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swarm-derive/: Generate OutEvent if not provided (#2792)

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Generate `NetworkBehaviour::OutEvent` if not provided through
`#[behaviour(out_event = "MyOutEvent")]` and event processing is
disabled (default).
This commit is contained in:
Max Inden
2022-08-08 07:18:32 +02:00
committed by GitHub
parent 028decec69
commit 579b1be5d5
8 changed files with 281 additions and 173 deletions
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2
CHANGELOG.md
View File

@ -47,6 +47,8 @@
- Update to [`libp2p-dcutr` `v0.5.0`](protocols/dcutr/CHANGELOG.md#050).
- Update to [`libp2p-derive` `v0.29.0`](swarm-derive/CHANGELOG.md#0290).
- Update to [`libp2p-rendezvous` `v0.8.0`](protocols/rendezvous/CHANGELOG.md#080).
- Update to [`libp2p-ping` `v0.38.0`](protocols/ping/CHANGELOG.md#0380).

2
Cargo.toml
View File

@ -93,7 +93,7 @@ libp2p-relay = { version = "0.11.0", path = "protocols/relay", optional = true }
libp2p-rendezvous = { version = "0.8.0", path = "protocols/rendezvous", optional = true }
libp2p-request-response = { version = "0.20.0", path = "protocols/request-response", optional = true }
libp2p-swarm = { version = "0.38.0", path = "swarm" }
libp2p-swarm-derive = { version = "0.28.0", path = "swarm-derive" }
libp2p-swarm-derive = { version = "0.29.0", path = "swarm-derive" }
libp2p-uds = { version = "0.34.0", path = "transports/uds", optional = true }
libp2p-wasm-ext = { version = "0.35.0", path = "transports/wasm-ext", default-features = false, optional = true }
libp2p-yamux = { version = "0.39.0", path = "muxers/yamux", optional = true }

5
swarm-derive/CHANGELOG.md
View File

@ -1,3 +1,8 @@
# 0.29.0 - [unreleased]
- Generate `NetworkBehaviour::OutEvent` if not provided through `#[behaviour(out_event =
"MyOutEvent")]` and event processing is disabled (default).
# 0.28.0
- Import `ListenerId` from `libp2p::core::transport`. See [PR 2652].

5
swarm-derive/Cargo.toml
View File

@ -3,7 +3,7 @@ name = "libp2p-swarm-derive"
edition = "2021"
rust-version = "1.56.1"
description = "Procedural macros of libp2p-core"
version = "0.28.0"
version = "0.29.0"
authors = ["Parity Technologies <admin@parity.io>"]
license = "MIT"
repository = "https://github.com/libp2p/rust-libp2p"
@ -14,8 +14,9 @@ categories = ["network-programming", "asynchronous"]
proc-macro = true
[dependencies]
syn = { version = "1.0.8", default-features = false, features = ["clone-impls", "derive", "parsing", "printing", "proc-macro"] }
heck = "0.4"
quote = "1.0"
syn = { version = "1.0.8", default-features = false, features = ["clone-impls", "derive", "parsing", "printing", "proc-macro"] }
[dev-dependencies]
libp2p = { path = "../", default-features = false, features = ["ping", "identify", "kad"] }

