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MXS-1889 Handle master used as slave

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Up until 2.1.12, if it in the configuration file said
'router_options=slave', the master was used if there were no
slaves at session creation time.

That broke in 2.1.13 as a side-effect of MXS-1516 that checks
at routing time whether the server initially selected as master
still is the master.

Now the required server status is stored separately for each
session, so that if the master was chosen, even though we have
'router_options=slave', we can turn on the SERVER_MASTER bit.

That allows us to handle the case correctly in connection_is_valid().
This commit is contained in:
Johan Wikman
2018-05-31 15:21:17 +03:00
parent 89296ed4e4
commit d77a9a3040
3 changed files with 20 additions and 3 deletions
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1
server/modules/routing/readconnroute/readconnection.h
View File

@ -49,6 +49,7 @@ typedef struct router_client_session
SERVER_REF *backend; /*< Backend used by the client session */
DCB *backend_dcb; /*< DCB Connection to the backend */
DCB *client_dcb; /**< Client DCB */
unsigned int bitvalue; /*< Session specific required value of server->status */
struct router_client_session *next;
#if defined(SS_DEBUG)
skygw_chk_t rses_chk_tail;

20
server/modules/routing/readconnroute/readconnroute.c
View File

@ -286,6 +286,7 @@ newSession(MXS_ROUTER *instance, MXS_SESSION *session)
client_rses->rses_chk_tail = CHK_NUM_ROUTER_SES;
#endif
client_rses->client_dcb = session->client_dcb;
client_rses->bitvalue = inst->bitvalue;
/**
* Find the Master host from available servers
@ -397,6 +398,14 @@ newSession(MXS_ROUTER *instance, MXS_SESSION *session)
if (master_host)
{
candidate = master_host;
// Even if we had 'router_options=slave' in the configuration file, we
// will still end up here if there are no slaves, but a sole master. So
// that the server will be considered valid in connection_is_valid(), we
// turn on the SERVER_MASTER bit.
//
// We must do that so that readconnroute in MaxScale 2.2 will again behave
// the same way as it did up until 2.1.12.
client_rses->bitvalue |= SERVER_MASTER;
}
else
{
@ -542,10 +551,17 @@ static inline bool connection_is_valid(ROUTER_INSTANCE* inst, ROUTER_CLIENT_SES*
{
bool rval = false;
// inst->bitvalue and router_cli_ses->bitvalue are different, if we had
// 'router_options=slave' in the configuration file and there was only
// the sole master available at session creation time.
if (SERVER_IS_RUNNING(router_cli_ses->backend->server) &&
(router_cli_ses->backend->server->status & inst->bitmask & inst->bitvalue))
(router_cli_ses->backend->server->status & inst->bitmask & router_cli_ses->bitvalue))
{
if ((inst->bitvalue == SERVER_MASTER) && router_cli_ses->backend->active)
// Note the use of '==' and not '|'. We must use the former to exclude a
// 'router_options=slave' that uses the master due to no slave having been
// available at session creation time. Its bitvalue is (SERVER_MASTER | SERVER_SLAVE).
if ((router_cli_ses->bitvalue == SERVER_MASTER) && router_cli_ses->backend->active)
{
// If we're using an active master server, verify that it is still a master
rval = router_cli_ses->backend == get_root_master(inst->service->dbref);