core/src/main/scala/spark/storage/BlockManagerId.scala


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package spark.storage

import java.io.{Externalizable, IOException, ObjectInput, ObjectOutput}
import java.util.concurrent.ConcurrentHashMap


private[spark] class BlockManagerId(var ip: String, var port: Int) extends Externalizable {
  def this() = this(null, 0)  // For deserialization only

  def this(in: ObjectInput) = this(in.readUTF(), in.readInt())

  override def writeExternal(out: ObjectOutput) {
    out.writeUTF(ip)
    out.writeInt(port)
  }

  override def readExternal(in: ObjectInput) {
    ip = in.readUTF()
    port = in.readInt()
  }

  @throws(classOf[IOException])
  private def readResolve(): Object = BlockManagerId.getCachedBlockManagerId(this)

  override def toString = "BlockManagerId(" + ip + ", " + port + ")"

  override def hashCode = ip.hashCode * 41 + port

  override def equals(that: Any) = that match {
    case id: BlockManagerId => port == id.port && ip == id.ip
    case _ => false
  }
}


private[spark] object BlockManagerId {

  val blockManagerIdCache = new ConcurrentHashMap[BlockManagerId, BlockManagerId]()

  def getCachedBlockManagerId(id: BlockManagerId): BlockManagerId = {
    if (blockManagerIdCache.containsKey(id)) {
      blockManagerIdCache.get(id)
    } else {
      blockManagerIdCache.put(id, id)
      id
    }
  }
}