[ISSUES #190] Add invoker extension and enhance extension design (#195)

* add Invoker extension

* refactor extension mod

* remove Extension constraint

* cargo fmt

* add license header

* cargo fmt

* add error handing

* fix compile error

* add load invoker method

Author: onewe

dubbo/src/extension/invoker_extension.rs

@@ -0,0 +1,303 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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::{
+    extension::{
+        invoker_extension::proxy::InvokerProxy, Extension, ExtensionFactories, ExtensionMetaInfo,
+        LoadExtensionPromise,
+    },
+    params::extension_param::{ExtensionName, ExtensionType},
+    url::UrlParam,
+    StdError, Url,
+};
+use async_trait::async_trait;
+use bytes::Bytes;
+use futures_core::Stream;
+use std::{collections::HashMap, future::Future, marker::PhantomData, pin::Pin};
+use thiserror::Error;
+
+#[async_trait]
+pub trait Invoker {
+    async fn invoke(
+        &self,
+        invocation: GrpcInvocation,
+    ) -> Result<Pin<Box<dyn Stream<Item = Bytes> + Send + 'static>>, StdError>;
+
+    async fn url(&self) -> Result<Url, StdError>;
+}
+
+pub enum CallType {
+    Unary,
+    ClientStream,
+    ServerStream,
+    BiStream,
+}
+
+pub struct GrpcInvocation {
+    service_name: String,
+    method_name: String,
+    arguments: Vec<Argument>,
+    attachments: HashMap<String, String>,
+    call_type: CallType,
+}
+
+pub struct Argument {
+    name: String,
+    value: Box<dyn Stream<Item = Box<dyn Serializable + Send + 'static>> + Send + 'static>,
+}
+
+pub trait Serializable {
+    fn serialize(&self, serialization_type: String) -> Result<Bytes, StdError>;
+}
+
+pub trait Deserializable {
+    fn deserialize(&self, bytes: Bytes, deserialization_type: String) -> Result<Self, StdError>
+    where
+        Self: Sized;
+}
+
+pub mod proxy {
+    use crate::{
+        extension::invoker_extension::{GrpcInvocation, Invoker},
+        StdError, Url,
+    };
+    use async_trait::async_trait;
+    use bytes::Bytes;
+    use futures_core::Stream;
+    use std::pin::Pin;
+    use thiserror::Error;
+    use tokio::sync::{mpsc::Sender, oneshot};
+    use tracing::error;
+
+    pub(super) enum InvokerOpt {
+        Invoke(
+            GrpcInvocation,
+            oneshot::Sender<Result<Pin<Box<dyn Stream<Item = Bytes> + Send + 'static>>, StdError>>,
+        ),
+        Url(oneshot::Sender<Result<Url, StdError>>),
+    }
+
+    #[derive(Clone)]
+    pub struct InvokerProxy {
+        tx: Sender<InvokerOpt>,
+    }
+
+    #[async_trait]
+    impl Invoker for InvokerProxy {
+        async fn invoke(
+            &self,
+            invocation: GrpcInvocation,
+        ) -> Result<Pin<Box<dyn Stream<Item = Bytes> + Send + 'static>>, StdError> {
+            let (tx, rx) = oneshot::channel();
+            let ret = self.tx.send(InvokerOpt::Invoke(invocation, tx)).await;
+            match ret {
+                Ok(_) => {}
+                Err(err) => {
+                    error!(
+                        "call invoke method failed by invoker proxy, error: {:?}",
+                        err
+                    );
+                    return Err(InvokerProxyError::new(
+                        "call invoke method failed by invoker proxy",
+                    )
+                    .into());
+                }
+            }
+            let ret = rx.await?;
+            ret
+        }
+
+        async fn url(&self) -> Result<Url, StdError> {
+            let (tx, rx) = oneshot::channel();
+            let ret = self.tx.send(InvokerOpt::Url(tx)).await;
+            match ret {
+                Ok(_) => {}
+                Err(err) => {
+                    error!("call url method failed by invoker proxy, error: {:?}", err);
+                    return Err(
+                        InvokerProxyError::new("call url method failed by invoker proxy").into(),
+                    );
+                }
+            }
+            let ret = rx.await?;
+            ret
+        }
+    }
+
+    impl From<Box<dyn Invoker + Send + 'static>> for InvokerProxy {
+        fn from(invoker: Box<dyn Invoker + Send + 'static>) -> Self {
+            let (tx, mut rx) = tokio::sync::mpsc::channel(64);
+            tokio::spawn(async move {
+                while let Some(opt) = rx.recv().await {
+                    match opt {
+                        InvokerOpt::Invoke(invocation, tx) => {
+                            let result = invoker.invoke(invocation).await;
+                            let callback_ret = tx.send(result);
+                            match callback_ret {
+                                Ok(_) => {}
+                                Err(Err(err)) => {
+                                    error!("invoke method has been called, but callback to caller failed. {:?}", err);
