RDD里的模式匹配：
def hasNext: Boolean = (thisIter.hasNext, otherIter.hasNext) match {
case (true, true) => true
case (false, false) => false
case _ => throw new SparkException("Can only zip RDDs with " +
"same number of elements in each partition")
}
jobResult = jobResult match {
case Some(value) => Some(f(value, taskResult.get))
case None => taskResult
}
take(1) match {
case Array(t) => t
case _ => throw new UnsupportedOperationException("empty collection")
}
下面的比较好理解：
val len = rdd.dependencies.length
len match {
case 0 => Seq.empty
case 1 =>
val d = rdd.dependencies.head
debugString(d.rdd, prefix, d.isInstanceOf[ShuffleDependency[_, _, _]], true)
case _ => //所有的都到碗里来
val frontDeps = rdd.dependencies.take(len - 1)
val frontDepStrings = frontDeps.flatMap(
d => debugString(d.rdd, prefix, d.isInstanceOf[ShuffleDependency[_, _, _]]))
val lastDep = rdd.dependencies.last
val lastDepStrings =
debugString(lastDep.rdd, prefix, lastDep.isInstanceOf[ShuffleDependency[_, _, _]], true)
(frontDepStrings ++ lastDepStrings)
}
另外有需要云服务器可以了解下创新互联scvps.cn，海内外云服务器15元起步，三天无理由+7*72小时售后在线，公司持有idc许可证，提供“云服务器、裸金属服务器、高防服务器、香港服务器、美国服务器、虚拟主机、免备案服务器”等云主机租用服务以及企业上云的综合解决方案，具有“安全稳定、简单易用、服务可用性高、性价比高”等特点与优势，专为企业上云打造定制，能够满足用户丰富、多元化的应用场景需求。