HADOOP-16830. Reinstate the deleted FunctionsRaisingIOE class.

This is to allow hadoop-aws to compile without needing to move to the
moved interfaces; it will also allow anything external which used those
methods (unlikely) to keep working.

Also: throw synchronized at methods to get findbugs to STFU.

Tempting just to turn it off on the basis that it is overkill, but it could
maybe be correct.

Making all of MeanStatistics synchronized is irritating, as it will hurt
performance on what should be a lightweight class. But it is needed to
ensure samples and sum are consistently set.

Change-Id: I4c3e2726e1e97d705c55dbb43a507ea4d0e81e28

Author: steveloughran

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/impl/FunctionsRaisingIOE.java

@@ -0,0 +1,73 @@
+/*
+ * 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.hadoop.fs.impl;
+
+import java.io.IOException;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+
+/**
+ * Support for functional programming/lambda-expressions.
+ * @deprecated use {@code org.apache.hadoop.util.functional} classes
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Unstable
+public final class FunctionsRaisingIOE {
+
+  private FunctionsRaisingIOE() {
+  }
+
+  /**
+   * Function of arity 1 which may raise an IOException.
+   * @param <T> type of arg1
+   * @param <R> type of return value.
+   * @deprecated use {@link org.apache.hadoop.util.functional.FunctionRaisingIOE}
+   */
+  @FunctionalInterface
+  public interface FunctionRaisingIOE<T, R> {
+
+    R apply(T t) throws IOException;
+  }
+
+  /**
+   * Function of arity 2 which may raise an IOException.
+   * @param <T> type of arg1
+   * @param <U> type of arg2
+   * @param <R> type of return value.
+   * @deprecated use {@link org.apache.hadoop.util.functional.BiFunctionRaisingIOE}
+   */
+  @FunctionalInterface
+  public interface BiFunctionRaisingIOE<T, U, R> {
+
+    R apply(T t, U u) throws IOException;
+  }
+
+  /**
+   * This is a callable which only raises an IOException.
+   * @param <R> return type
+   * @deprecated use {@link org.apache.hadoop.util.functional.CallableRaisingIOE}
+   */
+  @FunctionalInterface
+  public interface CallableRaisingIOE<R> {
+
+    R apply() throws IOException;
+  }
+
+}

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/statistics/IOStatisticsSnapshot.java

@@ -179,27 +179,27 @@ public synchronized boolean aggregate(
   }
 
   @Override
-  public Map<String, Long> counters() {
+  public synchronized Map<String, Long> counters() {
     return counters;
   }
 
   @Override
-  public Map<String, Long> gauges() {
+  public synchronized Map<String, Long> gauges() {
     return gauges;
   }
 
   @Override
-  public Map<String, Long> minimums() {
+  public synchronized Map<String, Long> minimums() {
     return minimums;
   }
 
   @Override
-  public Map<String, Long> maximums() {
+  public synchronized Map<String, Long> maximums() {
     return maximums;
   }
 
   @Override
-  public Map<String, MeanStatistic> meanStatistics() {
+  public synchronized Map<String, MeanStatistic> meanStatistics() {
     return meanStatistics;
   }
 

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/statistics/MeanStatistic.java

@@ -258,8 +258,8 @@ public synchronized boolean equals(final Object o) {
       // if we are empty, then so must the other.
       return that.isEmpty();
     }
-    return sum == that.sum &&
-        samples == that.samples;
+    return getSum() == that.getSum() &&
+        getSamples() == that.getSamples();
   }
 
   @Override