package liquibase.executor;

 import liquibase.database.Database;

 import liquibase.exception.UnexpectedLiquibaseException;

 import liquibase.servicelocator.ServiceLocator;

 import java.util.Map;

 import java.util.concurrent.ConcurrentHashMap;

 public class ExecutorService {

     private static ExecutorService instance = new ExecutorService();

     private Map<Database, Executor> executors = new ConcurrentHashMap<Database, Executor>();

     private ExecutorService() {

     }

     public static ExecutorService getInstance() {

         return instance;

     }

     public Executor getExecutor(Database database) {

         if (!executors.containsKey(database)) {

             try {

                 Executor executor = (Executor) ServiceLocator.getInstance().newInstance(Executor.class);

                 executor.setDatabase(database);

                 executors.put(database, executor);

             } catch (Exception e) {

                 throw new UnexpectedLiquibaseException(e);

             }

         }

         return executors.get(database);

     }

     public void setExecutor(Database database, Executor executor) {

         executors.put(database, executor);

     }

     public void clearExecutor(Database database) {

         executors.remove(database);

     }

     public void reset() {

         executors.clear();

     }

 }