Add protocols_handler::multi module. (libp2p#1497)

* Add `protocols_handler::multi` module.

An implementation of `ProtocolsHandler` that contains multiple other
`ProtocolsHandler`s indexed by some key type.

* Randomise start position of handler polling.

* Address some review concerns.

* Add `IntoMultiHandler`.

* Check protocol names for uniqueness.

* Changes due to review.

- No more `Debug` bound for the key type and more generic log messages.
- Additional comments.
- Imports instead of fully-qualified use.
- Renamed `DuplicateProtoname` to `DuplicateProtonameError`.

* Replace `HashMap` with `Vec` in `Upgrades`.

* Review suggestion.

Co-authored-by: Roman Borschel <romanb@users.noreply.github.com>
Co-authored-by: Pierre Krieger <pierre.krieger1708@gmail.com>

swarm/Cargo.toml

@@ -13,6 +13,7 @@ categories = ["network-programming", "asynchronous"]
 futures = "0.3.1"
 libp2p-core = { version = "0.16.0", path = "../core" }
 log = "0.4"
+rand = "0.7"
 smallvec = "1.0"
 wasm-timer = "0.2"
 void = "1"

swarm/src/protocols_handler.rs

@@ -43,6 +43,7 @@ mod map_out;
 mod node_handler;
 mod one_shot;
 mod select;
+pub mod multi;
 
