HADOOP-19712. S3A: Deadlock in EvaluatingStatisticsMap.entryset()

Add a test with a larger set of entries (env vars) and more assertions.

Due diligence.

Author: steveloughran

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

@@ -24,6 +24,7 @@
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.function.BiConsumer;
@@ -190,7 +191,7 @@ public void forEach(final BiConsumer<? super String, ? super E> action) {
    */
   private static final class EntryImpl<E> implements Entry<String, E> {
 
-    private String key;
+    private final String key;
 
     private E value;
 
@@ -214,6 +215,18 @@ public E setValue(final E val) {
       this.value = val;
       return val;
     }
+
+    @Override
+    public boolean equals(final Object o) {
+      if (!(o instanceof Entry)) {return false;}
+      Entry<String, ?> entry = (Entry<String, ?>) o;
+      return Objects.equals(key, entry.getKey()) && Objects.equals(value, entry.getValue());
+    }
+
+    @Override
+    public int hashCode() {
+      return Objects.hashCode(key);
+    }
   }
 
 }

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/statistics/impl/TestEvaluatingStatisticsMap.java

@@ -0,0 +1,71 @@
+/*
+ * 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.statistics.impl;
+
+import java.util.Map;
+
+import org.assertj.core.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import org.apache.hadoop.test.AbstractHadoopTestBase;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class TestEvaluatingStatisticsMap extends AbstractHadoopTestBase {
+
+
+  @Test
+  public void testEvaluatingStatisticsMap() {
+    EvaluatingStatisticsMap<String> map = new EvaluatingStatisticsMap<>();
+
+    Assertions.assertThat(map).isEmpty();
+    Assertions.assertThat(map.keySet()).isEmpty();
+    Assertions.assertThat(map.values()).isEmpty();
+    Assertions.assertThat(map.entrySet()).isEmpty();
+
+    // fill the map with the environment vars
+    final Map<String, String> env = System.getenv();
+    env.forEach((k, v) -> map.addFunction(k, any -> v));
+
+    // verify the keys match
+    assertThat(map.keySet())
+        .describedAs("keys")
+        .containsExactlyInAnyOrderElementsOf(env.keySet());
+
+    // and that the values do
+    assertThat(map.values())
+        .describedAs("Evaluated values")
+        .containsExactlyInAnyOrderElementsOf(env.values());
+
+    // now assert that this holds for the entryset.
+    env.forEach((k, v) ->
+        assertThat(map.get(k))
+            .describedAs("looked up key %s", k)
+            .isNotNull()
+            .isEqualTo(v));
+
+    map.forEach((k, v) ->
+        assertThat(env.get(k))
+            .describedAs("env var %s", k)
+            .isNotNull()
+            .isEqualTo(v));
+
+
+  }
+}