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Cluster: detect cluster reconfiguration when master slots drop to 0.
The old algorithm used a PROMOTED flag and explicitly checks about slave->master convertions. Wit the new cluster meta-data propagation algorithm we just look at the configEpoch to check if we need to reconfigure slots, then: 1) If a node is a master but it reaches zero served slots becuase of reconfiguration. 2) If a node is a slave but the master reaches zero served slots because of a reconfiguration. We switch as a replica of the new slots owner.
This commit is contained in:
antirez
parent
62b1591439
commit
4dc247eb31
@ -135,8 +135,6 @@ int clusterLoadConfig(char *filename) {
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n->flags |= REDIS_NODE_HANDSHAKE;
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} else if (!strcasecmp(s,"noaddr")) {
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n->flags |= REDIS_NODE_NOADDR;
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} else if (!strcasecmp(s,"promoted")) {
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n->flags |= REDIS_NODE_PROMOTED;
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} else if (!strcasecmp(s,"noflags")) {
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/* nothing to do */
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} else {
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@ -755,7 +753,6 @@ void clusterProcessGossipSection(clusterMsg *hdr, clusterLink *link) {
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if (flags & REDIS_NODE_FAIL) ci = sdscat(ci,"fail,");
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if (flags & REDIS_NODE_HANDSHAKE) ci = sdscat(ci,"handshake,");
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if (flags & REDIS_NODE_NOADDR) ci = sdscat(ci,"noaddr,");
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if (flags & REDIS_NODE_PROMOTED) ci = sdscat(ci,"promoted,");
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if (ci[sdslen(ci)-1] == ',') ci[sdslen(ci)-1] = ' ';
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redisLog(REDIS_DEBUG,"GOSSIP %.40s %s:%d %s",
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@ -1051,9 +1048,6 @@ int clusterProcessPacket(clusterLink *link) {
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{
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/* Node is a master. */
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if (sender->flags & REDIS_NODE_SLAVE) {
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/* Slave turned into master! */
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clusterNode *oldmaster = sender->slaveof;
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/* Reconfigure node as master. */
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if (sender->slaveof)
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clusterNodeRemoveSlave(sender->slaveof,sender);
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@ -1061,29 +1055,6 @@ int clusterProcessPacket(clusterLink *link) {
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sender->flags |= REDIS_NODE_MASTER;
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sender->slaveof = NULL;
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/* If this node used to be our slave, and now has the
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* PROMOTED flag set. We'll turn ourself into a slave
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* of the new master. */
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if (flags & REDIS_NODE_PROMOTED &&
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oldmaster == server.cluster->myself)
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{
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redisLog(REDIS_WARNING,"One of my slaves took my place. Reconfiguring myself as a replica of %.40s", sender->name);
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clusterDelNodeSlots(server.cluster->myself);
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clusterSetMaster(sender);
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}
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/* If we are a slave, and this node used to be a slave
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* of our master, and now has the PROMOTED flag set, we
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* need to switch our replication setup over it. */
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if (flags & REDIS_NODE_PROMOTED &&
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server.cluster->myself->flags & REDIS_NODE_SLAVE &&
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server.cluster->myself->slaveof == oldmaster)
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{
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redisLog(REDIS_WARNING,"One of the slaves failed over my master. Reconfiguring myself as a replica of %.40s", sender->name);
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clusterDelNodeSlots(server.cluster->myself);
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clusterSetMaster(sender);
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}
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/* Update config and state. */
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update_state = 1;
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update_config = 1;
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@ -1125,26 +1096,55 @@ int clusterProcessPacket(clusterLink *link) {
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changes =
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memcmp(sender->slots,hdr->myslots,sizeof(hdr->myslots)) != 0;
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if (changes) {
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clusterNode *curmaster, *newmaster = NULL;
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/* Here we set curmaster to this node or the node this node
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* replicates to if it's a slave. In the for loop we are
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* interested to check if slots are taken away from curmaster. */
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if (server.cluster->myself->flags & REDIS_NODE_MASTER)
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curmaster = server.cluster->myself;
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else
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curmaster = server.cluster->myself->slaveof;
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for (j = 0; j < REDIS_CLUSTER_SLOTS; j++) {
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if (bitmapTestBit(hdr->myslots,j)) {
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/* If this slot was not served, or served by a node
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* in FAIL state, update the table with the new node
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* claiming to serve the slot. */
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/* We rebind the slot to the new node claiming it if:
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* 1) The slot was unassigned.
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* 2) The new node claims it with a greater configEpoch. */
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if (server.cluster->slots[j] == sender) continue;
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if (server.cluster->slots[j] == NULL ||
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server.cluster->slots[j]->flags & REDIS_NODE_FAIL)
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server.cluster->slots[j]->configEpoch <
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senderConfigEpoch)
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{
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if (server.cluster->slots[j] == curmaster)
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newmaster = sender;
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clusterDelSlot(j);
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clusterAddSlot(sender,j);
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update_state = update_config = 1;
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}
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} else {
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/* This node claims to no longer handling the slot,
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* however we don't change our config as this is likely
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* happening because a resharding is in progress, and
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* it already knows where to redirect clients. */
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* however we don't change our config as this is likely:
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* 1) Rehashing in progress.
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* 2) Failover.
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* In both cases we'll be informed about who is serving
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* the slot eventually. In the meantime it's up to the
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* original owner to try to redirect our clients to the
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* right node. */
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}
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}
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/* If at least one slot was reassigned from a node to another node
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* with a greater configEpoch, it is possible that:
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* 1) We are a master is left without slots. This means that we were
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* failed over and we should turn into a replica of the new
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* master.
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* 2) We are a slave and our master is left without slots. We need
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* to replicate to the new slots owner. */
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if (newmaster && curmaster->numslots == 0) {
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redisLog(REDIS_WARNING,"Configuration change detected. Reconfiguring myself as a replica of %.40s", sender->name);
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clusterSetMaster(sender);
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}
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}
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}
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@ -1681,7 +1681,6 @@ void clusterHandleSlaveFailover(void) {
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server.cluster->myself);
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server.cluster->myself->flags &= ~REDIS_NODE_SLAVE;
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server.cluster->myself->flags |= REDIS_NODE_MASTER;
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server.cluster->myself->flags |= REDIS_NODE_PROMOTED;
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server.cluster->myself->slaveof = NULL;
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replicationUnsetMaster();
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@ -2109,9 +2108,6 @@ void clusterSetMaster(clusterNode *n) {
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myself->flags &= ~REDIS_NODE_MASTER;
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myself->flags |= REDIS_NODE_SLAVE;
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}
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/* Clear the promoted flag anyway if we are a slave, to ensure it will
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* be set only when the node turns into a master because of fail over. */
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myself->flags &= ~REDIS_NODE_PROMOTED;
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myself->slaveof = n;
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replicationSetMaster(n->ip, n->port);
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}
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@ -2159,7 +2155,6 @@ sds clusterGenNodesDescription(int filter) {
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if (node->flags & REDIS_NODE_FAIL) ci = sdscat(ci,"fail,");
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if (node->flags & REDIS_NODE_HANDSHAKE) ci =sdscat(ci,"handshake,");
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if (node->flags & REDIS_NODE_NOADDR) ci = sdscat(ci,"noaddr,");
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if (node->flags & REDIS_NODE_PROMOTED) ci = sdscat(ci,"promoted,");
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if (ci[sdslen(ci)-1] == ',') ci[sdslen(ci)-1] = ' ';
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/* Slave of... or just "-" */
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