simplify MessageBody::complete_body interface (#2522)

actix-http/src/body/boxed.rs

@@ -8,10 +8,16 @@ use std::{
 use bytes::Bytes;
 
 use super::{BodySize, MessageBody, MessageBodyMapErr};
-use crate::Error;
+use crate::body;
 
 /// A boxed message body with boxed errors.
-pub struct BoxBody(Pin<Box<dyn MessageBody<Error = Box<dyn StdError>>>>);
+pub struct BoxBody(BoxBodyInner);
+
+enum BoxBodyInner {
+    None(body::None),
+    Bytes(Bytes),
+    Stream(Pin<Box<dyn MessageBody<Error = Box<dyn StdError>>>>),
+}
 
 impl BoxBody {
     /// Same as `MessageBody::boxed`.
@@ -23,29 +29,42 @@ impl BoxBody {
     where
         B: MessageBody + 'static,
     {
-        let body = MessageBodyMapErr::new(body, Into::into);
+        match body.size() {
-        Self(Box::pin(body))
+            BodySize::None => Self(BoxBodyInner::None(body::None)),
+            _ => match body.try_into_bytes() {
+                Ok(bytes) => Self(BoxBodyInner::Bytes(bytes)),
+                Err(body) => {
+                    let body = MessageBodyMapErr::new(body, Into::into);
+                    Self(BoxBodyInner::Stream(Box::pin(body)))
+                }
+            },
+        }
     }
 
     /// Returns a mutable pinned reference to the inner message body type.
     #[inline]
-    pub fn as_pin_mut(&mut self) -> Pin<&mut (dyn MessageBody<Error = Box<dyn StdError>>)> {
+    pub fn as_pin_mut(&mut self) -> Pin<&mut Self> {
-        self.0.as_mut()
+        Pin::new(self)
     }
 }
 
 impl fmt::Debug for BoxBody {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        // TODO show BoxBodyInner
         f.write_str("BoxBody(dyn MessageBody)")
     }
 }
 
 impl MessageBody for BoxBody {
-    type Error = Error;
+    type Error = Box<dyn StdError>;
 
     #[inline]
     fn size(&self) -> BodySize {
-        self.0.size()
+        match &self.0 {
+            BoxBodyInner::None(none) => none.size(),
+            BoxBodyInner::Bytes(bytes) => bytes.size(),
+            BoxBodyInner::Stream(stream) => stream.size(),
+        }
     }
 
     #[inline]
@@ -53,20 +72,20 @@ impl MessageBody for BoxBody {
         mut self: Pin<&mut Self>,
         cx: &mut Context<'_>,
     ) -> Poll<Option<Result<Bytes, Self::Error>>> {
-        self.0
+        match &mut self.0 {
-            .as_mut()
+            BoxBodyInner::None(_) => Poll::Ready(None),
-            .poll_next(cx)
+            BoxBodyInner::Bytes(bytes) => Pin::new(bytes).poll_next(cx).map_err(Into::into),
-            .map_err(|err| Error::new_body().with_cause(err))
+            BoxBodyInner::Stream(stream) => Pin::new(stream).poll_next(cx),
+        }
     }
 
     #[inline]
-    fn is_complete_body(&self) -> bool {
+    fn try_into_bytes(self) -> Result<Bytes, Self> {
-        self.0.is_complete_body()
+        match self.0 {
-    }
+            BoxBodyInner::None(none) => Ok(none.try_into_bytes().unwrap()),
-
+            BoxBodyInner::Bytes(bytes) => Ok(bytes.try_into_bytes().unwrap()),
-    #[inline]
+            _ => Err(self),
-    fn take_complete_body(&mut self) -> Bytes {
+        }
-        self.0.take_complete_body()
     }
 
