From 027a61a48dc1df2be8bf3430844489171204765f Mon Sep 17 00:00:00 2001
From: Anton Lazarev <antonok35@gmail.com>
Date: Thu, 31 Oct 2019 22:08:26 -0700
Subject: [PATCH] return Result instead of panic

---
 examples/triangle/main.c      |  4 ++++
 wgpu-native/src/id.rs         |  2 ++
 wgpu-native/src/swap_chain.rs | 15 +++++++++++----
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/examples/triangle/main.c b/examples/triangle/main.c
index db711c62a6..711508ada5 100644
--- a/examples/triangle/main.c
+++ b/examples/triangle/main.c
@@ -211,6 +211,10 @@ int main() {
 
         WGPUSwapChainOutput next_texture =
             wgpu_swap_chain_get_next_texture(swap_chain);
+        if (!next_texture.view_id) {
+            printf("Cannot acquire next swap chain texture");
+            return 1;
+        }
 
         WGPUCommandEncoderId cmd_encoder = wgpu_device_create_command_encoder(
             device, &(WGPUCommandEncoderDescriptor){.todo = 0});
diff --git a/wgpu-native/src/id.rs b/wgpu-native/src/id.rs
index 839c8521a7..403dd23863 100644
--- a/wgpu-native/src/id.rs
+++ b/wgpu-native/src/id.rs
@@ -16,6 +16,8 @@ type Dummy = crate::backend::Empty;
 pub struct Id<T>(u64, PhantomData<T>);
 
 impl<T> Id<T> {
+    pub const ERROR: Self = Self(0, PhantomData);
+
     pub fn backend(&self) -> Backend {
         match self.0 >> (64 - BACKEND_BITS) as u8 {
             0 => Backend::Empty,
diff --git a/wgpu-native/src/swap_chain.rs b/wgpu-native/src/swap_chain.rs
index d085b3e228..de84ab678a 100644
--- a/wgpu-native/src/swap_chain.rs
+++ b/wgpu-native/src/swap_chain.rs
@@ -128,11 +128,16 @@ pub struct SwapChainOutput {
     pub view_id: TextureViewId,
 }
 
+#[derive(Debug)]
+pub enum SwapChainGetNextTextureError {
+    GpuProcessingTimeout,
+}
+
 pub fn swap_chain_get_next_texture<B: GfxBackend>(
     global: &Global,
     swap_chain_id: SwapChainId,
     view_id_in: Input<TextureViewId>,
-) -> SwapChainOutput {
+) -> Result<SwapChainOutput, SwapChainGetNextTextureError> {
     let hub = B::hub(global);
     let mut token = Token::root();
 
@@ -148,7 +153,7 @@ pub fn swap_chain_get_next_texture<B: GfxBackend>(
         match unsafe { suf.acquire_image(FRAME_TIMEOUT_MS * 1_000_000) } {
             Ok(surface_image) => surface_image,
             Err(hal::window::AcquireError::Timeout) => {
-                panic!("GPU took too much time processing last frames :(");
+                return Err(SwapChainGetNextTextureError::GpuProcessingTimeout);
             }
             Err(e) => {
                 log::warn!("acquire_image() failed ({:?}), reconfiguring swapchain", e);
@@ -197,13 +202,15 @@ pub fn swap_chain_get_next_texture<B: GfxBackend>(
         ref_count,
     });
 
-    SwapChainOutput { view_id }
+    Ok(SwapChainOutput { view_id })
 }
 
 #[cfg(feature = "local")]
 #[no_mangle]
 pub extern "C" fn wgpu_swap_chain_get_next_texture(swap_chain_id: SwapChainId) -> SwapChainOutput {
-    gfx_select!(swap_chain_id => swap_chain_get_next_texture(&*GLOBAL, swap_chain_id, PhantomData))
+    gfx_select!(swap_chain_id => swap_chain_get_next_texture(&*GLOBAL, swap_chain_id, PhantomData)).unwrap_or(SwapChainOutput {
+        view_id: TextureViewId::ERROR,
+    })
 }
 
 pub fn swap_chain_present<B: GfxBackend>(global: &Global, swap_chain_id: SwapChainId) {