See individual [changelogs](https://github.com/libp2p/rust-libp2p/blob/libp2p-v0.56.0/CHANGELOG.md) for details. Notably, we've removed support for `async-std` in all crates, as `async-std` [has been discontinued](https://github.com/async-rs/async-std/pull/1099). Users should switch to using tokio instead. For now, we've kept the abstractions for supporting alternative runtimes, although not all parts may be public. Please open an issue if you are planning to support a custom runtime and run into any issues with that.. Thanks to everyone who contributed to the release!

See individual [changelogs](CHANGELOG.md) for details. Thanks everyone who contributed to it! :heart:

See individual [changelogs](CHANGELOG.md) for details.

See individual [changelogs](CHANGELOG.md) for details. Thanks everyone who contributed to it! :heart:

See individual [changelogs](CHANGELOG.md) for details.

See individual [changelogs](CHANGELOG.md) for details.

The most ergonomic version of rust-libp2p yet! We've been busy again, with over [250](https://github.com/libp2p/rust-libp2p/compare/libp2p-v0.52.0...master) PRs being merged into `master` since `v0.52.0` (excluding dependency updates). ## Backwards-compatible features Numerous improvements landed as patch releases since the `v0.52.0` release, for example a new, type-safe [`SwarmBuilder`](https://github.com/libp2p/rust-libp2p/pull/4120) that also encompasses the most common transport protocols: ```rust let mut swarm = libp2p::SwarmBuilder::with_new_identity() .with_tokio() .with_tcp( tcp::Config::default().port_reuse(true).nodelay(true), noise::Config::new, yamux::Config::default, )? .with_quic() .with_dns()? .with_relay_client(noise::Config::new, yamux::Config::default)? .with_behaviour(|keypair, relay_client| Behaviour { relay_client, ping: ping::Behaviour::default(), dcutr: dcutr::Behaviour::new(keypair.public().to_peer_id()), })? .build(); ``` The new builder makes heavy use of the type-system to guide you towards a correct composition of all transports. For example, it is important to compose the DNS transport as a wrapper around all other transports but before the relay transport. Luckily, you no longer need to worry about these details as the builder takes care of that for you! Have a look yourself if you dare [here](https://github.com/libp2p/rust-libp2p/tree/master/libp2p/src/builder) but be warned, the internals are a bit wild :) Some more features that we were able to ship in `v0.52.X` patch-releases include: - [stable QUIC implementation](https://github.com/libp2p/rust-libp2p/pull/4325) - for rust-libp2p compiled to WASM running in the browser - [WebTransport support](https://github.com/libp2p/rust-libp2p/pull/4015) - [WebRTC support](https://github.com/libp2p/rust-libp2p/pull/4248) - [UPnP implementation to automatically configure port-forwarding with ones gateway](https://github.com/libp2p/rust-libp2p/pull/4156) - [option to limit connections based on available memory](https://github.com/libp2p/rust-libp2p/pull/4281) We always try to ship as many features as possible in a backwards-compatible way to get them to you faster. Often times, these come with deprecations to give you a heads-up about what will change in a future version. We advise updating to each intermediate version rather than skipping directly to the most recent one, to avoid missing any crucial deprecation warnings. We highly recommend you stay up-to-date with the latest version to make upgrades as smooth as possible. Some improvments we unfortunately cannot ship in a way that Rust considers a non-breaking change but with every release, we attempt to smoothen the way for future upgrades. ## `#[non_exhaustive]` on key enums We've identified that adding a new "message" to the `ToSwarm` enum is a common cause for breaking changes. This enum is used by plugins (i.e. `NetworkBehaviour`s) to communicate with the `Swarm`. Similarly, the `FromSwarm` enum is used to inform plugins about state changes. By adding `#[non_exhaustive]` to these and other enums we enable future additions to be non-breaking changes. For example, [we plan](https://github.com/libp2p/rust-libp2p/issues/4302) to allow `NetworkBehaviour`s to share addresses of peers they've discovered with each other. Previously, we had to queue this feature until the next breaking change whereas