only use cache if username matches

[eladyn]

This is a follow-up to #1019 and reorders the credential cache logic.

Previously:

• username and password are specified: use that
• cached credentials exist: use that
• else: start discovery

Now:

• cached credentials exist for given username: use that
• username and password are specified: use that
• else: start discovery

Also, a cache initialization failure is properly reported to the user.

[eladyn]

@aanno, if you've got the time, I'd be happy if you could test this version and see if it fixes the problem (again 😅).

[slondr]

I'll hold off on merging until @aanno confirms, but code looks great

[aanno]

Well, I tried but currently I run into problems to compile. Error is:

Compiling spotifyd v0.3.3 (/root/spotifyd)
error[E0658]: use of unstable library feature 'bool_to_option'
   --> src/config.rs:593:57
    |
593 |         .map(|path| Cache::new(Some(&path), audio_cache.then_some(&path), size_limit))
    |                                                         ^^^^^^^^^
    |
    = note: see issue #80967 <https://github.com/rust-lang/rust/issues/80967> for more information

For more information about this error, try `rustc --explain E0658`.
error: could not compile `spotifyd` due to previous error
Error: error building at STEP "RUN set -ex;  mkdir /opt/owntone || true;   cd;   export DEBIAN_FRONTEND=noninteractive;   export FEATURES="--no-default-features --all-features --features pulseaudio_backend,portaudio_backend,alsa_backend,dbus_keyring,dbus_mpris";   ln -fs /usr/share/zoneinfo/Europe/Berlin /etc/localtime;   apt update;   apt -y install   git rustc cargo libasound2-dev libssl-dev pkg-config     portaudio19-dev libdbus-1-dev libpulse-dev libogg-dev;   echo not using git clone -b zeroconf_cache_fix https://github.com/eladyn/spotifyd.git;   echo not using git clone https://github.com/Spotifyd/spotifyd.git;   git clone -b cached_credentials_fix https://github.com/eladyn/spotifyd.git;   cd spotifyd;   cargo build $FEATURES --release;   cargo install $FEATURES --path . --locked;   cp -r target/release/spotifyd ~/.cargo /opt/owntone/;": error while running runtime: exit status 101

[eladyn]

.then_some() should be stable since 1.62.0, so you'd just need to upgrade your toolchain to a more recent version, and it should work. :)

[aanno]

Updated my building hack at https://github.com/aanno/linux-config/tree/master/build-with-docker to build with rustup (instead of the rustc that comes with ubuntu jammy).

Yes, I tested it and it is working as expected. Great work! Thank you very much!

[eladyn]

Thank you!