1 files changed, 154 insertions, 0 deletions
diff --git a/third_party/rust/rkv/src/readwrite.rs b/third_party/rust/rkv/src/readwrite.rs
new file mode 100644
index 0000000000..38b4746210
--- /dev/null
+++ b/third_party/rust/rkv/src/readwrite.rs
@@ -0,0 +1,154 @@
+// Copyright 2018-2019 Mozilla
+//
+// 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 crate::{
+    backend::{
+        BackendDatabase, BackendRoCursor, BackendRoCursorTransaction, BackendRoTransaction,
+        BackendRwCursorTransaction, BackendRwTransaction,
+    },
+    error::StoreError,
+    helpers::read_transform,
+    value::Value,
+};
+
+pub struct Reader<T>(T);
+pub struct Writer<T>(T);
+
+pub trait Readable<'r> {
+    type Database: BackendDatabase;
+    type RoCursor: BackendRoCursor<'r>;
+
+    fn get<K>(&'r self, db: &Self::Database, k: &K) -> Result<Option<Value<'r>>, StoreError>
+    where
+        K: AsRef<[u8]>;
+
+    fn open_ro_cursor(&'r self, db: &Self::Database) -> Result<Self::RoCursor, StoreError>;
+}
+
+impl<'r, T> Readable<'r> for Reader<T>
+where
+    T: BackendRoCursorTransaction<'r>,
+{
+    type Database = T::Database;
+    type RoCursor = T::RoCursor;
+
+    fn get<K>(&'r self, db: &T::Database, k: &K) -> Result<Option<Value<'r>>, StoreError>
+    where
+        K: AsRef<[u8]>,
+    {
+        let bytes = self.0.get(db, k.as_ref()).map_err(|e| e.into());
+        match read_transform(bytes).map(Some) {
+            Err(StoreError::KeyValuePairNotFound) => Ok(None),
+            result => result,
+        }
+    }
+
+    fn open_ro_cursor(&'r self, db: &T::Database) -> Result<T::RoCursor, StoreError> {
+        self.0.open_ro_cursor(db).map_err(|e| e.into())
+    }
+}
+
+impl<T> Reader<T> {
+    pub(crate) fn new(txn: T) -> Reader<T> {
+        Reader(txn)
+    }
+}
+
+impl<T> Reader<T>
+where
+    T: BackendRoTransaction,
+{
+    pub fn abort(self) {
+        self.0.abort();
+    }
+}
+
+impl<'r, T> Readable<'r> for Writer<T>
+where
+    T: BackendRwCursorTransaction<'r>,
+{
+    type Database = T::Database;
+    type RoCursor = T::RoCursor;
+
+    fn get<K>(&'r self, db: &T::Database, k: &K) -> Result<Option<Value<'r>>, StoreError>
+    where
+        K: AsRef<[u8]>,
+    {
+        let bytes = self.0.get(db, k.as_ref()).map_err(|e| e.into());
+        match read_transform(bytes).map(Some) {
+            Err(StoreError::KeyValuePairNotFound) => Ok(None),
+            result => result,
+        }
+    }
+
+    fn open_ro_cursor(&'r self, db: &T::Database) -> Result<T::RoCursor, StoreError> {
+        self.0.open_ro_cursor(db).map_err(|e| e.into())
+    }
+}
+
+impl<T> Writer<T> {
+    pub(crate) fn new(txn: T) -> Writer<T> {
+        Writer(txn)
+    }
+}
+
+impl<T> Writer<T>
+where
+    T: BackendRwTransaction,
+{
+    pub fn commit(self) -> Result<(), StoreError> {
+        self.0.commit().map_err(|e| e.into())
+    }
+
+    pub fn abort(self) {
+        self.0.abort();
+    }
+
+    pub(crate) fn put<K>(
+        &mut self,
+        db: &T::Database,
+        k: &K,
+        v: &Value,
+        flags: T::Flags,
+    ) -> Result<(), StoreError>
+    where
+        K: AsRef<[u8]>,
+    {
+        // TODO: don't allocate twice.
+        self.0
+            .put(db, k.as_ref(), &v.to_bytes()?, flags)
+            .map_err(|e| e.into())
+    }
+
+    #[cfg(not(feature = "db-dup-sort"))]
+    pub(crate) fn delete<K>(&mut self, db: &T::Database, k: &K) -> Result<(), StoreError>
+    where
+        K: AsRef<[u8]>,
+    {
+        self.0.del(db, k.as_ref()).map_err(|e| e.into())
+    }
+
+    #[cfg(feature = "db-dup-sort")]
+    pub(crate) fn delete<K>(
+        &mut self,
+        db: &T::Database,
+        k: &K,
+        v: Option<&[u8]>,
+    ) -> Result<(), StoreError>
+    where
+        K: AsRef<[u8]>,
+    {
+        self.0.del(db, k.as_ref(), v).map_err(|e| e.into())
+    }
+
+    pub(crate) fn clear(&mut self, db: &T::Database) -> Result<(), StoreError> {
+        self.0.clear_db(db).map_err(|e| e.into())
+    }
+}