Struct Ring

pkg/ring/ring.go:179–219

Ring holds the information about the members of the consistent hash ring.

// Ring holds the information about the members of the consistent hash ring.
type Ring struct {
	services.Service

	key      string
	cfg      Config
	KVClient kv.Client
	strategy ReplicationStrategy

	mtx              sync.RWMutex
	ringDesc         *Desc
	ringTokens       []uint32
	ringTokensByZone map[string][]uint32

	// Maps a token with the information of the instance holding it. This map is immutable and
	// cannot be chanced in place because it's shared "as is" between subrings (the only way to
	// change it is to create a new one and replace it).
	ringInstanceByToken map[uint32]instanceInfo

	ringInstanceIdByAddr map[string]string

	// When did a set of instances change the last time (instance changing state or heartbeat is ignored for this timestamp).
	lastTopologyChange time.Time

	// List of zones for which there's at least 1 instance in the ring. This list is guaranteed
	// to be sorted alphabetically.
	ringZones         []string
	previousRingZones []string

	// Cache of shuffle-sharded subrings per identifier. Invalidated when topology changes.
	// If set to nil, no caching is done (used by tests, and subrings).
	shuffledSubringCache map[subringCacheKey]*Ring

	memberOwnershipGaugeVec *prometheus.GaugeVec
	numMembersGaugeVec      *prometheus.GaugeVec
	totalTokensGauge        prometheus.Gauge
	numTokensGaugeVec       *prometheus.GaugeVec
	oldestTimestampGaugeVec *prometheus.GaugeVec
	reportedOwners          map[string]struct{}

	logger log.Logger
}

type subringCacheKey struct {
	identifier string