add gets scheduled times by expect fire times (#1113)

* rename from DatasourceUserMapper to DataSourceUserMapper

* add unit test in UserMapper and WorkerGroupMapper

* change cn.escheduler to org.apache.dolphinscheduler

* add unit test in UdfFuncMapperTest

* add unit test in UdfFuncMapperTest

* remove DatabaseConfiguration

* add ConnectionFactoryTest

* cal duration in processInstancesList

* change desc to description

* change table name in mysql ddl

* change table name in mysql ddl

* change escheduler to dolphinscheduler

* change escheduler to dolphinscheduler

* change escheduler to dolphinscheduler

* remove log4j-1.2-api and modify AlertMapperTest

* remove log4j-1.2-api

* Add alertDao to spring management

* Add alertDao to spring management

* get SqlSessionFactory from MybatisSqlSessionFactoryBean

* get processDao by DaoFactory

* read druid properties in ConneciontFactory

* read druid properties in ConneciontFactory

* change get alertDao by spring to DaoFactory

* add log4j to resolve #967

* resole verify udf name error and delete udf error

* Determine if principal is empty

* Determine whether the logon user has the right to delete the project

* Fixed an issue that produced attatch file named such as ATT00002.bin

* fix too many connection in upgrade or create

* fix NEED_FAULT_TOLERANCE and WAITTING_THREAD count fail

* Added a judgment on whether the currently login user is an administrator

* fix update udf database not change and create time is changed

* add enterprise.wechat.enable to decide whether to send enterprise WeChat

* change method check

* Remove the administrator's judgment on query access token list

* only admin can create worker group

* delete alert group need delete the relation of user and alert group

* add timeout in proxy when upload large resource

* add gets scheduled times by expect fire times

* add gets scheduled times by expect fire times

dolphinscheduler-api/src/main/java/org/apache/dolphinscheduler/api/service/SchedulerService.java

@@ -572,8 +572,8 @@ public class SchedulerService extends BaseService {
             putMsg(result,Status.PARSE_TO_CRON_EXPRESSION_ERROR);
             return result;
         }
-        List<Date> selfFireDateList = CronUtils.getSelfFireDateList(startTime, endTime,cronExpression);
-        result.put(Constants.DATA_LIST, selfFireDateList.stream().map(t -> DateUtils.dateToString(t)).limit(Constants.PREVIEW_SCHEDULE_EXECUTE_COUNT));
+        List<Date> selfFireDateList = CronUtils.getSelfFireDateList(startTime, endTime,cronExpression,Constants.PREVIEW_SCHEDULE_EXECUTE_COUNT);
+        result.put(Constants.DATA_LIST, selfFireDateList.stream().map(t -> DateUtils.dateToString(t)));
         putMsg(result, Status.SUCCESS);
         return result;
     }

dolphinscheduler-dao/src/main/java/org/apache/dolphinscheduler/dao/utils/cron/CronUtils.java

@@ -129,6 +129,29 @@ public class CronUtils {
     return dateList;
   }
 
+  /**
+   * gets expect scheduled times for a period of time based on self dependency
+   * @param startTime
+   * @param endTime
+   * @param cronExpression
+   * @param fireTimes
+   * @return
+   */
+  public static List<Date> getSelfFireDateList(Date startTime, Date endTime, CronExpression cronExpression,int fireTimes) {
+    List<Date> dateList = new ArrayList<>();
+    while (fireTimes > 0) {
+      startTime = cronExpression.getNextValidTimeAfter(startTime);
+      if (startTime.after(endTime) || startTime.equals(endTime)) {
+        break;
+      }
+      dateList.add(startTime);
+      fireTimes--;
+    }
+
+    return dateList;
+  }
+
+
   /**
    * gets all scheduled times for a period of time based on self dependency
    * @param startTime