146
swarm-derive/src/lib.rs
View File

@ -20,6 +20,7 @@
#![recursion_limit = "256"]
use heck::ToUpperCamelCase;
use proc_macro::TokenStream;
use quote::quote;
use syn::{parse_macro_input, Data, DataStruct, DeriveInput, Ident};
@ -99,49 +100,106 @@ fn build_struct(ast: &DeriveInput, data_struct: &DataStruct) -> TokenStream {
.filter(|f| !is_ignored(f))
.collect::<Vec<_>>();
// The final out event.
// If we find a `#[behaviour(out_event = "Foo")]` attribute on the struct, we set `Foo` as
// the out event. Otherwise we use `()`.
let out_event = {
let mut out = quote! {()};
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("out_event") =>
{
let (out_event_name, out_event_definition, out_event_from_clauses) = {
// If we find a `#[behaviour(out_event = "Foo")]` attribute on the
// struct, we set `Foo` as the out event. If not, the `OutEvent` is
// generated.
let user_provided_out_event_name: Option<syn::Type> = ast
.attrs
.iter()
.filter_map(get_meta_items)
.flatten()
.filter_map(|meta_item| {
if let syn::NestedMeta::Meta(syn::Meta::NameValue(ref m)) = meta_item {
if m.path.is_ident("out_event") {
if let syn::Lit::Str(ref s) = m.lit {
let ident: syn::Type = syn::parse_str(&s.value()).unwrap();
out = quote! {#ident};
return Some(syn::parse_str(&s.value()).unwrap());
}
}
_ => (),
}
None
})
.next();
match (user_provided_out_event_name, event_process) {
// User provided `OutEvent`.
(Some(name), false) => {
let definition = None;
let from_clauses = data_struct_fields
.iter()
.map(|field| {
let ty = &field.ty;
quote! {#name #ty_generics: From< <#ty as #trait_to_impl>::OutEvent >}
})
.collect::<Vec<_>>();
(name, definition, from_clauses)
}
// User did not provide `OutEvent`. Generate it.
(None, false) => {
let name: syn::Type = syn::parse_str(&(ast.ident.to_string() + "Event")).unwrap();
let definition = {
let fields = data_struct_fields
.iter()
.map(|field| {
let variant: syn::Variant = syn::parse_str(
&field
.ident
.clone()
.expect(
"Fields of NetworkBehaviour implementation to be named.",
)
.to_string()
.to_upper_camel_case(),
)
.unwrap();
let ty = &field.ty;
quote! {#variant(<#ty as NetworkBehaviour>::OutEvent)}
})
.collect::<Vec<_>>();
let visibility = &ast.vis;
Some(quote! {
#visibility enum #name #impl_generics {
#(#fields),*
}
})
};
let from_clauses = vec![];
(name, definition, from_clauses)
}
// User uses `NetworkBehaviourEventProcess`.
(name, true) => {
let definition = None;
let from_clauses = data_struct_fields
.iter()
.map(|field| {
let ty = &field.ty;
quote! {Self: #net_behv_event_proc<<#ty as #trait_to_impl>::OutEvent>}
})
.collect::<Vec<_>>();
(
name.unwrap_or_else(|| syn::parse_str("()").unwrap()),
definition,
from_clauses,
)
}
}
out
};
// Build the `where ...` clause of the trait implementation.
let where_clause = {
let additional = data_struct_fields
.iter()
.flat_map(|field| {
.map(|field| {
let ty = &field.ty;
vec![
quote! {#ty: #trait_to_impl},
if event_process {
quote! {Self: #net_behv_event_proc<<#ty as #trait_to_impl>::OutEvent>}
} else {
quote! {#out_event: From< <#ty as #trait_to_impl>::OutEvent >}
},
]
quote! {#ty: #trait_to_impl}
})
.chain(out_event_from_clauses)
.collect::<Vec<_>>();
