Put everything in Context behind the same Mutex (#1050)

* Move all interior mutability from Context to CtxRef and make it a handle
* Rename `CtxRef` to `Context`
* The old `Context` is now `ContextImpl` and is non-pub
* Add benchmark Painter::rect

Co-authored-by: Daniel Keller <dklr433@gmail.com>

epaint/src/mutex.rs

@@ -114,10 +114,10 @@ mod mutex_impl {
 #[cfg(feature = "multi_threaded")]
 mod rw_lock_impl {
     /// The lock you get from [`RwLock::read`].
-    pub use parking_lot::RwLockReadGuard;
+    pub use parking_lot::MappedRwLockReadGuard as RwLockReadGuard;
 
     /// The lock you get from [`RwLock::write`].
-    pub use parking_lot::RwLockWriteGuard;
+    pub use parking_lot::MappedRwLockWriteGuard as RwLockWriteGuard;
 
     /// Provides interior mutability. Only thread-safe if the `multi_threaded` feature is enabled.
     #[derive(Default)]
@@ -131,16 +131,21 @@ mod rw_lock_impl {
 
         #[inline(always)]
         pub fn read(&self) -> RwLockReadGuard<'_, T> {
-            self.0.read()
+            parking_lot::RwLockReadGuard::map(self.0.read(), |v| v)
         }
 
         #[inline(always)]
         pub fn write(&self) -> RwLockWriteGuard<'_, T> {
-            self.0.write()
+            parking_lot::RwLockWriteGuard::map(self.0.write(), |v| v)
         }
     }
 }
 
+#[cfg(feature = "multi_threaded")]
+mod arc_impl {
+    pub use std::sync::Arc;
+}
+
 // ----------------------------------------------------------------------------
 
 #[cfg(not(feature = "multi_threaded"))]
@@ -201,8 +206,15 @@ mod rw_lock_impl {
     }
 }
 
+#[cfg(not(feature = "multi_threaded"))]
+mod arc_impl {
+    // pub use std::rc::Rc as Arc; // TODO(emilk): optimize single threaded code by using `Rc` instead of `Arc`.
+    pub use std::sync::Arc;
+}
+
 // ----------------------------------------------------------------------------
 
+pub use arc_impl::Arc;
 pub use mutex_impl::{Mutex, MutexGuard};
 pub use rw_lock_impl::{RwLock, RwLockReadGuard, RwLockWriteGuard};
 

epaint/src/shape.rs

@@ -132,7 +132,7 @@ impl Shape {
     }
 
     #[inline]
-    pub fn galley(pos: Pos2, galley: std::sync::Arc<Galley>) -> Self {
+    pub fn galley(pos: Pos2, galley: crate::mutex::Arc<Galley>) -> Self {
         TextShape::new(pos, galley).into()
     }
 
@@ -355,7 +355,7 @@ pub struct TextShape {
     pub pos: Pos2,
 
     /// The layed out text, from [`Fonts::layout_job`].
-    pub galley: std::sync::Arc<Galley>,
+    pub galley: crate::mutex::Arc<Galley>,
 
     /// Add this underline to the whole text.
     /// You can also set an underline when creating the galley.
@@ -373,7 +373,7 @@ pub struct TextShape {
 
 impl TextShape {
     #[inline]
-    pub fn new(pos: Pos2, galley: std::sync::Arc<Galley>) -> Self {
+    pub fn new(pos: Pos2, galley: crate::mutex::Arc<Galley>) -> Self {
         Self {
             pos,
             galley,

epaint/src/text/font.rs

@@ -1,12 +1,11 @@
 use crate::{
-    mutex::{Mutex, RwLock},
+    mutex::{Arc, Mutex, RwLock},
     text::TextStyle,
     TextureAtlas,
 };
 use ahash::AHashMap;
 use emath::{vec2, Vec2};
 use std::collections::BTreeSet;
-use std::sync::Arc;
 
 // ----------------------------------------------------------------------------
 

epaint/src/text/fonts.rs

@@ -1,7 +1,7 @@
-use std::{collections::BTreeMap, sync::Arc};
+use std::collections::BTreeMap;
 
 use crate::{
-    mutex::Mutex,
+    mutex::{Arc, Mutex},
     text::{
         font::{Font, FontImpl},
         Galley, LayoutJob,

epaint/src/text/text_layout.rs

@@ -1,8 +1,7 @@
 use std::ops::RangeInclusive;
-use std::sync::Arc;
 
 use super::{Fonts, Galley, Glyph, LayoutJob, LayoutSection, Row, RowVisuals};
-use crate::{Color32, Mesh, Stroke, Vertex};
+use crate::{mutex::Arc, Color32, Mesh, Stroke, Vertex};
 use emath::*;
 
 /// Temporary storage before line-wrapping.

epaint/src/text/text_layout_types.rs

@@ -1,10 +1,9 @@
 #![allow(clippy::derive_hash_xor_eq)] // We need to impl Hash for f32, but we don't implement Eq, which is fine
 
 use std::ops::Range;
-use std::sync::Arc;
 
 use super::{cursor::*, font::UvRect};
-use crate::{Color32, Mesh, Stroke, TextStyle};
+use crate::{mutex::Arc, Color32, Mesh, Stroke, TextStyle};
 use emath::*;
 
 /// Describes the task of laying out text.