Method buildRingForTheShard

ring/ring.go:1169–1203

buildRingForTheShard builds read-only ring for the shard (this ring won't be updated in the future).

(shard map[string]InstanceDesc)

// buildRingForTheShard builds read-only ring for the shard (this ring won't be updated in the future).
func (r *Ring) buildRingForTheShard(shard map[string]InstanceDesc) *Ring {
	shardDesc := &Desc{Ingesters: shard}
	shardTokensByZone := shardDesc.getTokensByZone()
	shardTokens := mergeTokenGroups(shardTokensByZone)
	zones := getZones(shardTokensByZone)

	ring := &Ring{
		cfg:                                     r.cfg,
		strategy:                                r.strategy,
		logger:                                  r.logger,
		ringDesc:                                shardDesc,
		ringTokens:                              shardTokens,
		ringTokensByZone:                        shardTokensByZone,
		ringZones:                               zones,
		trackedRingZones:                        map[string]struct{}{},
		instancesWithTokensCount:                shardDesc.instancesWithTokensCount(),
		instancesCountPerZone:                   shardDesc.instancesCountPerZone(),
		instancesWithTokensCountPerZone:         shardDesc.instancesWithTokensCountPerZone(),
		writableInstancesWithTokensCount:        shardDesc.writableInstancesWithTokensCount(),
		writableInstancesWithTokensCountPerZone: shardDesc.writableInstancesWithTokensCountPerZone(),

		oldestRegisteredTimestamp: shardDesc.getOldestRegisteredTimestamp(),

		// We reference the original map as is in order to avoid copying. It's safe to do
		// because this map is immutable by design and it's a superset of the actual instances
		// with the subring.
		ringInstanceByToken: r.ringInstanceByToken,

		// For caching to work, remember these values.
		lastTopologyChange: r.lastTopologyChange,
	}

	ring.updateRingZones(zones)
	return ring
}

// mergeTokenGroups returns a sorted list of all tokens in each entry in groupsByName.
// Each element of groupsByName is assumed to already be sorted.