if let Some(where_clause) = where_clause {
if where_clause.predicates.trailing_punct() {
Some(quote! {#where_clause #(#additional),*})
Some(quote! {#where_clause #(#additional),* })
} else {
Some(quote! {#where_clause, #(#additional),*})
}
@ -437,18 +495,18 @@ fn build_struct(ast: &DeriveInput, data_struct: &DataStruct) -> TokenStream {
// List of statements to put in `poll()`.
//
// We poll each child one by one and wrap around the output.
let poll_stmts = data_struct_fields.iter().enumerate().enumerate().map(|(enum_n, (field_n, field))| {
let field_name = match field.ident {
Some(ref i) => quote!{ self.#i },
None => quote!{ self.#field_n },
};
let poll_stmts = data_struct_fields.iter().enumerate().map(|(field_n, field)| {
let field = field
.ident
.clone()
.expect("Fields of NetworkBehaviour implementation to be named.");
let mut wrapped_event = if enum_n != 0 {
let mut wrapped_event = if field_n != 0 {
quote!{ #either_ident::Second(event) }
} else {
quote!{ event }
};
for _ in 0 .. data_struct_fields.len() - 1 - enum_n {
for _ in 0 .. data_struct_fields.len() - 1 - field_n {
wrapped_event = quote!{ #either_ident::First(#wrapped_event) };
}
@ -460,7 +518,6 @@ fn build_struct(ast: &DeriveInput, data_struct: &DataStruct) -> TokenStream {
let mut out_handler = None;
for (f_n, f) in data_struct_fields.iter().enumerate() {
let f_name = match f.ident {
Some(ref i) => quote! { self.#i },
None => quote! { self.#f_n },
@ -492,16 +549,31 @@ fn build_struct(ast: &DeriveInput, data_struct: &DataStruct) -> TokenStream {
}
}
} else {
// If the `NetworkBehaviour`'s `OutEvent` is generated by the derive macro, wrap the sub
// `NetworkBehaviour` `OutEvent` in the variant of the generated `OutEvent`. If the
// `NetworkBehaviour`'s `OutEvent` is provided by the user, use the corresponding `From`
// implementation.
let into_out_event = if out_event_definition.is_some() {
let event_variant: syn::Variant = syn::parse_str(
&field
.to_string()
.to_upper_camel_case()
).unwrap();
quote! { #out_event_name::#event_variant(event) }
} else {
quote! { event.into() }
};
quote! {
std::task::Poll::Ready(#network_behaviour_action::GenerateEvent(event)) => {
return std::task::Poll::Ready(#network_behaviour_action::GenerateEvent(event.into()))
return std::task::Poll::Ready(#network_behaviour_action::GenerateEvent(#into_out_event))
}
}
};
Some(quote!{
loop {
match #trait_to_impl::poll(&mut #field_name, cx, poll_params) {
match #trait_to_impl::poll(&mut self.#field, cx, poll_params) {
#generate_event_match_arm
std::task::Poll::Ready(#network_behaviour_action::Dial { opts, handler: provided_handler }) => {
return std::task::Poll::Ready(#network_behaviour_action::Dial { opts, handler: #provided_handler_and_new_handlers });
@ -527,11 +599,13 @@ fn build_struct(ast: &DeriveInput, data_struct: &DataStruct) -> TokenStream {
// Now the magic happens.
let final_quote = quote! {
#out_event_definition
impl #impl_generics #trait_to_impl for #name #ty_generics
#where_clause
{
type ConnectionHandler = #connection_handler_ty;
type OutEvent = #out_event;
type OutEvent = #out_event_name #ty_generics;
fn new_handler(&mut self) -> Self::ConnectionHandler {
use #into_connection_handler;

