Change MainThread<T> abstraction

Don't force the internal use of `RefCell<T>`, let the caller place that into
`MainThread<>` manually. This lets us remove the reference to `MainThread<>`
from the definition of `Screen` again and reduces the number of
`assert_is_main_thread()` calls.

Author: mqudsi

src/output.rs

@@ -6,6 +6,7 @@ use crate::env::EnvVar;
 use crate::threads::MainThread;
 use crate::wchar::prelude::*;
 use bitflags::bitflags;
+use std::cell::RefCell;
 use std::ffi::CStr;
 use std::io::{Result, Write};
 use std::os::fd::RawFd;
@@ -444,10 +445,10 @@ impl Outputter {
 
     /// Access the outputter for stdout.
     /// This should only be used from the main thread.
-    pub fn stdoutput() -> &'static MainThread<Outputter> {
-        static STDOUTPUT: MainThread<Outputter> =
-            MainThread::new(Outputter::new_from_fd(libc::STDOUT_FILENO));
-        &STDOUTPUT
+    pub fn stdoutput() -> &'static RefCell<Outputter> {
+        static STDOUTPUT: MainThread<RefCell<Outputter>> =
+            MainThread::new(RefCell::new(Outputter::new_from_fd(libc::STDOUT_FILENO)));
+        STDOUTPUT.get()
     }
 }
 

src/reader.rs

@@ -1902,7 +1902,8 @@ impl ReaderData {
                 perror("tcsetattr"); // return to previous mode
             }
             Outputter::stdoutput()
-                .with_mut(|output| output.set_color(RgbColor::RESET, RgbColor::RESET));
+                .borrow_mut()
+                .set_color(RgbColor::RESET, RgbColor::RESET);
         }
         rls.finished.then(|| zelf.command_line.text().to_owned())
     }
@@ -2941,9 +2942,9 @@ impl ReaderData {
                 el.end_edit_group();
             }
             rl::DisableMouseTracking => {
-                Outputter::stdoutput().with_mut(|outp| {
-                    outp.write_wstr(L!("\x1B[?1000l"));
-                });
+                Outputter::stdoutput()
+                    .borrow_mut()
+                    .write_wstr(L!("\x1B[?1000l"));
             }
             rl::ClearScreenAndRepaint => {
                 self.parser().libdata_mut().pods.is_repaint = true;
@@ -2954,9 +2955,7 @@ impl ReaderData {
                     // and *then* reexecute the prompt and overdraw it.
                     // This removes the flicker,
                     // while keeping the prompt up-to-date.
-                    Outputter::stdoutput().with_mut(|outp| {
-                        outp.write_wstr(&clear);
-                    });
+                    Outputter::stdoutput().borrow_mut().write_wstr(&clear);
                     self.screen.reset_line(/*repaint_prompt=*/ true);
                     self.layout_and_repaint(L!("readline"));
                 }
@@ -3488,9 +3487,9 @@ fn reader_interactive_init(parser: &Parser) {
 
 /// Destroy data for interactive use.
 fn reader_interactive_destroy() {
-    Outputter::stdoutput().with_mut(|outp| {
-        outp.set_color(RgbColor::RESET, RgbColor::RESET);
-    });
+    Outputter::stdoutput()
+        .borrow_mut()
+        .set_color(RgbColor::RESET, RgbColor::RESET);
 }
 
 /// \return whether fish is currently unwinding the stack in preparation to exit.
@@ -3571,9 +3570,9 @@ pub fn reader_write_title(
         let _ = write_loop(&STDOUT_FILENO, &narrow);
     }
 
