前言
单位上有个 Rust 项目,orm 选型很长时间都没定下来,故先设计了抽象的仓储层方便写业务逻辑。
设计抽象接口
抽象只读接口,仅读取使用,目前需求仅用查询 id、查询全部和按名称搜索,当然理应设计上分页。
//! read_only_repository.rs
/// 只读仓储,对仅限读取的仓储进行抽象
#[async_trait::async_trait]
pub trait IReadOnlyRepository<T>
where
T: std::marker::Send,
{
/// 根据 id 获取唯一对象
async fn get_by_id(&self, id: &str) -> anyhow::Result<T>;
/// 获取所有对象
async fn get_all(&self) -> anyhow::Result<Vec<T>>;
/// 根据名称搜索
async fn search_by_name(&self, &str) -> anyhow::Result<Vec<T>>;
}
抽象可变接口,目前仅考虑了插入、修改、删除以及事务提交。
//! mutable_repository.rs
/// 可变仓储,对修改数据的仓储进行抽象
#[async_trait::async_trait]
pub trait IMutableRepository<T>
where
T: std::marker::Send,
{
/// 更新数据
async fn update(&self, entity: T) -> anyhow::Result<T>;
/// 插入数据
async fn insert(&self, entity: T) -> anyhow::Result<T>;
/// 删除数据
async fn delete(&self, entity: T) -> anyhow::Result<bool>;
/// 使用 uuid 删除数据,`entity` 是用于指示当前实现类型的泛型模板,防止 Rust 产生方法重载的问题,
/// 但对于大多数数据库可尝试使用以下代码:
/// ``` no_run
/// // 建立一个空的枚举用于指示类型
/// let n: Option<TYPE> = None;
/// self.delete_by_id(entity.id.as_str(), n).await?;
/// ```
async fn delete_by_id(&self, uuid: &str, entity: Option<T>) -> anyhow::Result<bool>;
/// 提交变更,在带有事务的数据库将提交事务,否则该方法应该仅返回 `Ok(true)`
///
async fn save_changed(&self) -> anyhow::Result<bool>;
}
租约仓储,为了支持非关系型数据库用的,或许会用到租约(生存时间)。
//! lease_repository.rs
/// 租约仓储,对带有租约的仓储进行抽象
#[async_trait::async_trait]
pub trait ILeaseRepository<T>
where
T: std::marker::Send,
{
/// 更新数据并更新租约
async fn update_with_lease(&self, key: &str, entity: T, ttl: i64) -> anyhow::Result<T>;
/// 插入数据并设定租约
async fn insert_with_lease(&self, key: &str, entity: T, ttl: i64) -> anyhow::Result<T>;
/// 延长特定数据的租约
async fn keep_alive(&self, key: &str) -> anyhow::Result<bool>;
}
最终整合的接口。
//! mod.rs
/// 对使用数据库仓储的抽象,带有可读仓储和可写仓储
#[async_trait::async_trait]
pub trait IDBRepository<T>: IReadOnlyRepository<T> + IMutableRepository<T>
where
T: std::marker::Send,
{
}
/// 对使用带有租约的数据库进行抽象,带有租约仓储、可读仓储和可写仓储
#[async_trait::async_trait]
pub trait ILeaseDBRepository<T>: IDBRepository<T> + ILeaseRepository<T>
where
T: std::marker::Send,
{
}
简单实现
泛型具体用起来有一定的生命周期的问题,解决问题的方法也并不难,加控制生命周期的标记。但我目前的实现方案为使用 marco 自动为每个实体类型生成代码。在这里我个人本地暂且先用了 etcd 数据库作为基础实现。
可变仓储的实现:
/// 针对 Etcd 数据库实现只读仓储 `repository::IMutableRepository`
///
/// struct 要求带有字段 `client: std::sync::Arc<etcd_client::Client>`
#[macro_export]
macro_rules! impl_etcd_mutable_repository {
($base_struct: ty, $domain: ty) => {
#[async_trait::async_trait]
impl IMutableRepository<$domain> for $base_struct {
async fn update(&self, entity: $domain) -> anyhow::Result<$domain> {
let mut kv_client = self.client.kv_client();
let key = format!("test_{}_{}", stringify!($domain), entity.id);
kv_client
.put(
key,
Into::<Vec<u8>>::into(serde_json::to_vec(&entity).unwrap()),
None,
)
.await?;
Ok(entity)
}
async fn insert(&self, entity: $domain) -> anyhow::Result<$domain> {
self.update(entity).await
}
async fn delete(&self, entity: $domain) -> anyhow::Result<bool> {
let n: Option<$domain> = None;
self.delete_by_id(entity.id.as_str(), n).await
}
async fn delete_by_id(
&self,
uuid: &str,
entity: Option<$domain>,
) -> anyhow::Result<bool> {
let mut kv_client = self.client.kv_client();
let key = format!("test_{}_{}", stringify!($domain), uuid);
match kv_client.delete(key, None).await {
Ok(x) => Ok(true),
Err(e) => anyhow::bail!(e),
}
}
async fn save_changed(&self) -> anyhow::Result<bool> {
Ok(true)
}
}
};
}
具体应用:
use crate::repository::*;
pub struct EtcdRepository {
client: std::sync::Arc<etcd_client::Client>,
}
impl EtcdRepository {
pub fn new(client: std::sync::Arc<etcd_client::Client>) -> Self {
Self { client }
}
}
impl_etcd_mutable_repository!(
EtcdRepository,
crate::models::UserInfo
);
调用
use crate::models::*;
use crate::repository::IMutableDBRepository;
pub struct UserInfoService {
user_info_repository: std::sync::Arc<dyn IMutableRepository<UserInfo> + Send + Sync>,
}
impl HeartbeatService {
pub fn new(
user_info_repository: std::sync::Arc<dyn IMutableRepository<UserInfo> + Send + Sync>,
) -> Self {
return Self { user_info_repository };
}
}
#[async_trait::async_trait]
pub trait IPluginManagementService {
async fn list_user_infos(&self) -> Result<Vec<UserInfo>>;
}
#[async_trait::async_trait]
impl IPluginManagementService for PluginManagementService {
async fn list_user_infos(&self) -> Result<Vec<UserInfo>> {
self.user_info_repository.get_all().await
}
}
参考