Modify readwritesplit to understand changes in server references
The readwritesplit now understands that the amount of servers can change and some of the items in the list of server references aren't in use. This allows dynamic changes to the number of servers used by readwritesplit.
This commit is contained in:
Markus Makela
parent
8982ee3db2
commit
dc8c068936
@ -65,6 +65,9 @@ MODULE_INFO info =
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* @endverbatim
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*/
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/** Maximum number of slaves */
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#define MAX_SLAVE_COUNT 255
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static char *version_str = "V1.1.0";
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/*
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@ -126,7 +129,6 @@ static void handle_error_reply_client(SESSION *ses, ROUTER_CLIENT_SES *rses,
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static bool handle_error_new_connection(ROUTER_INSTANCE *inst,
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ROUTER_CLIENT_SES **rses,
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DCB *backend_dcb, GWBUF *errmsg);
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static int router_get_servercount(ROUTER_INSTANCE *inst);
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static bool have_enough_servers(ROUTER_CLIENT_SES **p_rses, const int min_nsrv,
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int router_nsrv, ROUTER_INSTANCE *router);
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@ -218,19 +220,12 @@ static ROUTER *createInstance(SERVICE *service, char **options)
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router->rwsplit_config.rw_max_sescmd_history_size = 0;
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}
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int nservers = 0;
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for (SERVER_REF *ref = service->dbref; ref; ref = ref->next)
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{
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nservers++;
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}
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/**
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* Set default value for max_slave_connections as 100%. This way
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* LEAST_CURRENT_OPERATIONS allows us to balance evenly across all the
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* configured slaves.
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*/
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router->rwsplit_config.rw_max_slave_conn_count = nservers;
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router->rwsplit_config.rw_max_slave_conn_count = MAX_SLAVE_COUNT;
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if (router->rwsplit_config.rw_slave_select_criteria == UNDEFINED_CRITERIA)
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{
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@ -306,7 +301,6 @@ static void *newSession(ROUTER *router_inst, SESSION *session)
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int router_nservers = 0; /*< # of servers in total */
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int max_nslaves; /*< max # of slaves used in this session */
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int max_slave_rlag; /*< max allowed replication lag for any slave */
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int i;
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const int min_nservers = 1; /*< hard-coded for now */
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client_rses = (ROUTER_CLIENT_SES *)MXS_CALLOC(1, sizeof(ROUTER_CLIENT_SES));
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@ -350,7 +344,7 @@ static void *newSession(ROUTER *router_inst, SESSION *session)
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client_rses->have_tmp_tables = false;
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client_rses->forced_node = NULL;
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router_nservers = router_get_servercount(router);
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router_nservers = router->service->n_dbref;
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if (!have_enough_servers(&client_rses, min_nservers, router_nservers, router))
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{
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@ -373,25 +367,35 @@ static void *newSession(ROUTER *router_inst, SESSION *session)
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* Initialize backend references with BACKEND ptr.
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* Initialize session command cursors for each backend reference.
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*/
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i = 0;
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for (SERVER_REF *sref = router->service->dbref; sref; sref = sref->next)
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int i = 0;
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for (SERVER_REF *sref = router->service->dbref; sref && i < router_nservers; sref = sref->next)
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{
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if (sref->active)
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{
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#if defined(SS_DEBUG)
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backend_ref[i].bref_chk_top = CHK_NUM_BACKEND_REF;
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backend_ref[i].bref_chk_tail = CHK_NUM_BACKEND_REF;
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backend_ref[i].bref_sescmd_cur.scmd_cur_chk_top = CHK_NUM_SESCMD_CUR;
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backend_ref[i].bref_sescmd_cur.scmd_cur_chk_tail = CHK_NUM_SESCMD_CUR;
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backend_ref[i].bref_chk_top = CHK_NUM_BACKEND_REF;
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backend_ref[i].bref_chk_tail = CHK_NUM_BACKEND_REF;
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backend_ref[i].bref_sescmd_cur.scmd_cur_chk_top = CHK_NUM_SESCMD_CUR;
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backend_ref[i].bref_sescmd_cur.scmd_cur_chk_tail = CHK_NUM_SESCMD_CUR;
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#endif
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backend_ref[i].bref_state = 0;
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backend_ref[i].ref = sref;
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/** store pointers to sescmd list to both cursors */
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backend_ref[i].bref_sescmd_cur.scmd_cur_rses = client_rses;
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backend_ref[i].bref_sescmd_cur.scmd_cur_active = false;
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backend_ref[i].bref_sescmd_cur.scmd_cur_ptr_property =
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&client_rses->rses_properties[RSES_PROP_TYPE_SESCMD];
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backend_ref[i].bref_sescmd_cur.scmd_cur_cmd = NULL;
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i++;
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backend_ref[i].bref_state = 0;
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backend_ref[i].ref = sref;
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/** store pointers to sescmd list to both cursors */
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backend_ref[i].bref_sescmd_cur.scmd_cur_rses = client_rses;
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backend_ref[i].bref_sescmd_cur.scmd_cur_active = false;
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backend_ref[i].bref_sescmd_cur.scmd_cur_ptr_property =
