Github user gzm55 commented on a diff in the pull request:
https://github.com/apache/spark/pull/151#discussion_r10638121
--- Diff:
core/src/main/scala/org/apache/spark/deploy/yarn/YarnAllocationHandlerMacro.scala
---
@@ -0,0 +1,46 @@
+/*
+ * 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.deploy.yarn
+
+import scala.language.experimental.macros
+import scala.reflect.macros.Context
+
+private[yarn] object YarnAllocationHandlerMacro {
+ def getAMResp(resp: Any): Any = macro getAMRespImpl
+
+ /**
+ * From Hadoop CDH 4.4.0+ (2.1.0-beta),
+ * AMResponse is merged into AllocateResponse,
+ * so we don't need to call getAMResponse(), just use AllocateResponse
directly.
+ * This macro will test the existence of AMResponse,
+ * and generate diffenert expressions.
+ *
+ * This macro now is only used in spark's alpha version of yarn api.
+ * It stays in the core project, for the two-stage compiling of
+ * the scala macro system.
+ */
+ def getAMRespImpl(c: Context)(resp: c.Expr[Any]) = {
+ try {
+ import c.universe._
+ c.mirror.staticClass("org.apache.hadoop.yarn.api.records.AMResponse")
+ c.Expr[Any](Apply(Select(resp.tree, newTermName("getAMResponse")),
List()))
+ } catch {
+ case _: Throwable => resp
+ }
--- End diff --
I tried to use runtime refleciton, and found some difficults. because
amResp will have different type, I've to give it a duck type like
AnyRef {
def getAllocatedContainers ...
def getAvailableResources ...
def getCompletedContainersStatuses ...
}
or have to cache four reflection methods (the upper three plus
getAMResponse()). in the future, each time we introduce a method of
AMResponse/AllocateResponse, we'll have to make additional cache for it.
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