Struct client

client.go:143–172

)

type client struct {
	// updateMetadataMs stores the time at which metadata was lasted updated.
	// Note: this accessed atomically so must be the first word in the struct
	// as per golang/go#41970
	updateMetadataMs atomic.Int64

	conf           *Config
	closer, closed chan none // for shutting down background metadata updater

	// the broker addresses given to us through the constructor are not guaranteed to be returned in
	// the cluster metadata (I *think* it only returns brokers who are currently leading partitions?)
	// so we store them separately
	seedBrokers []*Broker
	deadSeeds   []*Broker

	controllerID            int32                                   // cluster controller broker id
	brokers                 map[int32]*Broker                       // maps broker ids to brokers
	metadata                map[string]map[int32]*PartitionMetadata // maps topics to partition ids to metadata
	metadataTopics          map[string]none                         // topics that need to collect metadata
	coordinators            map[string]int32                        // Maps consumer group names to coordinating broker IDs
	transactionCoordinators map[string]int32                        // Maps transaction ids to coordinating broker IDs

	// If the number of partitions is large, we can get some churn calling cachedPartitions,
	// so the result is cached.  It is important to update this value whenever metadata is changed
	cachedPartitionsResults map[string][maxPartitionIndex][]int32

	lock sync.RWMutex // protects access to the maps that hold cluster state.

	metadataRefresh metadataRefresh
}

// NewClient creates a new Client. It connects to one of the given broker addresses
// and uses that broker to automatically fetch metadata on the rest of the kafka cluster. If metadata cannot