geotrellis.spark.io.ValueReader.scala Maven / Gradle / Ivy

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GeoTrellis is an open source geographic data processing engine for high performance applications.

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package geotrellis.spark.io

import geotrellis.spark._
import geotrellis.spark.io.avro._
import geotrellis.spark.io.json._

import spray.json._

import scala.reflect._

/** A key-value reader producer to read a layer one value at a time.
 * This interface abstracts over various construction requirements for
 * constructing a storage back-end specific reader. */
trait ValueReader[ID] {

  /** Produce a key value reader for a specific layer, prefetching layer metadata once at construction time */
  def reader[K: AvroRecordCodec: JsonFormat: ClassTag, V: AvroRecordCodec](layerId: ID): Reader[K, V]
}