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/*
* 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 spark.partial
class PartialResult[R](initialVal: R, isFinal: Boolean) {
private var finalValue: Option[R] = if (isFinal) Some(initialVal) else None
private var failure: Option[Exception] = None
private var completionHandler: Option[R => Unit] = None
private var failureHandler: Option[Exception => Unit] = None
def initialValue: R = initialVal
def isInitialValueFinal: Boolean = isFinal
/**
* Blocking method to wait for and return the final value.
*/
def getFinalValue(): R = synchronized {
while (finalValue == None && failure == None) {
this.wait()
}
if (finalValue != None) {
return finalValue.get
} else {
throw failure.get
}
}
/**
* Set a handler to be called when this PartialResult completes. Only one completion handler
* is supported per PartialResult.
*/
def onComplete(handler: R => Unit): PartialResult[R] = synchronized {
if (completionHandler != None) {
throw new UnsupportedOperationException("onComplete cannot be called twice")
}
completionHandler = Some(handler)
if (finalValue != None) {
// We already have a final value, so let's call the handler
handler(finalValue.get)
}
return this
}
/**
* Set a handler to be called if this PartialResult's job fails. Only one failure handler
* is supported per PartialResult.
*/
def onFail(handler: Exception => Unit) {
synchronized {
if (failureHandler != None) {
throw new UnsupportedOperationException("onFail cannot be called twice")
}
failureHandler = Some(handler)
if (failure != None) {
// We already have a failure, so let's call the handler
handler(failure.get)
}
}
}
/**
* Transform this PartialResult into a PartialResult of type T.
*/
def map[T](f: R => T) : PartialResult[T] = {
new PartialResult[T](f(initialVal), isFinal) {
override def getFinalValue() : T = synchronized {
f(PartialResult.this.getFinalValue())
}
override def onComplete(handler: T => Unit): PartialResult[T] = synchronized {
PartialResult.this.onComplete(handler.compose(f)).map(f)
}
override def onFail(handler: Exception => Unit) {
synchronized {
PartialResult.this.onFail(handler)
}
}
override def toString : String = synchronized {
PartialResult.this.getFinalValueInternal() match {
case Some(value) => "(final: " + f(value) + ")"
case None => "(partial: " + initialValue + ")"
}
}
def getFinalValueInternal() = PartialResult.this.getFinalValueInternal().map(f)
}
}
private[spark] def setFinalValue(value: R) {
synchronized {
if (finalValue != None) {
throw new UnsupportedOperationException("setFinalValue called twice on a PartialResult")
}
finalValue = Some(value)
// Call the completion handler if it was set
completionHandler.foreach(h => h(value))
// Notify any threads that may be calling getFinalValue()
this.notifyAll()
}
}
private def getFinalValueInternal() = finalValue
private[spark] def setFailure(exception: Exception) {
synchronized {
if (failure != None) {
throw new UnsupportedOperationException("setFailure called twice on a PartialResult")
}
failure = Some(exception)
// Call the failure handler if it was set
failureHandler.foreach(h => h(exception))
// Notify any threads that may be calling getFinalValue()
this.notifyAll()
}
}
override def toString: String = synchronized {
finalValue match {
case Some(value) => "(final: " + value + ")"
case None => "(partial: " + initialValue + ")"
}
}
}
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