s2core/src/main/scala/org/apache/s2graph/core/utils/Importer.scala

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.s2graph.core.utils

import java.io.File

import com.typesafe.config.Config
import org.apache.hadoop.conf.Configuration
import org.apache.hadoop.fs.{FileSystem, Path}
import org.apache.s2graph.core.{S2GraphLike}

import scala.concurrent.{ExecutionContext, Future}

object Importer {
  def toHDFSConfiguration(hdfsConfDir: String): Configuration = {
    val conf = new Configuration

    val hdfsConfDirectory = new File(hdfsConfDir)
    if (hdfsConfDirectory.exists()) {
      if (!hdfsConfDirectory.isDirectory || !hdfsConfDirectory.canRead) {
        throw new IllegalStateException(s"HDFS configuration directory ($hdfsConfDirectory) cannot be read.")
      }

      val path = hdfsConfDirectory.getAbsolutePath
      conf.addResource(new Path(s"file:///$path/core-site.xml"))
      conf.addResource(new Path(s"file:///$path/hdfs-site.xml"))
    } else {
      logger.warn("RocksDBImporter doesn't have valid hadoop configuration directory..")
    }
    conf
  }
}

trait Importer {
  @volatile var isFinished: Boolean = false

  def run(config: Config)(implicit ec: ExecutionContext): Future[Importer]

  def status: Boolean = isFinished

  def setStatus(otherStatus: Boolean): Boolean = {
    this.isFinished = otherStatus
    this.isFinished
  }

  def close(): Unit
}

case class IdentityImporter(graph: S2GraphLike) extends Importer {
  override def run(config: Config)(implicit ec: ExecutionContext): Future[Importer] = {
    Future.successful(this)
  }

  override def close(): Unit = {}
}

object HDFSImporter {

  import scala.collection.JavaConverters._

  val PathsKey = "paths"
  val HDFSConfDirKey = "hdfsConfDir"

  def extractPaths(config: Config): Map[String, String] = {
    config.getConfigList(PathsKey).asScala.map { e =>
      val key = e.getString("src")
      val value = e.getString("tgt")

      key -> value
    }.toMap
  }
}

case class HDFSImporter(graph: S2GraphLike) extends Importer {

  import HDFSImporter._

  override def run(config: Config)(implicit ec: ExecutionContext): Future[Importer] = {
    Future {
      val paths = extractPaths(config)
      val hdfsConfiDir = config.getString(HDFSConfDirKey)

      val hadoopConfig = Importer.toHDFSConfiguration(hdfsConfiDir)
      val fs = FileSystem.get(hadoopConfig)

      def copyToLocal(remoteSrc: String, localSrc: String): Unit = {
        val remoteSrcPath = new Path(remoteSrc)
        val localSrcPath = new Path(localSrc)

        fs.copyToLocalFile(remoteSrcPath, localSrcPath)
      }

      paths.foreach { case (srcPath, tgtPath) =>
        copyToLocal(srcPath, tgtPath)
      }

      this
    }
  }

  //  override def status: ImportStatus = ???

  override def close(): Unit = {}
}