Add Client Workaround With a Load Balancer (#220)

* add the load_malance_made attribute to the Client Options.

Author: JiaYingZhang

README.md

@@ -86,6 +86,19 @@ let environment = Environment::builder()
     .build()
 ```
 
+##### Building the environment with a load balancer
+
+```rust,no_run
+use rabbitmq_stream_client::Environment;
+
+
+let environment = Environment::builder()
+    .load_balancer_mode(true)
+    .build()
+```
+
+
+
 ##### Publishing messages
 
 ```rust,no_run

src/client/options.rs

@@ -12,6 +12,7 @@ pub struct ClientOptions {
     pub(crate) v_host: String,
     pub(crate) heartbeat: u32,
     pub(crate) max_frame_size: u32,
+    pub(crate) load_balancer_mode: bool,
     pub(crate) tls: TlsConfiguration,
     pub(crate) collector: Arc<dyn MetricsCollector>,
 }
@@ -39,6 +40,7 @@ impl Default for ClientOptions {
             v_host: "/".to_owned(),
             heartbeat: 60,
             max_frame_size: 1048576,
+            load_balancer_mode: false,
             collector: Arc::new(NopMetricsCollector {}),
             tls: TlsConfiguration {
                 enabled: false,
@@ -117,6 +119,11 @@ impl ClientOptionsBuilder {
         self
     }
 
+    pub fn load_balancer_mode(mut self, load_balancer_mode: bool) -> Self {
+        self.0.load_balancer_mode = load_balancer_mode;
+        self
+    }
+
     pub fn build(self) -> ClientOptions {
         self.0
     }
@@ -145,6 +152,7 @@ mod tests {
                 client_keys_path: String::from(""),
             })
             .collector(Arc::new(NopMetricsCollector {}))
+            .load_balancer_mode(true)
             .build();
         assert_eq!(options.host, "test");
         assert_eq!(options.port, 8888);
@@ -154,5 +162,6 @@ mod tests {
         assert_eq!(options.heartbeat, 10000);
         assert_eq!(options.max_frame_size, 1);
         assert_eq!(options.tls.enabled, true);
+        assert_eq!(options.load_balancer_mode, true);
     }
 }

src/consumer.rs

@@ -76,12 +76,27 @@ impl ConsumerBuilder {
                     metadata.replicas,
                     stream
                 );
-                client = Client::connect(ClientOptions {
-                    host: replica.host.clone(),
-                    port: replica.port as u16,
-                    ..self.environment.options.client_options
-                })
-                .await?;
+                let load_balancer_mode = self.environment.options.client_options.load_balancer_mode;
+                if load_balancer_mode {
+                    let options = self.environment.options.client_options.clone();
+                    loop {
+                        let temp_client = Client::connect(options.clone()).await?;
+                        let mapping = temp_client.connection_properties().await;
+                        if let Some(advertised_host) = mapping.get("advertised_host") {
+                            if *advertised_host == replica.host.clone() {
+                                client = temp_client;
+                                break;
+                            }
+                        }
+                    }
+                } else {
+                    client = Client::connect(ClientOptions {
+                        host: replica.host.clone(),
+                        port: replica.port as u16,
+                        ..self.environment.options.client_options
+                    })
+                    .await?;
+                }
             }
         } else {
             return Err(ConsumerCreateError::StreamDoesNotExist {
@@ -100,7 +115,6 @@ impl ConsumerBuilder {
             waker: AtomicWaker::new(),
             metrics_collector: collector,
         });
-
         let msg_handler = ConsumerMessageHandler(consumer.clone());
         client.set_handler(msg_handler).await;
 

src/environment.rs

@@ -121,11 +121,16 @@ impl EnvironmentBuilder {
     }
     pub fn metrics_collector(
         mut self,
-        collector: impl MetricsCollector + Send + Sync + 'static,
+        collector: impl MetricsCollector + 'static,
     ) -> EnvironmentBuilder {
         self.0.client_options.collector = Arc::new(collector);
         self
     }
+
+    pub fn load_balancer_mode(mut self, load_balancer_mode: bool) -> EnvironmentBuilder {
+        self.0.client_options.load_balancer_mode = load_balancer_mode;
+        self
+    }
 }
 #[derive(Clone, Default)]
 pub struct EnvironmentOptions {

src/producer.rs

@@ -119,13 +119,29 @@ impl<T> ProducerBuilder<T> {
                 metadata.leader,
                 stream
             );
-            client.close().await?;
-            client = Client::connect(ClientOptions {
-                host: metadata.leader.host.clone(),
-                port: metadata.leader.port as u16,
-                ..self.environment.options.client_options
-            })
-            .await?;
+            let load_balancer_mode = self.environment.options.client_options.load_balancer_mode;
+            if load_balancer_mode {
+                // Producer must connect to leader node
+                let options: ClientOptions = self.environment.options.client_options.clone();
+                loop {
+                    let temp_client = Client::connect(options.clone()).await?;
+                    let mapping = temp_client.connection_properties().await;
+                    if let Some(advertised_host) = mapping.get("advertised_host") {
+                        if *advertised_host == metadata.leader.host.clone() {
+                            client = temp_client;
+                            break;
+                        }
+                    }
+                }
+            } else {
+                client.close().await?;
+                client = Client::connect(ClientOptions {
+                    host: metadata.leader.host.clone(),
+                    port: metadata.leader.port as u16,
+                    ..self.environment.options.client_options
+                })
+                .await?
+            };
         } else {
             return Err(ProducerCreateError::StreamDoesNotExist {
                 stream: stream.into(),