jdbc-v2: swallow chunked-stream drain errors on ResultSet.close (fixes #2361)

client-v2/src/main/java/com/clickhouse/client/api/data_formats/internal/AbstractBinaryFormatReader.java

@@ -1086,7 +1086,36 @@ public ClickHouseBitmap getClickHouseBitmap(int index) {
 
     @Override
     public void close() throws Exception {
-        input.close();
+        try {
+            input.close();
+        } catch (Exception e) {
+            // Apache HttpComponents ChunkedInputStream.close() drains remaining bytes and
+            // throws ConnectionClosedException ("Premature end of chunk coded message body")
+            // when the server tore the connection down mid-response (e.g. send_timeout fired
+            // before the terminating zero-length chunk was written). Any real iteration-time
+            // failure has already surfaced through nextRecord(); a drain failure at close()
+            // is informational only and should not punish callers of try-with-resources.
+            if (isConnectionClosedException(e)) {
+                LOG.debug("Swallowing chunked-stream drain on reader close: {}", e.toString());
+                return;
+            }
+            throw e;
+        }
+    }
+
+    /**
+     * Walks the cause chain looking for an {@code org.apache.hc.core5.http.ConnectionClosedException}.
+     * Matched by class-name suffix so it works against both directly-referenced and shaded copies of
+     * the HC class without taking a compile-time dependency on it from this layer.
+     */
+    static boolean isConnectionClosedException(Throwable t) {
+        while (t != null) {
+            if (t.getClass().getName().endsWith(".ConnectionClosedException")) {
+                return true;
+            }
+            t = t.getCause();
+        }
+        return false;
     }
 
     private static class RecordWrapper implements Map<String, Object> {

client-v2/src/test/java/com/clickhouse/client/api/data_formats/internal/AbstractBinaryFormatReaderCloseTest.java

@@ -0,0 +1,36 @@
+package com.clickhouse.client.api.data_formats.internal;
+
+import org.apache.hc.core5.http.ConnectionClosedException;
+import org.testng.annotations.DataProvider;
+import org.testng.annotations.Test;
+
+import java.io.IOException;
+
+import static org.testng.Assert.assertEquals;
+
+/**
+ * Verifies that the reader's close path recognises Apache HC's
+ * ConnectionClosedException (the "Premature end of chunk coded message body"
+ * surface that fires when the server tore the connection down before writing
+ * the terminating zero-length chunk) and is willing to swallow it on close.
+ * Matched by class-name suffix so the recogniser works against both the
+ * directly-referenced and the shaded copy of the HC class.
+ */
+@Test(groups = {"unit"})
+public class AbstractBinaryFormatReaderCloseTest {
+
+    @DataProvider(name = "cases")
+    public Object[][] cases() {
+        return new Object[][] {
+                { new ConnectionClosedException("Premature end of chunk coded message body: closing chunk expected"), true },
+                { new IOException("close failed", new ConnectionClosedException("closing chunk expected")), true },
+                { new IOException("disk full"), false },
+                { null, false },
+        };
+    }
+
+    @Test(dataProvider = "cases")
+    public void recognisesHcConnectionClosed(Throwable t, boolean expected) {
+        assertEquals(AbstractBinaryFormatReader.isConnectionClosedException(t), expected);
+    }
+}