From 81817309d3f1e19636fdc310ca3b393ccabe254a Mon Sep 17 00:00:00 2001
From: Maxime Beauchemin <maximebeauchemin@gmail.com>
Date: Mon, 14 Aug 2017 17:55:30 -0700
Subject: [PATCH] [sql lab] fix sluggish backspace in editor (#3286)

Somehow Ace's "changeSelection" event is triggered when hitting
backspace (and shouldn't!).

changeSelection on our side triggers enough work to make the
holding backspace sluggish and laggy.

This fix ignores selection with a length of 1, avoiding mutating the
state altogether when hitting/holding backspace.
---
 .../javascripts/SqlLab/components/AceEditorWrapper.jsx | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/superset/assets/javascripts/SqlLab/components/AceEditorWrapper.jsx b/superset/assets/javascripts/SqlLab/components/AceEditorWrapper.jsx
index 37b884a6f6b..15adf0b80d9 100644
--- a/superset/assets/javascripts/SqlLab/components/AceEditorWrapper.jsx
+++ b/superset/assets/javascripts/SqlLab/components/AceEditorWrapper.jsx
@@ -45,6 +45,7 @@ class AceEditorWrapper extends React.PureComponent {
     super(props);
     this.state = {
       sql: props.sql,
+      selectedText: '',
     };
   }
   componentDidMount() {
@@ -77,8 +78,13 @@ class AceEditorWrapper extends React.PureComponent {
     });
     editor.$blockScrolling = Infinity; // eslint-disable-line no-param-reassign
     editor.selection.on('changeSelection', () => {
-      this.props.actions.queryEditorSetSelectedText(
-        this.props.queryEditor, editor.getSelectedText());
+      const selectedText = editor.getSelectedText();
+      // Backspace trigger 1 character selection, ignoring
+      if (selectedText !== this.state.selectedText && selectedText.length !== 1) {
+        this.setState({ selectedText });
+        this.props.actions.queryEditorSetSelectedText(
+          this.props.queryEditor, selectedText);
+      }
     });
   }
   getCompletions(aceEditor, session, pos, prefix, callback) {