now, we can simply ship it as soon as it is ready! Thanks to [@dhuseby](https://github.com/dhuseby) for getting the ball rolling on this one. See [PR 4581](https://github.com/libp2p/rust-libp2p/pull/4581) for details. ## Smarter keep-alive algorithm Prior to this release, a protocol (i.e. `ConnectionHandler`) had to diligently track streams and other state to correctly compute the `KeepAlive` for the connection. A bug in this computation sometimes caused the connection to be shut down, despite it still being in use by the protocol. Earlier this year, I thought "there is gotta be a better way" and drafted up [some ideas](https://github.com/libp2p/rust-libp2p/discussions/3353#discussioncomment-6144804). Eventually [@mxinden](https://github.com/mxinden) and myself hashed out the key-points around being smart in regards to keeping connections alive: - By default, any existing stream will keep the connection alive. - Protocols like `ping` can opt out of this with `Stream::ignore_for_keep_alive()`. - `ConnectionHandler::connection_keep_alive` only comes into effect once a connection _would_ be shut down. This allows protocols like [Circuit Relay V2](https://github.com/libp2p/specs/blob/master/relay/circuit-v2.md) to keep the connection alive despite there not being any streams. The nice benefit for you as a user is that connections are shut down more aggressivley, minimizing system resource use. Should you want to keep idle connections alive nonetheless, you can configure an additional delay using [`libp2p::swarm::Config::with_idle_connection_timeout`](https://docs.rs/libp2p/latest/libp2p/swarm/struct.Config.html#method.with_idle_connection_timeout). This also makes wiritng your own protocols simpler. The tracking issue for this effort was [#4306](https://github.com/libp2p/rust-libp2p/issues/4306) if you wanted to have a closer look. Special thanks to [@leonzchang](https://github.com/leonzchang) for landing many small PRs that made this possible! ## Be gone `ConnectionHandler::Error`! Talking about closing of connections, say goodbye to `ConnectionHandler::Error` and its related components. It took many months of careful [planning](https://github.com/libp2p/rust-libp2p/issues/3591), [numerous discussions](https://github.com/libp2p/rust-libp2p/discussions/3353), [failed attempts](https://github.com/libp2p/rust-libp2p/pull/3201) and [s](https://github.com/libp2p/rust-libp2p/pull/4749)-[e](https://github.com/libp2p/rust-libp2p/pull/4745)-[v](https://github.com/libp2p/rust-libp2p/pull/4718)-[e](https://github.com/libp2p/rust-libp2p/pull/4715)-[r](https://github.com/libp2p/rust-libp2p/pull/3577)-[a](https://github.com/libp2p/rust-libp2p/pull/3913)-[l](https://github.com/libp2p/rust-libp2p/pull/3947) refactorings but we finally [delete](https://github.com/libp2p/rust-libp2p/pull/4755) `ConnectionHandler::Error` with this release. There's lots to be excited about with this change; let me explain. Deleting `ConnectionHandler::Error` also means: - Removing a type-parameter from `SwarmEvent`. No more ```rust SwarmEvent<MyBehaviourEvent, Either<Either<Either<Either<Either<io::Error, Void>, io::Error>, io::Error>, Void>, io::Error>, StreamUpgradeError<Void>>, Void> ``` Just: ```rust SwarmEvent<MyBehaviourEvent> ``` Isn't that neat? :tada: - `ConnectionHandlerEvent::Close` is gone too and together with it, a type parameter on its definition! - `FromSwarm` also as a type-parameter removed which makes it easier and more concise to reference! - Fewer force-closing of connections. Prior to this change, a `ConnectionHandler` could simply close an entire connection at any point, despite the connection still being in use by other protocols. (Remember that protocols are multiplexed over a single connection.) For example, an error while making a reservation with a relay would lead to the entire relayed connection being closed, even though other protocols might still have been using it. This means more reliable connections and protocol executions as no one is pulling the rug out from underneath your protocol's legs as they run across the wire :running: ## `tracing` > Protocols don't actually have legs, Thomas. That is true. But if we imagine for a moment that they do, using the latest migration to `tracing` we can now watch them! I am not sure if [@eserilev](https://github.com/eserilev) knew