investigate searching is closed notebooks

[andreamah]

This issue is for tracking research on how we should handle searching in closed notebooks. Functionality for searching opened/rendered notebooks is in #164926.

The main problem is that the notebook must be rendered/opened for the find widget to be used on it.

[andreamah]

Some possibilities:

1. New extension provider API - extensions provide info on what the search results are for the notebook/editor that they provide, given the search query

Pros:

• extendable; we can ask the extensions how they'd want to express their info
  • even hex editor wouldn't be able to rely on native webview find (ie: would strings that wrap-around be captured)?
• the best way to support custom editors

Cons:

• if we kept what we have for open notebooks, would create 2 ways of searching for notebooks
• overhead of maintaining extension API
• extensions would be responsible for processing regexes/etc.
• extensions would need to do stuff like highlighting, which might be a lot of work
• extensions would probably want to add UI buttons to toggle in search view

2. Mostly relying on what we already have in core - use Notebook Find widget results to search

Pros

• we already have the find widget to give us results and highlight the results
• aligns with what we are already doing with open notebooks

Cons:

• heavy performance for rendering all notebooks upon search

[andreamah]

Discussed options that involved only searching for inputs in closed notebooks, which can be deduced once notebooks are serialized. Tested deserializing performance here:

vscode/src/vs/workbench/contrib/notebook/browser/controller/executeActions.ts

Line 97 in dcd234e

registerAction2(class NotebookDeserializeTest extends Action2 {

Results:

Repo 1:
9.63MB Processed | Number of Files: 42 | Number of Cells: 1697
Execution Times: 1031ms // 800ms // 913ms // 815ms
Avg: 889.75ms -> 21.2ms per file

Repo 2:
19.42MB Processed | Number of Files: 68 | Number of Cells: 3034
Execution Times: 1677ms // 1435ms // 1463ms // 1779ms 
Avg: 1588.5ms -> 23.36ms per file

Repo 3:
18.46MB Processed | Number of Files: 110 | Number of Cells: 4394
Execution Times: 2218ms // 2137ms // 2248ms // 2101ms
Avg: 2176 -> 19.8ms per file