[kvdb-rocksdb] switch to upstream

kvdb-rocksdb/Cargo.toml

@@ -11,12 +11,13 @@ edition = "2018"
 elastic-array = "0.10.2"
 fs-swap = "0.2.4"
 interleaved-ordered = "0.1.1"
-kvdb = { version = "0.1", path = "../kvdb" }
+kvdb = { path = "../kvdb", version = "0.1" }
 log = "0.4.8"
 num_cpus = "1.10.1"
 parking_lot = "0.9.0"
 regex = "1.3.1"
-parity-rocksdb = "0.5.1"
+rocksdb = { version = "0.13", features = ["snappy"], default-features = false }
+owning_ref = "0.4.0"
 
 [dev-dependencies]
 tempdir = "0.3.7"

kvdb-rocksdb/src/iter.rs

@@ -0,0 +1,128 @@
+// Copyright 2019 Parity Technologies (UK) Ltd.
+// This file is part of Parity.
+
+// Parity is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity.  If not, see <http://www.gnu.org/licenses/>.
+
+//! This module contains an implementation of a RocksDB iterator
+//! wrapped inside a `RwLock`. Since `RwLock` "owns" the inner data,
+//! we're using `owning_ref` to work around the borrowing rules of Rust.
+
+use crate::DBAndColumns;
+use owning_ref::{OwningHandle, StableAddress};
+use parking_lot::RwLockReadGuard;
+use rocksdb::{DBIterator, IteratorMode};
+use std::ops::{Deref, DerefMut};
+
+/// A tuple holding key and value data, used as the iterator item type.
+pub type KeyValuePair = (Box<[u8]>, Box<[u8]>);
+
+/// Iterator with built-in synchronization.
+pub struct ReadGuardedIterator<'a, I, T> {
+	inner: OwningHandle<UnsafeStableAddress<'a, Option<T>>, DerefWrapper<Option<I>>>,
+}
+
+// We can't implement `StableAddress` for a `RwLockReadGuard`
+// directly due to orphan rules.
+#[repr(transparent)]
+struct UnsafeStableAddress<'a, T>(RwLockReadGuard<'a, T>);
+
+impl<'a, T> Deref for UnsafeStableAddress<'a, T> {
+	type Target = T;
+	fn deref(&self) -> &Self::Target {
+		self.0.deref()
+	}
+}
+
+// RwLockReadGuard dereferences to a stable address; qed
+unsafe impl<'a, T> StableAddress for UnsafeStableAddress<'a, T> {}
+
+struct DerefWrapper<T>(T);
+
+impl<T> Deref for DerefWrapper<T> {
+	type Target = T;
+	fn deref(&self) -> &Self::Target {
+		&self.0
+	}
+}
+
+impl<T> DerefMut for DerefWrapper<T> {
+	fn deref_mut(&mut self) -> &mut Self::Target {
+		&mut self.0
+	}
+}
+
+impl<'a, I: Iterator, T> Iterator for ReadGuardedIterator<'a, I, T> {
+	type Item = I::Item;
+
+	fn next(&mut self) -> Option<Self::Item> {
+		self.inner.deref_mut().as_mut().and_then(|iter| iter.next())
+	}
+}
+
+/// Instantiate iterators yielding `KeyValuePair`s.
+pub trait IterationHandler {
+	type Iterator: Iterator<Item = KeyValuePair>;
+
+	/// Create an `Iterator` over the default DB column or over a `ColumnFamily` if a column number
+	/// is passed.
+	fn iter(&self, col: Option<u32>) -> Self::Iterator;
+	/// Create an `Iterator` over the default DB column or over a `ColumnFamily` if a column number
+	/// is passed. The iterator starts from the first key having the provided `prefix`.
+	fn iter_from_prefix(&self, col: Option<u32>, prefix: &[u8]) -> Self::Iterator;
+}
+
+impl<'a, T> ReadGuardedIterator<'a, <&'a T as IterationHandler>::Iterator, T>
+where
+	&'a T: IterationHandler,
+{
+	pub fn new(read_lock: RwLockReadGuard<'a, Option<T>>, col: Option<u32>) -> Self {
+		Self { inner: Self::new_inner(read_lock, |db| db.iter(col)) }
+	}
+
+	pub fn new_from_prefix(read_lock: RwLockReadGuard<'a, Option<T>>, col: Option<u32>, prefix: &[u8]) -> Self {
+		Self { inner: Self::new_inner(read_lock, |db| db.iter_from_prefix(col, prefix)) }
+	}
+
+	fn new_inner(
+		rlock: RwLockReadGuard<'a, Option<T>>,
+		f: impl FnOnce(&'a T) -> <&'a T as IterationHandler>::Iterator,
+	) -> OwningHandle<UnsafeStableAddress<'a, Option<T>>, DerefWrapper<Option<<&'a T as IterationHandler>::Iterator>>> {
+		OwningHandle::new_with_fn(UnsafeStableAddress(rlock), move |rlock| {
+			let rlock = unsafe { rlock.as_ref().expect("initialized as non-null; qed") };
+			DerefWrapper(rlock.as_ref().map(f))
+		})
+	}
+}
+
+impl<'a> IterationHandler for &'a DBAndColumns {
+	type Iterator = DBIterator<'a>;
+
+	fn iter(&self, col: Option<u32>) -> Self::Iterator {
+		col.map_or_else(
+			|| self.db.iterator(IteratorMode::Start),
+			|c| {
+				self.db
+					.iterator_cf(self.get_cf(c as usize), IteratorMode::Start)
+					.expect("iterator params are valid; qed")
+			},
+		)
+	}
+
+	fn iter_from_prefix(&self, col: Option<u32>, prefix: &[u8]) -> Self::Iterator {
+		col.map_or_else(
+			|| self.db.prefix_iterator(prefix),
+			|c| self.db.prefix_iterator_cf(self.get_cf(c as usize), prefix).expect("iterator params are valid; qed"),
+		)
+	}
+}