swarm-derive/: Remove support for custom poll method (#2841)

With the removal of `NetworkBehaviourEventProcess` there is no more need for a
custom poll method.

CHANGELOG.md

@@ -45,6 +45,8 @@
 
 # 0.48.0 [unreleased]
 
+- Update to [`libp2p-swarm-derive` `v0.30.0`](swarm-derive/CHANGELOG.md#0300).
+
 - Update to [`libp2p-dcutr` `v0.6.0`](protocols/dcutr/CHANGELOG.md#060).
 
 - Update to [`libp2p-rendezvous` `v0.9.0`](protocols/rendezvous/CHANGELOG.md#090).

swarm-derive/CHANGELOG.md

@@ -1,6 +1,12 @@
 # 0.30.0 - [unreleased]
 
-- Remove support for removed `NetworkBehaviourEventProcess`.
+- Remove support for removed `NetworkBehaviourEventProcess`. See [PR 2840].
+
+- Remove support for custom `poll` method on `NetworkBehaviour` via `#[behaviour(poll_method =
+  "poll")]`. See [PR 2841].
+
+[PR 2840]: https://github.com/libp2p/rust-libp2p/pull/2840
+[PR 2841]: https://github.com/libp2p/rust-libp2p/pull/2841
 
 # 0.29.0
 

swarm-derive/src/lib.rs

@@ -23,7 +23,7 @@
 use heck::ToUpperCamelCase;
 use proc_macro::TokenStream;
 use quote::quote;
-use syn::{parse_macro_input, Data, DataStruct, DeriveInput, Ident};
+use syn::{parse_macro_input, Data, DataStruct, DeriveInput};
 
 /// Generates a delegating `NetworkBehaviour` implementation for the struct this is used for. See
 /// the trait documentation for better description.
@@ -433,29 +433,6 @@ fn build_struct(ast: &DeriveInput, data_struct: &DataStruct) -> TokenStream {
         out_handler.unwrap_or(quote! {()}) // TODO: See test `empty`.
     };
 
-    // The method to use to poll.
-    // If we find a `#[behaviour(poll_method = "poll")]` attribute on the struct, we call
-    // `self.poll()` at the end of the polling.
-    let poll_method = {
-        let mut poll_method = quote! {std::task::Poll::Pending};
-        for meta_items in ast.attrs.iter().filter_map(get_meta_items) {
-            for meta_item in meta_items {
-                match meta_item {
-                    syn::NestedMeta::Meta(syn::Meta::NameValue(ref m))
-                        if m.path.is_ident("poll_method") =>
-                    {
-                        if let syn::Lit::Str(ref s) = m.lit {
-                            let ident: Ident = syn::parse_str(&s.value()).unwrap();
-                            poll_method = quote! {#name::#ident(self, cx, poll_params)};
-                        }
-                    }
-                    _ => (),
-                }
-            }
-        }
-        poll_method
-    };
-
     // List of statements to put in `poll()`.
     //
     // We poll each child one by one and wrap around the output.
@@ -638,8 +615,7 @@ fn build_struct(ast: &DeriveInput, data_struct: &DataStruct) -> TokenStream {
             fn poll(&mut self, cx: &mut std::task::Context, poll_params: &mut impl #poll_parameters) -> std::task::Poll<#network_behaviour_action<Self::OutEvent, Self::ConnectionHandler>> {
                 use libp2p::futures::prelude::*;
                 #(#poll_stmts)*
-                let f: std::task::Poll<#network_behaviour_action<Self::OutEvent, Self::ConnectionHandler>> = #poll_method;
+                std::task::Poll::Pending
-                f
             }
         }
     };

swarm-derive/tests/test.rs

@@ -128,38 +128,7 @@ fn three_fields_non_last_ignored() {
 }
 
 #[test]
-fn custom_polling() {
+fn custom_event() {
-    #[allow(dead_code)]
-    #[derive(NetworkBehaviour)]
-    #[behaviour(poll_method = "foo")]
-    struct Foo {
-        ping: libp2p::ping::Ping,
-        identify: libp2p::identify::Identify,
-    }
-
-    impl Foo {
-        fn foo(
-            &mut self,
-            _: &mut std::task::Context,
-            _: &mut impl libp2p::swarm::PollParameters,
-        ) -> std::task::Poll<
-            libp2p::swarm::NetworkBehaviourAction<
-                <Self as NetworkBehaviour>::OutEvent,
-                <Self as NetworkBehaviour>::ConnectionHandler,
-            >,
-        > {
-            std::task::Poll::Pending
-        }
-    }
-
-    #[allow(dead_code)]
-    fn foo() {
-        require_net_behaviour::<Foo>();
-    }
-}
-
-#[test]
-fn custom_event_no_polling() {
     #[allow(dead_code)]
     #[derive(NetworkBehaviour)]
     #[behaviour(out_event = "MyEvent")]
@@ -191,54 +160,6 @@ fn custom_event_no_polling() {
     }
 }
 
-#[test]
-fn custom_event_and_polling() {
-    #[allow(dead_code)]
-    #[derive(NetworkBehaviour)]
-    #[behaviour(poll_method = "foo", out_event = "MyEvent")]
-    struct Foo {
-        ping: libp2p::ping::Ping,
-        identify: libp2p::identify::Identify,
-    }
-
-    enum MyEvent {
-        Ping(libp2p::ping::PingEvent),
-        Identify(libp2p::identify::IdentifyEvent),
-    }
-
-    impl From<libp2p::ping::PingEvent> for MyEvent {
-        fn from(event: libp2p::ping::PingEvent) -> Self {
-            MyEvent::Ping(event)
-        }
-    }
-
-    impl From<libp2p::identify::IdentifyEvent> for MyEvent {
-        fn from(event: libp2p::identify::IdentifyEvent) -> Self {
-            MyEvent::Identify(event)
-        }
-    }
-
-    impl Foo {
-        fn foo(
-            &mut self,
-            _: &mut std::task::Context,
-            _: &mut impl libp2p::swarm::PollParameters,
-        ) -> std::task::Poll<
-            libp2p::swarm::NetworkBehaviourAction<
-                <Self as NetworkBehaviour>::OutEvent,
-                <Self as NetworkBehaviour>::ConnectionHandler,
-            >,
-        > {
-            std::task::Poll::Pending
-        }
-    }
-
-    #[allow(dead_code)]
-    fn foo() {
-        require_net_behaviour::<Foo>();
-    }
-}
-
 #[test]
 fn custom_event_mismatching_field_names() {
     #[allow(dead_code)]

swarm/src/behaviour.rs

@@ -118,10 +118,6 @@ pub(crate) type THandlerOutEvent<THandler> =
 /// }
 /// ```
 ///
-/// Optionally one can provide a custom `poll` function through the `#[behaviour(poll_method =
-/// "poll")]` attribute. This function must have the same signature as the [`NetworkBehaviour#poll`]
-/// function and will be called last within the generated [`NetworkBehaviour`] implementation.
-///
 /// Struct members that don't implement [`NetworkBehaviour`] must be annotated with
 /// `#[behaviour(ignore)]`.
 ///