jni: Implement NativeBwtDaemon.testRpc()

contrib/jni/src/main/java/dev/bwt/daemon/NativeBwtDaemon.java

@@ -6,10 +6,14 @@ public class NativeBwtDaemon {
     }
 
     // Start the bwt daemon with the configured server(s)
-    // Blocks until the initial indexing is completed and the servers are ready.
+    // Blocks the current thread until the daemon is stopped.
     // Returns a pointer to be used with shutdown().
     public static native long start(String jsonConfig, CallbackNotifier callback);
 
     // Shutdown thw bwt daemon
     public static native void shutdown(long shutdownPtr);
-}
+
+    // Test the Bitcoin Core RPC connection details
+    // Throws an exception on failures.
+    public static native void testRpc(String jsonConfig);
+}

src/app.rs

@@ -166,6 +166,12 @@ impl App {
         Some(self.http.as_ref()?.addr())
     }
 
+    pub fn test_rpc(config: &Config) -> Result<()> {
+        let rpc = RpcClient::new(config.bitcoind_url(), config.bitcoind_auth()?)?;
+        rpc.get_wallet_info()?;
+        Ok(())
+    }
+
     // Pipe the shutdown receiver `rx` to trigger `sync_tx`. This is needed to start the next
     // sync loop run immediately, which will then process the shutdown signal itself. Without
     // this, the shutdown signal will only be noticed after a delay.

src/interface.rs

@@ -201,6 +201,23 @@ mod jni {
         Box::from_raw(shutdown_ptr as *mut ShutdownHandler);
     }
 
+    #[no_mangle]
+    pub extern "system" fn Java_dev_bwt_daemon_NativeBwtDaemon_testRpc(
+        env: JNIEnv,
+        _: JClass,
+        json_config: JString,
+    ) {
+        let json_config: String = env.get_string(json_config).unwrap().into();
+
+        let test = || App::test_rpc(&serde_json::from_str(&json_config)?);
+
+        if let Err(e) = test() {
+            warn!("test rpc failed: {:?}", e);
+            env.throw_new("dev/bwt/daemon/BwtException", &e.to_string())
+                .unwrap();
+        }
+    }
+
     fn spawn_recv_progress_thread(
         progress_rx: mpsc::Receiver<Progress>,
         jvm: JavaVM,