func New()

in pkg/export/export.go [377:437]
52 lines of code
7 McCabe index (conditional complexity)

func New(ctx context.Context, logger log.Logger, reg prometheus.Registerer, opts ExporterOpts, lease Lease) (*Exporter, error) {
	grpc_prometheus.EnableClientHandlingTimeHistogram(
		grpc_prometheus.WithHistogramBuckets([]float64{0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10, 15, 20, 30, 40, 50, 60}),
	)

	if logger == nil {
		logger = log.NewNopLogger()
	}
	if reg != nil {
		reg.MustRegister(
			prometheusSamplesDiscarded,
			samplesExported,
			samplesDropped,
			samplesSent,
			samplesSendErrors,
			sendIterations,
			shardProcess,
			shardProcessPending,
			shardProcessSamplesTaken,
			pendingRequests,
			projectsPerBatch,
			samplesPerRPCBatch,
		)
	}

	if err := opts.Validate(); err != nil {
		return nil, err
	}
	if lease == nil {
		lease = NopLease()
	}

	metricClient, err := defaultNewMetricClient(ctx, opts)
	if err != nil {
		return nil, fmt.Errorf("create metric client: %w", err)
	}

	e := &Exporter{
		logger:               logger,
		ctx:                  ctx,
		opts:                 opts,
		metricClient:         metricClient,
		seriesCache:          newSeriesCache(logger, reg, opts.MetricTypePrefix, opts.Matchers),
		externalLabels:       createLabelSet(&config.Config{}, &opts),
		newMetricClient:      defaultNewMetricClient,
		nextc:                make(chan struct{}, 1),
		shards:               make([]*shard, opts.Efficiency.ShardCount),
		warnedUntypedMetrics: map[string]struct{}{},
		lease:                lease,
	}

	// Whenever the lease is lost, clear the series cache so we don't start off of out-of-range
	// reset timestamps when we gain the lease again.
	lease.OnLeaderChange(e.seriesCache.clear)

	for i := range e.shards {
		e.shards[i] = newShard(opts.Efficiency.ShardBufferSize)
	}

	return e, nil
}