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&client_rses->rses_properties[RSES_PROP_TYPE_SESCMD];
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backend_ref[i].bref_sescmd_cur.scmd_cur_cmd = NULL;
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i++;
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}
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}
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if (i < router_nservers)
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{
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/** The service reported more servers than we took into use */
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router_nservers = i;
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}
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max_nslaves = rses_get_max_slavecount(client_rses, router_nservers);
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max_slave_rlag = rses_get_max_replication_lag(client_rses);
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@ -434,7 +438,6 @@ static void *newSession(ROUTER *router_inst, SESSION *session)
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/** Copy backend pointers to router session. */
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client_rses->rses_master_ref = master_ref;
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client_rses->rses_backend_ref = backend_ref;
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client_rses->rses_nbackends = router_nservers; /*< # of backend servers */
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if (client_rses->rses_config.rw_max_slave_conn_percent)
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@ -447,11 +450,6 @@ static void *newSession(ROUTER *router_inst, SESSION *session)
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router->stats.n_sessions += 1;
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/**
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* Version is bigger than zero once initialized.
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*/
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atomic_add(&client_rses->rses_versno, 2);
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ss_dassert(client_rses->rses_versno == 2);
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/**
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* Add this session to end of the list of active sessions in router.
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*/
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@ -1656,7 +1654,6 @@ static bool handle_error_new_connection(ROUTER_INSTANCE *inst,
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{
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ROUTER_CLIENT_SES *myrses;
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SESSION *ses;
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int router_nservers;
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int max_nslaves;
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int max_slave_rlag;
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backend_ref_t *bref;
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@ -1710,8 +1707,8 @@ static bool handle_error_new_connection(ROUTER_INSTANCE *inst,
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*/
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dcb_remove_callback(backend_dcb, DCB_REASON_NOT_RESPONDING,
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&router_handle_state_switch, (void *)bref);
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router_nservers = router_get_servercount(inst);
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max_nslaves = rses_get_max_slavecount(myrses, router_nservers);
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max_nslaves = rses_get_max_slavecount(myrses, myrses->rses_nbackends);
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max_slave_rlag = rses_get_max_replication_lag(myrses);
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/**
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* Try to get replacement slave or at least the minimum
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@ -1719,13 +1716,13 @@ static bool handle_error_new_connection(ROUTER_INSTANCE *inst,
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*/
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if (inst->rwsplit_config.rw_disable_sescmd_hist)
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{
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succp = have_enough_servers(&myrses, 1, router_nservers, inst) ? true : false;
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succp = have_enough_servers(&myrses, 1, myrses->rses_nbackends, inst) ? true : false;
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}
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else
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{
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succp = select_connect_backend_servers(&myrses->rses_master_ref,
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myrses->rses_backend_ref,
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router_nservers,
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myrses->rses_nbackends,
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max_nslaves, max_slave_rlag,
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myrses->rses_config.rw_slave_select_criteria,
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ses, inst);
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@ -1735,25 +1732,6 @@ return_succp:
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return succp;
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}
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/**
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* @brief Calculate the number of backend servers
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*
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* @param inst Router instance
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*
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* @return int - count of servers
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*/
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static int router_get_servercount(ROUTER_INSTANCE *inst)
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{
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int router_nservers = 0;
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for (SERVER_REF *ref = inst->service->dbref; ref; ref = ref->next)
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{
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router_nservers++;
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}
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return router_nservers;
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}
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/**
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* @brief Calculate whether we have enough servers to route a query
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*
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@ -281,7 +281,6 @@ struct router_client_session
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skygw_chk_t rses_chk_top;
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#endif
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SPINLOCK rses_lock; /*< protects rses_deleted */
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int rses_versno; /*< even = no active update, else odd. not used 4/14 */
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bool rses_closed; /*< true when closeSession is called */
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rses_property_t* rses_properties[RSES_PROP_TYPE_COUNT]; /*< Properties listed by their type */
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backend_ref_t* rses_master_ref;
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