Use XDG_CACHE_HOME on Linux systems for the default databaseFilename

[pwaller]

Environment

• OS and Version: NixOS 22.11
• VS Code Version: 1.73.1
• C/C++ Extension Version: v1.11.0
• Other extensions you installed (and if the issue persists after disabling them): N/A
• If using SSH remote, specify OS of remote machine: N/A
• Numerous workspaces

Bug Summary and Steps to Reproduce

I hack on a number of large C/C++ projects including the linux kernel and llvm-project.

What I see is that my $HOME/.config directory contains many large binaries (tens of gigabytes, individual files >2.5GiB each), where I would rather it did not. These are the .config/Code/User/workspaceStorage/<randomhex>/ms-vscode.cpptools/.browse.VC.db files.

I consider XDG_CONFIG_HOME is meant to be the place I can store configuration I intend version control and to backup, but I can't easily do this if it contains a lot of large binaries.

I expected these large binaries to live in XDG_CACHE_HOME, which is where I go to delete things if I'm running out of disk space, the place where things should live which can be recomputed.

As an additional note, I see multiple <randomhex> directories where the workspace.json indicates that these several caches of the large caches belong to the same workspace-on-disk, so there is some unexpected duplication going on as well. The workspace.json is identical. I presume these are outdated and unused, and I would naturally clear them out by blatting my $XDG_CACHE_HOME directory, not something I intend to do with my $XDG_CONFIG_HOME.

Expected behavior

I think that large recomputable binary databases should be stored in $XDG_CACHE_DIR/vscode-cpptools alongside the existing ipch cache.

Code sample and Logs

N/A, but these repos are examples of large ones:

https://github.com/llvm/llvm-project
https://github.com/torvalds/linux

Screenshots

No response

Additional context

No response

[sean-mcmanus]

Yes, the normal behavior, which I repro, is for the database files to be written to the .cache location -- see the previously fixed bug at #3979 . i.e. something unexpected is happening for you -- do you have any idea why we may not be using your XDG_CACHE_DIR? We could also review that for possible causes.

Are those old files from an older version of our extension? Do you have the C_Cpp.default.browse.databaseFilename set?

[pwaller]

I have not configured C_Cpp.default.browse.databaseFilename.

I do also have ipch cache files in ~/.cache/vscode-cpptools/ipch/*/*.ipch, in addition to the hidden browse database files living at ~/.config/Code/User/workspaceStorage/*/ms-vscode.cpptools/.browse.VC.db.

I have many of these files and they have been created recently.

I am running vscode-cpptools v1.11.0 on this version of vscode:

Version: 1.73.1
Commit: 6261075646f055b99068d3688932416f2346dd3b
Date: 2022-11-09T03:54:53.913Z
Electron: 19.0.17
Chromium: 102.0.5005.167
Node.js: 16.14.2
V8: 10.2.154.15-electron.0
OS: Linux x64 6.0.9
Sandboxed: No

[sean-mcmanus]

Ah, okay, you're right, I was mistaken. The database still defaults to the .config location (the referenced issue was for the IntelliSense cache files).

[sean-mcmanus]

This issue was previously tracked by #1404, but it got closed due to not having enough up votes, although having a setting and changing the default are slightly different requests.

A potential workaround is to use --user-data-dir <dir> when launching VS Code to change the workspaceStorage path location.

[pwaller]

I don't understand the workaround. This makes vscode write all personalized things somewhere else, yes? I wish to separate the cache from the config, since the cache is large and config is small, and I want to retain a backup of the config. If I include the caches in my backup it bloats the backups and causes differential churn in them unnecessarily, which is a problem for quick backups on low bandwidth connections and ultimately consumes more disk space in the backup than needed.

[sean-mcmanus]

@pwaller Yes, if you use the --user-data-dir then it won't write the files to the XDG_CONFIG_HOME.

[sean-mcmanus]

Fixed with https://github.com/microsoft/vscode-cpptools/releases/tag/v1.18.0

[sean-mcmanus]

There's a follow up issue at #11696