what they were signing up for when they suggested to tackle [#1533](https://github.com/libp2p/rust-libp2p/issues/1533) back in August. A lot of impressive work and pretty much exactly three months later though, we merged [#4282](https://github.com/libp2p/rust-libp2p/pull/4282) which: - migrates the entire workspace from `log` to `tracing` - adds several spans to interesting functions - [showcases](https://github.com/libp2p/rust-libp2p/tree/master/examples/metrics) how to ingest this data into Jaeger Enough talking, here is a screenshot:  Here we can see what _one_ particular call to `Connection::poll` actually did. We can see how much time is spent in the respective `identify` and `ping` handlers as well as interaction with the stream multiplexer. We put some consideration in to which spans might be useful but we are excited to hear from users how useful they are and what else might need instrumentation. ## `PollParameters` has been removed A relict from earlier designs of `rust-libp2p` is finally gone too: `PollParameters`. The `NetworkBehaviour::poll` function now just takes a `&mut Context` as you'd expect it to, without any additional clutter. All features of `PollParameters` have previously already been deprecated and alternatives were offered in terms of events. If you enforce no warnings in your codebase, you should be able to just delete that (unused) parameter from the function. ## Credits This release would not have been possible without the contributions of many people. Thank you to (in alphabetical order): - [@0x7CFE](https://github.com/0x7CFE) - [@0xcrust](https://github.com/0xcrust) - [@ackintosh](https://github.com/ackintosh) - [@AgeManning](https://github.com/AgeManning) - [@arpankapoor](https://github.com/arpankapoor) - [@arsenron](https://github.com/arsenron) - [@bgins](https://github.com/bgins) - [@binsta](https://github.com/binsta) - [@b-zee](https://github.com/b-zee) - [@chirag-bgh](https://github.com/chirag-bgh) - [@clebrin](https://github.com/clebrin) - [@contrun](https://github.com/contrun) - [@dariusc93](https://github.com/dariusc93) - [@Dejiah](https://github.com/Dejiah) - [@dgarus](https://github.com/dgarus) - [@dhuseby](https://github.com/dhuseby) - [@divagant-martian](https://github.com/divagant-martian) - [@DougAnderson444](https://github.com/DougAnderson444) - [@dvorakchen](https://github.com/dvorakchen) - [@eserilev](https://github.com/eserilev) - [@gurinderu](https://github.com/gurinderu) - [@hanabi1224](https://github.com/hanabi1224) - [@joshuef](https://github.com/joshuef) - [@kayabaNerve](https://github.com/kayabaNerve) - [@kpp](https://github.com/kpp) - [@leonzchang](https://github.com/leonzchang) - [@maqi](https://github.com/maqi) - [@Marcel-G](https://github.com/Marcel-G) - [@mcamou](https://github.com/mcamou) - [@melekes](https://github.com/melekes) - [@monoid](https://github.com/monoid) - [@MOZGIII](https://github.com/MOZGIII) - [@nathanielc](https://github.com/nathanielc) - [@oblique](https://github.com/oblique) - [@onur-ozkan](https://github.com/onur-ozkan) - [@p0mvn](https://github.com/p0mvn) - [@PanGan21](https://github.com/PanGan21) - [@pradt2](https://github.com/pradt2) - [@p-shahi](https://github.com/p-shahi) - [@quininer](https://github.com/quininer) - [@radiohertz](https://github.com/radiohertz) - [@randommm](https://github.com/randommm) - [@shamil-gadelshin](https://github.com/shamil-gadelshin) - [@startup-dreamer](https://github.com/startup-dreamer) - [@StemCll](https://github.com/StemCll) - [@sufferpurrityxd](https://github.com/sufferpurrityxd) - [@tcoratger](https://github.com/tcoratger) - [@thomas-senechal](https://github.com/thomas-senechal) - [@umgefahren](https://github.com/umgefahren) - [@whtsht](https://github.com/whtsht) - [@yerayrodriguez](https://github.com/yerayrodriguez) - [@zeeshanlakhani](https://github.com/zeeshanlakhani) - [@zrus](https://github.com/zrus) - [@zvolin](https://github.com/zvolin) ## Closing As always, a detailed log of changes for every release can be found in our repository: [CHANGELOG.md](https://github.com/libp2p/rust-libp2p/blob/master/CHANGELOG.md). If you are struggling with an upgrade, feel free to tag Max ([@mxinden](https://github.com/mxinden)) or myself ([@thomaseizinger](https://github.com/thomaseizinger)) in a PR and we'll try to help. Happy coding!

