HADOOP-14096 s3guard: regression in dirListingUnion (Contributed by Aaron Fabbri)

hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/s3guard/S3Guard.java

@@ -195,7 +195,8 @@ public final class S3Guard {
       // Any FileSystem has similar race conditions, but we could persist
       // a stale entry longer.  We could expose an atomic
       // DirListingMetadata#putIfNotPresent()
-      changed = changed || dirMeta.put(s);
+      boolean updated = dirMeta.put(s);
+      changed = changed || updated;
     }
 
     if (changed && isAuthoritative) {

hadoop-tools/hadoop-aws/src/test/java/org/apache/hadoop/fs/s3a/s3guard/TestS3Guard.java

@@ -0,0 +1,92 @@
+/*
+ * 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.s3a.s3guard;
+
+import org.apache.hadoop.fs.FileStatus;
+import org.apache.hadoop.fs.Path;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * Tests for the {@link S3Guard} utility class.
+ */
+public class TestS3Guard extends Assert {
+
+  /**
+   * Basic test to ensure results from S3 and MetadataStore are merged
+   * correctly.
+   */
+  @Test
+  public void testDirListingUnion() throws Exception {
+    MetadataStore ms = new LocalMetadataStore();
+
+    Path dirPath = new Path("s3a://bucket/dir");
+
+    // Two files in metadata store listing
+    PathMetadata m1 = makePathMeta("s3a://bucket/dir/ms-file1", false);
+    PathMetadata m2 = makePathMeta("s3a://bucket/dir/ms-file2", false);
+    DirListingMetadata dirMeta = new DirListingMetadata(dirPath,
+        Arrays.asList(m1, m2), false);
+
+    // Two other files in s3
+    List<FileStatus> s3Listing = Arrays.asList(
+        makeFileStatus("s3a://bucket/dir/s3-file3", false),
+        makeFileStatus("s3a://bucket/dir/s3-file4", false)
+    );
+
+    FileStatus[] result = S3Guard.dirListingUnion(ms, dirPath, s3Listing,
+        dirMeta, false);
+
+    assertEquals("listing length", 4, result.length);
+    assertContainsPath(result, "s3a://bucket/dir/ms-file1");
+    assertContainsPath(result, "s3a://bucket/dir/ms-file2");
+    assertContainsPath(result, "s3a://bucket/dir/s3-file3");
+    assertContainsPath(result, "s3a://bucket/dir/s3-file4");
+  }
+
+  void assertContainsPath(FileStatus[] statuses, String pathStr) {
+    assertTrue("listing doesn't contain " + pathStr,
+        containsPath(statuses, pathStr));
+  }
+
+  boolean containsPath(FileStatus[] statuses, String pathStr) {
+    for (FileStatus s : statuses) {
+      if (s.getPath().toString().equals(pathStr)) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  private PathMetadata makePathMeta(String pathStr, boolean isDir) {
+    return new PathMetadata(makeFileStatus(pathStr, isDir));
+  }
+
+  private FileStatus makeFileStatus(String pathStr, boolean isDir) {
+    Path p = new Path(pathStr);
+    if (isDir) {
+      return new FileStatus(0, true, 1, 1, System.currentTimeMillis(), p);
+    } else {
+      return new FileStatus(100, false, 1, 1, System.currentTimeMillis(), p);
+    }
+  }
+}