1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67
// Copyright 2019 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. //! Peer selection strategies for queries in the form of iterator-like state machines. //! //! Using a peer iterator in a query involves performing the following steps //! repeatedly and in an alternating fashion: //! //! 1. Calling `next` to observe the next state of the iterator and determine //! what to do, which is to either issue new requests to peers or continue //! waiting for responses. //! //! 2. When responses are received or requests fail, providing input to the //! iterator via the `on_success` and `on_failure` callbacks, //! respectively, followed by repeating step (1). //! //! When a call to `next` returns [`Finished`], no more peers can be obtained //! from the iterator and the results can be obtained from `into_result`. //! //! A peer iterator can be finished prematurely at any time through `finish`. //! //! [`Finished`]: PeersIterState::Finished pub mod closest; pub mod fixed; use libp2p_core::PeerId; use std::borrow::Cow; /// The state of a peer iterator. #[derive(Debug, Clone, PartialEq, Eq)] pub enum PeersIterState<'a> { /// The iterator is waiting for results. /// /// `Some(peer)` indicates that the iterator is now waiting for a result /// from `peer`, in addition to any other peers for which it is already /// waiting for results. /// /// `None` indicates that the iterator is waiting for results and there is no /// new peer to contact, despite the iterator not being at capacity w.r.t. /// the permitted parallelism. Waiting(Option<Cow<'a, PeerId>>), /// The iterator is waiting for results and is at capacity w.r.t. the /// permitted parallelism. WaitingAtCapacity, /// The iterator finished. Finished }