Support recording swapchain commands from multiple threads

Cargo.lock

@@ -593,6 +593,7 @@ dependencies = [
  "gfx-hal 0.6.0 (git+https://github.com/gfx-rs/gfx)",
  "lazy_static 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.11 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parking_lot 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "renderdoc 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "typed-arena 2.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]

libportability-gfx/Cargo.toml

@@ -23,6 +23,7 @@ copyless = "0.1.1"
 env_logger = { version = "0.7", optional = true }
 lazy_static = "1"
 log = { version = "0.4", features = ["release_max_level_error"] }
+parking_lot = "0.11"
 renderdoc = { version = "0.3", optional = true }
 typed-arena = "2"
 

libportability-gfx/src/impls.rs

@@ -1,3 +1,5 @@
+use super::*;
+
 use hal::{
     adapter::PhysicalDevice,
     buffer::IndexBufferView,
@@ -10,6 +12,9 @@ use hal::{
     {command as com, memory, pass, pso, queue}, {Features, Instance},
 };
 
+use parking_lot::Mutex;
+use typed_arena::Arena;
+
 #[cfg(feature = "gfx-backend-metal")]
 use std::env;
 use std::{
@@ -19,9 +24,6 @@ use std::{
     os::raw::{c_int, c_void},
     ptr, str,
 };
-use typed_arena::Arena;
-
-use super::*;
 
 const VERSION: (u32, u32, u32) = (1, 0, 66);
 const DRIVER_VERSION: u32 = 1;
@@ -3292,16 +3294,20 @@ pub unsafe extern "C" fn gfxBeginCommandBuffer(
     pBeginInfo: *const VkCommandBufferBeginInfo,
 ) -> VkResult {
     let info = &*pBeginInfo;
+    let fb_resolve;
     let inheritance = match info.pInheritanceInfo.as_ref() {
         Some(ii) => com::CommandBufferInheritanceInfo {
             subpass: ii.renderPass.as_ref().map(|rp| pass::Subpass {
                 main_pass: &rp.raw,
                 index: ii.subpass as _,
             }),
-            framebuffer: ii
-                .framebuffer
-                .as_ref()
-                .map(|fbo| fbo.resolve(ii.renderPass)),
+            framebuffer: match ii.framebuffer.as_ref() {
+                Some(fbo) => {
+                    fb_resolve = fbo.resolve(ii.renderPass);
+                    Some(&*fb_resolve)
+                }
+                None => None,
+            },
             occlusion_query_enable: ii.occlusionQueryEnable != VK_FALSE,
             occlusion_query_flags: conv::map_query_control(ii.queryFlags),
             pipeline_statistics: conv::map_pipeline_statistics(ii.pipelineStatistics),
@@ -4110,7 +4116,7 @@ pub unsafe extern "C" fn gfxCmdBeginRenderPass(
 
     commandBuffer.begin_render_pass(
         &info.renderPass.raw,
-        framebuffer,
+        &*framebuffer,
         render_area,
         clear_values,
         contents,
@@ -4375,7 +4381,7 @@ pub unsafe extern "C" fn gfxCreateSwapchainKHR(
                 count: info.minImageCount as u8,
                 current_index: 0,
                 active: None,
-                lazy_framebuffers: Vec::with_capacity(1),
+                lazy_framebuffers: Mutex::new(Vec::with_capacity(1)),
             };
             *pSwapchain = Handle::new(swapchain);
             VkResult::VK_SUCCESS
@@ -4709,7 +4715,7 @@ pub unsafe extern "C" fn gfxQueuePresentKHR(
         } else {
             warn!("Swapchain frame {} is stale, can't be presented.", *index);
         }
-        for framebuffer in sc.lazy_framebuffers.drain(..) {
+        for framebuffer in sc.lazy_framebuffers.lock().drain(..) {
             sc.gpu.device.destroy_framebuffer(framebuffer)
         }
     }

libportability-gfx/src/lib.rs

@@ -39,11 +39,12 @@ mod conv;
 mod handle;
 mod impls;
 
-use crate::back::Backend as B;
-use crate::handle::{DispatchHandle, Handle};
+use crate::{
+    back::Backend as B,
+    handle::{DispatchHandle, Handle},
+};
 
-use std::collections::HashMap;
-use std::slice;
+use std::{collections::HashMap, slice};
 
 pub use crate::impls::*;
 
@@ -157,11 +158,26 @@ pub enum Framebuffer {
     },
 }
 
+enum FramebufferResolve<'a> {
+    Native(&'a <B as hal::Backend>::Framebuffer),
+    Lazy(parking_lot::MappedMutexGuard<'a, <B as hal::Backend>::Framebuffer>),
+}
+
+impl std::ops::Deref for FramebufferResolve<'_> {
+    type Target = <B as hal::Backend>::Framebuffer;
+    fn deref(&self) -> &Self::Target {
+        match *self {
+            FramebufferResolve::Native(fb) => fb,
+            FramebufferResolve::Lazy(ref guard) => &*guard,
+        }
+    }
+}
+
 impl Framebuffer {
-    fn resolve(&self, render_pass: VkRenderPass) -> &<B as hal::Backend>::Framebuffer {
+    fn resolve(&self, render_pass: VkRenderPass) -> FramebufferResolve {
         let mut sc = None;
         match *self {
-            Framebuffer::Native(ref fbo) => fbo,
+            Framebuffer::Native(ref fbo) => FramebufferResolve::Native(fbo),
             Framebuffer::Lazy { extent, ref views } => {
                 for view in views {
                     if let Some(&mut ImageView::SwapchainFrame { ref swapchain, .. }) =
@@ -189,13 +205,19 @@ impl Framebuffer {
 
                 let sc = sc.expect("No swapchain frames detected");
                 let gpu = sc.gpu;
-                sc.lazy_framebuffers.push(unsafe {
-                    use hal::device::Device;
-                    gpu.device
-                        .create_framebuffer(&render_pass.raw, attachments, extent)
-                        .unwrap()
-                });
-                sc.lazy_framebuffers.last().unwrap()
+
+                FramebufferResolve::Lazy(parking_lot::MutexGuard::map(
+                    sc.lazy_framebuffers.lock(),
+                    |lazy_framebuffers| {
+                        lazy_framebuffers.push(unsafe {
+                            use hal::device::Device;
+                            gpu.device
+                                .create_framebuffer(&render_pass.raw, attachments, extent)
+                                .unwrap()
+                        });
+                        lazy_framebuffers.last_mut().unwrap()
+                    },
+                ))
             }
         }
     }
@@ -227,9 +249,7 @@ pub struct Swapchain<B: hal::Backend> {
     count: u8,
     current_index: u8,
     active: Option<<B::Surface as hal::window::PresentationSurface<B>>::SwapchainImage>,
-    // This is totally unsafe: if multiple threads would start recording render passes into
-    // that uses this swapchain, we'd have a race condition.
-    lazy_framebuffers: Vec<<B as hal::Backend>::Framebuffer>,
+    lazy_framebuffers: parking_lot::Mutex<Vec<<B as hal::Backend>::Framebuffer>>,
 }
 
 /* automatically generated by rust-bindgen */