262
swarm-derive/tests/test.rs
View File

@ -38,18 +38,17 @@ fn empty() {
fn one_field() {
#[allow(dead_code)]
#[derive(NetworkBehaviour)]
#[behaviour(event_process = true)]
struct Foo {
ping: libp2p::ping::Ping,
}
impl libp2p::swarm::NetworkBehaviourEventProcess<libp2p::ping::PingEvent> for Foo {
fn inject_event(&mut self, _: libp2p::ping::PingEvent) {}
}
#[allow(dead_code)]
#[allow(unreachable_code)]
fn foo() {
require_net_behaviour::<Foo>();
let _out_event: <Foo as NetworkBehaviour>::OutEvent = unimplemented!();
match _out_event {
FooEvent::Ping(libp2p::ping::Event { .. }) => {}
}
}
}
@ -57,23 +56,21 @@ fn one_field() {
fn two_fields() {
#[allow(dead_code)]
#[derive(NetworkBehaviour)]
#[behaviour(event_process = true)]
struct Foo {
ping: libp2p::ping::Ping,
identify: libp2p::identify::Identify,
}
impl libp2p::swarm::NetworkBehaviourEventProcess<libp2p::identify::IdentifyEvent> for Foo {
fn inject_event(&mut self, _: libp2p::identify::IdentifyEvent) {}
}
impl libp2p::swarm::NetworkBehaviourEventProcess<libp2p::ping::PingEvent> for Foo {
fn inject_event(&mut self, _: libp2p::ping::PingEvent) {}
}
#[allow(dead_code)]
#[allow(unreachable_code)]
fn foo() {
require_net_behaviour::<Foo>();
let _out_event: <Foo as NetworkBehaviour>::OutEvent = unimplemented!();
match _out_event {
FooEvent::Ping(libp2p::ping::Event { .. }) => {}
FooEvent::Identify(event) => {
let _: libp2p::identify::IdentifyEvent = event;
}
}
}
}
@ -81,7 +78,6 @@ fn two_fields() {
fn three_fields() {
#[allow(dead_code)]
#[derive(NetworkBehaviour)]
#[behaviour(event_process = true)]
struct Foo {
ping: libp2p::ping::Ping,
identify: libp2p::identify::Identify,
@ -90,21 +86,19 @@ fn three_fields() {
foo: String,
}
impl libp2p::swarm::NetworkBehaviourEventProcess<libp2p::ping::PingEvent> for Foo {
fn inject_event(&mut self, _: libp2p::ping::PingEvent) {}
}
impl libp2p::swarm::NetworkBehaviourEventProcess<libp2p::identify::IdentifyEvent> for Foo {
fn inject_event(&mut self, _: libp2p::identify::IdentifyEvent) {}
}
impl libp2p::swarm::NetworkBehaviourEventProcess<libp2p::kad::KademliaEvent> for Foo {
fn inject_event(&mut self, _: libp2p::kad::KademliaEvent) {}
}
#[allow(dead_code)]
#[allow(unreachable_code)]
fn foo() {
require_net_behaviour::<Foo>();
let _out_event: <Foo as NetworkBehaviour>::OutEvent = unimplemented!();
match _out_event {
FooEvent::Ping(libp2p::ping::Event { .. }) => {}
FooEvent::Identify(event) => {
let _: libp2p::identify::IdentifyEvent = event;
}
FooEvent::Kad(event) => {
let _: libp2p::kad::KademliaEvent = event;
}
}
}
}
@ -112,7 +106,6 @@ fn three_fields() {
fn three_fields_non_last_ignored() {
#[allow(dead_code)]
#[derive(NetworkBehaviour)]
#[behaviour(event_process = true)]
struct Foo {
ping: libp2p::ping::Ping,
#[behaviour(ignore)]
@ -120,17 +113,16 @@ fn three_fields_non_last_ignored() {
kad: libp2p::kad::Kademlia<libp2p::kad::record::store::MemoryStore>,
}
impl libp2p::swarm::NetworkBehaviourEventProcess<libp2p::ping::PingEvent> for Foo {
fn inject_event(&mut self, _: libp2p::ping::PingEvent) {}
}
impl libp2p::swarm::NetworkBehaviourEventProcess<libp2p::kad::KademliaEvent> for Foo {
fn inject_event(&mut self, _: libp2p::kad::KademliaEvent) {}
}
#[allow(dead_code)]
#[allow(unreachable_code)]
fn foo() {
require_net_behaviour::<Foo>();
let _out_event: <Foo as NetworkBehaviour>::OutEvent = unimplemented!();
match _out_event {
FooEvent::Ping(libp2p::ping::Event { .. }) => {}
FooEvent::Kad(event) => {
let _: libp2p::kad::KademliaEvent = event;
}
}
}
}
@ -138,20 +130,12 @@ fn three_fields_non_last_ignored() {
fn custom_polling() {
#[allow(dead_code)]
