src/vs/workbench/contrib/comments/browser/commentsEditorContribution.ts/CommentController/beginCompute
class CommentController:	private beginCompute(): Promise<void> {
		this._computePromise = createCancelablePromise(token => {
			const editorURI = this.editor && this.editor.hasModel() && this.editor.getModel().uri;

			if (editorURI) {
				return this.commentService.getComments(editorURI);
			}

			return Promise.resolve([]);
		});

		return this._computePromise.then(commentInfos => {
			this.setComments(coalesce(commentInfos));
			this._computePromise = null;
		}, error => console.log(error));
	}