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Cluster: set slot error if we receive an update for a busy slot.

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By manually modifying nodes configurations in random ways, it is possible
to create the following scenario:

A is serving keys for slot 10
B is manually configured to serve keys for slot 10

A receives an update from B (or another node) where it is informed that
the slot 10 is now claimed by B with a greater configuration epoch,
however A still has keys from slot 10.

With this commit A will put the slot in error setting it in IMPORTING
state, so that redis-trib can detect the issue.
This commit is contained in:
antirez 2014-03-11 11:49:47 +01:00
parent 1ed0ad77f0
commit a2ff90919f
1 changed files with 22 additions and 5 deletions
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27
src/cluster.c
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@ -1099,9 +1099,7 @@ void clusterSetNodeAsMaster(clusterNode *n) {
* The 'sender' is the node for which we received a configuration update.
* Sometimes it is not actaully the "Sender" of the information, like in the case
* we receive the info via an UPDATE packet. */
void clusterUpdateSlotsConfigWith(clusterNode *sender, uint64_t senderConfigEpoch,
unsigned char *slots)
{
void clusterUpdateSlotsConfigWith(clusterNode *sender, uint64_t senderConfigEpoch, unsigned char *slots) {
int j;
clusterNode *curmaster, *newmaster = NULL;
@ -1112,15 +1110,34 @@ void clusterUpdateSlotsConfigWith(clusterNode *sender, uint64_t senderConfigEpoc
for (j = 0; j < REDIS_CLUSTER_SLOTS; j++) {
if (bitmapTestBit(slots,j)) {
/* The slot is already bound to the sender of this message. */
if (server.cluster->slots[j] == sender) continue;
/* The slot is in importing state, it should be modified only
* manually via redis-trib (example: a resharding is in progress
* and the migrating side slot was already closed and is advertising
* a new config. We still want the slot to be closed manually). */
if (server.cluster->importing_slots_from[j]) continue;
/* We rebind the slot to the new node claiming it if:
* 1) The slot was unassigned or the new node claims it with a
* greater configEpoch.
* 2) We are not currently importing the slot. */
if (server.cluster->slots[j] == sender ||
server.cluster->importing_slots_from[j]) continue;
if (server.cluster->slots[j] == NULL ||
server.cluster->slots[j]->configEpoch < senderConfigEpoch)
{
/* Was this slot mine, and still contains keys? Something
* odd happened, put the slot in importing state so that
* redis-trib fix can detect the condition (and no further
* updates will be processed before the slot gets fixed). */
if (server.cluster->slots[j] == myself &&
countKeysInSlot(j) &&
sender != myself)
{
redisLog(REDIS_WARNING,"Slot update for a slot I still have keys received. Putting the slot in IMPORTING state. Please run the 'redis-trib fix' command.");
server.cluster->importing_slots_from[j] = sender;
}
if (server.cluster->slots[j] == curmaster)
newmaster = sender;
clusterDelSlot(j);