OAK-10150 | Add a test for index purge command where the latest OOB i…

…ndex is disabled and the queries are served by a lower versioned index (#875)

Co-authored-by: Nitin Gupta <nitigup@adobe.com>

oak-run/src/test/java/org/apache/jackrabbit/oak/indexversion/LucenePurgeOldIndexVersionTest.java

@@ -176,6 +176,67 @@ public void noDeleteIfNoActiveIndex() throws Exception {
         }
     }
 
+    // Test the scenario where the latest index is an OOB index but is disabled, and a lower versioned custom index is actually the only active index serving queries.
+    // Verify that the lower versioned index that is being used for queries should not get purged.
+    @Test
+    public void noDeleteIfLatestOOBIndexIsDisabled() throws Exception {
+        LogCustomizer custom = LogCustomizer.forLogger("org.apache.jackrabbit.oak.indexversion.IndexVersionOperation")
+                .enable(Level.INFO)
+                .create();
+        try {
+            custom.starting();
+            createTestData(false);
+            createCustomIndex(TEST_INDEX_PATH, 2, 1, false);
+            createCustomIndex(TEST_INDEX_PATH, 3, 0, false);
+            createCustomIndex(TEST_INDEX_PATH, 3, 1, false);
+            createCustomIndex(TEST_INDEX_PATH, 3, 2, false);
+            createCustomIndex(TEST_INDEX_PATH, 3, 3, false);
+            createCustomIndex(TEST_INDEX_PATH, 4, 0, false);
+
+            NodeStore store = fixture.getNodeStore();
+            NodeBuilder rootBuilder = store.getRoot().builder();
+            rootBuilder.getChildNode("oak:index")
+                    .getChildNode("fooIndex-4")
+                    .setProperty("type", "disabled");
+            rootBuilder.getChildNode("oak:index")
+                    .getChildNode("fooIndex-3-custom-3")
+                    .setProperty("type", "disabled")
+                    .setProperty(":originalType", "lucene");
+            store.merge(rootBuilder, EmptyHook.INSTANCE, CommitInfo.EMPTY);
+
+            addMockHiddenOakMount(fixture.getNodeStore(), Arrays.asList("fooIndex-3-custom-1", "fooIndex-3-custom-2"));
+
+            // At this point of time - we have /oak:index/fooIndex-4 and /oak:index/fooIndex-3-custom-3 which are disabled
+            // /oak:index/fooIndex-3-custom-2 and /oak:index/fooIndex-3-custom-1 which are active (hidden mount exists)
+            // Indexes of lower versions are all inactive (not disabled but no hidden oak-mount-exists)
+
+            runIndexPurgeCommand(true, 1, "");
+
+            List<String> logs = custom.getLogs();
+            // This log verification shows that /oak:index/fooIndex-4 gets filtered at the very first stage (before the list is sent to IndexVersionOperation)
+            // This is because it is disabled and does not have :originalType property - so it was disabled manually and not by auto purge command - hence it's simply ignored.
+            assertThat(logs.toString(), containsString("Reverse Sorted list [/oak:index/fooIndex-3-custom-3"));
+
+            // This log verifies that /oak:index/fooIndex-3-custom-3 (which is disabled and has :originalType property) is moved to disabled list to be handled accordingly
+            assertThat(logs.toString(), containsString("Disabled index list [/oak:index/fooIndex-3-custom-3"));
+
+            // This verifies that the index that is considered for isActive check and further verifications is /oak:index/fooIndex-3-custom-2
+            assertThat(logs.toString(), containsString("new reverse sorted list after removing disabled indexes[/oak:index/fooIndex-3-custom-2"));
+
+            NodeState indexRootNode = fixture.getNodeStore().getRoot().getChildNode("oak:index");
+            Assert.assertFalse(indexRootNode.getChildNode("fooIndex-2-custom-1").exists());
+            Assert.assertTrue(indexRootNode.getChildNode("fooIndex-3").exists());
+            Assert.assertEquals("disabled", indexRootNode.getChildNode("fooIndex-3").getProperty("type").getValue(Type.STRING));
+            Assert.assertTrue(indexRootNode.getChildNode("fooIndex-3-custom-1").exists());
+            Assert.assertEquals("disabled", indexRootNode.getChildNode("fooIndex-3-custom-1").getProperty("type").getValue(Type.STRING));
+            Assert.assertTrue(indexRootNode.getChildNode("fooIndex-3-custom-2").exists());
+            Assert.assertFalse(indexRootNode.getChildNode("fooIndex-3-custom-3").exists());
+            Assert.assertTrue(indexRootNode.getChildNode("fooIndex-4").exists());
+        } finally {
+            custom.finished();
+        }
+    }
+
     // currently, there is known issue where indexing time will be missed during indexing job running, that need to be fixed separately.
     // but before which is fixed, the purging will not do deletion in that case
     @Test