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//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
//
use anyhow::Result;
use async_trait::async_trait;
use crate::NodeId;
use crate::Node;
/// An interface to a DAG backend storage
///
/// A DAG backend storage is nothing more than a thing that can store (`DagBackend::put`) and load
/// (`DagBackend::get`) nodes.
#[async_trait]
pub trait DagBackend<Id, N>
where N: Node,
Id: NodeId + Send
{
/// Get a `Node` from the backend that is identified by `id`
///
/// # Returns
///
/// * Should return Err(_) if the operation failed.
/// * Should return Ok(None) if there is no node that is identified by `id`
/// * Otherwise return the Id along with the node identified by it
async fn get(&self, id: Id) -> Result<Option<(Id, N)>>;
/// Store a `node` in the backend, returning its `Id`
///
/// This function should store the `node` in the backend and return the `id` the node has.
async fn put(&mut self, node: N) -> Result<Id>;
}
#[cfg(test)]
mod tests {
use crate::test_impl as test;
use crate::*;
#[test]
fn test_backend_get() {
let b = test::Backend::new(vec![Some(test::Node {
parents: vec![],
data: 0,
})]);
let node = tokio_test::block_on(b.get(test::Id(0)));
assert!(node.is_ok());
let node = node.unwrap();
assert!(node.is_some());
let node = node.unwrap();
assert_eq!(node.0, test::Id(0));
assert!(node.1.parents.is_empty());
}
#[test]
fn test_backend_put() {
let mut b = test::Backend::new(vec![Some(test::Node {
parents: vec![],
data: 0,
})]);
let _ = tokio_test::block_on(b.put({
test::Node {
parents: vec![],
data: 1,
}
}));
{
let node = tokio_test::block_on(b.get(test::Id(0)));
assert!(node.is_ok());
let node = node.unwrap();
assert!(node.is_some());
let node = node.unwrap();
assert_eq!(node.0, test::Id(0));
assert!(node.1.parents.is_empty());
}
{
let node = tokio_test::block_on(b.get(test::Id(1)));
assert!(node.is_ok());
let node = node.unwrap();
assert!(node.is_some());
let node = node.unwrap();
assert_eq!(node.0, test::Id(1));
assert!(node.1.parents.is_empty());
}
{
let node = tokio_test::block_on(b.get(test::Id(2)));
assert!(node.is_ok());
let node = node.unwrap();
assert!(node.is_none());
}
}
}
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