#[derive(NetworkBehaviour)]
#[behaviour(poll_method = "foo", event_process = true)]
#[behaviour(poll_method = "foo")]
struct Foo {
ping: libp2p::ping::Ping,
identify: libp2p::identify::Identify,
}
impl libp2p::swarm::NetworkBehaviourEventProcess<libp2p::ping::PingEvent> for Foo {
fn inject_event(&mut self, _: libp2p::ping::PingEvent) {}
}
impl libp2p::swarm::NetworkBehaviourEventProcess<libp2p::identify::IdentifyEvent> for Foo {
fn inject_event(&mut self, _: libp2p::identify::IdentifyEvent) {}
}
impl Foo {
fn foo(
&mut self,
@ -177,18 +161,27 @@ fn custom_polling() {
fn custom_event_no_polling() {
#[allow(dead_code)]
#[derive(NetworkBehaviour)]
#[behaviour(out_event = "Vec<String>", event_process = true)]
#[behaviour(out_event = "MyEvent")]
struct Foo {
ping: libp2p::ping::Ping,
identify: libp2p::identify::Identify,
}
impl libp2p::swarm::NetworkBehaviourEventProcess<libp2p::ping::PingEvent> for Foo {
fn inject_event(&mut self, _: libp2p::ping::PingEvent) {}
enum MyEvent {
Ping(libp2p::ping::PingEvent),
Identify(libp2p::identify::IdentifyEvent),
}
impl libp2p::swarm::NetworkBehaviourEventProcess<libp2p::identify::IdentifyEvent> for Foo {
fn inject_event(&mut self, _: 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)
}
}
#[allow(dead_code)]
@ -201,18 +194,27 @@ fn custom_event_no_polling() {
fn custom_event_and_polling() {
#[allow(dead_code)]
#[derive(NetworkBehaviour)]
#[behaviour(poll_method = "foo", out_event = "String", event_process = true)]
#[behaviour(poll_method = "foo", out_event = "MyEvent")]
struct Foo {
ping: libp2p::ping::Ping,
identify: libp2p::identify::Identify,
}
impl libp2p::swarm::NetworkBehaviourEventProcess<libp2p::ping::PingEvent> for Foo {
fn inject_event(&mut self, _: libp2p::ping::PingEvent) {}
enum MyEvent {
Ping(libp2p::ping::PingEvent),
Identify(libp2p::identify::IdentifyEvent),
}
impl libp2p::swarm::NetworkBehaviourEventProcess<libp2p::identify::IdentifyEvent> for Foo {
fn inject_event(&mut self, _: 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 {
@ -236,12 +238,44 @@ fn custom_event_and_polling() {
}
}
#[test]
fn custom_event_mismatching_field_names() {
#[allow(dead_code)]
#[derive(NetworkBehaviour)]
#[behaviour(out_event = "MyEvent")]
struct Foo {
a: libp2p::ping::Ping,
b: 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)
}
}
#[allow(dead_code)]
fn foo() {
require_net_behaviour::<Foo>();
}
}
#[test]
fn where_clause() {
#[allow(dead_code)]
#[derive(NetworkBehaviour)]
#[behaviour(event_process = true)]
struct Foo<T: Copy> {
struct Foo<T: Copy + NetworkBehaviour> {
ping: libp2p::ping::Ping,
bar: T,
}
@ -249,38 +283,30 @@ fn where_clause() {
#[test]
fn nested_derives_with_import() {
use libp2p::swarm::NetworkBehaviourEventProcess;
#[allow(dead_code)]
#[derive(NetworkBehaviour)]
#[behaviour(event_process = true)]
struct Foo {
ping: libp2p::ping::Ping,
}
#[allow(dead_code)]
#[derive(NetworkBehaviour)]
#[behaviour(event_process = true)]
struct Bar {
foo: Foo,
}
impl NetworkBehaviourEventProcess<libp2p::ping::PingEvent> for Foo {
fn inject_event(&mut self, _: libp2p::ping::PingEvent) {}
}
impl NetworkBehaviourEventProcess<()> for Bar {
fn inject_event(&mut self, _: ()) {}
}
#[allow(dead_code)]
fn bar() {
require_net_behaviour::<Bar>();
#[allow(unreachable_code)]
fn foo() {
let _out_event: <Bar as NetworkBehaviour>::OutEvent = unimplemented!();
match _out_event {
BarEvent::Foo(FooEvent::Ping(libp2p::ping::Event { .. })) => {}
}
}
}
#[test]
fn event_process_false() {
fn custom_event_emit_event_through_poll() {
enum BehaviourOutEvent {
Ping(libp2p::ping::PingEvent),