     #[inline]

actix-http/src/body/either.rs

@@ -74,18 +74,14 @@ where
     }
 
     #[inline]
-    fn is_complete_body(&self) -> bool {
+    fn try_into_bytes(self) -> Result<Bytes, Self> {
         match self {
-            EitherBody::Left { body } => body.is_complete_body(),
+            EitherBody::Left { body } => body
-            EitherBody::Right { body } => body.is_complete_body(),
+                .try_into_bytes()
-        }
+                .map_err(|body| EitherBody::Left { body }),
-    }
+            EitherBody::Right { body } => body
-
+                .try_into_bytes()
-    #[inline]
+                .map_err(|body| EitherBody::Right { body }),
-    fn take_complete_body(&mut self) -> Bytes {
-        match self {
-            EitherBody::Left { body } => body.take_complete_body(),
-            EitherBody::Right { body } => body.take_complete_body(),
         }
     }
 

actix-http/src/body/message_body.rs

@@ -31,51 +31,14 @@ pub trait MessageBody {
         cx: &mut Context<'_>,
     ) -> Poll<Option<Result<Bytes, Self::Error>>>;
 
-    /// Returns true if entire body bytes chunk is obtainable in one call to `poll_next`.
+    /// Convert this body into `Bytes`.
     ///
-    /// This method's implementation should agree with [`take_complete_body`] and should always be
+    /// Bodies with `BodySize::None` are allowed to return empty `Bytes`.
-    /// checked before taking the body.
+    fn try_into_bytes(self) -> Result<Bytes, Self>
-    ///
+    where
-    /// The default implementation returns `false.
+        Self: Sized,
-    ///
+    {
-    /// [`take_complete_body`]: MessageBody::take_complete_body
+        Err(self)
-    fn is_complete_body(&self) -> bool {
-        false
-    }
-
-    /// Returns the complete chunk of body bytes.
-    ///
-    /// Implementors of this method should note the following:
-    /// - It is acceptable to skip the omit checks of [`is_complete_body`]. The responsibility of
-    ///   performing this check is delegated to the caller.
-    /// - If the result of [`is_complete_body`] is conditional, that condition should be given
-    ///   equivalent attention here.
-    /// - A second call call to [`take_complete_body`] should return an empty `Bytes` or panic.
-    /// - A call to [`poll_next`] after calling [`take_complete_body`] should return `None` unless
-    ///   the chunk is guaranteed to be empty.
-    ///
-    /// The default implementation panics unconditionally, indicating a control flow bug in the
-    /// calling code.
-    ///
-    /// # Panics
-    /// With a correct implementation, panics if called without first checking [`is_complete_body`].
-    ///
-    /// [`is_complete_body`]: MessageBody::is_complete_body
-    /// [`take_complete_body`]: MessageBody::take_complete_body
-    /// [`poll_next`]: MessageBody::poll_next
-    fn take_complete_body(&mut self) -> Bytes {
-        assert!(
-            self.is_complete_body(),
-            "type ({}) allows taking complete body but did not provide an implementation \
-            of `take_complete_body`",
-            std::any::type_name::<Self>()
-        );
-
-        unimplemented!(
-            "type ({}) does not allow taking complete body; caller should make sure to \
-            check `is_complete_body` first",
-            std::any::type_name::<Self>()
-        );
     }
 
     /// Converts this body into `BoxBody`.
@@ -104,14 +67,6 @@ mod foreign_impls {
         ) -> Poll<Option<Result<Bytes, Self::Error>>> {
             match *self {}
         }
-
-        fn is_complete_body(&self) -> bool {
-            true
-        }
-
-        fn take_complete_body(&mut self) -> Bytes {
-            match *self {}
-        }
     }
 
     impl MessageBody for () {
@@ -131,13 +86,8 @@ mod foreign_impls {
         }
 
         #[inline]
-        fn is_complete_body(&self) -> bool {
+        fn try_into_bytes(self) -> Result<Bytes, Self> {
-            true
+            Ok(Bytes::new())
-        }
-
-        #[inline]
-        fn take_complete_body(&mut self) -> Bytes {
-            Bytes::new()
         }
     }
 
