8248006: Revisit exceptions thrown when creating an HttpClient fails due to unavailability of underlying resources

This fix updates jdk.internal.net.http.HttpClientImpl to throw an UncheckedIOException instead of InternalError.

Reviewed-by: chegar, dfuchs

src/java.net.http/share/classes/java/net/http/HttpClient.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -26,6 +26,8 @@
 package java.net.http;
 
 import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.nio.channels.Selector;
 import java.net.Authenticator;
 import java.net.CookieHandler;
 import java.net.InetSocketAddress;
@@ -153,6 +155,8 @@ public abstract class HttpClient {
      * built instances.
      *
      * @return a new HttpClient
+     * @throws UncheckedIOException if necessary underlying IO resources required to
+     * {@linkplain Builder#build() build a new HttpClient} cannot be allocated.
      */
     public static HttpClient newHttpClient() {
         return newBuilder().build();
@@ -352,6 +356,11 @@ public abstract class HttpClient {
          * builder.
          *
          * @return a new {@code HttpClient}
+         *
+         * @throws UncheckedIOException may be thrown if underlying IO resources required
+         * by the implementation cannot be allocated. For instance,
+         * if the implementation requires a {@link Selector}, and opening
+         * one fails due to {@linkplain Selector#open() lack of necessary resources}.
          */
         public HttpClient build();
     }

src/java.net.http/share/classes/jdk/internal/net/http/HttpClientImpl.java

@@ -310,7 +310,7 @@ final class HttpClientImpl extends HttpClient implements Trackable {
             selmgr = new SelectorManager(this);
         } catch (IOException e) {
             // unlikely
-            throw new InternalError(e);
+            throw new UncheckedIOException(e);
         }
         selmgr.setDaemon(true);
         filters = new FilterFactory();

test/jdk/java/net/httpclient/HttpClientExceptionTest.java

@@ -0,0 +1,105 @@
+/*
+ * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+import org.testng.Assert;
+import org.testng.annotations.Test;
+import java.io.IOException;
+import java.net.ProtocolFamily;
+import java.net.http.HttpClient;
+import java.nio.channels.DatagramChannel;
+import java.nio.channels.Pipe;
+import java.nio.channels.ServerSocketChannel;
+import java.nio.channels.SocketChannel;
+import java.nio.channels.Channel;
+import java.nio.channels.spi.AbstractSelector;
+import java.nio.channels.spi.SelectorProvider;
+
+/*
+ * @test
+ * @bug 8248006
+ * @summary The test checks if UncheckedIOException is thrown
+ * @build  HttpClientExceptionTest
+ * @run testng/othervm -Djava.nio.channels.spi.SelectorProvider=HttpClientExceptionTest$CustomSelectorProvider
+ *                      HttpClientExceptionTest
+ */
+
+public class HttpClientExceptionTest {
+
+    static final int ITERATIONS = 10;
+
+    @Test
+    public void testHttpClientException() {
+        for(int i = 0; i < ITERATIONS; i++) {
+            Assert.assertThrows(HttpClient.newBuilder()::build);
+            Assert.assertThrows(HttpClient::newHttpClient);
+        }
+    }
+
+    public static class CustomSelectorProvider extends SelectorProvider {
+
+        @Override
+        public DatagramChannel openDatagramChannel() throws IOException {
+            throw new IOException();
+        }
+
+        @Override
+        public DatagramChannel openDatagramChannel(ProtocolFamily family) throws IOException {
+            throw new IOException();
+        }
+
+        @Override
+        public Pipe openPipe() throws IOException {
+            throw new IOException();
+        }
+
+        @Override
+        public ServerSocketChannel openServerSocketChannel() throws IOException {
+            throw new IOException();
+        }
+
+        @Override
+        public SocketChannel openSocketChannel() throws IOException {
+            throw new IOException();
+        }
+
+        @Override
+        public Channel inheritedChannel() throws IOException {
+            return super.inheritedChannel();
+        }
+
+        @Override
+        public SocketChannel openSocketChannel(ProtocolFamily family) throws IOException {
+            return super.openSocketChannel(family);
+        }
+
+        @Override
+        public ServerSocketChannel openServerSocketChannel(ProtocolFamily family) throws IOException {
+            return super.openServerSocketChannel(family);
+        }
+
+        @Override
+        public AbstractSelector openSelector() throws IOException {
+            throw new IOException();
+        }
+    }
+}