Add RawJson implementor for ToObjectRef

Motivation explained in #1389

Depends on #1393 to ease reflector bounds

Signed-off-by: SOFe <[email protected]>

kube-runtime/Cargo.toml

@@ -42,7 +42,7 @@ tokio = { workspace = true, features = ["time"] }
 tokio-util = { workspace = true, features = ["time"] }
 tracing.workspace = true
 json-patch.workspace = true
-serde_json.workspace = true
+serde_json = { workspace = true, features = ["raw_value"] }
 thiserror.workspace = true
 backoff.workspace = true
 async-trait.workspace = true

kube-runtime/src/lib.rs

@@ -22,6 +22,7 @@ pub mod controller;
 pub mod events;
 
 pub mod finalizer;
+pub mod raw_json;
 pub mod reflector;
 pub mod scheduler;
 pub mod utils;
@@ -30,6 +31,7 @@ pub mod watcher;
 
 pub use controller::{applier, Config, Controller};
 pub use finalizer::finalizer;
+pub use raw_json::RawJson;
 pub use reflector::reflector;
 pub use scheduler::scheduler;
 pub use utils::WatchStreamExt;

kube-runtime/src/raw_json.rs

@@ -0,0 +1,304 @@
+//! Utilities for dynamic objects represented in raw JSON.
+
+use std::{borrow::Cow, convert::Infallible, fmt, num::NonZeroU32, ops::Index};
+
+use kube_client::discovery::ApiResource;
+use serde_json::value::RawValue;
+
+use crate::reflector;
+
+/// The offsets of a string value within a JSON buffer.
+#[derive(Clone, Copy)]
+pub struct StrOffset {
+    /// The starting offset.
+    ///
+    /// This value is always positive since a string must start with a `"` first.
+    ///
+    /// `buffer[start]` may be out-of-bounds if `start == end`.
+    start: NonZeroU32,
+    /// The exclusive ending offset.
+    ///
+    /// This value is always positive since a string must start with a `"` first.
+    end: NonZeroU32,
+}
+
+impl StrOffset {
+    /// Converts a substring slice into string offsets within the buffer.
+    ///
+    /// This function is purely arithmetic and O(1).
+    #[allow(clippy::missing_panics_doc)] // cannot panic
+    #[must_use]
+    pub fn new(buffer: &str, substr: &str) -> Option<Self> {
+        if substr.is_empty() {
+            return Some(Self {
+                start: NonZeroU32::new(1).expect("1 != 0"),
+                end: NonZeroU32::new(1).expect("1 != 0"),
+            });
+        }
+
+        let start = substr.as_ptr() as isize - buffer.as_ptr() as isize;
+        let end = usize::try_from(start).ok()?.checked_add(substr.len())?;
+
+        let start = NonZeroU32::new(u32::try_from(start).ok()?)?;
+        let end = NonZeroU32::new(u32::try_from(end).ok()?)?;
+        Some(Self { start, end })
+    }
+}
+
+impl Index<StrOffset> for str {
+    type Output = str;
+
+    fn index(&self, index: StrOffset) -> &str {
+        &self[index.start.get() as usize..index.end.get() as usize]
+    }
+}
+
+/// A dynamic object represented in raw JSON that can be used in [`reflector`](crate::reflector).
+///
+/// Offsets of certain required fields are cached for efficient interaction with caches.
+pub struct RawJson<X> {
+    ref_fields: ObjectRefFields,
+    /// Extra data to cache from the object.
+    pub extra: X,
+    /// The raw JSON data.
+    pub buffer: Box<RawValue>,
+}
+
+struct ObjectRefFields {
+    namespace: Option<StrOffset>,
+    name: StrOffset,
+    resource_version: StrOffset,
+    uid: StrOffset,
+}
+
+/// Extra data to store within a [`RawJson`] object.
+pub trait Extra: Sized + 'static {
+    /// Extra data to parse from the raw root.
+    type Root<'a>: Sized;
+    /// Extra data to parse from the raw meta.
+    type Meta<'a>: Sized;
+
+    /// The type of error returned when [`new`] fails.
+    type Error: fmt::Display;
+
+    /// Constructs this type from the two parsed parts.
+    ///
+    /// # Errors
+    /// Returns `Err` if the `root` or `meta` contains invalid data.
+    fn new(buffer: &str, root: Self::Root<'_>, meta: Self::Meta<'_>) -> Result<Self, Self::Error>;
+}
+
+#[allow(clippy::missing_fields_in_debug)] // All fields are actually included
+impl<X: fmt::Debug> fmt::Debug for RawJson<X> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("RawJson")
+            .field("namespace", &self.namespace())
+            .field("name", &self.name())
+            .field("resource_version", &self.resource_version())
+            .field("uid", &self.uid())
+            .field("extra", &self.extra)
+            .field("buffer", &&*self.buffer)
+            .finish()
+    }
+}
+
+impl<X> RawJson<X> {
+    /// Namespace of this object.
+    pub fn namespace(&self) -> Option<&str> {
+        self.ref_fields.namespace.map(|offset| &self.buffer.get()[offset])
+    }
+
+    /// Name of this object.
+    pub fn name(&self) -> &str {
+        &self.buffer.get()[self.ref_fields.name]
+    }
+
+    /// Resource version of this object.
+    pub fn resource_version(&self) -> &str {
+        &self.buffer.get()[self.ref_fields.resource_version]
+    }
+
+    /// UID of this object.
+    pub fn uid(&self) -> &str {
+        &self.buffer.get()[self.ref_fields.uid]
+    }
+}
+
+impl<X> serde::Serialize for RawJson<X> {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        self.buffer.serialize(serializer)
+    }
+}
+
