Support for reading constraints by schema

community/kernel-api/src/main/java/org/neo4j/internal/kernel/api/SchemaRead.java

@@ -19,6 +19,11 @@
  */
 package org.neo4j.internal.kernel.api;
 
+import java.util.Iterator;
+
+import org.neo4j.internal.kernel.api.schema.SchemaDescriptor;
+import org.neo4j.internal.kernel.api.schema.constraints.ConstraintDescriptor;
+
 /**
  * Surface for getting schema information, such as fetching specific indexes or constraints.
  */
@@ -32,4 +37,25 @@ public interface SchemaRead
      * @return the IndexReference, or {@link CapableIndexReference#NO_INDEX} if such an index does not exist.
      */
     CapableIndexReference index( int label, int... properties );
+
+    /**
+     * Finds all constraints for the given schema
+     * @param descriptor The descriptor of the schema
+     * @return All constraints for the given schema
+     */
+    Iterator<ConstraintDescriptor> constraintsGetForSchema( SchemaDescriptor descriptor );
+
+    /**
+     * Checks if a constraint exists
+     * @param descriptor The descriptor of the constraint to check.
+     * @return <tt>true</tt> if the constraint exists, otherwise <tt>false</tt>
+     */
+    boolean constraintExists( ConstraintDescriptor descriptor );
+
+    /**
+     * Finds all constraints for the given label
+     * @param labelId The id of the label
+     * @return All constraints for the given label
+     */
+    Iterator<ConstraintDescriptor> constraintsGetForLabel( int labelId );
 }

community/kernel-api/src/test/java/org/neo4j/internal/kernel/api/ConstraintTestBase.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2002-2017 "Neo Technology,"
+ * Network Engine for Objects in Lund AB [http://neotechnology.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Neo4j is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.neo4j.internal.kernel.api;
+
+import org.junit.Test;
+
+import java.util.Iterator;
+
+import org.neo4j.graphdb.Label;
+import org.neo4j.internal.kernel.api.schema.LabelSchemaDescriptor;
+import org.neo4j.internal.kernel.api.schema.constraints.ConstraintDescriptor;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.equalTo;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+@SuppressWarnings( "Duplicates" )
+public abstract class ConstraintTestBase<G extends KernelAPIWriteTestSupport> extends KernelAPIWriteTestBase<G>
+{
+    protected abstract LabelSchemaDescriptor labelSchemaDescriptor( int labelId, int... propertyIds );
+
+    @Test
+    public void shouldFindConstraintsBySchema() throws Exception
+    {
+        // GIVEN
+        try ( org.neo4j.graphdb.Transaction tx = graphDb.beginTx() )
+        {
+            graphDb.schema().constraintFor( Label.label( "FOO" ) ).assertPropertyIsUnique( "prop" ).create();
+            tx.success();
+        }
+
+        try ( Transaction tx = session.beginTransaction() )
+        {
+            int label = tx.tokenWrite().labelGetOrCreateForName( "FOO" );
+            int prop = tx.tokenWrite().propertyKeyGetOrCreateForName( "prop" );
+            LabelSchemaDescriptor descriptor = labelSchemaDescriptor( label, prop );
+
+            //WHEN
+            Iterator<ConstraintDescriptor> constraints =
+                    tx.schemaRead().constraintsGetForSchema( descriptor );
+
+            // THEN
+            ConstraintDescriptor next = constraints.next();
+            assertTrue( next.enforcesUniqueness() );
+            assertThat( next.schema(), equalTo( descriptor ) );
+            assertFalse( constraints.hasNext() );
+        }
+    }
+}

community/kernel/src/main/java/org/neo4j/kernel/impl/api/KernelTransactionImplementation.java

@@ -50,6 +50,7 @@
 import org.neo4j.internal.kernel.api.security.SecurityContext;
 import org.neo4j.io.pagecache.tracing.cursor.PageCursorTracer;
 import org.neo4j.io.pagecache.tracing.cursor.PageCursorTracerSupplier;
+import org.neo4j.kernel.api.AssertOpen;
 import org.neo4j.kernel.api.KernelTransaction;
 import org.neo4j.kernel.api.KeyReadTokenNameLookup;
 import org.neo4j.kernel.api.exceptions.ConstraintViolationTransactionFailureException;
@@ -98,7 +99,7 @@
  * as
  * {@code TransitionalTxManagementKernelTransaction} is gone from {@code server}.
  */
-public class KernelTransactionImplementation implements KernelTransaction, TxStateHolder
+public class KernelTransactionImplementation implements KernelTransaction, TxStateHolder, AssertOpen
 {
     /*
      * IMPORTANT:
@@ -201,8 +202,7 @@ public KernelTransactionImplementation( StatementOperationParts statementOperati
         this.statistics = new Statistics( this, cpuClock, heapAllocation );
         this.userMetaData = new HashMap<>();
         AllStoreHolder allStoreHolder =
-                new AllStoreHolder( storageEngine, storageStatement, this, cursors, explicitIndexStore,
-                        this::assertOpen );
+                new AllStoreHolder( storageEngine, storageStatement, this, cursors, explicitIndexStore );
         this.operations =
                 new Operations(
                         allStoreHolder,
@@ -467,10 +467,9 @@ private void assertTransactionOpen()
 
