Make MASTERDOWN a retriable error in RedisCluster client #3164
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When clusters are running with `replica-server-stale-data no`, replicas
will return a MASTERDOWN error under two conditions:
1. The primary has failed and we are not serving requests.
2. A replica has just started and has not yet synced from the primary.
The former, primary has failed and we are not serving requests, is
similar to a CLUSTERDOWN error and should be similarly retriable.
When a replica has just started and has not yet synced from the primary
the request should be retried on other available nodes in the shard.
Otherwise a percentage of the read requests to the shard will fail.
Examples when `replica-server-stale-data no` is enabled:
1. In a cluster using `ReadOnly` with a single read replica, every
read request will return errors to the client because MASTERDOWN is
not a retriable error.
2. In a cluster using `RouteRandomly` a percentage of the requests
will return errors to the client based on if this server was
selected.
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When clusters are running with
replica-server-stale-data no, replicas will return a MASTERDOWN error under two conditions:The former, primary has failed and we are not serving requests, is similar to a CLUSTERDOWN error and should be similarly retriable.
When a replica has just started and has not yet synced from the primary the request should be retried on other available nodes in the shard. Otherwise a percentage of the read requests to the shard will fail.
Examples when
replica-server-stale-data nois enabled:ReadOnlywith a single read replica, every read request will return errors to the client because MASTERDOWN is not a retriable error.RouteRandomlya percentage of the requests will return errors to the client based on if this server was selected.