POC synchronized output leveraging work by Funami580

Cargo.toml

@@ -13,7 +13,7 @@ readme = "README.md"
 exclude = ["screenshots/*"]
 
 [dependencies]
-console = { version = "0.15", default-features = false, features = ["ansi-parsing"] }
+console = { git = "https://github.com/chris-laplante/console.git", branch = "cpl/sync-output-drop-guard", default-features = false, features = ["ansi-parsing"] }
 futures-core = { version = "0.3", default-features = false, optional = true }
 number_prefix = "0.4"
 portable-atomic = "1.0.0"

src/draw_target.rs

@@ -472,6 +472,8 @@ impl DrawState {
             return Ok(());
         }
 
+        let sync_guard = term.begin_sync();
+
         if !self.lines.is_empty() && self.move_cursor {
             term.move_cursor_up(last_line_count.as_usize())?;
         } else {
@@ -547,6 +549,9 @@ impl DrawState {
         }
         term.write_str(&" ".repeat(last_line_filler))?;
 
+        // End synchronized update
+        drop(sync_guard);
+
         term.flush()?;
         *last_line_count = real_len - orphan_visual_line_count + shift;
         Ok(())

src/lib.rs

@@ -269,4 +269,4 @@ pub use crate::progress_bar::{ProgressBar, WeakProgressBar};
 pub use crate::rayon::ParallelProgressIterator;
 pub use crate::state::{ProgressFinish, ProgressState};
 pub use crate::style::ProgressStyle;
-pub use crate::term_like::TermLike;
+pub use crate::term_like::{NoOpSyncGuard, SyncGuardLike, TermLike};

src/term_like.rs

@@ -3,6 +3,24 @@ use std::io;
 
 use console::Term;
 
+pub trait SyncGuardLike<'a> {
+    fn finish_sync(self) -> io::Result<()>;
+}
+
+impl<'a> SyncGuardLike<'a> for console::SyncGuard<'a> {
+    fn finish_sync(self) -> io::Result<()> {
+        self.finish_sync()
+    }
+}
+
+pub struct NoOpSyncGuard;
+
+impl<'a> SyncGuardLike<'a> for NoOpSyncGuard {
+    fn finish_sync(self) -> io::Result<()> {
+        Ok(())
+    }
+}
+
 /// A trait for minimal terminal-like behavior.
 ///
 /// Anything that implements this trait can be used a draw target via [`ProgressDrawTarget::term_like`].
@@ -34,6 +52,10 @@ pub trait TermLike: Debug + Send + Sync {
     fn clear_line(&self) -> io::Result<()>;
 
     fn flush(&self) -> io::Result<()>;
+
+    fn begin_sync<'a>(&'a self) -> io::Result<Box<dyn SyncGuardLike<'a> + 'a>> {
+        Ok(Box::new(NoOpSyncGuard))
+    }
 }
 
 impl TermLike for Term {
@@ -76,4 +98,9 @@ impl TermLike for Term {
     fn flush(&self) -> io::Result<()> {
         self.flush()
     }
+
+    fn begin_sync<'a>(&'a self) -> io::Result<Box<dyn SyncGuardLike<'a> + 'a>> {
+        console::SyncGuard::begin_sync(self)
+            .map(|guard| Box::new(guard) as Box<dyn SyncGuardLike<'a>>)
+    }
 }