rust-libp2p/libp2p-peerstore/src/json_peerstore.rs

// Copyright 2017 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.
//
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// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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//! Implementation of the `Peerstore` trait that uses a single JSON file as backend.

use super::TTL;
use PeerId;
use base58::{FromBase58, ToBase58};
use datastore::{Datastore, Query, JsonFileDatastore, JsonFileDatastoreEntry};
use futures::{Future, Stream};
use multiaddr::Multiaddr;
use peer_info::{PeerInfo, AddAddrBehaviour};
use peerstore::{Peerstore, PeerAccess};
use std::io::Error as IoError;
use std::iter;
use std::path::PathBuf;
use std::vec::IntoIter as VecIntoIter;

/// Peerstore backend that uses a Json file.
pub struct JsonPeerstore {
	store: JsonFileDatastore<PeerInfo>,
}

impl JsonPeerstore {
	/// Opens a new peerstore tied to a JSON file at the given path.
	///
	/// If the file exists, this function will open it. In any case, flushing the peerstore or
	/// destroying it will write to the file.
	#[inline]
	pub fn new<P>(path: P) -> Result<JsonPeerstore, IoError>
		where P: Into<PathBuf>
	{
		Ok(JsonPeerstore { store: JsonFileDatastore::new(path)? })
	}

	/// Flushes the content of the peer store to the disk.
	///
	/// This function can only fail in case of a disk access error. If an error occurs, any change
	/// to the peerstore that was performed since the last successful flush will be lost. No data
	/// will be corrupted.
	#[inline]
	pub fn flush(&self) -> Result<(), IoError> {
		self.store.flush()
	}
}

impl<'a> Peerstore for &'a JsonPeerstore {
	type PeerAccess = JsonPeerstoreAccess<'a>;
	type PeersIter = Box<Iterator<Item = PeerId>>;

	#[inline]
	fn peer(self, peer_id: &PeerId) -> Option<Self::PeerAccess> {
		let hash = peer_id.to_base58();
		self.store.lock(hash.into()).map(JsonPeerstoreAccess)
	}

	#[inline]
	fn peer_or_create(self, peer_id: &PeerId) -> Self::PeerAccess {
		let hash = peer_id.to_base58();
		JsonPeerstoreAccess(self.store.lock_or_create(hash.into()))
	}

	fn peers(self) -> Self::PeersIter {
		let query = self.store.query(Query {
			prefix: "".into(),
			filters: vec![],
			orders: vec![],
			skip: 0,
			limit: u64::max_value(),
			keys_only: true,
		});

		let list = query.filter_map(|(key, _)| {
			// We filter out invalid elements. This can happen if the JSON storage file was
			// corrupted or manually modified by the user.
			key.from_base58().ok()
		})
		                .collect()
		                .wait(); // Wait can never block for the JSON datastore.

		// Need to handle I/O errors. Again we just ignore.
		if let Ok(list) = list {
			Box::new(list.into_iter()) as Box<_>
		} else {
			Box::new(iter::empty()) as Box<_>
		}
	}
}

pub struct JsonPeerstoreAccess<'a>(JsonFileDatastoreEntry<'a, PeerInfo>);

impl<'a> PeerAccess for JsonPeerstoreAccess<'a> {
	type AddrsIter = VecIntoIter<Multiaddr>;

	#[inline]
	fn addrs(&self) -> Self::AddrsIter {
		self.0.addrs().cloned().collect::<Vec<_>>().into_iter()
	}

	#[inline]
	fn add_addr(&mut self, addr: Multiaddr, ttl: TTL) {
		self.0.add_addr(addr, ttl, AddAddrBehaviour::IgnoreTtlIfInferior);
	}

	#[inline]
	fn set_addr_ttl(&mut self, addr: Multiaddr, ttl: TTL) {
		self.0.add_addr(addr, ttl, AddAddrBehaviour::OverwriteTtl);
	}

	#[inline]
	fn clear_addrs(&mut self) {
		self.0.set_addrs(iter::empty());
	}

	#[inline]
	fn get_pub_key(&self) -> Option<&[u8]> {
		self.0.public_key()
	}

	#[inline]
	fn set_pub_key(&mut self, key: Vec<u8>) {
		self.0.set_public_key(key);
	}
}

#[cfg(test)]
mod tests {
	extern crate tempfile;
	peerstore_tests!(
		{::json_peerstore::JsonPeerstore::new(temp_file.path()).unwrap()}
		{let temp_file = self::tempfile::NamedTempFile::new().unwrap()}
	);
}