HBASE-23309: Adding the flexibility to ChainWalEntryFilter to filter the whole entry if all cells get filtered

hbase-server/src/main/java/org/apache/hadoop/hbase/replication/ChainWALEntryFilter.java

@@ -68,17 +68,26 @@ public void initCellFilters() {
 
   @Override
   public Entry filter(Entry entry) {
+    entry = filterEntry(entry);
+    if (entry == null) {
+      return null;
+    }
+
+    filterCells(entry);
+    return entry;
+  }
+
+  protected Entry filterEntry(Entry entry) {
     for (WALEntryFilter filter : filters) {
       if (entry == null) {
         return null;
       }
       entry = filter.filter(entry);
     }
-    filterCells(entry);
     return entry;
   }
 
-  private void filterCells(Entry entry) {
+  protected void filterCells(Entry entry) {
     if (entry == null || cellFilters.length == 0) {
       return;
     }

hbase-server/src/main/java/org/apache/hadoop/hbase/replication/CustomChainWALEntryFilter.java

@@ -0,0 +1,68 @@
+/**
+ * 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
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.replication;
+
+import org.apache.hadoop.hbase.HBaseInterfaceAudience;
+import org.apache.hadoop.hbase.wal.WAL;
+import org.apache.hbase.thirdparty.com.google.common.annotations.VisibleForTesting;
+import org.apache.yetus.audience.InterfaceAudience;
+
+import java.util.List;
+
+/**
+ * A {@link ChainWALEntryFilter} for providing more flexible options
+ */
+@InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.REPLICATION)
+public class CustomChainWALEntryFilter extends ChainWALEntryFilter {
+
+  private boolean filterEmptyEntry = false;
+
+  public CustomChainWALEntryFilter(final WALEntryFilter... filters) {
+    super(filters);
+  }
+
+  public CustomChainWALEntryFilter(final List<WALEntryFilter> filters) {
+    super(filters);
+  }
+
+  @Override
+  public WAL.Entry filter(WAL.Entry entry) {
+    filterEntry(entry);
+    if (entry == null) {
+      return null;
+    }
+
+    filterCells(entry);
+    if (filterEmptyEntry && entry != null && entry.getEdit().isEmpty()) {
+      return null;
+    }
+    return entry;
+  }
+
+  /**
+   * To allow the empty entries to get filtered, we want to set this optional flag to decide
+   * if we want to filter the entries which have no cells or all cells got filtered
+   * though {@link WALCellFilter}.
+   *
+   * @param filterEmptyEntry flag
+   */
+  @VisibleForTesting
+  public void setFilterEmptyEntry(final boolean filterEmptyEntry) {
+    this.filterEmptyEntry = filterEmptyEntry;
+  }
+}

hbase-server/src/test/java/org/apache/hadoop/hbase/replication/TestReplicationWALEntryFilters.java

@@ -155,6 +155,53 @@ public Entry filter(Entry entry) {
     }
   };
 
+  public static class FilterSomeCellsWALCellFilter implements WALEntryFilter, WALCellFilter {
+    @Override
+    public Entry filter(Entry entry) {
+      return entry;
+    }
+
+    @Override
+    public Cell filterCell(Entry entry, Cell cell) {
+      if (Bytes.toString(cell.getRowArray(), cell.getRowOffset(), cell.getRowLength()).equals("a")) {
+        return null;
+      } else {
+        return cell;
+      }
+    }
+  }
+
+  public static class FilterAllCellsWALCellFilter implements WALEntryFilter, WALCellFilter {
+    @Override
+    public Entry filter(Entry entry) {
+      return entry;
+    }
+
+    @Override
+    public Cell filterCell(Entry entry, Cell cell) {
+      return null;
+    }
+  }
+
+  @Test
+  public void testChainWALEntryWithCellFilter() {
+    Entry userEntry = createEntry(null, a, b, c);
+    CustomChainWALEntryFilter filterSomeCells = new CustomChainWALEntryFilter(new FilterSomeCellsWALCellFilter());
+    // since WALCellFilter filter cells with rowkey 'a'
+    assertEquals(createEntry(null, b,c), filterSomeCells.filter(userEntry));
+
+    Entry userEntry2 = createEntry(null, b, c, d);
+    // since there is no cell to get filtered, nothing should get filtered
+    assertEquals(userEntry2, filterSomeCells.filter(userEntry2));
+
+    CustomChainWALEntryFilter filterAllCells = new CustomChainWALEntryFilter(new FilterAllCellsWALCellFilter());
+    assertEquals(createEntry(null), filterAllCells.filter(userEntry));
+    // let's set the filter empty entry flag to true now for the above case
+    filterAllCells.setFilterEmptyEntry(true);
+    // since WALCellFilter filter all cells, whole entry should be filtered
+    assertEquals(null, filterAllCells.filter(userEntry));
+  }
+
   @Test
   public void testChainWALEntryFilter() {
     Entry userEntry = createEntry(null, a, b, c);