[metal] remove extraneous main thread check (#7692)

Author: jamesordner

CHANGELOG.md

@@ -80,6 +80,10 @@ Naga now infers the correct binding layout when a resource appears only in an as
 
 - Get `vertex_index` & `instance_index` builtins working for indirect draws. By @teoxoy in [#7535](https://github.com/gfx-rs/wgpu/pull/7535)
 
+#### Metal
+
+- Remove extraneous main thread warning in `fn surface_capabilities()`. By @jamesordner in [#7692](https://github.com/gfx-rs/wgpu/pull/7692)
+
 ### Changes
 
 - Loosen Viewport validation requirements to match the [new specs](https://github.com/gpuweb/gpuweb/pull/5025). By @ebbdrop in [#7564](https://github.com/gfx-rs/wgpu/pull/7564)

wgpu-hal/src/metal/adapter.rs

@@ -7,7 +7,6 @@ use parking_lot::Mutex;
 use wgt::{AstcBlock, AstcChannel};
 
 use alloc::sync::Arc;
-use std::thread;
 
 use super::TimestampQuerySupport;
 
@@ -342,13 +341,6 @@ impl crate::Adapter for super::Adapter {
         &self,
         surface: &super::Surface,
     ) -> Option<crate::SurfaceCapabilities> {
-        let current_extent = if surface.main_thread_id == thread::current().id() {
-            Some(surface.dimensions())
-        } else {
-            log::warn!("Unable to get the current view dimensions on a non-main thread");
-            None
-        };
-
         let mut formats = vec![
             wgt::TextureFormat::Bgra8Unorm,
             wgt::TextureFormat::Bgra8UnormSrgb,
@@ -380,7 +372,7 @@ impl crate::Adapter for super::Adapter {
                 wgt::CompositeAlphaMode::PostMultiplied,
             ],
 
-            current_extent,
+            current_extent: Some(surface.dimensions()),
             usage: wgt::TextureUses::COLOR_TARGET
                 | wgt::TextureUses::COPY_SRC
                 | wgt::TextureUses::COPY_DST

wgpu-hal/src/metal/mod.rs

@@ -28,7 +28,6 @@ mod time;
 
 use alloc::{borrow::ToOwned as _, string::String, sync::Arc, vec::Vec};
 use core::{fmt, iter, ops, ptr::NonNull, sync::atomic};
-use std::thread;
 
 use arrayvec::ArrayVec;
 use bitflags::bitflags;
@@ -376,7 +375,6 @@ pub struct Surface {
     render_layer: Mutex<metal::MetalLayer>,
     swapchain_format: RwLock<Option<wgt::TextureFormat>>,
     extent: RwLock<wgt::Extent3d>,
-    main_thread_id: thread::ThreadId,
     // Useful for UI-intensive applications that are sensitive to
     // window resizing.
     pub present_with_transaction: bool,

wgpu-hal/src/metal/surface.rs

@@ -3,7 +3,6 @@
 use alloc::borrow::ToOwned as _;
 use core::mem::ManuallyDrop;
 use core::ptr::NonNull;
-use std::thread;
 
 use core_graphics_types::{
     base::CGFloat,
@@ -29,7 +28,6 @@ impl super::Surface {
             render_layer: Mutex::new(layer),
             swapchain_format: RwLock::new(None),
             extent: RwLock::new(wgt::Extent3d::default()),
-            main_thread_id: thread::current().id(),
             present_with_transaction: false,
         }
     }
@@ -109,6 +107,13 @@ impl super::Surface {
         }
     }
 
+    /// Gets the current dimensions of the `Surface`.
+    ///
+    /// This function is safe to call off of the main thread. However, note that
+    /// `bounds` and `contentsScale` may be modified by the main thread while
+    /// this function is running, possibly resulting in the two values being out
+    /// of sync. This is sound, as these properties are accessed atomically.
+    /// See: <https://github.com/gfx-rs/wgpu/pull/7692>
     pub(super) fn dimensions(&self) -> wgt::Extent3d {
         let (size, scale): (CGSize, CGFloat) = unsafe {
             let render_layer_borrow = self.render_layer.lock();