# v0.53 release The most ergonomic version of rust-libp2p yet! We've been busy again, with over [250](https://github.com/libp2p/rust-libp2p/compare/libp2p-v0.52.0...master) PRs being merged into `master` since `v0.52.0` (excluding dependency updates). ## Backwards-compatible features Numerous improvements landed as patch releases since the `v0.52.0` release, for example a new, type-safe [`SwarmBuilder`](https://github.com/libp2p/rust-libp2p/pull/4120) that also encompasses the most common transport protocols: ```rust let mut swarm = libp2p::SwarmBuilder::with_new_identity() .with_tokio() .with_tcp( tcp::Config::default().port_reuse(true).nodelay(true), noise::Config::new, yamux::Config::default, )? .with_quic() .with_dns()? .with_relay_client(noise::Config::new, yamux::Config::default)? .with_behaviour(|keypair, relay_client| Behaviour { relay_client, ping: ping::Behaviour::default(), dcutr: dcutr::Behaviour::new(keypair.public().to_peer_id()), })? .build(); ``` The new builder makes heavy use of the type-system to guide you towards a correct composition of all transports. For example, it is important to compose the DNS transport as a wrapper around all other transports but before the relay transport. Luckily, you no longer need to worry about these details as the builder takes care of that for you! Have a look yourself if you dare [here](https://github.com/libp2p/rust-libp2p/tree/master/libp2p/src/builder) but be warned, the internals are a bit wild :) Some more features that we were able to ship in `v0.52.X` patch-releases include: - [stable QUIC implementation](https://github.com/libp2p/rust-libp2p/pull/4325) - for rust-libp2p compiled to WASM running in the browser - [WebTransport support](https://github.com/libp2p/rust-libp2p/pull/4015) - [WebRTC support](https://github.com/libp2p/rust-libp2p/pull/4248) - [UPnP implementation to automatically configure port-forwarding with ones gateway](https://github.com/libp2p/rust-libp2p/pull/4156) - [option to limit connections based on available memory](https://github.com/libp2p/rust-libp2p/pull/4281) We always try to ship as many features as possible in a backwards-compatible way to get them to you faster. Often times, these come with deprecations to give you a heads-up about what will change in a future version. We advise updating to each intermediate version rather than skipping directly to the most recent one, to avoid missing any crucial deprecation warnings. We highly recommend you stay up-to-date with the latest version to make upgrades as smooth as possible. Some improvments we unfortunately cannot ship in a way that Rust considers a non-breaking change but with every release, we attempt to smoothen the way for future upgrades. ## `#[non_exhaustive]` on key enums We've identified that adding a new "message" to the `ToSwarm` enum is a common cause for breaking changes. This enum is used by plugins (i.e. `NetworkBehaviour`s) to communicate with the `Swarm`. Similarly, the `FromSwarm` enum is used to inform plugins about state changes. By adding `#[non_exhaustive]` to these and other enums we enable future additions to be non-breaking changes. For example, [we plan](https://github.com/libp2p/rust-libp2p/issues/4302) to allow `NetworkBehaviour`s to share addresses of peers they've discovered with each other. Previously, we had to queue this feature until the next breaking change whereas now, we can simply ship it as soon as it is ready! Thanks to [@dhuseby](https://github.com/dhuseby) for getting the ball rolling on this one. See [PR 4581](https://github.com/libp2p/rust-libp2p/pull/4581) for details. ## Smarter keep-alive algorithm Prior to this release, a protocol (i.e. `ConnectionHandler`) had to diligently track streams and other state to correctly compute the `KeepAlive` for the connection. A bug in this computation sometimes caused the connection to be shut down, despite it still being in use by the protocol. Earlier this year, I thought "there is gotta be a better way" and drafted up [some