Http Upstream client

src/extensions/client/http.rs

@@ -0,0 +1,45 @@
+use crate::middlewares::CallResult;
+use jsonrpsee::{
+    core::{
+        client::{ClientT, Error},
+        JsonValue,
+    },
+    http_client::HttpClient as RpcClient,
+    types::{error::INTERNAL_ERROR_CODE, ErrorObject},
+};
+use std::sync::atomic::{AtomicUsize, Ordering};
+
+/// Very simple struct to have a set of JsonRpsee HTTP clients and send requests to them
+pub struct HttpClient {
+    clients: Vec<RpcClient>,
+    last_sent: AtomicUsize,
+}
+
+impl HttpClient {
+    pub fn new(endpoints: &[String]) -> Result<Self, Error> {
+        let clients = endpoints
+            .iter()
+            .map(|url| RpcClient::builder().build(url))
+            .collect::<Result<Vec<_>, _>>()?;
+
+        Ok(Self {
+            clients,
+            last_sent: AtomicUsize::new(0),
+        })
+    }
+
+    /// Sends a request to one of the clients
+    ///
+    /// The client is selected in a round-robin fashion as fair as possible
+    pub async fn request(&self, method: &str, params: Vec<JsonValue>) -> CallResult {
+        let client_id = self.last_sent.fetch_add(1, Ordering::Relaxed) % self.clients.len();
+
+        self.clients[client_id]
+            .request(method, params)
+            .await
+            .map_err(|e| match e {
+                jsonrpsee::core::client::Error::Call(e) => e,
+                e => ErrorObject::owned(INTERNAL_ERROR_CODE, e.to_string(), None::<String>),
+            })
+    }
+}