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
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143

// Copyright 2017, 2018 Parity Technologies
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use hash_db::{HashDBRef, Hasher};
use super::{Result, DBValue, TrieDB, Trie, TrieDBIterator, TrieItem, TrieIterator, Query};
use node_codec::NodeCodec;

/// A `Trie` implementation which hashes keys and uses a generic `HashDB` backing database.
/// Additionaly it stores inserted hash-key mappings for later retrieval.
///
/// Use it as a `Trie` or `TrieMut` trait object.
pub struct FatDB<'db, H, C>
where
	H: Hasher + 'db,
	C: NodeCodec<H>
{
	raw: TrieDB<'db, H, C>,
}

impl<'db, H, C> FatDB<'db, H, C>
where
	H: Hasher,
	C: NodeCodec<H>
{
	/// Create a new trie with the backing database `db` and empty `root`
	/// Initialise to the state entailed by the genesis block.
	/// This guarantees the trie is built correctly.
	pub fn new(db: &'db HashDBRef<H, DBValue>, root: &'db H::Out) -> Result<Self, H::Out, C::Error> {
		Ok(FatDB { raw: TrieDB::new(db, root)? })
	}

	/// Get the backing database.
	pub fn db(&self) -> &HashDBRef<H, DBValue> { self.raw.db() }
}

impl<'db, H, C> Trie<H, C> for FatDB<'db, H, C>
where
	H: Hasher,
	C: NodeCodec<H>
{
	fn root(&self) -> &H::Out { self.raw.root() }

	fn contains(&self, key: &[u8]) -> Result<bool, H::Out, C::Error> {
		self.raw.contains(H::hash(key).as_ref())
	}

	fn get_with<'a, 'key, Q: Query<H>>(&'a self, key: &'key [u8], query: Q) -> Result<Option<Q::Item>, H::Out, C::Error>
		where 'a: 'key
	{
		self.raw.get_with(H::hash(key).as_ref(), query)
	}

	fn iter<'a>(&'a self) -> Result<Box<TrieIterator<H, C, Item = TrieItem<H::Out, C::Error>> + 'a>, <H as Hasher>::Out, C::Error> {
		FatDBIterator::<H, C>::new(&self.raw).map(|iter| Box::new(iter) as Box<_>)
	}
}

/// Itarator over inserted pairs of key values.
pub struct FatDBIterator<'db, H, C>
where
	H: Hasher + 'db,
	C: NodeCodec<H> + 'db
{
	trie_iterator: TrieDBIterator<'db, H, C>,
	trie: &'db TrieDB<'db, H, C>,
}

impl<'db, H, C> FatDBIterator<'db, H, C>
where
	H: Hasher,
	C: NodeCodec<H>
{
	/// Creates new iterator.
	pub fn new(trie: &'db TrieDB<H, C>) -> Result<Self, H::Out, C::Error> {
		Ok(FatDBIterator {
			trie_iterator: TrieDBIterator::new(trie)?,
			trie: trie,
		})
	}
}

impl<'db, H, C> TrieIterator<H, C> for FatDBIterator<'db, H, C>
where
	H: Hasher,
	C: NodeCodec<H>
{
	fn seek(&mut self, key: &[u8]) -> Result<(), H::Out, C::Error> {
		let hashed_key = H::hash(key);
		self.trie_iterator.seek(hashed_key.as_ref())
	}
}

impl<'db, H, C> Iterator for FatDBIterator<'db, H, C>
where
	H: Hasher,
	C: NodeCodec<H>
{
	type Item = TrieItem<'db, H::Out, C::Error>;

	fn next(&mut self) -> Option<Self::Item> {
		self.trie_iterator.next()
			.map(|res| {
				res.map(|(hash, value)| {
					let aux_hash = H::hash(&hash);
					(self.trie.db().get(&aux_hash).expect("Missing fatdb hash").into_vec(), value)
				})
			})
	}
}

#[cfg(test)]
mod test {
	use memory_db::MemoryDB;
	use DBValue;
	use keccak_hasher::KeccakHasher;
	use reference_trie::{RefFatDBMut, RefFatDB, Trie, TrieMut};

	#[test]
	fn fatdb_to_trie() {
		let mut memdb = MemoryDB::<KeccakHasher, DBValue>::default();
		let mut root = Default::default();
		{
			let mut t = RefFatDBMut::new(&mut memdb, &mut root);
			t.insert(&[0x01u8, 0x23], &[0x01u8, 0x23]).unwrap();
		}
		let t = RefFatDB::new(&memdb, &root).unwrap();
		assert_eq!(t.get(&[0x01u8, 0x23]).unwrap().unwrap(), DBValue::from_slice(&[0x01u8, 0x23]));
		assert_eq!(
			t.iter().unwrap().map(Result::unwrap).collect::<Vec<_>>(),
			vec![(vec![0x01u8, 0x23], DBValue::from_slice(&[0x01u8, 0x23] as &[u8]))]);
	}
}