Guard against null JetSqlBackend (#19147)

hazelcast-sql/src/main/java/com/hazelcast/sql/impl/calcite/OptimizerContext.java

@@ -50,6 +50,7 @@
 import org.apache.calcite.tools.RuleSet;
 
 import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
 import java.util.List;
 
 /**
@@ -96,7 +97,7 @@ public static OptimizerContext create(
             List<Object> arguments,
             int memberCount,
             @Nonnull SqlBackend sqlBackend,
-            @Nonnull SqlBackend jetSqlBackend
+            @Nullable SqlBackend jetSqlBackend
     ) {
         // Resolve tables.
         HazelcastSchema rootSchema = HazelcastSchemaUtils.createRootSchema(schema);
@@ -110,7 +111,7 @@ public static OptimizerContext create(
             List<Object> arguments,
             int memberCount,
             @Nonnull SqlBackend sqlBackend,
-            @Nonnull SqlBackend jetSqlBackend
+            @Nullable SqlBackend jetSqlBackend
     ) {
         DistributionTraitDef distributionTraitDef = new DistributionTraitDef(memberCount);
 

hazelcast-sql/src/main/java/com/hazelcast/sql/impl/calcite/parse/QueryParser.java

@@ -36,6 +36,7 @@
 import org.apache.calcite.sql.validate.SqlConformance;
 
 import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
 import java.util.List;
 
 /**
@@ -59,7 +60,7 @@ public QueryParser(
             SqlConformance jetConformance,
             List<Object> arguments,
             @Nonnull SqlBackend sqlBackend,
-            @Nonnull SqlBackend jetSqlBackend
+            @Nullable SqlBackend jetSqlBackend
     ) {
         this.typeFactory = typeFactory;
         this.catalogReader = catalogReader;
@@ -76,7 +77,12 @@ public QueryParseResult parse(String sql) {
             try {
                 return parse(sql, sqlBackend, conformance);
             } catch (Exception e) {
-                return parse(sql, jetSqlBackend, jetConformance);
+                // TODO: once IMDG engine is removed, move the check (and fail fast) to SqlServiceImpl?
+                if (jetSqlBackend != null) {
+                    return parse(sql, jetSqlBackend, jetConformance);
+                } else {
+                    throw e;
+                }
             }
         } catch (Exception e) {
             String message;

hazelcast-sql/src/test/java/com/hazelcast/jet/sql/SqlTest.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2021 Hazelcast Inc.
+ *
+ * Licensed under the Hazelcast Community License (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://hazelcast.com/hazelcast-community-license
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.hazelcast.jet.sql;
+
+import com.hazelcast.config.Config;
+import com.hazelcast.core.HazelcastInstance;
+import com.hazelcast.jet.core.JetTestSupport;
+import com.hazelcast.sql.HazelcastSqlException;
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+public class SqlTest extends JetTestSupport {
+
+    @Test
+    public void when_jetDisabled_and_usingClient_then_sqlThrowsException() {
+        Config config = smallInstanceConfig();
+        config.getJetConfig().setEnabled(false);
+        createHazelcastInstance(config);
+
+        HazelcastInstance client = createHazelcastClient();
+
+        assertThatThrownBy(() -> client.getSql().execute("SELECT * FROM TABLE(GENERATE_SERIES(1, 1))").iterator().next())
+                .isInstanceOf(HazelcastSqlException.class)
+                .hasMessageContaining("Function 'TABLE' does not exist");
+    }
+}