HBASE-22623 - Add RegionObserver coprocessor hook for preWALAppend

Author: gjacoby126

hbase-server/src/main/java/org/apache/hadoop/hbase/coprocessor/RegionObserver.java

@@ -1112,7 +1112,8 @@ default DeleteTracker postInstantiateDeleteTracker(
    * @param ctx the environment provided by the region server
    * @param key the WALKey associated with a particular append to a WAL
    */
-  default void preWALAppend(ObserverContext<RegionCoprocessorEnvironment> ctx, WALKey key)
+  default void preWALAppend(ObserverContext<RegionCoprocessorEnvironment> ctx, WALKey key,
+                            WALEdit edit)
     throws IOException {
   }
 }

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java

@@ -7952,7 +7952,7 @@ private WriteEntry doWALAppend(WALEdit walEdit, Durability durability, List<UUID
       walKey.setOrigLogSeqNum(origLogSeqNum);
     }
     if (this.coprocessorHost != null) {
-      this.coprocessorHost.preWALAppend(walKey);
+      this.coprocessorHost.preWALAppend(walKey, walEdit);
     }
     WriteEntry writeEntry = null;
     try {

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RegionCoprocessorHost.java

@@ -1720,14 +1720,14 @@ public List<Pair<Cell, Cell>> call(RegionObserver observer) throws IOException {
         });
   }
 
-  public void preWALAppend(WALKey key) throws IOException {
+  public void preWALAppend(WALKey key, WALEdit edit) throws IOException {
     if (this.coprocEnvironments.isEmpty()){
       return;
     }
     execOperation(new RegionObserverOperationWithoutResult() {
       @Override
       public void call(RegionObserver observer) throws IOException {
-        observer.preWALAppend(this, key);
+        observer.preWALAppend(this, key, edit);
       }
     });
   }

hbase-server/src/main/java/org/apache/hadoop/hbase/wal/WALEdit.java

@@ -48,8 +48,6 @@
  * Used in HBase's transaction log (WAL) to represent a collection of edits (Cell/KeyValue objects)
  * that came in as a single transaction. All the edits for a given transaction are written out as a
  * single record, in PB format, followed (optionally) by Cells written via the WALCellEncoder.
- * <p>This class is LimitedPrivate for CPs to read-only. The {@link #add} methods are
- * classified as private methods, not for use by CPs.</p>
  * <p>WALEdit will accumulate a Set of all column family names referenced by the Cells
  * {@link #add(Cell)}'d. This is an optimization. Usually when loading a WALEdit, we have the
  * column family name to-hand.. just shove it into the WALEdit if available. Doing this, we can
@@ -163,13 +161,11 @@ public boolean isReplay() {
     return this.replay;
   }
 
-  @InterfaceAudience.Private
   public WALEdit add(Cell cell, byte [] family) {
     getOrCreateFamilies().add(family);
     return addCell(cell);
   }
 
-  @InterfaceAudience.Private
   public WALEdit add(Cell cell) {
     // We clone Family each time we add a Cell. Expensive but safe. For CPU savings, use
     // add(Map) or add(Cell, family).

hbase-server/src/test/java/org/apache/hadoop/hbase/coprocessor/SimpleRegionObserver.java

@@ -638,7 +638,7 @@ public StoreFileReader postStoreFileReaderOpen(ObserverContext<RegionCoprocessor
 
   @Override
   public void preWALAppend(ObserverContext<RegionCoprocessorEnvironment> ctx,
-                                 WALKey key) throws IOException {
+                                 WALKey key, WALEdit edit) throws IOException {
     ctPreWALAppend.incrementAndGet();
 
     key.addExtendedAttribute(Integer.toString(ctPreWALAppend.get()),

hbase-server/src/test/java/org/apache/hadoop/hbase/coprocessor/TestRegionObserverInterface.java

@@ -707,7 +707,8 @@ public void testPreWALAppend() throws Exception {
     ObserverContext ctx = Mockito.mock(ObserverContext.class);
     WALKey key = new WALKeyImpl(Bytes.toBytes("region"), TEST_TABLE,
         EnvironmentEdgeManager.currentTime());
-    sro.preWALAppend(ctx, key);
+    WALEdit edit = new WALEdit();
+    sro.preWALAppend(ctx, key, edit);
     Assert.assertEquals(1, key.getExtendedAttributes().size());
     Assert.assertArrayEquals(SimpleRegionObserver.WAL_EXTENDED_ATTRIBUTE_BYTES,
         key.getExtendedAttribute(Integer.toString(sro.getCtPreWALAppend())));