ideas](https://github.com/libp2p/rust-libp2p/discussions/3353#discussioncomment-6144804). Eventually [@mxinden](https://github.com/mxinden) and myself hashed out the key-points around being smart in regards to keeping connections alive: - By default, any existing stream will keep the connection alive. - Protocols like `ping` can opt out of this with `Stream::ignore_for_keep_alive()`. - `ConnectionHandler::connection_keep_alive` only comes into effect once a connection _would_ be shut down. This allows protocols like [Circuit Relay V2](https://github.com/libp2p/specs/blob/master/relay/circuit-v2.md) to keep the connection alive despite there not being any streams. The nice benefit for you as a user is that connections are shut down more aggressivley, minimizing system resource use. Should you want to keep idle connections alive nonetheless, you can configure an additional delay using [`libp2p::swarm::Config::with_idle_connection_timeout`](https://docs.rs/libp2p/latest/libp2p/swarm/struct.Config.html#method.with_idle_connection_timeout). This also makes wiritng your own protocols simpler. The tracking issue for this effort was [#4306](https://github.com/libp2p/rust-libp2p/issues/4306) if you wanted to have a closer look. Special thanks to [@leonzchang](https://github.com/leonzchang) for landing many small PRs that made this possible! ## Be gone `ConnectionHandler::Error`! Talking about closing of connections, say goodbye to `ConnectionHandler::Error` and its related components. It took many months of careful [planning](https://github.com/libp2p/rust-libp2p/issues/3591), [numerous discussions](https://github.com/libp2p/rust-libp2p/discussions/3353), [failed attempts](https://github.com/libp2p/rust-libp2p/pull/3201) and [s](https://github.com/libp2p/rust-libp2p/pull/4749)-[e](https://github.com/libp2p/rust-libp2p/pull/4745)-[v](https://github.com/libp2p/rust-libp2p/pull/4718)-[e](https://github.com/libp2p/rust-libp2p/pull/4715)-[r](https://github.com/libp2p/rust-libp2p/pull/3577)-[a](https://github.com/libp2p/rust-libp2p/pull/3913)-[l](https://github.com/libp2p/rust-libp2p/pull/3947) refactorings but we finally [delete](https://github.com/libp2p/rust-libp2p/pull/4755) `ConnectionHandler::Error` with this release. There's lots to be excited about with this change; let me explain. Deleting `ConnectionHandler::Error` also means: - Removing a type-parameter from `SwarmEvent`. No more ```rust SwarmEvent<MyBehaviourEvent, Either<Either<Either<Either<Either<io::Error, Void>, io::Error>, io::Error>, Void>, io::Error>, StreamUpgradeError<Void>>, Void> ``` Just: ```rust SwarmEvent<MyBehaviourEvent> ``` Isn't that neat? :tada: - `ConnectionHandlerEvent::Close` is gone too and together with it, a type parameter on its definition! - `FromSwarm` also as a type-parameter removed which makes it easier and more concise to reference! - Fewer force-closing of connections. Prior to this change, a `ConnectionHandler` could simply close an entire connection at any point, despite the connection still being in use by other protocols. (Remember that protocols are multiplexed over a single connection.) For example, an error while making a reservation with a relay would lead to the entire relayed connection being closed, even though other protocols might still have been using it. This means more reliable connections and protocol executions as no one is pulling the rug out from underneath your protocol's legs as they run across the wire :running: ## `tracing` > Protocols don't actually have legs, Thomas. That is true. But if we imagine for a moment that they do, using the latest migration to `tracing` we can now watch them! I am not sure if [@eserilev](https://github.com/eserilev) knew what they were signing up for when they suggested to tackle [#1533](https://github.com/libp2p/rust-libp2p/issues/1533) back in August. A lot of impressive work and pretty much exactly three months later though, we merged [#4282](https://github.com/libp2p/rust-libp2p/pull/4282) which: - migrates the