org.apache.spark.deploy.master.FileSystemPersistenceEngine.scala Maven / Gradle / Ivy
/*
* 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,
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* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.spark.deploy.master
import java.io._
import scala.reflect.ClassTag
import org.apache.spark.internal.Logging
import org.apache.spark.serializer.{DeserializationStream, SerializationStream, Serializer}
import org.apache.spark.util.Utils
/**
* Stores data in a single on-disk directory with one file per application and worker.
* Files are deleted when applications and workers are removed.
*
* @param dir Directory to store files. Created if non-existent (but not recursively).
* @param serializer Used to serialize our objects.
*/
private[master] class FileSystemPersistenceEngine(
val dir: String,
val serializer: Serializer)
extends PersistenceEngine with Logging {
new File(dir).mkdir()
override def persist(name: String, obj: Object): Unit = {
serializeIntoFile(new File(dir + File.separator + name), obj)
}
override def unpersist(name: String): Unit = {
val f = new File(dir + File.separator + name)
if (!f.delete()) {
logWarning(s"Error deleting ${f.getPath()}")
}
}
override def read[T: ClassTag](prefix: String): Seq[T] = {
val files = new File(dir).listFiles().filter(_.getName.startsWith(prefix))
files.map(deserializeFromFile[T])
}
private def serializeIntoFile(file: File, value: AnyRef) {
val created = file.createNewFile()
if (!created) { throw new IllegalStateException("Could not create file: " + file) }
val fileOut = new FileOutputStream(file)
var out: SerializationStream = null
Utils.tryWithSafeFinally {
out = serializer.newInstance().serializeStream(fileOut)
out.writeObject(value)
} {
fileOut.close()
if (out != null) {
out.close()
}
}
}
private def deserializeFromFile[T](file: File)(implicit m: ClassTag[T]): T = {
val fileIn = new FileInputStream(file)
var in: DeserializationStream = null
try {
in = serializer.newInstance().deserializeStream(fileIn)
in.readObject[T]()
} finally {
fileIn.close()
if (in != null) {
in.close()
}
}
}
}