Function iredismodule::avoid_replica_traffic

pub fn avoid_replica_traffic() -> Result<(), Error>

Returns true if some client sent the CLIENT PAUSE command to the server or if Redis Cluster is doing a manual failover, and paused tue clients.

This is needed when we have a master with replicas, and want to write, without adding further data to the replication channel, that the replicas replication offset, match the one of the master. When this happens, it is safe to failover the master without data loss.

However modules may generate traffic by calling Context::call with the "!" flag, or by calling Context::replicate, in a context outside commands execution, for instance in timeout callbacks, threads safe contexts, and so forth. When modules will generate too much traffic, it will be hard for the master and replicas offset to match, because there is more data to send in the replication channel.

So modules may want to try to avoid very heavy background work that has the effect of creating data to the replication channel, when this function returns true. This is mostly useful for modules that have background garbage collection tasks, or that do writes and replicate such writes periodically in timer callbacks or other periodic callbacks.