libp2p_kad/query/
peers.rs

1// Copyright 2019 Parity Technologies (UK) Ltd.
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20
21//! Peer selection strategies for queries in the form of iterator-like state machines.
22//!
23//! Using a peer iterator in a query involves performing the following steps
24//! repeatedly and in an alternating fashion:
25//!
26//!   1. Calling `next` to observe the next state of the iterator and determine what to do, which is
27//!      to either issue new requests to peers or continue waiting for responses.
28//!
29//!   2. When responses are received or requests fail, providing input to the iterator via the
30//!      `on_success` and `on_failure` callbacks, respectively, followed by repeating step (1).
31//!
32//! When a call to `next` returns [`Finished`], no more peers can be obtained
33//! from the iterator and the results can be obtained from `into_result`.
34//!
35//! A peer iterator can be finished prematurely at any time through `finish`.
36//!
37//! [`Finished`]: PeersIterState::Finished
38
39pub(crate) mod closest;
40pub(crate) mod fixed;
41use std::borrow::Cow;
42
43use libp2p_identity::PeerId;
44
45/// The state of a peer iterator.
46#[derive(Debug, Clone, PartialEq, Eq)]
47pub enum PeersIterState<'a> {
48    /// The iterator is waiting for results.
49    ///
50    /// `Some(peer)` indicates that the iterator is now waiting for a result
51    /// from `peer`, in addition to any other peers for which it is already
52    /// waiting for results.
53    ///
54    /// `None` indicates that the iterator is waiting for results and there is no
55    /// new peer to contact, despite the iterator not being at capacity w.r.t.
56    /// the permitted parallelism.
57    Waiting(Option<Cow<'a, PeerId>>),
58
59    /// The iterator is waiting for results and is at capacity w.r.t. the
60    /// permitted parallelism.
61    WaitingAtCapacity,
62
63    /// The iterator finished.
64    Finished,
65}
libp2p_kad/query/peers.rs

libp2p_kad/query/
peers.rs
