webgpu: Add a `webgpu_traits` crate (#36320)

This breaks the `script_traits` dependency  on `webgpu`. In general, the
`traits` crates shouldn't depend on Servo non-`traits` crates. This is
necessary to move "script to constellation" messages to the
`constellation_traits` crate, making it the entire API for talking to
the
constellation. This will break a circular dependency when that happens.

Testing: Successfully building is enough of a test for this one as
it is mainly moving types around.

Signed-off-by: Martin Robinson <mrobinson@igalia.com>

Signed-off-by: Martin Robinson <mrobinson@igalia.com>

1 files changed, 97 insertions, 0 deletions

diff --git a/components/shared/webgpu/error.rs b/components/shared/webgpu/error.rs
new file mode 100644
index 00000000000..4669a605840
--- /dev/null
+++ b/components/shared/webgpu/error.rs
@@ -0,0 +1,97 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+//! Error scopes and GPUError types
+
+use std::fmt;
+
+use serde::{Deserialize, Serialize};
+use wgpu_core::device::DeviceError;
+
+/// <https://www.w3.org/TR/webgpu/#gpu-error-scope>
+#[derive(Clone, Debug, Eq, Hash, PartialEq)]
+pub struct ErrorScope {
+    pub errors: Vec<Error>,
+    pub filter: ErrorFilter,
+}
+
+impl ErrorScope {
+    pub fn new(filter: ErrorFilter) -> Self {
+        Self {
+            filter,
+            errors: Vec::new(),
+        }
+    }
+}
+
+/// <https://www.w3.org/TR/webgpu/#enumdef-gpuerrorfilter>
+#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, PartialEq, Serialize)]
+pub enum ErrorFilter {
+    Validation,
+    OutOfMemory,
+    Internal,
+}
+
+/// <https://www.w3.org/TR/webgpu/#gpuerror>
+#[derive(Clone, Debug, Deserialize, Eq, Hash, PartialEq, Serialize)]
+pub enum Error {
+    Validation(String),
+    OutOfMemory(String),
+    Internal(String),
+}
+
+impl std::error::Error for Error {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        None
+    }
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str(self.message())
+    }
+}
+
+impl Error {
+    pub fn filter(&self) -> ErrorFilter {
+        match self {
+            Error::Validation(_) => ErrorFilter::Validation,
+            Error::OutOfMemory(_) => ErrorFilter::OutOfMemory,
+            Error::Internal(_) => ErrorFilter::Internal,
+        }
+    }
+
+    pub fn message(&self) -> &str {
+        match self {
+            Error::Validation(m) => m,
+            Error::OutOfMemory(m) => m,
+            Error::Internal(m) => m,
+        }
+    }
+
+    // TODO: labels
+    // based on https://github.com/gfx-rs/wgpu/blob/trunk/wgpu/src/backend/wgpu_core.rs#L289
+    pub fn from_error<E: std::error::Error + 'static>(error: E) -> Self {
+        let mut source_opt: Option<&(dyn std::error::Error + 'static)> = Some(&error);
+        while let Some(source) = source_opt {
+            if let Some(DeviceError::OutOfMemory) = source.downcast_ref::<DeviceError>() {
+                return Self::OutOfMemory(error.to_string());
+            }
+            source_opt = source.source();
+        }
+        // TODO: This hack is needed because there are
+        // multiple OutOfMemory error variant in wgpu-core
+        // and even upstream does not handle them correctly
+        if format!("{error:?}").contains("OutOfMemory") {
+            return Self::OutOfMemory(error.to_string());
+        }
+        Self::Validation(error.to_string())
+    }
+}
+
+#[derive(Clone, Copy, Debug, Deserialize, Serialize)]
+pub enum PopError {
+    Lost,
+    Empty,
+}