@@ -159,16 +109,6 @@ mod foreign_impls {
         ) -> Poll<Option<Result<Bytes, Self::Error>>> {
             Pin::new(self.get_mut().as_mut()).poll_next(cx)
         }
-
-        #[inline]
-        fn is_complete_body(&self) -> bool {
-            self.as_ref().is_complete_body()
-        }
-
-        #[inline]
-        fn take_complete_body(&mut self) -> Bytes {
-            self.as_mut().take_complete_body()
-        }
     }
 
     impl<B> MessageBody for Pin<Box<B>>
@@ -189,38 +129,6 @@ mod foreign_impls {
         ) -> Poll<Option<Result<Bytes, Self::Error>>> {
             self.get_mut().as_mut().poll_next(cx)
         }
-
-        #[inline]
-        fn is_complete_body(&self) -> bool {
-            self.as_ref().is_complete_body()
-        }
-
-        #[inline]
-        fn take_complete_body(&mut self) -> Bytes {
-            debug_assert!(
-                self.is_complete_body(),
-                "inner type \"{}\" does not allow taking complete body; caller should make sure to \
-                call `is_complete_body` first",
-                std::any::type_name::<B>(),
-            );
-
-            // we do not have DerefMut access to call take_complete_body directly but since
-            // is_complete_body is true we should expect the entire bytes chunk in one poll_next
-
-            let waker = futures_task::noop_waker();
-            let mut cx = Context::from_waker(&waker);
-
-            match self.as_mut().poll_next(&mut cx) {
-                Poll::Ready(Some(Ok(data))) => data,
-                _ => {
-                    panic!(
-                        "inner type \"{}\" indicated it allows taking complete body but failed to \
-                        return Bytes when polled",
-                        std::any::type_name::<B>()
-                    );
-                }
-            }
-        }
     }
 
     impl MessageBody for &'static [u8] {
@@ -232,24 +140,19 @@ mod foreign_impls {
         }
 
         fn poll_next(
-            mut self: Pin<&mut Self>,
+            self: Pin<&mut Self>,
             _cx: &mut Context<'_>,
         ) -> Poll<Option<Result<Bytes, Self::Error>>> {
             if self.is_empty() {
                 Poll::Ready(None)
             } else {
-                Poll::Ready(Some(Ok(self.take_complete_body())))
+                Poll::Ready(Some(Ok(Bytes::from_static(mem::take(self.get_mut())))))
             }
         }
 
         #[inline]
-        fn is_complete_body(&self) -> bool {
+        fn try_into_bytes(self) -> Result<Bytes, Self> {
-            true
+            Ok(Bytes::from_static(self))
-        }
-
-        #[inline]
-        fn take_complete_body(&mut self) -> Bytes {
-            Bytes::from_static(mem::take(self))
         }
     }
 
@@ -262,24 +165,19 @@ mod foreign_impls {
         }
 
         fn poll_next(
-            mut self: Pin<&mut Self>,
+            self: Pin<&mut Self>,
             _cx: &mut Context<'_>,
         ) -> Poll<Option<Result<Bytes, Self::Error>>> {
             if self.is_empty() {
                 Poll::Ready(None)
             } else {
-                Poll::Ready(Some(Ok(self.take_complete_body())))
+                Poll::Ready(Some(Ok(mem::take(self.get_mut()))))
             }
         }
 
         #[inline]
-        fn is_complete_body(&self) -> bool {
+        fn try_into_bytes(self) -> Result<Bytes, Self> {
-            true
+            Ok(self)
-        }
-
-        #[inline]
-        fn take_complete_body(&mut self) -> Bytes {
-            mem::take(self)
         }
     }
 
@@ -292,24 +190,19 @@ mod foreign_impls {
         }
 
         fn poll_next(
-            mut self: Pin<&mut Self>,
+            self: Pin<&mut Self>,
             _cx: &mut Context<'_>,
         ) -> Poll<Option<Result<Bytes, Self::Error>>> {
             if self.is_empty() {
                 Poll::Ready(None)
             } else {
-                Poll::Ready(Some(Ok(self.take_complete_body())))
+                Poll::Ready(Some(Ok(mem::take(self.get_mut()).freeze())))
             }
         }
 