-    Outputter::stdoutput().with_mut(|outp| {
-        outp.set_color(RgbColor::RESET, RgbColor::RESET);
-    });
+    Outputter::stdoutput()
+        .borrow_mut()
+        .set_color(RgbColor::RESET, RgbColor::RESET);
     if reset_cursor_position && !lst.is_empty() {
         // Put the cursor back at the beginning of the line (issue #2453).
         let _ = write_to_fd(b"\r", STDOUT_FILENO);
@@ -4585,7 +4584,9 @@ fn reader_run_command(parser: &Parser, cmd: &wstr) -> EvalRes {
     }
 
     reader_write_title(cmd, parser, true);
-    Outputter::stdoutput().with_mut(|outp| outp.set_color(RgbColor::NORMAL, RgbColor::NORMAL));
+    Outputter::stdoutput()
+        .borrow_mut()
+        .set_color(RgbColor::NORMAL, RgbColor::NORMAL);
     term_donate(false);
 
     let time_before = Instant::now();

src/screen.rs

@@ -8,7 +8,7 @@
 //! of text around to handle text insertion.
 
 use crate::pager::{PageRendering, Pager};
-use crate::threads::MainThread;
+use std::cell::RefCell;
 use std::collections::LinkedList;
 use std::ffi::{CStr, CString};
 use std::io::Write;
@@ -177,7 +177,7 @@ pub struct Screen {
     pub autosuggestion_is_truncated: bool,
 
     /// Receiver for our output.
-    outp: &'static MainThread<Outputter>,
+    outp: &'static RefCell<Outputter>,
 
     /// The internal representation of the desired screen contents.
     desired: ScreenData,
@@ -638,9 +638,9 @@ impl Screen {
             // Either issue a cr to go back to the beginning of this line, or a nl to go to the
             // beginning of the next one, depending on what we think is more efficient.
             if new_y <= zelf.actual.cursor.y {
-                zelf.outp.with_mut(|outp| outp.push(b'\r'));
+                zelf.outp.borrow_mut().push(b'\r');
             } else {
-                zelf.outp.with_mut(|outp| outp.push(b'\n'));
+                zelf.outp.borrow_mut().push(b'\n');
                 zelf.actual.cursor.y += 1;
             }
             // Either way we're not in the first column.
@@ -674,16 +674,14 @@ impl Screen {
             None
         };
 
-        zelf.outp.with_mut(|outp| {
-            for _ in 0..y_steps.abs_diff(0) {
-                outp.tputs_if_some(&s);
-            }
-        });
+        for _ in 0..y_steps.abs_diff(0) {
+            zelf.outp.borrow_mut().tputs_if_some(&s);
+        }
 
         let mut x_steps =
             isize::try_from(new_x).unwrap() - isize::try_from(zelf.actual.cursor.x).unwrap();
         if x_steps != 0 && new_x == 0 {
-            zelf.outp.with_mut(|outp| outp.push(b'\r'));
+            zelf.outp.borrow_mut().push(b'\r');
             x_steps = 0;
         }
 
@@ -703,10 +701,10 @@ impl Screen {
                 multi_str.as_ref().unwrap(),
                 i32::try_from(x_steps.abs_diff(0)).unwrap(),
             );
-            zelf.outp.with_mut(|outp| outp.tputs_if_some(&multi_param));
+            zelf.outp.borrow_mut().tputs_if_some(&multi_param);
         } else {
             for _ in 0..x_steps.abs_diff(0) {
-                zelf.outp.with_mut(|outp| outp.tputs_if_some(&s));
+                zelf.outp.borrow_mut().tputs_if_some(&s);
             }
         }
 
@@ -718,7 +716,7 @@ impl Screen {
     fn write_char(&mut self, c: char, width: isize) {
         let mut zelf = self.scoped_buffer();
         zelf.actual.cursor.x = zelf.actual.cursor.x.wrapping_add(width as usize);
-        zelf.outp.with_mut(|outp| outp.writech(c));
+        zelf.outp.borrow_mut().writech(c);
         if Some(zelf.actual.cursor.x) == zelf.actual.screen_width && allow_soft_wrap() {
             zelf.soft_wrap_location = Some(Cursor {
                 x: 0,
@@ -735,16 +733,16 @@ impl Screen {
 
     /// Send the specified string through tputs and append the output to the screen's outputter.
     fn write_mbs(&mut self, s: &CStr) {
-        self.outp.with_mut(|outp| outp.tputs(s));
+        self.outp.borrow_mut().tputs(s);
     }
 
     fn write_mbs_if_some(&mut self, s: &Option<impl AsRef<CStr>>) -> bool {
-        self.outp.with_mut(|outp| outp.tputs_if_some(s))
+        self.outp.borrow_mut().tputs_if_some(s)
     }
 
