Allow an init path that doesn't require a non-null Cassandra/DataStax session/cluster context.

src/main/java/net/helenus/core/Helenus.java

@@ -33,10 +33,8 @@ import net.helenus.support.HelenusMappingException;
 
 public final class Helenus {
 
-  private static final ConcurrentMap<Class<?>, Object> dslCache =
+  private static final ConcurrentMap<Class<?>, Object> dslCache = new ConcurrentHashMap<Class<?>, Object>();
-      new ConcurrentHashMap<Class<?>, Object>();
+  private static final ConcurrentMap<Class<?>, Metadata> metadataForEntity = new ConcurrentHashMap<Class<?>, Metadata>();
-  private static final ConcurrentMap<Class<?>, Metadata> metadataForEntity =
-      new ConcurrentHashMap<Class<?>, Metadata>();
   private static final Set<HelenusSession> sessions = new HashSet<HelenusSession>();
   private static volatile HelenusSettings settings = new DefaultHelenusSettings();
   private static volatile HelenusSession singleton;
@@ -81,6 +79,10 @@ public final class Helenus {
     return new SessionInitializer(session);
   }
 
+  public static SessionInitializer init(Session session, String keyspace) {
+      return new SessionInitializer(session, keyspace);
+  }
+
   public static SessionInitializer init(Session session) {
 
     if (session == null) {

src/main/java/net/helenus/core/HelenusSession.java

@@ -100,7 +100,7 @@ public class HelenusSession extends AbstractSessionOperations implements Closeab
     this.showCql = showCql;
     this.showValues = showValues;
     this.printStream = printStream;
-    this.sessionRepository = sessionRepositoryBuilder.build();
+    this.sessionRepository = sessionRepositoryBuilder == null ? null : sessionRepositoryBuilder.build();
     this.executor = executor;
     this.dropSchemaOnClose = dropSchemaOnClose;
     this.defaultConsistencyLevel = consistencyLevel;
@@ -117,7 +117,7 @@ public class HelenusSession extends AbstractSessionOperations implements Closeab
 
     this.valueProvider = new RowColumnValueProvider(this.sessionRepository);
     this.valuePreparer = new StatementColumnValuePreparer(this.sessionRepository);
-    this.metadata = session.getCluster().getMetadata();
+    this.metadata = session == null ? null : session.getCluster().getMetadata();
   }
 
   @Override
@@ -794,6 +794,9 @@ public class HelenusSession extends AbstractSessionOperations implements Closeab
   }
 
   public void close() {
+    if (session == null) {
+      return;
+    }
 
     if (session.isClosed()) {
       return;

src/main/java/net/helenus/core/SessionInitializer.java

@@ -15,16 +15,28 @@
  */
 package net.helenus.core;
 
-import brave.Tracer;
-import com.codahale.metrics.MetricRegistry;
-import com.datastax.driver.core.*;
-import com.google.common.util.concurrent.MoreExecutors;
 import java.io.IOException;
 import java.io.PrintStream;
-import java.util.*;
+import java.util.ArrayDeque;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Objects;
+import java.util.Set;
 import java.util.concurrent.Executor;
 import java.util.concurrent.Executors;
 import java.util.function.Consumer;
+
+import brave.Tracer;
+import com.codahale.metrics.MetricRegistry;
+import com.datastax.driver.core.CodecRegistry;
+import com.datastax.driver.core.ConsistencyLevel;
+import com.datastax.driver.core.KeyspaceMetadata;
+import com.datastax.driver.core.Session;
+import com.datastax.driver.core.TableMetadata;
+import com.datastax.driver.core.UserType;
+import com.google.common.util.concurrent.MoreExecutors;
 import net.helenus.core.cache.SessionCache;
 import net.helenus.core.reflect.DslExportable;
 import net.helenus.mapping.HelenusEntity;
@@ -58,6 +70,14 @@ public final class SessionInitializer extends AbstractSessionOperations {
   private AutoDdl autoDdl = AutoDdl.UPDATE;
   private SessionCache sessionCache = null;
 
+  SessionInitializer(Session session, String keyspace) {
+      this.session = session;
+      this.usingKeyspace = keyspace;
+      if (session != null) {
+          this.sessionRepository = new SessionRepositoryBuilder(session);
+      }
+  }
+
   SessionInitializer(Session session) {
       this.session = Objects.requireNonNull(session, "empty session");
       this.usingKeyspace = session.getLoggedKeyspace(); // can be null
@@ -284,6 +304,7 @@ public final class SessionInitializer extends AbstractSessionOperations {
         idempotent,
         unitOfWorkClass,
         sessionCache,
+        statementCache,
         metricRegistry,
         zipkinTracer);
   }
@@ -302,10 +323,17 @@ public final class SessionInitializer extends AbstractSessionOperations {
           }
 
           DslExportable dsl = (DslExportable) Helenus.dsl(iface);
+          if (session != null) {
               dsl.setCassandraMetadataForHelenusSession(session.getCluster().getMetadata());
+          }
+          if (sessionRepository != null) {
               sessionRepository.add(dsl);
+          }
         });
 
+    if (session == null)
+        return;
+
     TableOperations tableOps = new TableOperations(this, dropUnusedColumns, dropUnusedIndexes);
     UserTypeOperations userTypeOps = new UserTypeOperations(this, dropUnusedColumns);
 

src/test/java/net/helenus/test/integration/core/ContextInitTest.java

@@ -17,6 +17,8 @@ package net.helenus.test.integration.core;
 
 import net.helenus.core.Helenus;
 import net.helenus.core.HelenusSession;
+import net.helenus.core.SessionInitializer;
+import net.helenus.core.UnitOfWork;
 import net.helenus.test.integration.build.AbstractEmbeddedCassandraTest;
 import org.junit.Test;
 
@@ -29,4 +31,11 @@ public class ContextInitTest extends AbstractEmbeddedCassandraTest {
 
     System.out.println("Works! " + session);
   }
+
+  @Test
+  public void testWithNullSession() {
+      HelenusSession session = Helenus.init(null, "foo").get();
+      UnitOfWork uow = session.begin();
+      uow.abort();
+  }
 }