[madSHaLz] APOC triggers aren't updated after a user deletes a database

build.gradle

@@ -71,7 +71,7 @@ subprojects {
         // neo4jDockerImage system property is used in TestContainerUtil
         systemProperties 'user.language' : 'en' ,
                 'user.country' : 'US',
-                'neo4jDockerImage' : System.getProperty("NEO4JVERSION") ? 'neo4j:' + System.getProperty("NEO4JVERSION") + '-enterprise' : 'neo4j:5.8.0-enterprise',
+                'neo4jDockerImage' : System.getProperty("NEO4JVERSION") ? 'neo4j:' + System.getProperty("NEO4JVERSION") + '-enterprise' : 'neo4j:5.6.0-enterprise',
                 'neo4jCommunityDockerImage': System.getProperty("NEO4JVERSION") ? 'neo4j:' + System.getProperty("NEO4JVERSION") : 'neo4j:5.8.0',
                 'coreDir': 'core'
 
@@ -128,6 +128,6 @@ subprojects {
 }
 
 ext {
-    neo4jVersionEffective = project.hasProperty("neo4jVersionOverride") ? project.getProperty("neo4jVersionOverride") : "5.8.0"
+    neo4jVersionEffective = project.hasProperty("neo4jVersionOverride") ? project.getProperty("neo4jVersionOverride") : "5.6.0"
     testContainersVersion = '1.17.6'
 }

common/src/main/java/apoc/ApocExtensionFactory.java

@@ -12,6 +12,7 @@
 import org.neo4j.kernel.internal.GraphDatabaseAPI;
 import org.neo4j.kernel.lifecycle.Lifecycle;
 import org.neo4j.kernel.lifecycle.LifecycleAdapter;
+import org.neo4j.kernel.monitoring.DatabaseEventListeners;
 import org.neo4j.logging.Log;
 import org.neo4j.logging.internal.LogService;
 import org.neo4j.scheduler.JobScheduler;
@@ -43,6 +44,7 @@ public interface Dependencies {
         AvailabilityGuard availabilityGuard();
         DatabaseManagementService databaseManagementService();
         ApocConfig apocConfig();
+        DatabaseEventListeners databaseEventListeners();
         @SuppressWarnings("unused") // used from extended
         GlobalProcedures globalProceduresRegistry();
         RegisterComponentFactory.RegisterComponentLifecycle registerComponentLifecycle();

core/src/main/java/apoc/CoreApocGlobalComponents.java

@@ -33,6 +33,10 @@ public Collection<Class> getContextClasses() {
 
     @Override
     public Iterable<AvailabilityListener> getListeners(GraphDatabaseAPI db, ApocExtensionFactory.Dependencies dependencies) {
-        return Collections.singleton(new CypherInitializer(db, dependencies.log().getUserLog(CypherInitializer.class)));
+        return Collections.singleton(new CypherInitializer(db,
+                dependencies.log().getUserLog(CypherInitializer.class),
+                dependencies.databaseManagementService(),
+                dependencies.databaseEventListeners())
+        );
     }
 }

core/src/main/java/apoc/cypher/CypherInitializer.java

@@ -1,35 +1,52 @@
 package apoc.cypher;
 
 import apoc.ApocConfig;
+import apoc.SystemLabels;
 import apoc.util.Util;
 import apoc.util.collection.Iterators;
 import apoc.version.Version;
 import org.apache.commons.configuration2.Configuration;
 import org.apache.commons.lang3.StringUtils;
 import org.neo4j.common.DependencyResolver;
+import org.neo4j.dbms.api.DatabaseManagementService;
+import org.neo4j.graphdb.Label;
+import org.neo4j.graphdb.Node;
+import org.neo4j.graphdb.Transaction;
+import org.neo4j.graphdb.event.DatabaseEventContext;
+import org.neo4j.graphdb.event.DatabaseEventListener;
 import org.neo4j.kernel.availability.AvailabilityListener;
 import org.neo4j.kernel.internal.GraphDatabaseAPI;
+import org.neo4j.kernel.monitoring.DatabaseEventListeners;
 import org.neo4j.logging.Log;
 
 import java.util.Collection;
 
 import java.util.Map;
 import java.util.TreeMap;
+import java.util.function.BiConsumer;
+
+import static apoc.SystemPropertyKeys.database;
 
 public class CypherInitializer implements AvailabilityListener {
 
     private final GraphDatabaseAPI db;
     private final Log userLog;
     private final DependencyResolver dependencyResolver;
+    private final DatabaseManagementService databaseManagementService;
+    private final DatabaseEventListeners databaseEventListeners;
 
     /**
      * indicates the status of the initializer, to be used for tests to ensure initializer operations are already done
      */
     private volatile boolean finished = false;
 
-    public CypherInitializer(GraphDatabaseAPI db, Log userLog) {
+    public CypherInitializer(GraphDatabaseAPI db, Log userLog,
+                             DatabaseManagementService databaseManagementService,
+                             DatabaseEventListeners databaseEventListeners) {
         this.db = db;
         this.userLog = userLog;
+        this.databaseManagementService = databaseManagementService;
+        this.databaseEventListeners = databaseEventListeners;
         this.dependencyResolver = db.getDependencyResolver();
     }
 
@@ -63,6 +80,9 @@ public void available() {
                     }
                 }
 
