Refactor filter model from Context->Response into ref mut Context

docs/src/filters/writing_custom_filters.md

@@ -40,13 +40,13 @@ sent to a downstream client.
 use quilkin::filters::prelude::*;
 
 impl Filter for Greet {
-    fn read(&self, mut ctx: ReadContext) -> Option<ReadResponse> {
+    fn read(&self, ctx: &mut ReadContext) -> Option<()> {
         ctx.contents.extend(b"Hello");
-        Some(ctx.into())
+        Some(())
     }
-    fn write(&self, mut ctx: WriteContext) -> Option<WriteResponse> {
+    fn write(&self, ctx: &mut WriteContext) -> Option<()> {
         ctx.contents.extend(b"Goodbye");
-        Some(ctx.into())
+        Some(())
     }
 }
 ```

examples/quilkin-filter-example/src/main.rs

@@ -58,15 +58,15 @@ struct Greet {
 }
 
 impl Filter for Greet {
-    fn read(&self, mut ctx: ReadContext) -> Option<ReadResponse> {
+    fn read(&self, ctx: &mut ReadContext) -> Option<()> {
         ctx.contents
             .splice(0..0, format!("{} ", self.config.greeting).into_bytes());
-        Some(ctx.into())
+        Some(())
     }
-    fn write(&self, mut ctx: WriteContext) -> Option<WriteResponse> {
+    fn write(&self, ctx: &mut WriteContext) -> Option<()> {
         ctx.contents
             .splice(0..0, format!("{} ", self.config.greeting).into_bytes());
-        Some(ctx.into())
+        Some(())
     }
 }
 // ANCHOR_END: filter

src/config/slot.rs

@@ -186,11 +186,11 @@ impl<T: JsonSchema + Default> JsonSchema for Slot<T> {
 }
 
 impl<T: crate::filters::Filter + Default> crate::filters::Filter for Slot<T> {
-    fn read(&self, ctx: ReadContext) -> Option<ReadResponse> {
+    fn read(&self, ctx: &mut ReadContext) -> Option<()> {
         self.load().read(ctx)
     }
 
-    fn write(&self, ctx: WriteContext) -> Option<WriteResponse> {
+    fn write(&self, ctx: &mut WriteContext) -> Option<()> {
         self.load().write(ctx)
     }
 }

src/filters.rs

@@ -43,7 +43,7 @@ pub mod token_router;
 pub mod prelude {
     pub use super::{
         ConvertProtoConfigError, CreateFilterArgs, Error, Filter, FilterInstance, ReadContext,
-        ReadResponse, StaticFilter, WriteContext, WriteResponse,
+        StaticFilter, WriteContext,
     };
 }
 
@@ -62,12 +62,12 @@ pub use self::{
     local_rate_limit::LocalRateLimit,
     pass::Pass,
     r#match::Match,
-    read::{ReadContext, ReadResponse},
+    read::ReadContext,
     registry::FilterRegistry,
     set::{FilterMap, FilterSet},
     timestamp::Timestamp,
     token_router::TokenRouter,
-    write::{WriteContext, WriteResponse},
+    write::WriteContext,
 };
 
 pub(crate) use self::chain::FilterChain;
@@ -83,13 +83,13 @@ pub(crate) use self::chain::FilterChain;
 /// struct Greet;
 ///
 /// impl Filter for Greet {
-///     fn read(&self, mut ctx: ReadContext) -> Option<ReadResponse> {
+///     fn read(&self, ctx: &mut ReadContext) -> Option<()> {
 ///         ctx.contents.splice(0..0, b"Hello ".into_iter().copied());
-///         Some(ctx.into())
+///         Some(())
 ///     }
-///     fn write(&self, mut ctx: WriteContext) -> Option<WriteResponse> {
+///     fn write(&self, ctx: &mut WriteContext) -> Option<()> {
 ///         ctx.contents.splice(0..0, b"Goodbye ".into_iter().copied());
-///         Some(ctx.into())
+///         Some(())
 ///     }
 /// }
 ///
@@ -194,23 +194,20 @@ pub trait Filter: Send + Sync {
     /// [`Filter::read`] is invoked when the proxy receives data from a
     /// downstream connection on the listening port.
     ///
-    /// This function should return a [`ReadResponse`] containing the array of
-    /// endpoints that the packet should be sent to and the packet that should
-    /// be sent (which may be manipulated) as well. If the packet should be
-    /// rejected, return [`None`].  By default, the context passes
-    /// through unchanged.
