refresh QWP WebSocket terminal error stack traces

Author: jerrinot

core/src/main/java/io/questdb/client/cutlass/qwp/client/QwpWebSocketSender.java

@@ -1202,6 +1202,10 @@ private void checkNotClosed() {
     private void checkConnectionError() {
         LineSenderException error = connectionError.get();
         if (error != null) {
+            // Refresh the stack so subsequent public API calls point at the
+            // call that observed the terminal sender state, not the I/O thread
+            // that originally recorded the failure.
+            error.fillInStackTrace();
             throw error;
         }
     }

core/src/test/java/io/questdb/client/test/cutlass/qwp/client/QwpWebSocketSenderStateTest.java

@@ -67,6 +67,7 @@ public void testConnectionFailureIsSenderLevelTerminalState() throws Exception {
                     Assert.fail("Expected sender-level connection failure");
                 } catch (LineSenderException e) {
                     Assert.assertSame(failure, e);
+                    assertStackContains(e, "table");
                 }
 
                 LineSenderException secondFailure = new LineSenderException("second failure");
@@ -77,6 +78,7 @@ public void testConnectionFailureIsSenderLevelTerminalState() throws Exception {
                     Assert.fail("Expected original sender-level connection failure");
                 } catch (LineSenderException e) {
                     Assert.assertSame(failure, e);
+                    assertStackContains(e, "flush");
                 }
             } finally {
                 sender.close();
@@ -354,6 +356,16 @@ private static void invokeResetSchemaStateForNewConnection(Object target) throws
         method.invoke(target);
     }
 
+    private static void assertStackContains(Throwable throwable, String methodName) {
+        for (StackTraceElement element : throwable.getStackTrace()) {
+            if (QwpWebSocketSender.class.getName().equals(element.getClassName())
+                    && methodName.equals(element.getMethodName())) {
+                return;
+            }
+        }
+        Assert.fail("Expected stack trace to contain QwpWebSocketSender." + methodName);
+    }
+
     private static boolean invokeRecordConnectionFailure(Object target, LineSenderException error) throws Exception {
         Method method = target.getClass().getDeclaredMethod("recordConnectionFailure", LineSenderException.class);
         method.setAccessible(true);