 pub use crate::upgrade::{
     InboundUpgradeSend,

swarm/src/protocols_handler/multi.rs

@@ -0,0 +1,376 @@
+// Copyright 2020 Parity Technologies (UK) Ltd.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the "Software"),
+// to deal in the Software without restriction, including without limitation
+// the rights to use, copy, modify, merge, publish, distribute, sublicense,
+// and/or sell copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+//! A [`ProtocolsHandler`] implementation that combines multiple other `ProtocolsHandler`s
+//! indexed by some key.
+
+use crate::NegotiatedSubstream;
+use crate::protocols_handler::{
+    KeepAlive,
+    IntoProtocolsHandler,
+    ProtocolsHandler,
+    ProtocolsHandlerEvent,
+    ProtocolsHandlerUpgrErr,
+    SubstreamProtocol
+};
+use crate::upgrade::{
+    InboundUpgradeSend,
+    OutboundUpgradeSend,
+    UpgradeInfoSend
+};
+use futures::{future::BoxFuture, prelude::*};
+use libp2p_core::{ConnectedPoint, PeerId, upgrade::ProtocolName};
+use rand::Rng;
+use std::{
+    collections::{HashMap, HashSet},
+    error,
+    fmt,
+    hash::Hash,
+    iter::{self, FromIterator},
+    task::{Context, Poll}
+};
+
+/// A [`ProtocolsHandler`] for multiple other `ProtocolsHandler`s.
+#[derive(Clone)]
+pub struct MultiHandler<K, H> {
+    handlers: HashMap<K, H>
+}
+
+impl<K, H> fmt::Debug for MultiHandler<K, H>
+where
+    K: fmt::Debug + Eq + Hash,
+    H: fmt::Debug
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("MultiHandler")
+            .field("handlers", &self.handlers)
+            .finish()
+    }
+}
+
+impl<K, H> MultiHandler<K, H>
+where
+    K: Hash + Eq,
+    H: ProtocolsHandler
+{
+    /// Create and populate a `MultiHandler` from the given handler iterator.
+    ///
+    /// It is an error for any two protocols handlers to share the same protocol name.
+    pub fn try_from_iter<I>(iter: I) -> Result<Self, DuplicateProtonameError>
+    where
+        I: IntoIterator<Item = (K, H)>
+    {
+        let m = MultiHandler { handlers: HashMap::from_iter(iter) };
+        uniq_proto_names(m.handlers.values().map(|h| h.listen_protocol().into_upgrade().1))?;
+        Ok(m)
+    }
+}
+
+impl<K, H> ProtocolsHandler for MultiHandler<K, H>
+where
+    K: Clone + Hash + Eq + Send + 'static,
+    H: ProtocolsHandler,
+    H::InboundProtocol: InboundUpgradeSend,
+    H::OutboundProtocol: OutboundUpgradeSend
+{
+    type InEvent = (K, <H as ProtocolsHandler>::InEvent);
+    type OutEvent = (K, <H as ProtocolsHandler>::OutEvent);
+    type Error = <H as ProtocolsHandler>::Error;
+    type InboundProtocol = Upgrade<K, <H as ProtocolsHandler>::InboundProtocol>;
+    type OutboundProtocol = <H as ProtocolsHandler>::OutboundProtocol;
+    type OutboundOpenInfo = (K, <H as ProtocolsHandler>::OutboundOpenInfo);
+
+    fn listen_protocol(&self) -> SubstreamProtocol<Self::InboundProtocol> {
+        let upgrades = self.handlers.iter()
+            .map(|(k, h)| (k.clone(), h.listen_protocol().into_upgrade().1))
+            .collect();
+        SubstreamProtocol::new(Upgrade { upgrades })
+    }
+
+    fn inject_fully_negotiated_outbound (
+        &mut self,
+        protocol: <Self::OutboundProtocol as OutboundUpgradeSend>::Output,
+        (key, arg): Self::OutboundOpenInfo
+    ) {
+        if let Some(h) = self.handlers.get_mut(&key) {
+            h.inject_fully_negotiated_outbound(protocol, arg)
+        } else {
+            log::error!("inject_fully_negotiated_outbound: no handler for key")
+        }
+    }
+
+    fn inject_fully_negotiated_inbound (
+        &mut self,
+        (key, arg): <Self::InboundProtocol as InboundUpgradeSend>::Output
+    ) {
+        if let Some(h) = self.handlers.get_mut(&key) {
+            h.inject_fully_negotiated_inbound(arg)
+        } else {
+            log::error!("inject_fully_negotiated_inbound: no handler for key")
+        }
+    }
+
+    fn inject_event(&mut self, (key, event): Self::InEvent) {
+        if let Some(h) = self.handlers.get_mut(&key) {
+            h.inject_event(event)
+        } else {
+            log::error!("inject_event: no handler for key")
+        }
+    }
+
+    fn inject_dial_upgrade_error (
+        &mut self,
+        (key, arg): Self::OutboundOpenInfo,
+        error: ProtocolsHandlerUpgrErr<<Self::OutboundProtocol as OutboundUpgradeSend>::Error>
+    ) {
+        if let Some(h) = self.handlers.get_mut(&key) {
+            h.inject_dial_upgrade_error(arg, error)
+        } else {
+            log::error!("inject_dial_upgrade_error: no handler for protocol")
+        }
+    }
+
+    fn connection_keep_alive(&self) -> KeepAlive {
+        self.handlers.values()
+            .map(|h| h.connection_keep_alive())
+            .max()
+            .unwrap_or(KeepAlive::No)
+    }
+
+    fn poll(&mut self, cx: &mut Context)
+        -> Poll<ProtocolsHandlerEvent<Self::OutboundProtocol, Self::OutboundOpenInfo, Self::OutEvent, Self::Error>>
+    {
+        // Not always polling handlers in the same order should give anyone the chance to make progress.
+        let pos = rand::thread_rng().gen_range(0, self.handlers.len());
+
+        for (k, h) in self.handlers.iter_mut().skip(pos) {
+            if let Poll::Ready(e) = h.poll(cx) {
+                let e = e.map_outbound_open_info(|i| (k.clone(), i)).map_custom(|p| (k.clone(), p));
+                return Poll::Ready(e)
+            }
+        }
+
+        for (k, h) in self.handlers.iter_mut().take(pos) {
+            if let Poll::Ready(e) = h.poll(cx) {
+                let e = e.map_outbound_open_info(|i| (k.clone(), i)).map_custom(|p| (k.clone(), p));
+                return Poll::Ready(e)
+            }
+        }
+
+        Poll::Pending