+impl<'de, X: Extra> serde::Deserialize<'de> for RawJson<X>
+where
+    for<'de2> X::Meta<'de2>: serde::Deserialize<'de2>,
+    for<'de2> X::Root<'de2>: serde::Deserialize<'de2>,
+{
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        #[derive(serde::Deserialize)]
+        struct Obj<'a, MetaX, RootX> {
+            #[serde(borrow)]
+            metadata: Metadata<'a, MetaX>,
+
+            #[serde(flatten)]
+            root_extra: RootX,
+        }
+        #[derive(serde::Deserialize)]
+        struct Metadata<'a, MetaX> {
+            namespace: Option<&'a str>,
+            name: &'a str,
+            #[serde(rename = "resourceVersion")]
+            resource_version: &'a str,
+            uid: &'a str,
+
+            #[serde(flatten)]
+            meta_extra: MetaX,
+        }
+
+        fn convert<'de, D: serde::Deserializer<'de>>(
+            buffer: &RawValue,
+            substr: &str,
+        ) -> Result<StrOffset, D::Error> {
+            StrOffset::new(buffer.get(), substr)
+                .ok_or_else(|| <D::Error as serde::de::Error>::custom("field not a substring of buffer"))
+        }
+
+        let buffer: Box<RawValue> = <_>::deserialize(deserializer)?;
+
+        let (ref_fields, extra) = {
+            let Obj::<'_, X::Meta<'_>, X::Root<'_>> { metadata, root_extra } =
+                Obj::deserialize(&*buffer).map_err(<D::Error as serde::de::Error>::custom)?;
+
+            let namespace = match metadata.namespace {
+                None => None,
+                Some(substr) => Some(convert::<D>(&buffer, substr)?),
+            };
+            let name = convert::<D>(&buffer, metadata.name)?;
+            let resource_version = convert::<D>(&buffer, metadata.resource_version)?;
+            let uid = convert::<D>(&buffer, metadata.uid)?;
+
+            (
+                ObjectRefFields {
+                    namespace,
+                    name,
+                    resource_version,
+                    uid,
+                },
+                X::new(buffer.get(), root_extra, metadata.meta_extra)
+                    .map_err(<D::Error as serde::de::Error>::custom)?,
+            )
+        };
+
+        Ok(Self {
+            ref_fields,
+            extra,
+            buffer,
+        })
+    }
+}
+
+impl<X> reflector::Lookup for RawJson<X> {
+    type DynamicType = ApiResource;
+
+    fn kind(dyntype: &Self::DynamicType) -> Cow<'_, str> {
+        dyntype.kind.as_str().into()
+    }
+
+    fn version(dyntype: &Self::DynamicType) -> Cow<'_, str> {
+        dyntype.version.as_str().into()
+    }
+
+    fn group(dyntype: &Self::DynamicType) -> Cow<'_, str> {
+        dyntype.group.as_str().into()
+    }
+
+    fn plural(dyntype: &Self::DynamicType) -> Cow<'_, str> {
+        dyntype.plural.as_str().into()
+    }
+
+    fn name(&self) -> Option<Cow<'_, str>> {
+        Some(Cow::Borrowed(RawJson::name(self)))
+    }
+
+    fn namespace(&self) -> Option<Cow<'_, str>> {
+        RawJson::namespace(self).map(Cow::Borrowed)
+    }
+
+    fn resource_version(&self) -> Option<Cow<'_, str>> {
+        Some(Cow::Borrowed(RawJson::resource_version(self)))
+    }
+
+    fn uid(&self) -> Option<Cow<'_, str>> {
+        Some(Cow::Borrowed(RawJson::uid(self)))
+    }
+}
+
+/// The base [`Extra`] implementor that does not store any extra data.
+impl Extra for () {
+    type Error = Infallible;
+    type Meta<'a> = ();
+    type Root<'a> = ();
+
+    fn new(_: &str, (): Self::Root<'_>, (): Self::Meta<'_>) -> Result<Self, Self::Error> {
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::raw_json::{Extra, RawJson, StrOffset};
+
+    struct AppLabelExtra(StrOffset);
+    #[derive(serde::Deserialize)]
+    struct AppLabelMeta<'a> {
+        #[serde(borrow)]
+        labels: AppLabels<'a>,
+    }
+    #[derive(serde::Deserialize)]
+    struct AppLabels<'a> {
+        app: &'a str,
+    }
+
+    impl Extra for AppLabelExtra {
+        type Error = &'static str;
+        type Meta<'a> = AppLabelMeta<'a>;
+        type Root<'a> = ();
+
+        fn new(buffer: &str, (): Self::Root<'_>, meta: Self::Meta<'_>) -> Result<Self, &'static str> {
+            Ok(Self(
+                StrOffset::new(buffer, meta.labels.app).ok_or("field not a substring of buffer")?,
+            ))
+        }
+    }
+
+    #[test]
+    fn test_deser_configmap() {
+        let object = r#"{
+            "apiVersion": "v1",
+            "kind": "ConfigMap",
+            "metadata": {
+                "namespace": "default",
+                "name": "foo",
+                "resourceVersion": "1",
+                "uid": "00000000-0000-0000-0000-000000000000",
+                "labels": {"app": "bar"}
+            },
+            "items": {}
+        }"#;
+
+        let raw: RawJson<AppLabelExtra> = serde_json::from_str(object).unwrap();
+        assert_eq!(raw.namespace(), Some("default"));
+        assert_eq!(raw.name(), "foo");
+        assert_eq!(raw.resource_version(), "1");
+        assert_eq!(raw.uid(), "00000000-0000-0000-0000-000000000000");
+        assert_eq!(&raw.buffer.get()[raw.extra.0], "bar");
+        assert_eq!(raw.buffer.get(), object);
+    }
+}