HBASE-25970 MOB data loss - incorrect concatenation of MOB_FILE_REFS (#3355)

Signed-off-by: Wellington Chevreuil <wchevreuil@apache.org>
Signed-off-by: Pankaj Kumar<pankajkumar@apache.org>

hbase-server/src/main/java/org/apache/hadoop/hbase/mob/MobUtils.java

@@ -720,20 +720,20 @@ public final class MobUtils {
       StringBuilder sb = new StringBuilder(100 + mobRefSet.size() * 105);
       boolean doubleSlash = false;
       for (TableName tableName : mobRefSet.keySet()) {
+        if (doubleSlash) {
+          sb.append("//");
+        } else {
+          doubleSlash = true;
+        }
         sb.append(tableName).append("/");
         boolean comma = false;
         for (String refs : mobRefSet.get(tableName)) {
-          sb.append(refs);
           if (comma) {
             sb.append(",");
           } else {
             comma = true;
           }
-        }
+          sb.append(refs);
-        if (doubleSlash) {
-          sb.append("//");
-        } else {
-          doubleSlash = true;
         }
       }
       return Bytes.toBytes(sb.toString());

hbase-server/src/test/java/org/apache/hadoop/hbase/mob/TestMobUtils.java

@@ -0,0 +1,94 @@
+/**
+ * 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.hbase.mob;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+import org.apache.hadoop.hbase.HBaseClassTestRule;
+import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.testclassification.SmallTests;
+import org.apache.hadoop.hbase.util.Bytes;
+import org.junit.ClassRule;
+import org.junit.Test;
+import org.junit.experimental.categories.Category;
+import org.apache.hbase.thirdparty.com.google.common.collect.ImmutableSet;
+import org.apache.hbase.thirdparty.com.google.common.collect.ImmutableSetMultimap;
+
+@Category(SmallTests.class)
+public class TestMobUtils {
+
+  @ClassRule
+  public static final HBaseClassTestRule CLASS_RULE =
+    HBaseClassTestRule.forClass(TestMobUtils.class);
+  public static final TableName TEST_TABLE_1 = TableName.valueOf("testTable1");
+  public static final TableName TEST_TABLE_2 = TableName.valueOf("testTable2");
+  public static final TableName TEST_TABLE_3 = TableName.valueOf("testTable3");
+
+  @Test
+  public void serializeSingleMobFileRefs() {
+    ImmutableSetMultimap<TableName, String> mobRefSet =
+      ImmutableSetMultimap.<TableName, String>builder()
+        .putAll(TEST_TABLE_1, "file1a")
+        .build();
+    byte[] result = MobUtils.serializeMobFileRefs(mobRefSet);
+    assertEquals("testTable1/file1a", Bytes.toString(result));
+  }
+
+  @Test
+  public void serializeMultipleMobFileRefs() {
+    ImmutableSetMultimap<TableName, String> mobRefSet =
+      ImmutableSetMultimap.<TableName, String>builder()
+        .putAll(TEST_TABLE_1, "file1a", "file1b")
+        .putAll(TEST_TABLE_2, "file2a")
+        .putAll(TEST_TABLE_3, "file3a", "file3b")
+        .build();
+    byte[] result = MobUtils.serializeMobFileRefs(mobRefSet);
+    assertEquals("testTable1/file1a,file1b//testTable2/file2a//testTable3/file3a,file3b",
+      Bytes.toString(result));
+  }
+
+  @Test
+  public void deserializeSingleMobFileRefs() {
+    ImmutableSetMultimap<TableName, String> mobRefSet =
+      MobUtils.deserializeMobFileRefs(Bytes.toBytes("testTable1/file1a")).build();
+    assertEquals(1, mobRefSet.size());
+    ImmutableSet<String> testTable1Refs = mobRefSet.get(TEST_TABLE_1);
+    assertEquals(1, testTable1Refs.size());
+    assertTrue(testTable1Refs.contains("file1a"));
+  }
+
+  @Test
+  public void deserializeMultipleMobFileRefs() {
+    ImmutableSetMultimap<TableName, String> mobRefSet =
+      MobUtils.deserializeMobFileRefs(Bytes.toBytes(
+        "testTable1/file1a,file1b//testTable2/file2a//testTable3/file3a,file3b")).build();
+    assertEquals(5, mobRefSet.size());
+    ImmutableSet<String> testTable1Refs = mobRefSet.get(TEST_TABLE_1);
+    ImmutableSet<String> testTable2Refs = mobRefSet.get(TEST_TABLE_2);
+    ImmutableSet<String> testTable3Refs = mobRefSet.get(TEST_TABLE_3);
+    assertEquals(2, testTable1Refs.size());
+    assertEquals(1, testTable2Refs.size());
+    assertEquals(2, testTable3Refs.size());
+    assertTrue(testTable1Refs.contains("file1a"));
+    assertTrue(testTable1Refs.contains("file1b"));
+    assertTrue(testTable2Refs.contains("file2a"));
+    assertTrue(testTable3Refs.contains("file3a"));
+    assertTrue(testTable3Refs.contains("file3b"));
+  }
+}