TextFileEditorModelManager disposes models it doesn't own

[rebornix]

• VSCode Version: 1.9.0-Insiders
• OS Version: macOS

Steps to Reproduce:

1. Go to https://github.com/Microsoft/vscode/blob/master/src/vs/workbench/electron-browser/actions.ts#L56
2. Right click on closeEditor, click Find all references
3. Cmd+Click on references in editorService, the file containing that reference will be opened on the right side editor group.
4. Expand references tree, part of the references are rendered as blank somtimes

Gif demonstrating the steps:

It's not that easy to reproduce, you might need to run step 4 several times.

[jrieken]

The is some textFileEditorManager disposing the models I have references/locked via createModelReference.

• insert the TS snippet below here: https://github.com/Microsoft/vscode/blob/master/src/vs/editor/contrib/referenceSearch/browser/referencesModel.ts#L158
• open reference search as described above
• expand a view nodes
• cmd click on an entry
• collapse/expand one of the open nodes -> node is empty

model.onDispose(() => {
	const {stack} = new Error();
	console.warn('DISPOSING MODEL FOR ' + this.uri);
	console.warn(stack);
});

DISPOSING MODEL FOR file:///Users/jrieken/Code/vscode/src/vs/workbench/parts/files/browser/editors/textFileEditor.ts
referencesModel.js:181 Error
    at file:////Users/jrieken/Code/vscode/out/vs/editor/contrib/referenceSearch/browser/referencesModel.js:179:33
    at CallbackList.invoke (file:////Users/jrieken/Code/vscode/out/vs/base/common/callbackList.js:57:43)
    at Emitter.fire (file:////Users/jrieken/Code/vscode/out/vs/base/common/event.js:88:40)
    at TextFileEditorModel.EditorModel.dispose (file:////Users/jrieken/Code/vscode/out/vs/workbench/common/editor.js:320:29)
    at TextFileEditorModel.BaseTextEditorModel.dispose (file:////Users/jrieken/Code/vscode/out/vs/workbench/common/editor/textEditorModel.js:146:38)
    at TextFileEditorModel.dispose (file:////Users/jrieken/Code/vscode/out/vs/workbench/services/textfile/common/textFileEditorModel.js:665:38)
    at TextFileEditorModelManager.disposeModelIfPossible (file:////Users/jrieken/Code/vscode/out/vs/workbench/services/textfile/common/textFileEditorModelManager.js:64:23)
    at file:////Users/jrieken/Code/vscode/out/vs/workbench/services/textfile/common/textFileEditorModelManager.js:356:58
    at Array.forEach (native)
    at TextFileEditorModelManager.disposeUnusedModels (file:////Users/jrieken/Code/vscode/out/vs/workbench/services/textfile/common/textFileEditorModelManager.js:356:18)

[bpasero]

Needs #17073 for file models.

[bpasero]

And actually blocked by #21709

[bpasero]

Fixed via 5ecf0cd