Log encountered errors on shutdown

src/logger.rs

@@ -67,6 +67,30 @@ impl ChatMsg for LogMsg {
     }
 }
 
+/// Prints all error messages when dropped.
+pub struct LoggerGuard {
+    messages: Arc<Mutex<Vec<LogMsg>>>,
+}
+
+impl Drop for LoggerGuard {
+    fn drop(&mut self) {
+        let guard = self.messages.lock();
+        let mut error_encountered = false;
+        for msg in &*guard {
+            if msg.level == Level::Error {
+                if !error_encountered {
+                    eprintln!();
+                    eprintln!("The following errors occurred while cove was running:");
+                    eprintln!();
+                }
+                error_encountered = true;
+                eprintln!("{}", msg.content);
+                eprintln!();
+            }
+        }
+    }
+}
+
 #[derive(Debug, Clone)]
 pub struct Logger {
     event_tx: mpsc::UnboundedSender<()>,
@@ -178,16 +202,19 @@ impl Log for Logger {
 }
 
 impl Logger {
-    pub fn init(level: Level) -> (Self, mpsc::UnboundedReceiver<()>) {
+    pub fn init(level: Level) -> (Self, LoggerGuard, mpsc::UnboundedReceiver<()>) {
         let (event_tx, event_rx) = mpsc::unbounded_channel();
         let logger = Self {
             event_tx,
             messages: Arc::new(Mutex::new(Vec::new())),
         };
+        let guard = LoggerGuard {
+            messages: logger.messages.clone(),
+        };
 
         log::set_boxed_logger(Box::new(logger.clone())).expect("logger already set");
         log::set_max_level(level.to_level_filter());
 
-        (logger, event_rx)
+        (logger, guard, event_rx)
     }
 }

src/main.rs

@@ -32,6 +32,7 @@ use clap::Parser;
 use cookie::CookieJar;
 use directories::{BaseDirs, ProjectDirs};
 use log::info;
+use tokio::sync::mpsc;
 use toss::terminal::Terminal;
 use ui::Ui;
 use vault::Vault;
@@ -117,6 +118,8 @@ fn set_offline(config: &mut Config, args_offline: bool) {
 
 #[tokio::main]
 async fn main() -> anyhow::Result<()> {
+    let (logger, logger_guard, logger_rx) = Logger::init(log::Level::Debug);
+
     let args = Args::parse();
     let dirs = ProjectDirs::from("de", "plugh", "cove").expect("unable to determine directories");
 
@@ -142,7 +145,7 @@ async fn main() -> anyhow::Result<()> {
     };
 
     match args.command.unwrap_or_default() {
-        Command::Run => run(config, &vault, args.measure_widths).await?,
+        Command::Run => run(logger, logger_rx, config, &vault, args.measure_widths).await?,
         Command::Export(args) => export::export(&vault.euph(), args).await?,
         Command::Gc => {
             println!("Cleaning up and compacting vault");
@@ -157,12 +160,22 @@ async fn main() -> anyhow::Result<()> {
 
     vault.close().await;
 
+    // Print all logged errors. This should always happen, even if cove panics,
+    // because the errors may be key in diagnosing what happened. Because of
+    // this, it is not implemented via a normal function call.
+    drop(logger_guard);
+
     println!("Goodbye!");
     Ok(())
 }
 
-async fn run(config: &'static Config, vault: &Vault, measure_widths: bool) -> anyhow::Result<()> {
-    let (logger, logger_rx) = Logger::init(log::Level::Debug);
+async fn run(
+    logger: Logger,
+    logger_rx: mpsc::UnboundedReceiver<()>,
+    config: &'static Config,
+    vault: &Vault,
+    measure_widths: bool,
+) -> anyhow::Result<()> {
     info!(
         "Welcome to {} {}",
         env!("CARGO_PKG_NAME"),
@@ -172,7 +185,7 @@ async fn run(config: &'static Config, vault: &Vault, measure_widths: bool) -> an
     let mut terminal = Terminal::new()?;
     terminal.set_measuring(measure_widths);
     Ui::run(config, &mut terminal, vault.clone(), logger, logger_rx).await?;
-    drop(terminal); // So the vault can print again
+    drop(terminal); // So other things can print again
 
     Ok(())
 }