     public void assertOpen()
     {
-        Optional<Status> terminationReason = getReasonIfTerminated();
-        if ( terminationReason.isPresent() )
+        if ( terminationReason != null )
         {
-            throw new TransactionTerminatedException( terminationReason.get() );
+            throw new TransactionTerminatedException( terminationReason );
         }
     }
 

community/kernel/src/main/java/org/neo4j/kernel/impl/newapi/AllStoreHolder.java

@@ -20,6 +20,7 @@
 package org.neo4j.kernel.impl.newapi;
 
 import java.nio.ByteBuffer;
+import java.util.Iterator;
 import java.util.Map;
 
 import org.neo4j.function.Suppliers;
@@ -31,8 +32,9 @@
 import org.neo4j.internal.kernel.api.exceptions.LabelNotFoundKernelException;
 import org.neo4j.internal.kernel.api.exceptions.PropertyKeyIdNotFoundKernelException;
 import org.neo4j.internal.kernel.api.exceptions.explicitindex.ExplicitIndexNotFoundKernelException;
+import org.neo4j.internal.kernel.api.schema.SchemaDescriptor;
+import org.neo4j.internal.kernel.api.schema.constraints.ConstraintDescriptor;
 import org.neo4j.io.pagecache.PageCursor;
-import org.neo4j.kernel.api.AssertOpen;
 import org.neo4j.kernel.api.ExplicitIndex;
 import org.neo4j.kernel.api.exceptions.index.IndexNotFoundKernelException;
 import org.neo4j.kernel.api.exceptions.schema.IllegalTokenNameException;
@@ -41,7 +43,7 @@
 import org.neo4j.kernel.api.schema.index.IndexDescriptorFactory;
 import org.neo4j.kernel.api.txstate.ExplicitIndexTransactionState;
 import org.neo4j.kernel.api.txstate.TransactionState;
-import org.neo4j.kernel.api.txstate.TxStateHolder;
+import org.neo4j.kernel.impl.api.KernelTransactionImplementation;
 import org.neo4j.kernel.impl.api.store.PropertyUtil;
 import org.neo4j.kernel.impl.index.ExplicitIndexStore;
 import org.neo4j.kernel.impl.store.RecordCursor;
@@ -74,15 +76,14 @@ public class AllStoreHolder extends Read implements Token
 
     public AllStoreHolder( StorageEngine engine,
             StorageStatement statement,
-            TxStateHolder txStateHolder,
+            KernelTransactionImplementation ktx,
             Cursors cursors,
-            ExplicitIndexStore explicitIndexStore,
-            AssertOpen assertOpen )
+            ExplicitIndexStore explicitIndexStore)
     {
-        super( cursors, txStateHolder, assertOpen );
+        super( cursors, ktx);
         this.storeReadLayer = engine.storeReadLayer();
         this.statement = statement; // use provided statement, to assert no leakage
-        this.explicitIndexes = Suppliers.lazySingleton( txStateHolder::explicitIndexTxState );
+        this.explicitIndexes = Suppliers.lazySingleton( ktx::explicitIndexTxState );
 
         this.nodes = statement.nodes();
         this.relationships = statement.relationships();
@@ -94,7 +95,7 @@ public AllStoreHolder( StorageEngine engine,
     @Override
     public boolean nodeExists( long id )
     {
-        assertOpen.assertOpen();
+        ktx.assertOpen();
 
         if ( hasTxStateWithChanges() )
         {
@@ -154,7 +155,7 @@ ExplicitIndex explicitRelationshipIndex( String indexName ) throws ExplicitIndex
     @Override
     public CapableIndexReference index( int label, int... properties )
     {
-        assertOpen.assertOpen();
+        ktx.assertOpen();
         IndexDescriptor indexDescriptor = storeReadLayer.indexGetForSchema( new LabelSchemaDescriptor( label, properties ) );
         if ( indexDescriptor == null )
         {
@@ -172,6 +173,31 @@ public CapableIndexReference index( int label, int... properties )
         }
     }
 
+    @Override
+    public Iterator<ConstraintDescriptor> constraintsGetForSchema( SchemaDescriptor descriptor )
+    {
+        sharedOptimisticLock( descriptor.keyType(), descriptor.keyId() );
+        ktx.assertOpen();
+        Iterator<ConstraintDescriptor> constraints = storeReadLayer.constraintsGetForSchema( descriptor );
+        if ( ktx.hasTxStateWithChanges() )
+        {
+            return ktx.txState().constraintsChangesForSchema( descriptor ).apply( constraints );
+        }
+        return constraints;
+    }
+
+    @Override
+    public boolean constraintExists( ConstraintDescriptor descriptor )
+    {
+        return false;
+    }
+
+    @Override
+    public Iterator<ConstraintDescriptor> constraintsGetForLabel( int labelId )
+    {
+        return null;
+    }
+
     @Override
     public int labelGetOrCreateForName( String labelName ) throws KernelException
     {