         #[inline]
-        fn is_complete_body(&self) -> bool {
+        fn try_into_bytes(self) -> Result<Bytes, Self> {
-            true
+            Ok(self.freeze())
-        }
-
-        #[inline]
-        fn take_complete_body(&mut self) -> Bytes {
-            mem::take(self).freeze()
         }
     }
 
@@ -322,24 +215,19 @@ mod foreign_impls {
         }
 
         fn poll_next(
-            mut self: Pin<&mut Self>,
+            self: Pin<&mut Self>,
             _cx: &mut Context<'_>,
         ) -> Poll<Option<Result<Bytes, Self::Error>>> {
             if self.is_empty() {
                 Poll::Ready(None)
             } else {
-                Poll::Ready(Some(Ok(self.take_complete_body())))
+                Poll::Ready(Some(Ok(mem::take(self.get_mut()).into())))
             }
         }
 
         #[inline]
-        fn is_complete_body(&self) -> bool {
+        fn try_into_bytes(self) -> Result<Bytes, Self> {
-            true
+            Ok(Bytes::from(self))
-        }
-
-        #[inline]
-        fn take_complete_body(&mut self) -> Bytes {
-            Bytes::from(mem::take(self))
         }
     }
 
@@ -365,13 +253,8 @@ mod foreign_impls {
         }
 
         #[inline]
-        fn is_complete_body(&self) -> bool {
+        fn try_into_bytes(self) -> Result<Bytes, Self> {
-            true
+            Ok(Bytes::from_static(self.as_bytes()))
-        }
-
-        #[inline]
-        fn take_complete_body(&mut self) -> Bytes {
-            Bytes::from_static(mem::take(self).as_bytes())
         }
     }
 
@@ -396,13 +279,8 @@ mod foreign_impls {
         }
 
         #[inline]
-        fn is_complete_body(&self) -> bool {
+        fn try_into_bytes(self) -> Result<Bytes, Self> {
-            true
+            Ok(Bytes::from(self))
-        }
-
-        #[inline]
-        fn take_complete_body(&mut self) -> Bytes {
-            Bytes::from(mem::take(self))
         }
     }
 
@@ -423,13 +301,8 @@ mod foreign_impls {
         }
 
         #[inline]
-        fn is_complete_body(&self) -> bool {
+        fn try_into_bytes(self) -> Result<Bytes, Self> {
-            true
+            Ok(self.into_bytes())
-        }
-
-        #[inline]
-        fn take_complete_body(&mut self) -> Bytes {
-            mem::take(self).into_bytes()
         }
     }
 }
@@ -486,13 +359,9 @@ where
     }
 
     #[inline]
-    fn is_complete_body(&self) -> bool {
+    fn try_into_bytes(self) -> Result<Bytes, Self> {
-        self.body.is_complete_body()
+        let Self { body, mapper } = self;
-    }
+        body.try_into_bytes().map_err(|body| Self { body, mapper })
-
-    #[inline]
-    fn take_complete_body(&mut self) -> Bytes {
-        self.body.take_complete_body()
     }
 }
 
@@ -503,6 +372,7 @@ mod tests {
     use bytes::{Bytes, BytesMut};
 
     use super::*;
+    use crate::body::{self, EitherBody};
 
     macro_rules! assert_poll_next {
         ($pin:expr, $exp:expr) => {
@@ -604,70 +474,45 @@ mod tests {
         assert_poll_next!(pl, Bytes::from("test"));
     }
 
