gatherer := h.metricsData.mgGatherers[collectorPath]

			// For Bucket metrics we need to set the buckets argument inside the
			// metric group, so that it will affect collection. If no buckets
			// are provided, we will not return bucket metrics.
			if bmg, ok := h.metricsData.bucketMGMap[collectorPath]; ok {
				if len(buckets) == 0 {
					continue
				}
				unLocker := bmg.LockAndSetBuckets(buckets)

	Compress bool
}

// Writer is a concurrency-safe writer with file rotation.
type Writer struct {
	// opts are the configuration options for this Writer
	opts Options

	// f is the currently open file used for appends.
	// Writes to f are only synchronized once Close() is called,
	// or when files are being rotated.
	f *os.File

	pw *xioutil.PipeWriter
	pr *xioutil.PipeReader
}