Logging

You should use the log crate to automatically log to logcat (on-device) or stdout (on-host):

hello_rust_logs/Android.bp:

  1. rust_binary {
  2.     name: "hello_rust_logs",
  3.     crate_name: "hello_rust_logs",
  4.     srcs: ["src/main.rs"],
  5.     rustlibs: [
  6.         "liblog_rust",
  7.         "liblogger",
  8.     ],
  9.     host_supported: true,
  10. }

hello_rust_logs/src/main.rs:

  1. //! Rust logging demo.
  3. use log::{debug, error, info};
  5. /// Logs a greeting.
  6. fn main() {
  7.     logger::init(
  8.         logger::Config::default()
  9.             .with_tag_on_device("rust")
  10.             .with_max_level(log::LevelFilter::Trace),
  11.     );
  12.     debug!("Starting program.");
  13.     info!("Things are going fine.");
  14.     error!("Something went wrong!");
  15. }

Build, push, and run the binary on your device:

  1. m hello_rust_logs
  2. adb push "$ANDROID_PRODUCT_OUT/system/bin/hello_rust_logs" /data/local/tmp
  3. adb shell /data/local/tmp/hello_rust_logs

The logs show up in adb logcat:

  1. adb logcat -s rust
  1. 09-08 08:38:32.454  2420  2420 D rust: hello_rust_logs: Starting program.
  2. 09-08 08:38:32.454  2420  2420 I rust: hello_rust_logs: Things are going fine.
  3. 09-08 08:38:32.454  2420  2420 E rust: hello_rust_logs: Something went wrong!
  • The logger implementation in liblogger is only needed in the final binary, if you’re logging from a library you only need the log facade crate.