Stabilizing Celery / SQL Lab (#2981)

* upgrade celery to 4.0.2
* using Redis for unit tests (sqla broker not supported in Celery 4)
* Setting Celery's soft_time_limit based on `SQLLAB_ASYNC_TIME_LIMIT_SEC` config
* Better error handling in async tasks
* Better statsd logging in async tasks
* show [pending/running] query status in Results tab
* systematically using sqla NullPool on worker (async) to limit number
  of database connections

superset/assets/javascripts/SqlLab/components/QueryStateLabel.jsx

@@ -0,0 +1,19 @@
+import React from 'react';
+import PropTypes from 'prop-types';
+import { Label } from 'react-bootstrap';
+
+import { STATE_BSSTYLE_MAP } from '../constants';
+
+const propTypes = {
+  query: PropTypes.object.isRequired,
+};
+
+export default function QueryStateLabel({ query }) {
+  const bsStyle = STATE_BSSTYLE_MAP[query.state];
+  return (
+    <Label className="m-r-3" bsStyle={bsStyle}>
+      {query.state}
+    </Label>
+  );
+}
+QueryStateLabel.propTypes = propTypes;

superset/assets/javascripts/SqlLab/components/QueryTable.jsx

@@ -9,9 +9,9 @@ import VisualizeModal from './VisualizeModal';
 import ResultSet from './ResultSet';
 import ModalTrigger from '../../components/ModalTrigger';
 import HighlightedSql from './HighlightedSql';
-import { STATE_BSSTYLE_MAP } from '../constants';
 import { fDuration } from '../../modules/dates';
 import { storeQuery } from '../../../utils/common';
+import QueryStateLabel from './QueryStateLabel';
 
 const propTypes = {
   columns: PropTypes.array,
@@ -164,9 +164,7 @@ class QueryTable extends React.PureComponent {
       }
       q.state = (
         <div>
-          <span className={'m-r-3 label label-' + STATE_BSSTYLE_MAP[q.state]}>
-            {q.state}
-          </span>
+          <QueryStateLabel query={query} />
           {errorTooltip}
         </div>
       );

superset/assets/javascripts/SqlLab/components/ResultSet.jsx

@@ -6,6 +6,7 @@ import shortid from 'shortid';
 import VisualizeModal from './VisualizeModal';
 import HighlightedSql from './HighlightedSql';
 import FilterableTable from '../../components/FilterableTable/FilterableTable';
+import QueryStateLabel from './QueryStateLabel';
 
 const propTypes = {
   actions: PropTypes.object,
@@ -165,6 +166,7 @@ export default class ResultSet extends React.PureComponent {
       return (
         <div>
           <img className="loading" alt="Loading..." src="/static/assets/images/loading.gif" />
+          <QueryStateLabel query={query} />
           {progressBar}
         </div>
       );