public static QueryResourceManager getInstance() {
    return QueryTokenManagerHelper.INSTANCE;
  }
QueryResourceManager manages resource (file streams) used by each read job, and assign Ids to the
jobs. During the life cycle of a read, the following methods must be called in strict order:

<p>1. assignQueryId - get an Id for the new read.

<p>2. getQueryDataSource - open files for the job or reuse existing readers.

<p>3. endQueryForGivenJob - release the resource used by this job.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/storageengine/dataregion/read/control/QueryResourceManager.java