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New rules for selecting Master/Slaves

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New rules for selecting Master/Slaves are based on MySQL depth in the
replication tree.
The only Master is the root server with SERVER_MASTER bit set
All other servers even with both SLAVE and MASTER bit will be selected
as slaves
This commit is contained in:
MassimilianoPinto 2014-06-24 15:44:14 +02:00
parent 584d8867bc
commit 52ef3b6718
1 changed files with 62 additions and 16 deletions
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78
server/modules/routing/readconnroute.c
View File

@ -65,6 +65,7 @@
* or take different actions such as open a new backend connection
* 20/02/2014 Massimiliano Pinto If router_options=slave, route traffic to master if no slaves available
* 06/03/2014 Massimiliano Pinto Server connection counter is now updated in closeSession
* 24/06/2014 Massimiliano Pinto New rules for selecting the Master server
*
* @endverbatim
*/
@ -299,7 +300,7 @@ ROUTER_INSTANCE *inst = (ROUTER_INSTANCE *)instance;
ROUTER_CLIENT_SES *client_rses;
BACKEND *candidate = NULL;
int i;
int master_host = -1;
BACKEND *master_host = NULL;
LOGIF(LD, (skygw_log_write_flush(
LOGFILE_DEBUG,
@ -321,6 +322,40 @@ int master_host = -1;
client_rses->rses_chk_tail = CHK_NUM_ROUTER_SES;
#endif
/********************************
* Get the root Master rule:
*
* 1) find server(s) with lowest replication depth level
* 2) check for SERVER_MASTER bitvalue in those servers
*
*/
/* 1) find root server(s) */
for (i = 0; inst->servers[i]; i++) {
if (inst->servers[i] && SERVER_IS_RUNNING(inst->servers[i]->server)) {
if (master_host && inst->servers[i]->server->depth < master_host->server->depth) {
master_host = inst->servers[i];
} else {
if (master_host == NULL) {
master_host = inst->servers[i];
}
}
}
}
/* 2) get the status of server(s) with lowest replication level and check it against SERVER_MASTER bitvalue */
if (master_host) {
int found = 0;
for (i = 0; inst->servers[i]; i++) {
if (inst->servers[i] && SERVER_IS_RUNNING(inst->servers[i]->server) && (inst->servers[i]->server->depth == master_host->server->depth)) {
if (inst->servers[i]->server->status & SERVER_MASTER)
found = 1;
}
}
if (!found)
master_host = NULL;
}
/**
* Find a backend server to connect to. This is the extent of the
* load balancing algorithm we need to implement for this simple
@ -356,21 +391,32 @@ int master_host = -1;
if (SERVER_IN_MAINT(inst->servers[i]->server))
continue;
/*
* If router_options=slave, get the running master
* It will be used if there are no running slaves at all
*/
if (inst->bitvalue == SERVER_SLAVE) {
if (master_host < 0 && (SERVER_IS_MASTER(inst->servers[i]->server))) {
master_host = i;
}
}
/* Check server status bits against bitvalue from router_options */
if (inst->servers[i] &&
SERVER_IS_RUNNING(inst->servers[i]->server) &&
(inst->servers[i]->server->status & inst->bitmask) ==
inst->bitvalue)
SERVER_IS_RUNNING(inst->servers[i]->server) &&
(inst->servers[i]->server->status & inst->bitmask & inst->bitvalue))
{
if (master_host) {
if (inst->servers[i] == master_host && (inst->bitvalue & SERVER_SLAVE)) {
/* skip root Master here, as it could also be slave of an external server
* that is not in the configuration.
* Intermediate masters (Relay Servers) are also slave and will be selected
* as Slave(s)
*/
continue;
}
if (inst->servers[i] == master_host && (inst->bitvalue & SERVER_MASTER)) {
/* If option is "master" return only the root Master as there
* could be intermediate masters (Relay Servers)
* and they must not be selected.
*/
candidate = master_host;
break;
}
}
/* If no candidate set, set first running server as
our initial candidate server */
if (candidate == NULL)
@ -403,8 +449,8 @@ int master_host = -1;
* Otherwise, just clean up and return NULL
*/
if (!candidate) {
if (master_host >= 0) {
candidate = inst->servers[master_host];
if (master_host) {
candidate = master_host;
} else {
LOGIF(LE, (skygw_log_write_flush(
LOGFILE_ERROR,