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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 org.apache.spark
import org.apache.spark.annotation.DeveloperApi
/**
* :: DeveloperApi ::
* An iterator that wraps around an existing iterator to provide task killing functionality.
* It works by checking the interrupted flag in [[TaskContext]].
*/
@DeveloperApi
class InterruptibleIterator[+T](val context: TaskContext, val delegate: Iterator[T])
extends Iterator[T] {
def hasNext: Boolean = {
// TODO(aarondav/rxin): Check Thread.interrupted instead of context.interrupted if interrupt
// is allowed. The assumption is that Thread.interrupted does not have a memory fence in read
// (just a volatile field in C), while context.interrupted is a volatile in the JVM, which
// introduces an expensive read fence.
if (context.isInterrupted) {
throw new TaskKilledException
} else {
delegate.hasNext
}
}
def next(): T = delegate.next()
}
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