Logging

[dikatok]

Hey, thanks for the awesome tools, how to do logging if I am using FRB to build Flutter package? Tried log::debug! and println! macros, but none are written in the debug console.

[fzyzcjy]

If you are using v2, then by default you can use the log crate. Have you tried log::info! or log::warn!?

[dikatok]

@fzyzcjy yeah, I am using v2, log::info! and log::warn! do not show either

flutter_rust_bridge = "=2.2.0"
hyper-rustls = { version = "0.25", features = ["webpki-roots"] }
lazy_static = "1.5.0"
libsql = "0.5.0"
log = "0.4.22"
tokio = "1.39.2"
uuid = "1.10.0"

This method is the only one needs to be called from flutter right?

#[flutter_rust_bridge::frb(init)]
pub fn init_app() {
    flutter_rust_bridge::setup_default_user_utils();
}

[fzyzcjy]

This method is the only one needs to be called from flutter right?

It is automatically called, so no need to manually call it.

Could you please follow quickstart and create a brand new project and see whether logs works?

[dikatok]

It was actually a brand new project and strictly following the quickstart https://github.com/dikatok/libsql_dart. But will try to create another new project later. Please keep this discussion open 😄

[dikatok]

@fzyzcjy I created a new frb flutter plugin library, put some logs in it, and use it in another new flutter app.

#[flutter_rust_bridge::frb(sync)] // Synchronous mode for simplicity of the demo
pub fn greet(name: String) -> String {
    log::info!("info");
    log::warn!("warn");
    log::debug!("debug");
    log::error!("error");
    format!("Hello, {name}!")
}

None of the logs are printed in the debug console. flutter_rust_bridge_codegen generate is already done after adding the log macros. Are logs in the dependency library supposed to be not printed?

UPDATE Tried tracing with tracing_subscriber yield no result as well.

[fzyzcjy]

Hmm... Firstly, have you tried to create a frb flutter app (instead of library)?

secondly, maybe try to copy the code in setup_default_user_utils and execute manually (more specifically, setup_log_to_console) to try to setup logging.

thirdly, maybe try the underlying mechanism of that logging helper, i.e. call low-level things to directly log to system and see whether it works.

[wxitcode]

This might help you. #2243 (comment)

[patmuk]

Hi,
I could not get logging working - but admittedly I haven't spend much time trying to do so.
@fzyzcjy you mentioned that the setup is described in the quickstart - but I could not find any word about logging there.
It would be good to explicitly describe the simplest way of making logging work, e.g.:

1. add "log = "version number" to cargo.toml
2. implement log statements with the log macros
3. look in console.app, select the simulator on the left, and filter for process "Runner"

just as an example, as this worked with the "workaround", but not anymore after frb v2.3.0 for me.

This could be extended with other use cases, e.g. "forward rust logs to Dart and configure logging from there" and the like.
Once I get logging working I volunteer to make a Doc PR :)

I tried to follow the quickstart guide and create a new project - but I am getting this error. Probably some needed permission in the file system is blocked in my case?

Here is the error I get - but admittedly it is a bit out of scope to this discussion :/ Just want to know if frb create is broken only for me (on an M3 max Mac)

code/own/frb_new_test via ❄️  impure (My-flutter-dev-shell-env) 
› flutter_rust_bridge_codegen create my_app                            
[2024-09-05T14:16:11.434Z INFO frb_codegen/src/library/commands/flutter.rs:23] Execute `flutter create my_app --template app` (this may take a while)
[2024-09-05T14:16:13.837Z INFO frb_codegen/src/library/integration/creator.rs:45] Step: Inject flutter_rust_bridge related code
[2024-09-05T14:16:13.839Z INFO frb_codegen/src/library/integration/integrator.rs:34] Overlay template onto project
[2024-09-05T14:16:13.842Z INFO frb_codegen/src/library/integration/integrator.rs:62] Modify file permissions
Error: No such file or directory (os error 2)

code/own/frb_new_test via ❄️  impure (My-flutter-dev-shell-env) took 2s 
› cd my_app               

own/frb_new_test/my_app is 📦 v1.0.0+1 via 🎯 v3.5.0 via ❄️  impure (My-flutter-dev-shell-env) 
› flutter run 
Launching lib/main.dart on iPhone 15 in debug mode...
Running Xcode build...                                                  
Xcode build done.                                            8.5s
Failed to build iOS app
Error (Xcode): Error: Couldn't resolve the package 'flutter_rust_bridge' in 'package:flutter_rust_bridge/flutter_rust_bridge_for_generated.dart'.


