Raise availability guard first in LocalDatabase#stop()

`LocalDatabase` raises the availability guard when it is stopped. It used to do
it after the datasource manager is stopped which could lead to transactions
starting when datasource is being stopped.

This commit makes `LocalDatabase` raise the guard as the first step
during stop.

enterprise/causal-clustering/src/main/java/org/neo4j/causalclustering/catchup/storecopy/LocalDatabase.java

@@ -236,11 +236,10 @@ public TransactionCommitProcess getCommitProcess()
     private synchronized void stopWithRequirement( AvailabilityRequirement requirement ) throws Throwable
     {
         log.info( "Stopping, reason: " + requirement.description() );
+        raiseAvailabilityGuard( requirement );
         databaseHealth = null;
         localCommit = null;
         dataSourceManager.stop();
-
-        raiseAvailabilityGuard( requirement );
     }
 
     private void raiseAvailabilityGuard( AvailabilityRequirement requirement )

enterprise/causal-clustering/src/test/java/org/neo4j/causalclustering/catchup/storecopy/LocalDatabaseTest.java

@@ -20,6 +20,7 @@
 package org.neo4j.causalclustering.catchup.storecopy;
 
 import org.junit.Test;
+import org.mockito.InOrder;
 
 import java.io.File;
 import java.time.Clock;
@@ -37,8 +38,11 @@
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertThat;
 import static org.junit.Assert.assertTrue;
+import static org.mockito.Matchers.any;
 import static org.mockito.Mockito.RETURNS_MOCKS;
+import static org.mockito.Mockito.inOrder;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
 
 public class LocalDatabaseTest
 {
@@ -98,9 +102,45 @@ public void availabilityGuardRaisedOnStopForStoreCopy() throws Throwable
         assertDatabaseIsStoppedForStoreCopyAndUnavailable( guard );
     }
 
+    @Test
+    public void availabilityGuardRaisedBeforeDataSourceManagerIsStopped() throws Throwable
+    {
+        AvailabilityGuard guard = mock( AvailabilityGuard.class );
+        DataSourceManager dataSourceManager = mock( DataSourceManager.class );
+
+        LocalDatabase localDatabase = newLocalDatabase( guard, dataSourceManager );
+        localDatabase.stop();
+
+        InOrder inOrder = inOrder( guard, dataSourceManager );
+        // guard should be raised twice - once during construction and once during stop
+        inOrder.verify( guard, times( 2 ) ).require( any() );
+        inOrder.verify( dataSourceManager ).stop();
+    }
+
+    @Test
+    public void availabilityGuardRaisedBeforeDataSourceManagerIsStoppedForStoreCopy() throws Throwable
+    {
+        AvailabilityGuard guard = mock( AvailabilityGuard.class );
+        DataSourceManager dataSourceManager = mock( DataSourceManager.class );
+
+        LocalDatabase localDatabase = newLocalDatabase( guard, dataSourceManager );
+        localDatabase.stopForStoreCopy();
+
+        InOrder inOrder = inOrder( guard, dataSourceManager );
+        // guard should be raised twice - once during construction and once during stop
+        inOrder.verify( guard, times( 2 ) ).require( any() );
+        inOrder.verify( dataSourceManager ).stop();
+    }
+
     private static LocalDatabase newLocalDatabase( AvailabilityGuard availabilityGuard )
     {
-        return new LocalDatabase( new File( "." ), mock( StoreFiles.class ), mock( DataSourceManager.class ),
+        return newLocalDatabase( availabilityGuard, mock( DataSourceManager.class ) );
+    }
+
+    private static LocalDatabase newLocalDatabase( AvailabilityGuard availabilityGuard,
+            DataSourceManager dataSourceManager )
+    {
+        return new LocalDatabase( new File( "." ), mock( StoreFiles.class ), dataSourceManager,
                 mock( PageCache.class, RETURNS_MOCKS ), mock( FileSystemAbstraction.class ),
                 () -> mock( DatabaseHealth.class ), availabilityGuard, NullLogProvider.getInstance() );
     }