-    #[test]
+    #[actix_rt::test]
-    fn take_string() {
+    async fn complete_body_combinators() {
-        let mut data = "test".repeat(2);
+        let body = Bytes::from_static(b"test");
-        let data_bytes = Bytes::from(data.clone());
+        let body = BoxBody::new(body);
-        assert!(data.is_complete_body());
+        let body = EitherBody::<_, ()>::left(body);
-        assert_eq!(data.take_complete_body(), data_bytes);
+        let body = EitherBody::<(), _>::right(body);
-
+        // Do not support try_into_bytes:
-        let mut big_data = "test".repeat(64 * 1024);
+        // let body = Box::new(body);
-        let data_bytes = Bytes::from(big_data.clone());
+        // let body = Box::pin(body);
-        assert!(big_data.is_complete_body());
+
-        assert_eq!(big_data.take_complete_body(), data_bytes);
+        assert_eq!(body.try_into_bytes().unwrap(), Bytes::from("test"));
-    }
+    }
-
+
-    #[test]
+    #[actix_rt::test]
-    fn take_boxed_equivalence() {
+    async fn complete_body_combinators_poll() {
-        let mut data = Bytes::from_static(b"test");
-        assert!(data.is_complete_body());
-        assert_eq!(data.take_complete_body(), b"test".as_ref());
-
-        let mut data = Box::new(Bytes::from_static(b"test"));
-        assert!(data.is_complete_body());
-        assert_eq!(data.take_complete_body(), b"test".as_ref());
-
-        let mut data = Box::pin(Bytes::from_static(b"test"));
-        assert!(data.is_complete_body());
-        assert_eq!(data.take_complete_body(), b"test".as_ref());
-    }
-
-    #[test]
-    fn take_policy() {
-        let mut data = Bytes::from_static(b"test");
-        // first call returns chunk
-        assert_eq!(data.take_complete_body(), b"test".as_ref());
-        // second call returns empty
-        assert_eq!(data.take_complete_body(), b"".as_ref());
-
-        let waker = futures_task::noop_waker();
-        let mut cx = Context::from_waker(&waker);
-        let mut data = Bytes::from_static(b"test");
-        // take returns whole chunk
-        assert_eq!(data.take_complete_body(), b"test".as_ref());
-        // subsequent poll_next returns None
-        assert_eq!(Pin::new(&mut data).poll_next(&mut cx), Poll::Ready(None));
-    }
-
-    #[test]
-    fn complete_body_combinators() {
-        use crate::body::{BoxBody, EitherBody};
-
         let body = Bytes::from_static(b"test");
         let body = BoxBody::new(body);
         let body = EitherBody::<_, ()>::left(body);
         let body = EitherBody::<(), _>::right(body);
-        let body = Box::new(body);
-        let body = Box::pin(body);
         let mut body = body;
 
-        assert!(body.is_complete_body());
+        assert_eq!(body.size(), BodySize::Sized(4));
-        assert_eq!(body.take_complete_body(), b"test".as_ref());
+        assert_poll_next!(Pin::new(&mut body), Bytes::from("test"));
+        assert_poll_next_none!(Pin::new(&mut body));
+    }
 
-        // subsequent poll_next returns None
+    #[actix_rt::test]
-        let waker = futures_task::noop_waker();
+    async fn none_body_combinators() {
-        let mut cx = Context::from_waker(&waker);
+        fn none_body() -> BoxBody {
-        assert!(Pin::new(&mut body).poll_next(&mut cx).map_err(drop) == Poll::Ready(None));
+            let body = body::None;
+            let body = BoxBody::new(body);
+            let body = EitherBody::<_, ()>::left(body);
+            let body = EitherBody::<(), _>::right(body);
+            body.boxed()
+        }
+
+        assert_eq!(none_body().size(), BodySize::None);
+        assert_eq!(none_body().try_into_bytes().unwrap(), Bytes::new());
+        assert_poll_next_none!(Pin::new(&mut none_body()));
     }
 