Identify(libp2p::identify::IdentifyEvent),
@ -331,20 +357,11 @@ fn with_toggle() {
#[allow(dead_code)]
#[derive(NetworkBehaviour)]
#[behaviour(event_process = true)]
struct Foo {
identify: libp2p::identify::Identify,
ping: Toggle<libp2p::ping::Ping>,
}
impl libp2p::swarm::NetworkBehaviourEventProcess<libp2p::identify::IdentifyEvent> for Foo {
fn inject_event(&mut self, _: libp2p::identify::IdentifyEvent) {}
}
impl libp2p::swarm::NetworkBehaviourEventProcess<libp2p::ping::PingEvent> for Foo {
fn inject_event(&mut self, _: libp2p::ping::PingEvent) {}
}
#[allow(dead_code)]
fn foo() {
require_net_behaviour::<Foo>();
@ -357,28 +374,11 @@ fn with_either() {
#[allow(dead_code)]
#[derive(NetworkBehaviour)]
#[behaviour(event_process = true)]
struct Foo {
kad: libp2p::kad::Kademlia<libp2p::kad::record::store::MemoryStore>,
ping_or_identify: Either<libp2p::ping::Ping, libp2p::identify::Identify>,
}
impl libp2p::swarm::NetworkBehaviourEventProcess<libp2p::kad::KademliaEvent> for Foo {
fn inject_event(&mut self, _: libp2p::kad::KademliaEvent) {}
}
impl
libp2p::swarm::NetworkBehaviourEventProcess<
Either<libp2p::ping::PingEvent, libp2p::identify::IdentifyEvent>,
> for Foo
{
fn inject_event(
&mut self,
_: Either<libp2p::ping::PingEvent, libp2p::identify::IdentifyEvent>,
) {
}
}
#[allow(dead_code)]
fn foo() {
require_net_behaviour::<Foo>();
@ -386,7 +386,7 @@ fn with_either() {
}
#[test]
fn no_event_with_either() {
fn custom_event_with_either() {
use either::Either;
enum BehaviourOutEvent {
@ -394,14 +394,6 @@ fn no_event_with_either() {
PingOrIdentify(Either<libp2p::ping::PingEvent, libp2p::identify::IdentifyEvent>),
}
#[allow(dead_code)]
#[derive(NetworkBehaviour)]
#[behaviour(out_event = "BehaviourOutEvent", event_process = false)]
struct Foo {
kad: libp2p::kad::Kademlia<libp2p::kad::record::store::MemoryStore>,
ping_or_identify: Either<libp2p::ping::Ping, libp2p::identify::Identify>,
}
impl From<libp2p::kad::KademliaEvent> for BehaviourOutEvent {
fn from(event: libp2p::kad::KademliaEvent) -> Self {
BehaviourOutEvent::Kad(event)
@ -414,6 +406,14 @@ fn no_event_with_either() {
}
}
#[allow(dead_code)]
#[derive(NetworkBehaviour)]
#[behaviour(out_event = "BehaviourOutEvent")]
struct Foo {
kad: libp2p::kad::Kademlia<libp2p::kad::record::store::MemoryStore>,
ping_or_identify: Either<libp2p::ping::Ping, libp2p::identify::Identify>,
}
#[allow(dead_code)]
fn foo() {
require_net_behaviour::<Foo>();
@ -425,7 +425,6 @@ fn mixed_field_order() {
struct Foo {}
#[derive(NetworkBehaviour)]
#[behaviour(event_process = true)]
pub struct Behaviour {
#[behaviour(ignore)]
_foo: Foo,
@ -437,12 +436,43 @@ fn mixed_field_order() {
_foo3: Foo,
}
impl<T> libp2p::swarm::NetworkBehaviourEventProcess<T> for Behaviour {
fn inject_event(&mut self, _evt: T) {}
}
#[allow(dead_code)]
fn behaviour() {
require_net_behaviour::<Behaviour>();
}
}
#[test]
fn event_process() {
#[allow(dead_code)]
#[derive(NetworkBehaviour)]
#[behaviour(event_process = true)]
struct Foo {
ping: libp2p::ping::Ping,
identify: libp2p::identify::Identify,
}
impl libp2p::swarm::NetworkBehaviourEventProcess<libp2p::identify::IdentifyEvent> for Foo {
fn inject_event(&mut self, _: libp2p::identify::IdentifyEvent) {}
}
impl libp2p::swarm::NetworkBehaviourEventProcess<libp2p::ping::PingEvent> for Foo {
fn inject_event(&mut self, _: libp2p::ping::PingEvent) {}
}
#[allow(dead_code, unreachable_code)]
fn bar() {
require_net_behaviour::<Foo>();
let mut _swarm: libp2p::Swarm<Foo> = unimplemented!();
let _ = async {
loop {
match _swarm.select_next_some().await {
SwarmEvent::Behaviour(()) => break,
_ => {}
}
}
};
}
}

