cli: hide cursor during progress display

src/progress.rs

@@ -4,12 +4,14 @@ use std::time::{Duration, Instant};
 use crossterm::terminal::{Clear, ClearType};
 use jujutsu_lib::git;
 
+use crate::cleanup_guard::CleanupGuard;
 use crate::ui::Ui;
 
 pub struct Progress {
     next_print: Instant,
     rate: RateEstimate,
     buffer: String,
+    guard: Option<CleanupGuard>,
 }
 
 impl Progress {
@@ -18,6 +20,7 @@ impl Progress {
             next_print: now + INITIAL_DELAY,
             rate: RateEstimate::new(),
             buffer: String::new(),
+            guard: None,
         }
     }
 
@@ -40,6 +43,14 @@ impl Progress {
         if now < self.next_print {
             return Ok(());
         }
+        if self.guard.is_none() {
+            let guard = self.ui.output_guard(crossterm::cursor::Show.to_string());
+            let guard = CleanupGuard::new(move || {
+                drop(guard);
+            });
+            _ = write!(self.ui, "{}", crossterm::cursor::Hide);
+            self.guard = Some(guard);
+        }
         self.next_print = now.min(self.next_print + Duration::from_secs(1) / UPDATE_HZ);
 
         self.buffer.clear();

src/ui.rs

@@ -234,8 +234,30 @@ impl Ui {
     pub fn size(&self) -> Option<(u16, u16)> {
         crossterm::terminal::size().ok()
     }
+
+    /// Construct a guard object which writes `data` when dropped. Useful for
+    /// restoring terminal state.
+    pub fn output_guard(&self, text: String) -> OutputGuard {
+        OutputGuard {
+            text,
+            output: match self.output_pair {
+                UiOutputPair::Terminal { .. } => io::stdout(),
+            },
+        }
+    }
 }
 
 enum UiOutputPair {
     Terminal { stdout: Stdout, stderr: Stderr },
 }
+
+pub struct OutputGuard {
+    text: String,
+    output: Stdout,
+}
+
+impl Drop for OutputGuard {
+    fn drop(&mut self) {
+        _ = self.output.write_all(self.text.as_bytes());
+    }
+}