dremio CommandCreator 简单说明

CommandCreator 主要是基于不同业务规则进行conmandrunner 的生成，以下是一个简单说明

CommandCreator 的作用

• 基于request 创建包装的command
• 包装多种conmandrunner （基于用户请求类型，包装不同的commandrunner）
• 构建后变任务处理需要的上下文信息（比如sqlConverter，sqlHandlerConfig）

参考类

 

 

CommandRunner 类

参考子类，后边会介绍下，jdbc 以及web 经常会用到HandlerToExec

 

 

调用

实际CommandCreator 的调用是由AttemptManager 的run 方法执行的，同时源头是ForemenWorkManager（和drill 一致）AttemptManager我以前简单介绍过，可以参考

• run 部分处理
  对于CommandCreator 的依赖处理核心是使用了CommandPool

 

@Override

  public void run() {

    // rename the thread we're using for debugging purposes

    final Thread currentThread = Thread.currentThread();

    final String originalName = currentThread.getName();

    currentThread.setName(queryIdString + ":foreman");

 

 

    try {

      injector.injectChecked(queryContext.getExecutionControls(), INJECTOR_TRY_BEGINNING_ERROR,

        ForemanException.class);

 

      observer.beginState(AttemptObserver.toEvent(AttemptEvent.State.PENDING));

 

      observer.queryStarted(queryRequest, queryContext.getSession().getCredentials().getUserName());

 

      String ruleSetEngine = ruleBasedEngineSelector.resolveAndUpdateEngine(queryContext);

      ResourceSchedulingProperties resourceSchedulingProperties = new ResourceSchedulingProperties();

      resourceSchedulingProperties.setRoutingEngine(queryContext.getSession().getRoutingEngine());

      resourceSchedulingProperties.setRuleSetEngine(ruleSetEngine);

      final GroupResourceInformation groupResourceInformation =

        maestroService.getGroupResourceInformation(queryContext.getOptions(), resourceSchedulingProperties);

      queryContext.setGroupResourceInformation(groupResourceInformation);

 

      // Checks for Run Query privileges for the selected Engine

      checkRunQueryAccessPrivilege(groupResourceInformation);

 

      // planning is done in the command pool

      commandPool.submit(CommandPool.Priority.LOW, attemptId.toString() + ":foreman-planning",

        (waitInMillis) -> {

          observer.commandPoolWait(waitInMillis);

 

          injector.injectPause(queryContext.getExecutionControls(), INJECTOR_PENDING_PAUSE, logger);

          injector.injectChecked(queryContext.getExecutionControls(), INJECTOR_PENDING_ERROR,

            ForemanException.class);

 

          plan();

          injector.injectPause(queryContext.getExecutionControls(), INJECTOR_PLAN_PAUSE, logger);

          injector.injectChecked(queryContext.getExecutionControls(), INJECTOR_PLAN_ERROR,

            ForemanException.class);

          return null;

        }, runInSameThread).get(); // 等待plan()中的创建成功

plan 方法,会等待实际的CommandRunner plan 执行完成

private void plan() throws Exception {

    // query parsing and dataset retrieval (both from source and kvstore).

    observer.beginState(AttemptObserver.toEvent(AttemptEvent.State.METADATA_RETRIEVAL));

 

    CommandCreator creator = newCommandCreator(queryContext, observer, prepareId);

    command = creator.toCommand();

    logger.debug("Using command: {}.", command);

 

    injector.injectPause(queryContext.getExecutionControls(), INJECTOR_METADATA_RETRIEVAL_PAUSE, logger);

 

    switch (command.getCommandType()) {

      case ASYNC_QUERY:

        Preconditions.checkState(command instanceof AsyncCommand, "Asynchronous query must be an AsyncCommand");

        command.plan();

        break;

 

      case SYNC_QUERY:

      case SYNC_RESPONSE:

        moveToState(QueryState.STARTING, null);

        command.plan();

        extraResultData = command.execute();

        addToEventQueue(QueryState.COMPLETED, null);

        break;

 

      default:

        throw new IllegalStateException(

          String.format("command type %s not supported in plan()", command.getCommandType()));

    }

    profileTracker.setPrepareId(prepareId.value);

  }

参考资料

sabot/kernel/src/main/java/com/dremio/exec/planner/sql/handlers/commands/CommandCreator.java
https://www.cnblogs.com/rongfengliang/p/15987562.html
sabot/kernel/src/main/java/com/dremio/exec/work/foreman/AttemptManager.java