entire workspace from `log` to `tracing` - adds several spans to interesting functions - [showcases](https://github.com/libp2p/rust-libp2p/tree/master/examples/metrics) how to ingest this data into Jaeger Enough talking, here is a screenshot:  Here we can see what _one_ particular call to `Connection::poll` actually did. We can see how much time is spent in the respective `identify` and `ping` handlers as well as interaction with the stream multiplexer. We put some consideration in to which spans might be useful but we are excited to hear from users how useful they are and what else might need instrumentation. ## `PollParameters` has been removed A relict from earlier designs of `rust-libp2p` is finally gone too: `PollParameters`. The `NetworkBehaviour::poll` function now just takes a `&mut Context` as you'd expect it to, without any additional clutter. All features of `PollParameters` have previously already been deprecated and alternatives were offered in terms of events. If you enforce no warnings in your codebase, you should be able to just delete that (unused) parameter from the function. ## Credits This release would not have been possible without the contributions of many people. Thank you to (in alphabetical order): - [@0x7CFE](https://github.com/0x7CFE) - [@0xcrust](https://github.com/0xcrust) - [@ackintosh](https://github.com/ackintosh) - [@AgeManning](https://github.com/AgeManning) - [@arpankapoor](https://github.com/arpankapoor) - [@arsenron](https://github.com/arsenron) - [@bgins](https://github.com/bgins) - [@binsta](https://github.com/binsta) - [@b-zee](https://github.com/b-zee) - [@chirag-bgh](https://github.com/chirag-bgh) - [@clebrin](https://github.com/clebrin) - [@contrun](https://github.com/contrun) - [@dariusc93](https://github.com/dariusc93) - [@Dejiah](https://github.com/Dejiah) - [@dgarus](https://github.com/dgarus) - [@dhuseby](https://github.com/dhuseby) - [@divagant-martian](https://github.com/divagant-martian) - [@DougAnderson444](https://github.com/DougAnderson444) - [@dvorakchen](https://github.com/dvorakchen) - [@eserilev](https://github.com/eserilev) - [@gurinderu](https://github.com/gurinderu) - [@hanabi1224](https://github.com/hanabi1224) - [@joshuef](https://github.com/joshuef) - [@kayabaNerve](https://github.com/kayabaNerve) - [@kpp](https://github.com/kpp) - [@leonzchang](https://github.com/leonzchang) - [@maqi](https://github.com/maqi) - [@Marcel-G](https://github.com/Marcel-G) - [@mcamou](https://github.com/mcamou) - [@melekes](https://github.com/melekes) - [@monoid](https://github.com/monoid) - [@MOZGIII](https://github.com/MOZGIII) - [@nathanielc](https://github.com/nathanielc) - [@oblique](https://github.com/oblique) - [@onur-ozkan](https://github.com/onur-ozkan) - [@p0mvn](https://github.com/p0mvn) - [@PanGan21](https://github.com/PanGan21) - [@pradt2](https://github.com/pradt2) - [@p-shahi](https://github.com/p-shahi) - [@quininer](https://github.com/quininer) - [@radiohertz](https://github.com/radiohertz) - [@randommm](https://github.com/randommm) - [@shamil-gadelshin](https://github.com/shamil-gadelshin) - [@startup-dreamer](https://github.com/startup-dreamer) - [@StemCll](https://github.com/StemCll) - [@sufferpurrityxd](https://github.com/sufferpurrityxd) - [@tcoratger](https://github.com/tcoratger) - [@thomas-senechal](https://github.com/thomas-senechal) - [@umgefahren](https://github.com/umgefahren) - [@whtsht](https://github.com/whtsht) - [@yerayrodriguez](https://github.com/yerayrodriguez) - [@zeeshanlakhani](https://github.com/zeeshanlakhani) - [@zrus](https://github.com/zrus) - [@zvolin](https://github.com/zvolin) ## Closing As always, a detailed log of changes for every release can be found in our repository: [CHANGELOG.md](https://github.com/libp2p/rust-libp2p/blob/master/CHANGELOG.md). If you are struggling with an upgrade, feel free to tag Max ([@mxinden](https://github.com/mxinden)) or myself ([@thomaseizinger](https://github.com/thomaseizinger)) in a PR and we'll try to help. Happy coding!