Could not build the application for the simulator.
Error launching application on iPhone 15.

own/frb_new_test/my_app is 📦 v1.0.0+1 via 🎯 v3.5.0 via ❄️  impure (My-flutter-dev-shell-env) took 15s 
› flutter_rust_bridge_codegen generate                                       
[2024-09-05T14:17:23.940Z INFO frb_codegen/src/library/commands/flutter.rs:32] Execute flutter pub add flutter_rust_bridge:2.3.0 (this may take a while)
[4.4s] Parse  
  └── [4.4s] Cargo expand & syn parse  
  └── [0.0s] Parse HIR  
  └── [0.0s] Parse MIR  
[0.0s] Generate  
[2.5s] Polish  
  └── [0.5s] Run Dart formatter  
  └── [0.0s] Run Rust formatter  
  └── [1.9s] Auto upgrade                                                                                                                                       Done!

own/frb_new_test/my_app is 📦 v1.0.0+1 via 🎯 v3.5.0 via ❄️  impure (My-flutter-dev-shell-env) took 8s 
› flutter run                         
Resolving dependencies... 
Downloading packages... 
  collection 1.18.0 (1.19.0 available)
  leak_tracker 10.0.5 (10.0.7 available)
  leak_tracker_flutter_testing 3.0.5 (3.0.8 available)
  material_color_utilities 0.11.1 (0.12.0 available)
  string_scanner 1.2.0 (1.3.0 available)
  test_api 0.7.2 (0.7.3 available)
  vm_service 14.2.4 (14.2.5 available)
Got dependencies!
7 packages have newer versions incompatible with dependency constraints.
Try `flutter pub outdated` for more information.
Launching lib/main.dart on iPhone 15 in debug mode...
Running Xcode build...                                                  
 └─Compiling, linking and signing...                      2,815ms
Xcode build done.                                           12.6s
[ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled Exception: Invalid argument(s): Failed to load dynamic library 'rust_lib_my_app.framework/rust_lib_my_app': dlopen(rust_lib_my_app.framework/rust_lib_my_app, 0x0001): tried: '/Library/Developer/CoreSimulator/Volumes/iOS_21F79/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 17.5.simruntime/Contents/Resources/RuntimeRootrust_lib_my_app.framework/rust_lib_my_app' (no such file), '/Library/Developer/CoreSimulator/Volumes/iOS_21F79/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 17.5.simruntime/Contents/Resources/RuntimeRoot/usr/lib/swift/rust_lib_my_app.framework/rust_lib_my_app' (no such file), '/usr/lib/swift/rust_lib_my_app.framework/rust_lib_my_app' (no such file, not in dyld cache), '/Users/patmuk/Library/Developer/CoreSimulator/Devices/B55F6ACA-3F12-4499-B302-B9FC98C36726/data/Containers/Bundle/Application/C1E4153B-377C-4AEA-979B-829E736DD2DD/Runner.app/Frameworks/rust_lib_my_app.framework/rust_lib_my_app' (no such file), '/us<…>
Syncing files to device iPhone 15...                                76ms

Flutter run key commands.
r Hot reload. 🔥🔥🔥
R Hot restart.
h List all available interactive commands.
d Detach (terminate "flutter run" but leave application running).
c Clear the screen
q Quit (terminate the application on the device).

A Dart VM Service on iPhone 15 is available at: http://127.0.0.1:53294/V29wIEGTkvI=/

Application finished.
  

[patmuk]

I created an own LogRecord as well. Though, on the Dart side the user only sees only the Logging packages LogRecord (which is a bit unintuitive, as Level.Debug doesn't exist (mapped it to Level.CONFIG - but I think it is good to stick to Darts default.

I finished the code, now re-writing the documentation. Next: Move the implementation from the example to frb's Runtime lib. Will ask here if I get stuck doing so :)

@MnlPhlp, please let me know if you implemented something I didn't. For example, I did not implement time stamps, as they are not in rust's log crate's Record structure - and the Dart logger is adding them.

[patmuk]

I just finished the documentation. Feel free to review :)

Next I will rewrite the code so it is in FRB.

[fzyzcjy]

Looks great and looking forward to the PR! Btw you can make a "draft PR" (create a normal PR and choose the draft option), s.t. the diff can be easily seen.

[MnlPhlp]

@MnlPhlp, please let me know if you implemented something I didn't. For example, I did not implement time stamps, as they are not in rust's log crate's Record structure - and the Dart logger is adding them.

The only think that might be interesting to add is a panic handler that sends the logs to dart. Or has this changed in frb and rust panics are shown somewhere by default?
When I used frb I had the problem that when running on android with flutter run and an attached device I did not see panics in rust. That is why flutter_logger has the feature. It is basically just one line:

    #[cfg(feature = "panic")]
    std::panic::set_hook(Box::new(|p| log::error!("panic occured: {p:?}")));

Might be useful to have by default so rust panics don't go unnoticed

[patmuk]

Great, many thanks! Yes, I planned to add that, now I know how :)
FRB has an opinionated logger implementation, which logs to a file. I am currently rewriting this. Here panics are handled as well.