kwsc98 commented on code in PR #184:
URL: https://github.com/apache/dubbo-rust/pull/184#discussion_r1528190054
##########
dubbo/src/extension/mod.rs:
##########
@@ -141,61 +141,95 @@ impl ExtensionDirectory {
}
}
+type ExtensionCreator<T> = Box<
+ dyn Fn(Url) -> Pin<Box<dyn Future<Output = Result<T, StdError>> + Send +
'static>>
+ + Send
+ + Sync
+ + 'static,
+>;
+pub(crate) struct ExtensionPromiseResolver<T> {
+ resolved_data: Option<T>,
+ creator: ExtensionCreator<T>,
+ url: Url,
+}
+
+impl<T> ExtensionPromiseResolver<T>
+where
+ T: Send + Clone + 'static,
+{
+ fn new(creator: ExtensionCreator<T>, url: Url) -> Self {
+ ExtensionPromiseResolver {
+ resolved_data: None,
+ creator,
+ url,
+ }
+ }
+
+ fn resolved_data(&self) -> Option<T> {
+ self.resolved_data.clone()
+ }
+
+ async fn resolve(&mut self) -> Result<T, StdError> {
+ match (self.creator)(self.url.clone()).await {
+ Ok(data) => {
+ self.resolved_data = Some(data.clone());
+ Ok(data)
+ }
+ Err(err) => {
+ error!("create extension failed: {}", err);
+ Err(LoadExtensionError::new(
+ "load extension failed, create extension occur an
error".to_string(),
+ )
+ .into())
+ }
+ }
+ }
+}
+
pub(crate) struct LoadExtensionPromise<T> {
- extension: Arc<Option<T>>,
- fut: Option<Pin<Box<dyn Future<Output = Result<T, StdError>> + Send +
'static>>>,
- semaphore: Arc<Semaphore>,
+ resolver: Arc<RwLock<ExtensionPromiseResolver<T>>>,
}
impl<T> LoadExtensionPromise<T>
where
T: Send + Clone + 'static,
{
- pub(crate) fn new(
- fut: Pin<Box<dyn Future<Output = Result<T, StdError>> + Send +
'static>>,
- ) -> Self {
+ pub(crate) fn new(creator: ExtensionCreator<T>, url: Url) -> Self {
+ let resolver = ExtensionPromiseResolver::new(creator, url);
LoadExtensionPromise {
- extension: Arc::new(None),
- fut: Some(fut),
- semaphore: Arc::new(Semaphore::new(0)),
+ resolver: Arc::new(RwLock::new(resolver)),
}
}
- fn get_extension(&self) -> Option<T> {
- self.extension.as_ref().as_ref().map(|a| a.clone())
- }
-
pub(crate) async fn resolve(&mut self) -> Result<T, StdError> {
Review Comment:
Can be simplified like
```rust
pub(crate) async fn resolve(&mut self) -> Result<T, StdError> {
// get read lock
let resolver_read_lock = self.resolver.read().await;
// if extension is not None, return it
if let Some(extension) = resolver_read_lock.resolved_data() {
return Ok(extension);
}
drop(resolver_read_lock);
let mut resolver_write_lock = self.resolver.write().await;
Ok(match resolver_write_lock.resolved_data() {
Some(data) => data,
None => resolver_write_lock.resolve().await?,
})
}
```
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