb);
dcb_close(bref->bref_dcb);
bref->closed_at = __LINE__;
RW_CLOSE_BREF(bref);
}
*reconnect = true;
gwbuf_free(replybuf);
@ -3604,7 +3612,7 @@ static GWBUF *sescmd_cursor_process_replies(GWBUF *replybuf,
{
RW_CHK_DCB(&ses->rses_backend_ref[i], ses->rses_backend_ref[i].bref_dcb);
dcb_close(ses->rses_backend_ref[i].bref_dcb);
ses->rses_backend_ref[i].closed_at = __LINE__;
RW_CLOSE_BREF(&ses->rses_backend_ref[i]);
}
*reconnect = true;
MXS_WARNING("Disabling slave %s:%d, result differs from "
@ -4425,6 +4433,13 @@ static void handleError(ROUTER *instance, void *router_session,
CHK_DCB(problem_dcb);
if (!rses_begin_locked_router_action(rses))
{
/** Session is already closed */
*succp = false;
return;
}
/** Don't handle same error twice on same DCB */
if (problem_dcb->dcb_errhandle_called)
{
@ -4434,6 +4449,7 @@ static void handleError(ROUTER *instance, void *router_session,
* be safe with the code as it stands on 9 Sept 2015 - MNB
*/
*succp = true;
rses_end_locked_router_action(rses);
return;
}
else
@ -4443,6 +4459,7 @@ static void handleError(ROUTER *instance, void *router_session,
session = problem_dcb->session;
bool close_dcb = true;
backend_ref_t *bref = get_bref_from_dcb(rses, problem_dcb);
if (session == NULL || rses == NULL)
{
@ -4461,17 +4478,6 @@ static void handleError(ROUTER *instance, void *router_session,
{
case ERRACT_NEW_CONNECTION:
{
if (!rses_begin_locked_router_action(rses))
{
close_dcb = false; /* With the assumption that if the router session is closed,
* then so is the dcb.
*/
*succp = false;
break;
}
backend_ref_t *bref = get_bref_from_dcb(rses, problem_dcb);
/**
* If master has lost its Master status error can't be
* handled so that session could continue.
@ -4516,12 +4522,11 @@ static void handleError(ROUTER *instance, void *router_session,
"corresponding backend ref.", srv->name, srv->port);
}
}
else
else if (bref)
{
/**
* This is called in hope of getting replacement for
* failed slave(s).
*/
/** We should reconnect only if we find a backend for this
* DCB. If this DCB is an older DCB that has been closed,
* we can ignore it. */
*succp = handle_error_new_connection(inst, &rses, problem_dcb, errmsgbuf);
}
@ -4535,7 +4540,7 @@ static void handleError(ROUTER *instance, void *router_session,
if (bref && bref->bref_dcb == problem_dcb)
{
bref->closed_at = __LINE__;
RW_CLOSE_BREF(bref);
}
}
else
@ -4549,7 +4554,6 @@ static void handleError(ROUTER *instance, void *router_session,
}
close_dcb = false;
rses_end_locked_router_action(rses);
break;
}
@ -4570,14 +4574,11 @@ static void handleError(ROUTER *instance, void *router_session,
if (close_dcb)
{
backend_ref_t *bref = get_bref_from_dcb(rses, problem_dcb);
RW_CHK_DCB(bref, problem_dcb);
dcb_close(problem_dcb);
if (bref)
{
bref->closed_at = __LINE__;
}
RW_CLOSE_BREF(bref);
}
rses_end_locked_router_action(rses);
}
static void handle_error_reply_client(SESSION *ses, ROUTER_CLIENT_SES *rses,
@ -4592,35 +4593,22 @@ static void handle_error_reply_client(SESSION *ses, ROUTER_CLIENT_SES *rses,
client_dcb = ses->client_dcb;
spinlock_release(&ses->ses_lock);
if (rses_begin_locked_router_action(rses))
if ((bref = get_bref_from_dcb(rses, backend_dcb)) != NULL)
{
/**
* If bref exists, mark it closed
*/
if ((bref = get_bref_from_dcb(rses, backend_dcb)) != NULL)
{
CHK_BACKEND_REF(bref);
CHK_BACKEND_REF(bref);
if (BREF_IS_IN_USE(bref))
{
close_failed_bref(bref, false);
RW_CHK_DCB(bref, backend_dcb);
dcb_close(backend_dcb);
bref->closed_at = __LINE__;
}
}
else
if (BREF_IS_IN_USE(bref))
{
// All dcbs should be associated with a backend reference.
ss_dassert(!true);
close_failed_bref(bref, false);
RW_CHK_DCB(bref, backend_dcb);
dcb_close(backend_dcb);
RW_CLOSE_BREF(bref);
}
rses_end_locked_router_action(rses);
}
else
{
// The session has already been closed, hence the dcb has been
// closed as well.
// All dcbs should be associated with a backend reference.
ss_dassert(!true);
}
if (sesstate == SESSION_STATE_ROUTER_READY)