openTextDocument resolves but returns undefined for files larger than about 4MB

[StephenWeatherford]

• VSCode Version: 1.20.0 (ia32)
• OS Version: win64

Steps to Reproduce:

1. Pass openTextDocument a file path to a text file on disk larger than 4MB
   const document = await vscode.workspace.openTextDocument(localFilePath);
2. The resolved value of the promise will be undefined
3. EXPECTED: The signature of the method does not include a possible undefined value, therefore it shouldn't return undefined. Here's the relevant code:

			openTextDocument(uriOrFileNameOrOptions?: vscode.Uri | string | { language?: string; content?: string; }) {
                                ...
				return uriPromise.then(uri => {
					return extHostDocuments.ensureDocumentData(uri).then(() => {
						const data = extHostDocuments.getDocumentData(uri);
						return data && data.document;  <<<<<<<<<<<
					});
				});
			},

NOTE: You can see this in my extension by following these steps, if you have an Azure subscription:

1. Install https://github.com/Microsoft/vscode-azurestorage/releases/tag/V0.2.0
2. In "Azure Storage" tree, browse to a text blob that's larger than 4MB
3. Click it
4. Extension will download and try to open it
   !) the download succeeds, but the open fails
5. If you click on the link to the file in the Output pane, the file gets opened properly

[kevcunnane]

I am having this exact same problem - I have saved a file to disk that's over 50MB and then want to open and show the file. The issue is that in mainThreadDocumentsAndEditors._updateState it doesn't call onDidStateChange for large files. Hence the mainThreadDocument manager never gets the notification, and returns undefined.

This seems inconsistent - this works with File -> Open, but programmatically fails when an extension tries to do the same thing. A workaround would be a single "open and show" command that doesn't register the file as usable by language services, but guarantees it'll open.

Repro of code that will fail with large file:

            let uri = vscode.Uri.file(filePath);
            vscode.workspace.openTextDocument(uri).then((doc: vscode.TextDocument) => {
                // Show open document and set focus
                vscode.window.showTextDocument(doc, 1, false).then(undefined, (error: any) => {
                    vscode.window.showErrorMessage(error);
                });
            }, (error: any) => {
                vscode.window.showErrorMessage(error);
            });

[jrieken]

Yeah, we should probably reject the promise... This challenge is that we technically support opening this (and do so) but we don't sync it to the extension host.

[jrieken]

command that doesn't register the file as usable by language services, but guarantees it'll open.

That actually could work with the vscode.open-command or this overload (didn't test that): export function showTextDocument(uri: Uri, options?: TextDocumentShowOptions): Thenable<TextEditor>; (update: tested that ;-))

[jrieken]

@StephenWeatherford I have pushed a change that rejects the returned promises with proper error message. We are a bit confused about the 4MB limit you have mentioned because since a few months the limit is 50MB. Where does that number come from?

In order to open very large files from an extensions you can use the vscode.open-command. This is a snippet that opens a huge file for me (>350MB).

    vscode.commands.registerCommand('extension.sayHello', () => {
        return vscode.commands.executeCommand(
           'vscode.open', 
           vscode.Uri.file('/Users/jrieken/Code/_samples/ConsoleAppDnx/large2.txt')
       );
    })

[tsalinger]

I can verify that the error message shows.
However, the file size limit is actually 20MB by accident.
Will open a new issue for this.

[kevcunnane]

Just as an FYI, the workaround to call the vscode.open command worked great. I'm unblocked now, appreciate you helping me understand how to get this going.