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MXS-406: Galeramon to set the preferred donor nodes

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Galeramon queries all slave nodes for SHOW VARIABLES LIKE
'wsrep_node_name'

The server list, currently not sorted, is used in SET GLOBAL
wsrep_sst_donor = “list”. The statement is sent to all slave nodes
This commit is contained in:
MassimilianoPinto 2017-01-16 11:25:47 +01:00
parent c2e14161bd
commit 3c532430f9
1 changed files with 141 additions and 0 deletions
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141
server/modules/monitor/galeramon/galeramon.c
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@ -39,6 +39,9 @@
#include <maxscale/dcb.h>
#include <maxscale/alloc.h>
#define DONOR_NODE_NAME_MAX_LEN 60
#define DONOR_LIST_SET_VAR "SET GLOBAL wsrep_sst_donor = \""
static void monitorMain(void *);
/** Log a warning when a bad 'wsrep_local_index' is found */
@ -51,6 +54,7 @@ static MONITOR_SERVERS *get_candidate_master(MONITOR*);
static MONITOR_SERVERS *set_cluster_master(MONITOR_SERVERS *, MONITOR_SERVERS *, int);
static void disableMasterFailback(void *, int);
bool isGaleraEvent(monitor_event_t event);
static void update_sst_donor_nodes(MONITOR*, int);
/**
* The module entry point routine. It is this routine that
@ -102,6 +106,7 @@ MXS_MODULE* MXS_CREATE_MODULE()
MXS_MODULE_OPT_NONE,
monitor_event_enum_values
},
{"set_donor_nodes", MXS_MODULE_PARAM_BOOL, "false"},
{MXS_END_MODULE_PARAMS}
}
};
@ -144,6 +149,7 @@ startMonitor(MONITOR *mon, const CONFIG_PARAMETER *params)
handle->use_priority = config_get_bool(params, "use_priority");
handle->script = config_copy_string(params, "script");
handle->events = config_get_enum(params, "events", monitor_event_enum_values);
handle->set_donor_nodes = config_get_bool(params, "set_donor_nodes");
/** SHOW STATUS doesn't require any special permissions */
if (!check_monitor_permissions(mon, "SHOW STATUS LIKE 'wsrep_local_state'"))
@ -191,6 +197,7 @@ diagnostics(DCB *dcb, const MONITOR *mon)
dcb_printf(dcb, "Available when Donor:\t%s\n", (handle->availableWhenDonor == 1) ? "on" : "off");
dcb_printf(dcb, "Master Role Setting Disabled:\t%s\n",
handle->disableMasterRoleSetting ? "on" : "off");
dcb_printf(dcb, "Set wsrep_sst_donor node list:\t%s\n", (handle->set_donor_nodes == 1) ? "on" : "off");
}
/**
@ -531,7 +538,17 @@ monitorMain(void *arg)
mon_process_state_changes(mon, handle->script, handle->events);
mon_hangup_failed_servers(mon);
servers_status_current_to_pending(mon);
/* Set the global var "wsrep_sst_donor"
* with a sorted list of "wsrep_node_name" for slave nodes
*/
if (handle->set_donor_nodes)
{
update_sst_donor_nodes(mon, is_cluster);
}
release_monitor_servers(mon);
}
}
@ -645,3 +662,127 @@ static MONITOR_SERVERS *set_cluster_master(MONITOR_SERVERS *current_master, MONI
}
}
}
/**
* Set the global variable wsrep_sst_donor in the cluster
*
* The monitor user must have the privileges for setting global vars.
*
* Galera monitor fetches from each joined slave node the var 'wsrep_node_name'
* A list of nodes is automatically build and it's sorted by wsrep_local_index DESC
* or by priority ASC if use_priority option is set.
*
* The list is then added to SET GLOBAL VARIABLE wrep_sst_donor =
* The variable must be sent to all slave nodes.
*
* All slave nodes have a sorted list of nodes tht can be used as donor nodes.
*
* If there is only one node the funcion returns,
*
* @param mon The monitor handler
* @param is_cluster The number of joined nodes
*/
static void update_sst_donor_nodes(MONITOR *mon, int is_cluster)
{
MONITOR_SERVERS *ptr;
MYSQL_ROW row;
MYSQL_RES *result;
if (is_cluster == 1)
{
MXS_DEBUG("Only one server in the cluster: update_sst_donor_nodes is not performed");
return;
}
/* Donor list size = DONOR_LIST_SET_VAR + n_hosts * max_host_len + n_hosts + 1 */
char *donor_list = MXS_CALLOC(1, strlen(DONOR_LIST_SET_VAR) +
is_cluster * DONOR_NODE_NAME_MAX_LEN +
is_cluster + 1);
if (donor_list == NULL)
{
MXS_ERROR("can't execute update_sst_donor_nodes() due to memory allocation error");
return;
}
strcpy(donor_list, DONOR_LIST_SET_VAR);
ptr = mon->databases;
while (ptr)
{
if (SERVER_IS_JOINED(ptr->server) && SERVER_IS_SLAVE(ptr->server))
{
/* Get the Galera node name */
if (mysql_query(ptr->con, "SHOW VARIABLES LIKE 'wsrep_node_name'") == 0
&& (result = mysql_store_result(ptr->con)) != NULL)
{
if (mysql_field_count(ptr->con) < 2)
{
mysql_free_result(result);
MXS_ERROR("Unexpected result for \"SHOW VARIABLES LIKE 'wsrep_node_name'\". "
"Expected 2 columns");
return;
}
while ((row = mysql_fetch_row(result)))
{
MXS_DEBUG("wsrep_node_name name for %s is [%s]",
ptr->server->unique_name,
row[1]);
strncat(donor_list, row[1], DONOR_NODE_NAME_MAX_LEN);
strcat(donor_list, ",");
}
mysql_free_result(result);
}
else
{
MXS_ERROR("Error while selecting 'wsrep_node_name' from node %s: %s",
ptr->server->unique_name,
mysql_error(ptr->con));
}
}
ptr = ptr->next;
}
int donor_list_size = strlen(donor_list);
if (donor_list[donor_list_size - 1] == ',')
{
donor_list[donor_list_size - 1] = '\0';
}
strcat(donor_list, "\"");
MXS_DEBUG("Sending %s to all slave nodes",
donor_list);
/* Set now rep_sst_donor in each slave node */
ptr = mon->databases;
while (ptr)
{
if (SERVER_IS_JOINED(ptr->server) && SERVER_IS_SLAVE(ptr->server))
{
/* Set the Galera SST donor node list */
if (mysql_query(ptr->con, donor_list) == 0)
{
MXS_DEBUG("SET GLOBAL rep_sst_donor OK in node %s",
ptr->server->unique_name);
}
else
{
MXS_ERROR("SET GLOBAL rep_sst_donor error in node %s: %s",
ptr->server->unique_name,
mysql_error(ptr->con));
}
}
ptr = ptr->next;
}
MXS_FREE(donor_list);
}