Support unsetting transaction-bound SchemaTemplate in a Transaction (#3496)

This PR add support for "unsetting" a transaction-bound SchemaTemplate
from the ongoing transaction. This is essential if we want to revert the
execution to using the SchemaTemplate from the catalog thereby undoing
all the temporary function definitions at once. Note that this could be
more efficient than the `DROP TEMPORARY FUNCTION ...` DDL introduced in
the previous PR and have the wider scope that is beyond `TEMPORARY
FUNCTIONS` definitions.

Also added a test for testing it in the context of
`TransactionBoundDatabase`.

Author: g31pranjal

fdb-relational-core/src/main/java/com/apple/foundationdb/relational/api/Transaction.java

@@ -58,6 +58,11 @@ public interface Transaction extends AutoCloseable {
      */
     void setBoundSchemaTemplate(@Nonnull SchemaTemplate schemaTemplate);
 
+    /**
+     * Unsets the bound schema template, if one exists.
+     */
+    void unsetBoundSchemaTemplate();
+
     @Override
     void close() throws RelationalException;
 

fdb-relational-core/src/main/java/com/apple/foundationdb/relational/recordlayer/RecordContextTransaction.java

@@ -91,10 +91,15 @@ public Optional<SchemaTemplate> getBoundSchemaTemplateMaybe() {
 
     @Override
     public void setBoundSchemaTemplate(@Nonnull final SchemaTemplate schemaTemplate) {
-        context.removeFromSession(SchemaTemplate.class.toString(), SchemaTemplate.class);
+        unsetBoundSchemaTemplate();
         context.putInSessionIfAbsent(SchemaTemplate.class.toString(), schemaTemplate);
     }
 
+    @Override
+    public void unsetBoundSchemaTemplate() {
+        context.removeFromSession(SchemaTemplate.class.toString(), SchemaTemplate.class);
+    }
+
     @Override
     public void close() throws RelationalException {
         abort();

fdb-relational-core/src/main/java/com/apple/foundationdb/relational/recordlayer/RecordStoreAndRecordContextTransaction.java

@@ -82,6 +82,11 @@ public void setBoundSchemaTemplate(@Nonnull final SchemaTemplate schemaTemplate)
         transaction.setBoundSchemaTemplate(schemaTemplate);
     }
 
+    @Override
+    public void unsetBoundSchemaTemplate() {
+        transaction.unsetBoundSchemaTemplate();
+    }
+
     @Override
     public void close() throws RelationalException {
         transaction.close();

fdb-relational-core/src/test/java/com/apple/foundationdb/relational/recordlayer/TransactionBoundDatabaseTest.java

@@ -224,6 +224,32 @@ void dropTemporaryIfExistFunction() throws RelationalException, SQLException {
         }
     }
 
+    @Test
+    void unsetTransactionBoundSchemaTemplate() throws RelationalException, SQLException {
+        final var embeddedConnection = connRule.getUnderlyingEmbeddedConnection();
+        final var store = getStore(embeddedConnection);
+        final var schemaTemplate = getSchemaTemplate(embeddedConnection);
+
+        try (FDBRecordContext context = createNewContext(embeddedConnection)) {
+            final var newStore = store.asBuilder().setMetaDataProvider(store.getMetaDataProvider()).setContext(context).open();
+            try (Transaction transaction = new RecordStoreAndRecordContextTransaction(newStore, context, schemaTemplate)) {
+                EmbeddedRelationalDriver driver = new EmbeddedRelationalDriver(new TransactionBoundEmbeddedRelationalEngine());
+                try (RelationalConnection conn = driver.connect(dbRule.getConnectionUri(), transaction, Options.NONE)) {
+                    conn.setSchema("TEST_SCHEMA");
+                    try (RelationalStatement statement = conn.createStatement()) {
+                        statement.executeUpdate("CREATE TEMPORARY FUNCTION REST_FUNC() ON COMMIT DROP FUNCTION AS SELECT * FROM RESTAURANT WHERE REST_NO > 1000");
+                    }
+                    Assertions.assertThat(transaction.getBoundSchemaTemplateMaybe()).isPresent();
+                    Assertions.assertThat(transaction.getBoundSchemaTemplateMaybe().get().getInvokedRoutines())
+                            .hasSize(1)
+                            .anyMatch(routine -> routine.getName().equals("REST_FUNC"));
+                    transaction.unsetBoundSchemaTemplate();
+                    Assertions.assertThat(transaction.getBoundSchemaTemplateMaybe()).isEmpty();
+                }
+            }
+        }
+    }
+
     static FDBRecordStore getStore(EmbeddedRelationalConnection connection) throws RelationalException, SQLException {
         connection.setAutoCommit(false);
         connection.createNewTransaction();

fdb-relational-core/src/test/java/com/apple/foundationdb/relational/utils/InMemoryTransactionManager.java

@@ -84,6 +84,11 @@ public void setBoundSchemaTemplate(@Nonnull final SchemaTemplate schemaTemplate)
             throw new NotImplementedException("method is not implemented");
         }
 
+        @Override
+        public void unsetBoundSchemaTemplate() {
+            throw new NotImplementedException("method is not implemented");
+        }
+
         @Override
         public void close() {
             //no-op