+    }
+}
+
+/// A [`IntoProtocolsHandler`] for multiple other `IntoProtocolsHandler`s.
+#[derive(Clone)]
+pub struct IntoMultiHandler<K, H> {
+    handlers: HashMap<K, H>
+}
+
+impl<K, H> fmt::Debug for IntoMultiHandler<K, H>
+where
+    K: fmt::Debug + Eq + Hash,
+    H: fmt::Debug
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("IntoMultiHandler")
+            .field("handlers", &self.handlers)
+            .finish()
+    }
+}
+
+
+impl<K, H> IntoMultiHandler<K, H>
+where
+    K: Hash + Eq,
+    H: IntoProtocolsHandler
+{
+    /// Create and populate an `IntoMultiHandler` from the given iterator.
+    ///
+    /// It is an error for any two protocols handlers to share the same protocol name.
+    pub fn try_from_iter<I>(iter: I) -> Result<Self, DuplicateProtonameError>
+    where
+        I: IntoIterator<Item = (K, H)>
+    {
+        let m = IntoMultiHandler { handlers: HashMap::from_iter(iter) };
+        uniq_proto_names(m.handlers.values().map(|h| h.inbound_protocol()))?;
+        Ok(m)
+    }
+}
+
+impl<K, H> IntoProtocolsHandler for IntoMultiHandler<K, H>
+where
+    K: Clone + Eq + Hash + Send + 'static,
+    H: IntoProtocolsHandler
+{
+    type Handler = MultiHandler<K, H::Handler>;
+
+    fn into_handler(self, p: &PeerId, c: &ConnectedPoint) -> Self::Handler {
+        MultiHandler {
+            handlers: self.handlers.into_iter()
+                .map(|(k, h)| (k, h.into_handler(p, c)))
+                .collect()
+        }
+    }
+
+    fn inbound_protocol(&self) -> <Self::Handler as ProtocolsHandler>::InboundProtocol {
+        Upgrade {
+            upgrades: self.handlers.iter()
+                .map(|(k, h)| (k.clone(), h.inbound_protocol()))
+                .collect()
+        }
+    }
+}
+
+/// Index and protocol name pair used as `UpgradeInfo::Info`.
+#[derive(Debug, Clone)]
+pub struct IndexedProtoName<H>(usize, H);
+
+impl<H: ProtocolName> ProtocolName for IndexedProtoName<H> {
+    fn protocol_name(&self) -> &[u8] {
+        self.1.protocol_name()
+    }
+}
+
+/// Inbound and outbound upgrade for all `ProtocolsHandler`s.
+#[derive(Clone)]
+pub struct Upgrade<K, H> {
+    upgrades: Vec<(K, H)>
+}
+
+impl<K, H> fmt::Debug for Upgrade<K, H>
+where
+    K: fmt::Debug + Eq + Hash,
+    H: fmt::Debug
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("Upgrade")
+            .field("upgrades", &self.upgrades)
+            .finish()
+    }
+}
+
+impl<K, H> UpgradeInfoSend for Upgrade<K, H>
+where
+    H: UpgradeInfoSend,
+    K: Send + 'static
+{
+    type Info = IndexedProtoName<H::Info>;
+    type InfoIter = std::vec::IntoIter<Self::Info>;
+
+    fn protocol_info(&self) -> Self::InfoIter {
+        self.upgrades.iter().enumerate()
+            .map(|(i, (_, h))| iter::repeat(i).zip(h.protocol_info()))
+            .flatten()
+            .map(|(i, h)| IndexedProtoName(i, h))
+            .collect::<Vec<_>>()
+            .into_iter()
+    }
+}
+
+impl<K, H> InboundUpgradeSend for Upgrade<K, H>
+where
+    H: InboundUpgradeSend,
+    K: Send + 'static
+{
+    type Output = (K, <H as InboundUpgradeSend>::Output);
+    type Error  = (K, <H as InboundUpgradeSend>::Error);
+    type Future = BoxFuture<'static, Result<Self::Output, Self::Error>>;
+
+    fn upgrade_inbound(mut self, resource: NegotiatedSubstream, info: Self::Info) -> Self::Future {
+        let IndexedProtoName(index, info) = info;
+        let (key, upgrade) = self.upgrades.remove(index);
+        upgrade.upgrade_inbound(resource, info)
+            .map(move |out| {
+                match out {
+                    Ok(o) => Ok((key, o)),
+                    Err(e) => Err((key, e))
+                }
+            })
+            .boxed()
+    }
+}
+
+impl<K, H> OutboundUpgradeSend for Upgrade<K, H>
+where
+    H: OutboundUpgradeSend,
+    K: Send + 'static
+{
+    type Output = (K, <H as OutboundUpgradeSend>::Output);
+    type Error  = (K, <H as OutboundUpgradeSend>::Error);
+    type Future = BoxFuture<'static, Result<Self::Output, Self::Error>>;
+
+    fn upgrade_outbound(mut self, resource: NegotiatedSubstream, info: Self::Info) -> Self::Future {
+        let IndexedProtoName(index, info) = info;
+        let (key, upgrade) = self.upgrades.remove(index);
+        upgrade.upgrade_outbound(resource, info)
+            .map(move |out| {
+                match out {
+                    Ok(o) => Ok((key, o)),
+                    Err(e) => Err((key, e))
+                }
+            })
+            .boxed()
+    }
+}
+
+/// Check that no two protocol names are equal.
+fn uniq_proto_names<I, T>(iter: I) -> Result<(), DuplicateProtonameError>
+where
+    I: Iterator<Item = T>,
+    T: UpgradeInfoSend
+{
+    let mut set = HashSet::new();
+    for infos in iter {
+        for i in infos.protocol_info() {
+            let v = Vec::from(i.protocol_name());
+            if set.contains(&v) {
+                return Err(DuplicateProtonameError(v))
+            } else {
+                set.insert(v);
+            }
+        }
+    }
+    Ok(())
+}
+
+/// It is an error if two handlers share the same protocol name.
+#[derive(Debug, Clone)]
+pub struct DuplicateProtonameError(Vec<u8>);
+
+impl DuplicateProtonameError {
+    /// The protocol name bytes that occured in more than one handler.
+    pub fn protocol_name(&self) -> &[u8] {
+        &self.0
+    }
+}
+
+impl fmt::Display for DuplicateProtonameError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        if let Ok(s) = std::str::from_utf8(&self.0) {
+            write!(f, "duplicate protocol name: {}", s)
+        } else {
+            write!(f, "duplicate protocol name: {:?}", self.0)
+        }
+    }
+}
+
+impl error::Error for DuplicateProtonameError {}
+