-    fn read(&self, ctx: ReadContext) -> Option<ReadResponse> {
-        Some(ctx.into())
+    /// This function should return an `Some` if the packet processing should
+    /// proceed. If the packet should be rejected, it will return [`None`]
+    /// instead. By default, the context passes through unchanged.
+    fn read(&self, _: &mut ReadContext) -> Option<()> {
+        Some(())
     }
 
     /// [`Filter::write`] is invoked when the proxy is about to send data to a
     /// downstream connection via the listening port after receiving it via one
     /// of the upstream Endpoints.
     ///
-    /// This function should return an [`WriteResponse`] containing the packet to
-    /// be sent (which may be manipulated). If the packet should be rejected,
-    /// return [`None`]. By default, the context passes through unchanged.
-    fn write(&self, ctx: WriteContext) -> Option<WriteResponse> {
-        Some(ctx.into())
+    /// This function should return an `Some` if the packet processing should
+    /// proceed. If the packet should be rejected, it will return [`None`]
+    fn write(&self, _: &mut WriteContext) -> Option<()> {
+        Some(())
     }
 }

src/filters/capture.rs

@@ -61,15 +61,15 @@ impl Capture {
 
 impl Filter for Capture {
     #[cfg_attr(feature = "instrument", tracing::instrument(skip(self, ctx)))]
-    fn read(&self, mut ctx: ReadContext) -> Option<ReadResponse> {
+    fn read(&self, ctx: &mut ReadContext) -> Option<()> {
         let capture = self.capture.capture(&mut ctx.contents, &self.metrics);
         ctx.metadata
             .insert(self.is_present_key.clone(), Value::Bool(capture.is_some()));
 
         if let Some(value) = capture {
             tracing::trace!(key=&**self.metadata_key, %value, "captured value");
             ctx.metadata.insert(self.metadata_key.clone(), value);
-            Some(ctx.into())
+            Some(())
         } else {
             tracing::trace!(key = &**self.metadata_key, "No value captured");
             None
@@ -163,13 +163,14 @@ mod tests {
         };
         let filter = Capture::from_config(config.into());
         let endpoints = vec![Endpoint::new("127.0.0.1:81".parse().unwrap())];
-        let response = filter.read(ReadContext::new(
-            endpoints,
-            (std::net::Ipv4Addr::LOCALHOST, 80).into(),
-            "abc".to_string().into_bytes(),
-        ));
+        assert!(filter
+            .read(&mut ReadContext::new(
+                endpoints,
+                (std::net::Ipv4Addr::LOCALHOST, 80).into(),
+                "abc".to_string().into_bytes(),
+            ))
+            .is_none());
 
-        assert!(response.is_none());
         let count = filter.metrics.packets_dropped_total.get();
         assert_eq!(1, count);
     }
@@ -243,21 +244,21 @@ mod tests {
         F: Filter + ?Sized,
     {
         let endpoints = vec![Endpoint::new("127.0.0.1:81".parse().unwrap())];
-        let response = filter
-            .read(ReadContext::new(
-                endpoints,
-                "127.0.0.1:80".parse().unwrap(),
-                "helloabc".to_string().into_bytes(),
-            ))
-            .unwrap();
+        let mut context = ReadContext::new(
+            endpoints,
+            "127.0.0.1:80".parse().unwrap(),
+            "helloabc".to_string().into_bytes(),
+        );
+
+        filter.read(&mut context).unwrap();
 
         if remove {
-            assert_eq!(b"hello".to_vec(), response.contents);
+            assert_eq!(b"hello", &*context.contents);
         } else {
-            assert_eq!(b"helloabc".to_vec(), response.contents);
+            assert_eq!(b"helloabc", &*context.contents);
         }
 
-        let token = response
+        let token = context
             .metadata
             .get(&Arc::new(key.into()))
             .unwrap()