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Added new criteria for slave selection: LEAST_ROUTER_CONNECTIONS which causes the servers having least connections from same router to become chosen.

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Added function pointer array which is indexed by enumerated selection criterias.
Selection criteria can now be switched by modifying config file and reloading it.
This commit is contained in:
VilhoRaatikka
2014-05-12 17:03:22 +03:00
parent 25cb08cc29
commit c5ec3cbc57
3 changed files with 122 additions and 48 deletions
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144
server/modules/routing/readwritesplit/readwritesplit.c
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@ -74,10 +74,22 @@ int bref_cmp_global_conn(
const void* bref1,
const void* bref2);
int bref_cmp_router_conn(
const void* bref1,
const void* bref2);
int bref_cmp_behind_master(
const void* bref1,
const void* bref2);
int (*criteria_cmpfun[LAST_CRITERIA])(const void*, const void*)=
{
NULL,
bref_cmp_global_conn,
bref_cmp_router_conn,
bref_cmp_behind_master
};
static bool select_connect_backend_servers(
backend_ref_t** p_master_ref,
backend_ref_t* backend_ref,
@ -1300,7 +1312,7 @@ lock_failed:
}
int bref_cmp_global_conn(
int bref_cmp_router_conn(
const void* bref1,
const void* bref2)
{
@ -1311,6 +1323,18 @@ int bref_cmp_global_conn(
((b1->backend_conn_count > b2->backend_conn_count) ? 1 : 0));
}
int bref_cmp_global_conn(
const void* bref1,
const void* bref2)
{
BACKEND* b1 = ((backend_ref_t *)bref1)->bref_backend;
BACKEND* b2 = ((backend_ref_t *)bref2)->bref_backend;
return ((b1->backend_server->stats.n_current < b2->backend_server->stats.n_current) ? -1 :
((b1->backend_server->stats.n_current > b2->backend_server->stats.n_current) ? 1 : 0));
}
int bref_cmp_behind_master(
const void* bref1,
const void* bref2)
@ -1374,21 +1398,13 @@ static bool select_connect_backend_servers(
goto return_succp;
}
/** Check slave selection criteria and set compare function */
switch (select_criteria) {
case LEAST_GLOBAL_CONNECTIONS:
p = bref_cmp_global_conn;
break;
case LEAST_BEHIND_MASTER:
p = bref_cmp_behind_master;
break;
default:
succp = false;
goto return_succp;
break;
}
p = criteria_cmpfun[select_criteria];
if (p == NULL)
{
succp = false;
goto return_succp;
}
if (router->bitvalue != 0) /*< 'synced' is the only bitvalue in rwsplit */
{
@ -1399,8 +1415,8 @@ static bool select_connect_backend_servers(
is_synced_master = false;
}
#if 0
LOGIF(LT, (skygw_log_write(LOGFILE_TRACE, "Servers and conns before ordering:")));
for (i=0; i<router_nservers; i++)
{
BACKEND* b = backend_ref[i].bref_backend;
@ -1410,27 +1426,52 @@ static bool select_connect_backend_servers(
b->backend_server->name,
b->backend_server->port,
b->backend_conn_count)));
}
}
#endif
/**
* Sort the pointer list to servers according to connection counts. As
* a consequence those backends having least connections are in the
* beginning of the list.
*/
qsort((void *)backend_ref, (size_t)router_nservers, sizeof(backend_ref_t), p);
LOGIF(LT, (skygw_log_write(LOGFILE_TRACE, "Servers and conns after ordering:")));
for (i=0; i<router_nservers; i++)
if (LOG_IS_ENABLED(LOGFILE_TRACE))
{
BACKEND* b = backend_ref[i].bref_backend;
LOGIF(LT, (skygw_log_write(LOGFILE_TRACE,
"%s %d:%d",
b->backend_server->name,
b->backend_server->port,
b->backend_conn_count)));
}
if (select_criteria == LEAST_GLOBAL_CONNECTIONS ||
select_criteria == LEAST_ROUTER_CONNECTIONS)
{
LOGIF(LT, (skygw_log_write(LOGFILE_TRACE,
"Servers and %s connection counts:",
select_criteria == LEAST_GLOBAL_CONNECTIONS ?
"all MaxScale" : "router")));
for (i=0; i<router_nservers; i++)
{
BACKEND* b = backend_ref[i].bref_backend;
switch(select_criteria) {
case LEAST_GLOBAL_CONNECTIONS:
LOGIF(LT, (skygw_log_write_flush(LOGFILE_TRACE,
"%s %d:%d",
b->backend_server->name,
b->backend_server->port,
b->backend_server->stats.n_current)));
break;
case LEAST_ROUTER_CONNECTIONS:
LOGIF(LT, (skygw_log_write_flush(LOGFILE_TRACE,
"%s %d:%d",
b->backend_server->name,
b->backend_server->port,
b->backend_conn_count)));
break;
default:
break;
}
}
}
}
/**
* Choose at least 1+1 (master and slave) and at most 1+max_nslaves
* servers from the sorted list. First master found is selected.
@ -1469,9 +1510,13 @@ static bool select_connect_backend_servers(
if (backend_ref[i].bref_dcb != NULL)
{
slaves_connected += 1;
/** Increase backend connection counter */
atomic_add(&b->backend_server->stats.n_current, 1);
atomic_add(&b->backend_server->stats.n_connections, 1);
/**
* Increase backend connection counter.
* Server's stats are _increased_ in
* dcb.c:dcb_alloc !
* But decreased in the calling function
* of dcb_close.
*/
atomic_add(&b->backend_conn_count, 1);
}
else
@ -2347,8 +2392,9 @@ static void rwsplit_process_options(
ROUTER_INSTANCE* router,
char** options)
{
int i;
char* value;
int i;
char* value;
select_criteria_t c;
for (i = 0; options[i]; i++)
{
@ -2366,16 +2412,28 @@ static void rwsplit_process_options(
value++;
if (strcmp(options[i], "slave_selection_criteria") == 0)
{
router->rwsplit_config.rw_slave_select_criteria =
GET_SELECT_CRITERIA(value);
c = GET_SELECT_CRITERIA(value);
ss_dassert(
router->rwsplit_config.rw_slave_select_criteria ==
LEAST_GLOBAL_CONNECTIONS ||
router->rwsplit_config.rw_slave_select_criteria ==
LEAST_BEHIND_MASTER ||
router->rwsplit_config.rw_slave_select_criteria ==
UNDEFINED_CRITERIA);
c == LEAST_GLOBAL_CONNECTIONS ||
c == LEAST_ROUTER_CONNECTIONS ||
c == LEAST_BEHIND_MASTER ||
c == UNDEFINED_CRITERIA);
if (c == UNDEFINED_CRITERIA)
{
LOGIF(LE, (skygw_log_write(
LOGFILE_ERROR, "Warning : Unknown "
"slave selection criteria \"%s\". "
"Allowed values are \"LEAST_GLOBAL_CONNECTIONS\", "
"LEAST_ROUTER_CONNECTIONS, "
"and \"LEAST_ROUTER_CONNECTIONS\".",
STRCRITERIA(router->rwsplit_config.rw_slave_select_criteria))));
}
else
{
router->rwsplit_config.rw_slave_select_criteria = c;
}
}
}
}
} /*< for */
}