+                // create listener for each database
+                databaseEventListeners.registerDatabaseEventListener(new SystemFunctionalityListener());
+
                 Configuration config = dependencyResolver.resolveDependency(ApocConfig.class).getConfig();
                 for (String query : collectInitializers(config)) {
                     try {
@@ -116,4 +136,37 @@ private void putIfNotBlank(Map<String,String> map, String key, String value) {
     public void unavailable() {
         // intentionally empty
     }
+
+    private class SystemFunctionalityListener implements DatabaseEventListener {
+
+        @Override
+        public void databaseDrop(DatabaseEventContext eventContext) {
+
+            forEachSystemLabel((tx, label) -> {
+                tx.findNodes(label, database.name(), eventContext.getDatabaseName())
+                        .forEachRemaining(Node::delete);
+            });
+        }
+
+        @Override
+        public void databaseStart(DatabaseEventContext eventContext) {}
+
+        @Override
+        public void databaseShutdown(DatabaseEventContext eventContext) {}
+
+        @Override
+        public void databasePanic(DatabaseEventContext eventContext) {}
+
+        @Override
+        public void databaseCreate(DatabaseEventContext eventContext) {}
+    }
+
+    private void forEachSystemLabel(BiConsumer<Transaction, Label> consumer) {
+        try (Transaction tx = db.beginTx()) {
+            for (Label label: SystemLabels.values()) {
+                consumer.accept(tx, label);
+            }
+            tx.commit();
+        }
+    }
 }

it/src/test/java/apoc/it/core/TriggerEnterpriseFeaturesTest.java

@@ -18,12 +18,14 @@
 import java.util.concurrent.TimeUnit;
 import java.util.stream.Stream;
 
+import static apoc.ApocConfig.APOC_CONFIG_INITIALIZER;
 import static apoc.ApocConfig.APOC_TRIGGER_ENABLED;
 import static apoc.trigger.TriggerHandler.TRIGGER_REFRESH;
 import static apoc.trigger.TriggerTestUtil.TIMEOUT;
 import static apoc.trigger.TriggerTestUtil.TRIGGER_DEFAULT_REFRESH;
 import static apoc.util.TestContainerUtil.createEnterpriseDB;
 import static apoc.util.TestContainerUtil.testCall;
+import static apoc.util.TestContainerUtil.testCallEmpty;
 import static apoc.util.TestContainerUtil.testResult;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
@@ -37,6 +39,7 @@
 
 public class TriggerEnterpriseFeaturesTest {
     private static final String FOO_DB = "foo";
+    private static final String INIT_DB = "initdb";
 
     private static final String NO_ADMIN_USER = "nonadmin";
     private static final String NO_ADMIN_PWD = "test1234";
@@ -46,10 +49,15 @@ public class TriggerEnterpriseFeaturesTest {
 
     @BeforeClass
     public static void beforeAll() {
+        final String cypherInitializer = String.format("%s.%s.0",
+                APOC_CONFIG_INITIALIZER, SYSTEM_DATABASE_NAME);
+        final String createInitDb = String.format("CREATE DATABASE %s IF NOT EXISTS", INIT_DB);
+
         // We build the project, the artifact will be placed into ./build/libs
         neo4jContainer = createEnterpriseDB(List.of(TestContainerUtil.ApocPackage.CORE), true)
                 .withEnv(APOC_TRIGGER_ENABLED, "true")
-                .withEnv(TRIGGER_REFRESH, String.valueOf(TRIGGER_DEFAULT_REFRESH));
+                .withEnv(TRIGGER_REFRESH, String.valueOf(TRIGGER_DEFAULT_REFRESH))
+                .withEnv(cypherInitializer, createInitDb);
         neo4jContainer.start();
         session = neo4jContainer.getSession();
 
@@ -150,8 +158,51 @@ public void testTriggerInstallInNewDatabase() {
             testCall(defaultDbSession, "MATCH (n:Something) RETURN n.created",
                     r -> assertNull(r.get("created")));
         }
-    }   
-
+    }
+
+    @Test
+    public void testDeleteTriggerAfterDatabaseDeletion() {
+        try (Session sysSession = neo4jContainer.getDriver().session(forDatabase(SYSTEM_DATABASE_NAME))) {
+            final String dbToDelete = "todelete";
+
+            // create database with name `todelete`
+            sysSession.writeTransaction(tx -> tx.run(String.format("CREATE DATABASE %s WAIT;", dbToDelete)));
+
+            testDeleteTriggerAfterDropDb(dbToDelete, sysSession);
+        }
+    }
+
+    @Test
+    public void testDeleteTriggerAfterDatabaseDeletionCreatedViaCypherInit() {
+        try (Session sysSession = neo4jContainer.getDriver().session(forDatabase(SYSTEM_DATABASE_NAME))) {
+            // the database `initDb` is created via `apoc.initializer.*`
+            testDeleteTriggerAfterDropDb(INIT_DB, sysSession);
+        }
+    }
+
+    private static void testDeleteTriggerAfterDropDb(String dbToDelete, Session sysSession) {
+        final String defaultTriggerName = UUID.randomUUID().toString();
+
+        // install and show a trigger in the database and check existence
+        testCall(sysSession, "CALL apoc.trigger.install($dbName, $name, 'return 1', {})",
+                Map.of("dbName", dbToDelete, "name", defaultTriggerName),
+                r -> assertEquals(defaultTriggerName, r.get("name"))
+        );
+
+        testCall(sysSession, "CALL apoc.trigger.show($dbName)",
+                Map.of("dbName", dbToDelete),
+                r -> assertEquals(defaultTriggerName, r.get("name"))
+        );
+
+        // drop database
+        sysSession.writeTransaction(tx -> tx.run(String.format("DROP DATABASE %s WAIT;", dbToDelete)));
+
+        // check that the trigger has been removed
+        testCallEmpty(sysSession, "CALL apoc.trigger.show($dbName)",
+                Map.of("dbName", dbToDelete)
+        );
+    }
+
     @Test
     public void testTriggersAllowedOnlyWithAdmin() {