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69 lines
2.9 KiB
Rust
69 lines
2.9 KiB
Rust
// Copyright 2019 Parity Technologies (UK) Ltd.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a
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// copy of this software and associated documentation files (the "Software"),
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// to deal in the Software without restriction, including without limitation
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// the rights to use, copy, modify, merge, publish, distribute, sublicense,
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// and/or sell copies of the Software, and to permit persons to whom the
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// Software is furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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// DEALINGS IN THE SOFTWARE.
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// The basis of this file has been taken from the rust-libp2p codebase:
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// https://github.com/libp2p/rust-libp2p
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//! Peer selection strategies for queries in the form of iterator-like state machines.
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//!
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//! Using a peer iterator in a query involves performing the following steps
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//! repeatedly and in an alternating fashion:
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//!
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//! 1. Calling `next` to observe the next state of the iterator and determine
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//! what to do, which is to either issue new requests to peers or continue
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//! waiting for responses.
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//!
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//! 2. When responses are received or requests fail, providing input to the
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//! iterator via the `on_success` and `on_failure` callbacks,
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//! respectively, followed by repeating step (1).
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//!
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//! When a call to `next` returns [`Finished`], no more peers can be obtained
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//! from the iterator and the results can be obtained from `into_result`.
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//!
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//! A peer iterator can be finished prematurely at any time through `finish`.
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//!
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//! [`Finished`]: QueryState::Finished
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pub mod closest;
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pub mod predicate;
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/// The state of the query reported by [`closest::FindNodeQuery::next`] or
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/// [`predicate::PredicateQuery::next`].
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#[derive(Debug, Clone, PartialEq, Eq)]
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pub enum QueryState<TNodeId> {
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/// The query is waiting for results.
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///
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/// `Some(peer)` indicates that the query is now waiting for a result
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/// from `peer`, in addition to any other peers for which the query is already
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/// waiting for results.
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///
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/// `None` indicates that the query is waiting for results and there is no
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/// new peer to contact, despite the query not being at capacity w.r.t.
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/// the permitted parallelism.
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Waiting(Option<TNodeId>),
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/// The query is waiting for results and is at capacity w.r.t. the
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/// permitted parallelism.
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WaitingAtCapacity,
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/// The query finished.
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Finished,
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}
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