JsonBody does not require Unpin

awc/src/response.rs

@@ -16,6 +16,7 @@ use actix_http::{
 use actix_rt::time::{sleep, Sleep};
 use bytes::{Bytes, BytesMut};
 use futures_core::{ready, Stream};
+use pin_project_lite::pin_project;
 use serde::de::DeserializeOwned;
 
 #[cfg(feature = "cookies")]
@@ -316,27 +317,30 @@ where
     }
 }
 
-/// Response's payload json parser, it resolves to a deserialized `T` value.
-///
-/// Returns error:
-///
-/// * content type is not `application/json`
-/// * content length is greater than 64k
-pub struct JsonBody<S, U> {
-    length: Option<usize>,
-    err: Option<JsonPayloadError>,
-    timeout: ResponseTimeout,
-    fut: Option<ReadBody<S>>,
-    _phantom: PhantomData<U>,
+pin_project! {
+    /// Response's payload json parser, it resolves to a deserialized `T` value.
+    ///
+    /// # Errors
+    /// `Future` implementation returns error if:
+    /// * content type is not `application/json`
+    /// * content length is greater than 64k
+    pub struct JsonBody<B, T> {
+        #[pin]
+        fut: Option<ReadBody<B>>,
+        length: Option<usize>,
+        timeout: ResponseTimeout,
+        err: Option<JsonPayloadError>,
+        _phantom: PhantomData<T>,
+    }
 }
 
-impl<S, U> JsonBody<S, U>
+impl<B, T> JsonBody<B, T>
 where
-    S: Stream<Item = Result<Bytes, PayloadError>>,
-    U: DeserializeOwned,
+    B: Stream<Item = Result<Bytes, PayloadError>>,
+    T: DeserializeOwned,
 {
     /// Create `JsonBody` for request.
-    pub fn new(res: &mut ClientResponse<S>) -> Self {
+    pub fn new(res: &mut ClientResponse<B>) -> Self {
         // check content-type
         let json = if let Ok(Some(mime)) = res.mime_type() {
             mime.subtype() == mime::JSON || mime.suffix() == Some(mime::JSON)
@@ -364,10 +368,10 @@ where
         }
 
         JsonBody {
-            length: len,
-            err: None,
-            timeout: std::mem::take(&mut res.timeout),
             fut: Some(ReadBody::new(res.take_payload(), 65536)),
+            length: len,
+            timeout: std::mem::take(&mut res.timeout),
+            err: None,
             _phantom: PhantomData,
         }
     }
@@ -381,41 +385,37 @@ where
     }
 }
 
-impl<T, U> Unpin for JsonBody<T, U>
+impl<B, T> Future for JsonBody<B, T>
 where
-    T: Stream<Item = Result<Bytes, PayloadError>> + Unpin,
-    U: DeserializeOwned,
+    B: Stream<Item = Result<Bytes, PayloadError>>,
+    T: DeserializeOwned,
 {
-}
+    type Output = Result<T, JsonPayloadError>;
 
-impl<T, U> Future for JsonBody<T, U>
-where
-    T: Stream<Item = Result<Bytes, PayloadError>> + Unpin,
-    U: DeserializeOwned,
-{
-    type Output = Result<U, JsonPayloadError>;
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        let this = self.project();
 
-    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
-        if let Some(err) = self.err.take() {
+        if let Some(err) = this.err.take() {
             return Poll::Ready(Err(err));
         }
 
-        if let Some(len) = self.length.take() {
-            if len > self.fut.as_ref().unwrap().limit {
+        if let Some(len) = this.length.take() {
+            let body = Option::as_ref(&this.fut).unwrap();
+            if len > body.limit {
                 return Poll::Ready(Err(JsonPayloadError::Payload(PayloadError::Overflow)));
             }
         }
 
-        self.timeout
+        this.timeout
             .poll_timeout(cx)
             .map_err(JsonPayloadError::Payload)?;
 
-        let body = ready!(Pin::new(&mut self.get_mut().fut.as_mut().unwrap()).poll(cx))?;
-        Poll::Ready(serde_json::from_slice::<U>(&body).map_err(JsonPayloadError::from))
+        let body = ready!(this.fut.as_pin_mut().unwrap().poll(cx))?;
+        Poll::Ready(serde_json::from_slice::<T>(&body).map_err(JsonPayloadError::from))
     }
 }
 
-pin_project_lite::pin_project! {
+pin_project! {
     struct ReadBody<S> {
         #[pin]
         stream: Payload<S>,
@@ -447,6 +447,7 @@ where
             if (this.buf.len() + chunk.len()) > *this.limit {
                 return Poll::Ready(Err(PayloadError::Overflow));
             }
+
             this.buf.extend_from_slice(&chunk);
         }
 
@@ -460,7 +461,12 @@ mod tests {
     use static_assertions::assert_impl_all;
 
     use super::*;
-    use crate::{http::header, test::TestResponse};
+    use crate::{any_body::AnyBody, http::header, test::TestResponse};
+
+    assert_impl_all!(ReadBody<()>: Unpin);
+    assert_impl_all!(ReadBody<AnyBody>: Unpin);
+
+    assert_impl_all!(JsonBody<BoxedPayloadStream, String>: Unpin);
 
     assert_impl_all!(ClientResponse: Unpin);