+                                }
+                                _ => {}
+                            }
+                        }
+                        InvokerOpt::Url(tx) => {
+                            let ret = tx.send(invoker.url().await);
+                            match ret {
+                                Ok(_) => {}
+                                Err(err) => {
+                                    error!("url method has been called, but callback to caller failed. {:?}", err);
+                                }
+                            }
+                        }
+                    }
+                }
+            });
+            InvokerProxy { tx }
+        }
+    }
+
+    #[derive(Error, Debug)]
+    #[error("invoker proxy error: {0}")]
+    pub struct InvokerProxyError(String);
+
+    impl InvokerProxyError {
+        pub fn new(msg: &str) -> Self {
+            InvokerProxyError(msg.to_string())
+        }
+    }
+}
+
+#[derive(Default)]
+pub(super) struct InvokerExtensionLoader {
+    factories: HashMap<String, InvokerExtensionFactory>,
+}
+
+impl InvokerExtensionLoader {
+    pub fn register(&mut self, extension_name: String, factory: InvokerExtensionFactory) {
+        self.factories.insert(extension_name, factory);
+    }
+
+    pub fn remove(&mut self, extension_name: String) {
+        self.factories.remove(&extension_name);
+    }
+
+    pub fn load(&mut self, url: Url) -> Result<LoadExtensionPromise<InvokerProxy>, StdError> {
+        let extension_name = url.query::<ExtensionName>();
+        let Some(extension_name) = extension_name else {
+            return Err(InvokerExtensionLoaderError::new(
+                "load invoker extension failed, extension mustn't be empty",
+            )
+            .into());
+        };
+        let extension_name = extension_name.value();
+        let factory = self.factories.get_mut(&extension_name);
+        let Some(factory) = factory else {
+            let err_msg = format!(
+                "load {} invoker extension failed, can not found extension factory",
+                extension_name
+            );
+            return Err(InvokerExtensionLoaderError(err_msg).into());
+        };
+        factory.create(url)
+    }
+}
+
+type InvokerExtensionConstructor = fn(
+    Url,
+) -> Pin<
+    Box<dyn Future<Output = Result<Box<dyn Invoker + Send + 'static>, StdError>> + Send + 'static>,
+>;
+pub(crate) struct InvokerExtensionFactory {
+    constructor: InvokerExtensionConstructor,
+    instances: HashMap<String, LoadExtensionPromise<InvokerProxy>>,
+}
+
+impl InvokerExtensionFactory {
+    pub fn new(constructor: InvokerExtensionConstructor) -> Self {
+        Self {
+            constructor,
+            instances: HashMap::default(),
+        }
+    }
+}
+
+impl InvokerExtensionFactory {
+    pub fn create(&mut self, url: Url) -> Result<LoadExtensionPromise<InvokerProxy>, StdError> {
+        let key = url.to_string();
+
+        match self.instances.get(&key) {
+            Some(instance) => Ok(instance.clone()),
+            None => {
+                let constructor = self.constructor;
+                let creator = move |url: Url| {
+                    let invoker_future = constructor(url);
+                    Box::pin(async move {
+                        let invoker = invoker_future.await?;
+                        Ok(InvokerProxy::from(invoker))
+                    })
+                        as Pin<
+                            Box<
+                                dyn Future<Output = Result<InvokerProxy, StdError>>
+                                    + Send
+                                    + 'static,
+                            >,
+                        >
+                };
+
+                let promise: LoadExtensionPromise<InvokerProxy> =
+                    LoadExtensionPromise::new(Box::new(creator), url);
+                self.instances.insert(key, promise.clone());
+                Ok(promise)
+            }
+        }
+    }
+}
+
+pub struct InvokerExtension<T>(PhantomData<T>)
+where
+    T: Invoker + Send + 'static;
+
+impl<T> ExtensionMetaInfo for InvokerExtension<T>
+where
+    T: Invoker + Send + 'static,
+    T: Extension<Target = Box<dyn Invoker + Send + 'static>>,
+{
+    fn name() -> String {
+        T::name()
+    }
+
+    fn extension_type() -> ExtensionType {
+        ExtensionType::Invoker
+    }
+
+    fn extension_factory() -> ExtensionFactories {
+        ExtensionFactories::InvokerExtensionFactory(InvokerExtensionFactory::new(
+            <T as Extension>::create,
+        ))
+    }
+}
+
+#[derive(Error, Debug)]
+#[error("{0}")]
+pub struct InvokerExtensionLoaderError(String);
+
+impl InvokerExtensionLoaderError {
+    pub fn new(msg: &str) -> Self {
+        InvokerExtensionLoaderError(msg.to_string())
+    }
+}