     /// Convert a wide string to a multibyte string and append it to the buffer.
     fn write_str(&mut self, s: &wstr) {
-        self.outp.with_mut(|outp| outp.write_wstr(s));
+        self.outp.borrow_mut().write_wstr(s);
     }
 
     /// Update the cursor as if soft wrapping had been performed.
@@ -769,9 +767,9 @@ impl Screen {
     }
 
     fn scoped_buffer(&mut self) -> impl ScopeGuarding<Target = &mut Screen> {
-        self.outp.with_mut(Outputter::begin_buffering);
+        self.outp.borrow_mut().begin_buffering();
         ScopeGuard::new(self, |zelf| {
-            zelf.outp.with_mut(Outputter::end_buffering);
+            zelf.outp.borrow_mut().end_buffering();
         })
     }
 
@@ -782,7 +780,7 @@ impl Screen {
         let mut set_color = |zelf: &mut Self, c| {
             let fg = color_resolver.resolve_spec(&c, false, vars);
             let bg = color_resolver.resolve_spec(&c, true, vars);
-            zelf.outp.with_mut(|outp| outp.set_color(fg, bg));
+            zelf.outp.borrow_mut().set_color(fg, bg);
         };
 
         let mut cached_layouts = LAYOUT_CACHE_SHARED.lock().unwrap();
@@ -837,9 +835,9 @@ impl Screen {
             let mut start = 0;
             for line_break in left_prompt_layout.line_breaks {
                 zelf.write_str(&left_prompt[start..line_break]);
-                zelf.outp.with_mut(|outp| {
-                    outp.tputs_if_some(&term.and_then(|term| term.clr_eol.as_ref()));
-                });
+                zelf.outp
+                    .borrow_mut()
+                    .tputs_if_some(&term.and_then(|term| term.clr_eol.as_ref()));
                 start = line_break;
             }
             zelf.write_str(&left_prompt[start..]);
@@ -1071,9 +1069,9 @@ impl Screen {
 
 /// Issues an immediate clr_eos.
 pub fn screen_force_clear_to_end() {
-    Outputter::stdoutput().with_mut(|outp| {
-        outp.tputs_if_some(&term().unwrap().clr_eos);
-    });
+    Outputter::stdoutput()
+        .borrow_mut()
+        .tputs_if_some(&term().unwrap().clr_eos);
 }
 
 /// Information about the layout of a prompt.

src/threads.rs

@@ -4,7 +4,6 @@
 use crate::flog::{FloggableDebug, FLOG};
 use crate::reader::ReaderData;
 use once_cell::race::OnceBox;
-use std::cell::RefCell;
 use std::marker::PhantomData;
 use std::num::NonZeroU64;
 use std::sync::atomic::{AtomicBool, Ordering};
@@ -363,7 +362,7 @@ impl ThreadPool {
 /// A `Sync` and `Send` wrapper for non-`Sync`/`Send` types.
 /// Only allows access from the main thread.
 pub struct MainThread<T> {
-    data: RefCell<T>,
+    data: T,
     // Make type !Send and !Sync by default
     _marker: PhantomData<*const ()>,
 }
@@ -376,25 +375,14 @@ unsafe impl<T: 'static> Sync for MainThread<T> {}
 impl<T> MainThread<T> {
     pub const fn new(value: T) -> Self {
         Self {
-            data: RefCell::new(value),
+            data: value,
             _marker: PhantomData,
         }
     }
 
-    pub fn with<F, R>(&self, f: F) -> R
-    where
-        F: FnOnce(&T) -> R,
-    {
-        assert_is_main_thread();
-        f(&self.data.borrow())
-    }
-
-    pub fn with_mut<F, R>(&self, f: F) -> R
-    where
-        F: FnOnce(&mut T) -> R,
-    {
+    pub fn get(&self) -> &T {
         assert_is_main_thread();
-        f(&mut self.data.borrow_mut())
+        &self.data
     }
 }