9
swarm/CHANGELOG.md
View File

@ -4,6 +4,15 @@
- Update to `libp2p-core` `v0.35.0`.
- When deriving `NetworkBehaviour` on a custom `struct` where the user does not specify their own
`OutEvent` via `#[behaviour(out_event = "MyBehaviourEvent")]` and where the user does not enable
`#[behaviour(event_process = true)]`, then the derive macro generates an `OutEvent` definition for
the user.
See [`NetworkBehaviour`
documentation](https://docs.rs/libp2p/latest/libp2p/swarm/trait.NetworkBehaviour.html) for
details.
[PR 2741]: https://github.com/libp2p/rust-libp2p/pull/2741/
# 0.37.0

23
swarm/src/behaviour.rs
View File

@ -79,16 +79,11 @@ pub(crate) type THandlerOutEvent<THandler> =
/// it will delegate to each `struct` member and return a concatenated array of all addresses
/// returned by the struct members.
///
/// When creating a custom [`NetworkBehaviour`], you must choose one of two methods to respond to
/// incoming events:
/// * One option is setting a custom `out_event` with `#[behaviour(out_event = "AnotherType")]`.
/// In this case, events generated by the custom [`NetworkBehaviour`] struct members will be
/// converted to your custom `out_event` for you to handle after polling the swarm.
/// * Alternatively, users that need access to the root [`NetworkBehaviour`] implementation while
/// processing emitted events, can specify `#[behaviour(event_process = true)]` (default is false).
/// Events generated by the behaviour's struct members are delegated to [`NetworkBehaviourEventProcess`]
/// trait implementations. Those must be provided by the user on the type that [`NetworkBehaviour`]
/// is derived on.
/// Events ([`NetworkBehaviour::OutEvent`]) returned by each `struct` member are wrapped in a new
/// `enum` event, with an `enum` variant for each `struct` member. Users can define this event
/// `enum` themselves and provide the name to the derive macro via `#[behaviour(out_event =
/// "MyCustomOutEvent")]`. If the user does not specify an `out_event`, the derive macro generates
/// the event definition itself, naming it `<STRUCT_NAME>Event`.
///
/// When setting a custom `out_event`, the aforementioned conversion of each of the event types
/// generated by the struct members to the custom `out_event` is handled by [`From`]
@ -123,14 +118,6 @@ pub(crate) type THandlerOutEvent<THandler> =
/// }
/// ```
///
/// When using `event_process = true` the [`NetworkBehaviourEventProcess`] trait implementations
/// are granted exclusive access to the [`NetworkBehaviour`], therefore
/// [blocking code](https://ryhl.io/blog/async-what-is-blocking/) in these implementations will
/// block the entire [`Swarm`](crate::Swarm) from processing new events, since the swarm cannot progress
/// without also having exclusive access to the [`NetworkBehaviour`]. A better alternative is to execute
/// blocking or asynchronous logic on a separate task, perhaps with the help of a bounded channel to
/// maintain backpressure. The sender for the channel could be included in the NetworkBehaviours constructor.
///
/// 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.