Closes Taskana#2374: Deadlock when creating HistoryEvents from many connections simultaneously

-Write operations are now performed with the regular TaskanEngine and its' SqlSession and TransactionFactory which provides the needed transactionality and doesn't open multiple connections

Author: Jörg Heffner

history/taskana-simplehistory-provider/src/main/java/pro/taskana/simplehistory/TaskanaHistoryEngine.java

@@ -2,7 +2,6 @@
 
 import static pro.taskana.common.api.BaseQuery.toLowerCopy;
 
-import java.sql.SQLException;
 import java.util.ArrayList;
 import java.util.List;
 import org.apache.ibatis.session.RowBounds;
@@ -12,6 +11,7 @@
 import pro.taskana.common.api.TimeInterval;
 import pro.taskana.common.api.exceptions.InvalidArgumentException;
 import pro.taskana.common.api.exceptions.SystemException;
+import pro.taskana.common.internal.InternalTaskanaEngine;
 import pro.taskana.simplehistory.impl.classification.ClassificationHistoryQuery;
 import pro.taskana.simplehistory.impl.classification.ClassificationHistoryQueryColumnName;
 import pro.taskana.spi.history.api.events.classification.ClassificationHistoryEvent;
@@ -33,7 +33,7 @@ public class ClassificationHistoryQueryImpl implements ClassificationHistoryQuer
   private static final String SQL_EXCEPTION_MESSAGE =
       "Method openConnection() could not open a connection to the database.";
 
-  private final TaskanaHistoryEngineImpl taskanaHistoryEngine;
+  private final InternalTaskanaEngine internalTaskanaEngine;
 
   private final List<String> orderBy = new ArrayList<>();
   private final List<String> orderColumns = new ArrayList<>();
@@ -82,8 +82,8 @@ public class ClassificationHistoryQueryImpl implements ClassificationHistoryQuer
   private String[] custom7Like;
   private String[] custom8Like;
 
-  public ClassificationHistoryQueryImpl(TaskanaHistoryEngineImpl internalTaskanaHistoryEngine) {
-    this.taskanaHistoryEngine = internalTaskanaHistoryEngine;
+  public ClassificationHistoryQueryImpl(InternalTaskanaEngine internalTaskanaEngine) {
+    this.internalTaskanaEngine = internalTaskanaEngine;
   }
 
   @Override
@@ -415,32 +415,26 @@ public ClassificationHistoryQuery orderByCustomAttribute(int num, SortDirection
 
   @Override
   public List<ClassificationHistoryEvent> list() {
-    List<ClassificationHistoryEvent> result = new ArrayList<>();
+    List<ClassificationHistoryEvent> result;
     try {
-      taskanaHistoryEngine.openConnection();
-      result = taskanaHistoryEngine.getSqlSession().selectList(LINK_TO_MAPPER, this);
-      return result;
-    } catch (SQLException e) {
-      LOGGER.error(SQL_EXCEPTION_MESSAGE, e.getCause());
+      internalTaskanaEngine.openConnection();
+      result = internalTaskanaEngine.getSqlSession().selectList(LINK_TO_MAPPER, this);
       return result;
     } finally {
-      taskanaHistoryEngine.returnConnection();
+      internalTaskanaEngine.returnConnection();
     }
   }
 
   @Override
   public List<ClassificationHistoryEvent> list(int offset, int limit) {
     List<ClassificationHistoryEvent> result = new ArrayList<>();
     try {
-      taskanaHistoryEngine.openConnection();
+      internalTaskanaEngine.openConnection();
       RowBounds rowBounds = new RowBounds(offset, limit);
-      result = taskanaHistoryEngine.getSqlSession().selectList(LINK_TO_MAPPER, this, rowBounds);
-      return result;
-    } catch (SQLException e) {
-      LOGGER.error(SQL_EXCEPTION_MESSAGE, e.getCause());
+      result = internalTaskanaEngine.getSqlSession().selectList(LINK_TO_MAPPER, this, rowBounds);
       return result;
     } finally {
-      taskanaHistoryEngine.returnConnection();
+      internalTaskanaEngine.returnConnection();
     }
   }
 
@@ -454,17 +448,14 @@ public List<String> listValues(
     this.addOrderCriteria(columnName.toString(), sortDirection);
 
     try {
-      taskanaHistoryEngine.openConnection();
-      result = taskanaHistoryEngine.getSqlSession().selectList(LINK_TO_VALUE_MAPPER, this);
-      return result;
-    } catch (SQLException e) {
-      LOGGER.error(SQL_EXCEPTION_MESSAGE, e.getCause());
+      internalTaskanaEngine.openConnection();
+      result = internalTaskanaEngine.getSqlSession().selectList(LINK_TO_VALUE_MAPPER, this);
       return result;
     } finally {
       this.orderBy.addAll(cacheOrderBy);
       this.columnName = null;
       this.orderColumns.remove(orderColumns.size() - 1);
-      taskanaHistoryEngine.returnConnection();
+      internalTaskanaEngine.returnConnection();
     }
   }
 
@@ -473,30 +464,24 @@ public ClassificationHistoryEvent single() {
     ClassificationHistoryEvent result = null;
     try {
 
-      taskanaHistoryEngine.openConnection();
-      result = taskanaHistoryEngine.getSqlSession().selectOne(LINK_TO_MAPPER, this);
+      internalTaskanaEngine.openConnection();
+      result = internalTaskanaEngine.getSqlSession().selectOne(LINK_TO_MAPPER, this);
 
-      return result;
-    } catch (SQLException e) {
-      LOGGER.error(SQL_EXCEPTION_MESSAGE, e.getCause());
       return result;
     } finally {
-      taskanaHistoryEngine.returnConnection();
+      internalTaskanaEngine.returnConnection();
     }
   }
 
   @Override
   public long count() {
     Long rowCount = null;
     try {
-      taskanaHistoryEngine.openConnection();
-      rowCount = taskanaHistoryEngine.getSqlSession().selectOne(LINK_TO_COUNTER, this);
+      internalTaskanaEngine.openConnection();
+      rowCount = internalTaskanaEngine.getSqlSession().selectOne(LINK_TO_COUNTER, this);
       return (rowCount == null) ? 0L : rowCount;
-    } catch (SQLException e) {
-      LOGGER.error(SQL_EXCEPTION_MESSAGE, e.getCause());
-      return -1;
     } finally {
-      taskanaHistoryEngine.returnConnection();
+      internalTaskanaEngine.returnConnection();
     }
   }