     // down-casting used to be done with a method on MessageBody trait

actix-http/src/body/none.rs

@@ -42,12 +42,7 @@ impl MessageBody for None {
     }
 
     #[inline]
-    fn is_complete_body(&self) -> bool {
+    fn try_into_bytes(self) -> Result<Bytes, Self> {
-        true
+        Ok(Bytes::new())
-    }
-
-    #[inline]
-    fn take_complete_body(&mut self) -> Bytes {
-        Bytes::new()
     }
 }

actix-http/src/encoding/encoder.rs

@@ -53,7 +53,7 @@ impl<B: MessageBody> Encoder<B> {
         }
     }
 
-    pub fn response(encoding: ContentEncoding, head: &mut ResponseHead, mut body: B) -> Self {
+    pub fn response(encoding: ContentEncoding, head: &mut ResponseHead, body: B) -> Self {
         let can_encode = !(head.headers().contains_key(&CONTENT_ENCODING)
             || head.status == StatusCode::SWITCHING_PROTOCOLS
             || head.status == StatusCode::NO_CONTENT
@@ -65,11 +65,9 @@ impl<B: MessageBody> Encoder<B> {
             return Self::none();
         }
 
-        let body = if body.is_complete_body() {
+        let body = match body.try_into_bytes() {
-            let body = body.take_complete_body();
+            Ok(body) => EncoderBody::Full { body },
-            EncoderBody::Full { body }
+            Err(body) => EncoderBody::Stream { body },
-        } else {
-            EncoderBody::Stream { body }
         };
 
         if can_encode {
@@ -133,21 +131,14 @@ where
         }
     }
 
-    fn is_complete_body(&self) -> bool {
+    fn try_into_bytes(self) -> Result<Bytes, Self>
+    where
+        Self: Sized,
+    {
         match self {
-            EncoderBody::None => true,
+            EncoderBody::None => Ok(Bytes::new()),
-            EncoderBody::Full { .. } => true,
+            EncoderBody::Full { body } => Ok(body),
-            EncoderBody::Stream { .. } => false,
+            _ => Err(self),
-        }
-    }
-
-    fn take_complete_body(&mut self) -> Bytes {
-        match self {
-            EncoderBody::None => Bytes::new(),
-            EncoderBody::Full { body } => body.take_complete_body(),
-            EncoderBody::Stream { .. } => {
-                panic!("EncoderBody::Stream variant cannot be taken")
-            }
         }
     }
 }
@@ -234,19 +225,20 @@ where
         }
     }
 
-    fn is_complete_body(&self) -> bool {
+    fn try_into_bytes(mut self) -> Result<Bytes, Self>
+    where
+        Self: Sized,
+    {
         if self.encoder.is_some() {
-            false
+            Err(self)
         } else {
-            self.body.is_complete_body()
+            match self.body.try_into_bytes() {
-        }
+                Ok(body) => Ok(body),
-    }
+                Err(body) => {
-
+                    self.body = body;
-    fn take_complete_body(&mut self) -> Bytes {
+                    Err(self)
-        if self.encoder.is_some() {
+                }
-            panic!("compressed body stream cannot be taken")
+            }
-        } else {
-            self.body.take_complete_body()
         }
     }
 }

actix-http/src/h1/dispatcher.rs

@@ -22,7 +22,7 @@ use crate::{
     config::ServiceConfig,
     error::{DispatchError, ParseError, PayloadError},
     service::HttpFlow,
-    Extensions, OnConnectData, Request, Response, StatusCode,
+    Error, Extensions, OnConnectData, Request, Response, StatusCode,
 };
 
 use super::{
@@ -494,7 +494,9 @@ where
                             }
 
                             Poll::Ready(Some(Err(err))) => {
-                                return Err(DispatchError::Body(err.into()))
+                                return Err(DispatchError::Body(
+                                    Error::new_body().with_cause(err).into(),
+                                ))
                             }
 
                             Poll::Pending => return Ok(PollResponse::DoNothing),

src/dev.rs

@@ -139,4 +139,12 @@ impl crate::body::MessageBody for AnyBody {
             AnyBody::Boxed { body } => body.as_pin_mut().poll_next(cx),
         }
     }
+
+    fn try_into_bytes(self) -> Result<crate::web::Bytes, Self> {
+        match self {
+            AnyBody::None => Ok(crate::web::Bytes::new()),
+            AnyBody::Full { body } => Ok(body),
+            _ => Err(self),
+        }
+    }
 }