changeset 53606:f39854fffca0

8213942: URLStreamHandler initialization race Reviewed-by: alanb, chegar, prappo
author coffeys
date Wed, 21 Nov 2018 15:09:27 +0000
parents 0877040ec224
children fa6e4d0216a1
files src/java.base/share/classes/java/net/URL.java test/jdk/java/net/URL/RacyHandler.java
diffstat 2 files changed, 140 insertions(+), 27 deletions(-) [+]
line wrap: on
line diff
--- a/src/java.base/share/classes/java/net/URL.java	Wed Nov 21 09:40:19 2018 -0500
+++ b/src/java.base/share/classes/java/net/URL.java	Wed Nov 21 15:09:27 2018 +0000
@@ -1393,39 +1393,39 @@
             }
         }
 
+        if (handler == null) {
+            // Try the built-in protocol handler
+            handler = defaultFactory.createURLStreamHandler(protocol);
+        }
+
         synchronized (streamHandlerLock) {
-            if (handler == null) {
-                // Try the built-in protocol handler
-                handler = defaultFactory.createURLStreamHandler(protocol);
-            } else {
-                URLStreamHandler handler2 = null;
+            URLStreamHandler handler2 = null;
 
-                // Check again with hashtable just in case another
-                // thread created a handler since we last checked
-                handler2 = handlers.get(protocol);
+            // Check again with hashtable just in case another
+            // thread created a handler since we last checked
+            handler2 = handlers.get(protocol);
 
-                if (handler2 != null) {
-                    return handler2;
-                }
-
-                // Check with factory if another thread set a
-                // factory since our last check
-                if (!checkedWithFactory && (fac = factory) != null) {
-                    handler2 = fac.createURLStreamHandler(protocol);
-                }
-
-                if (handler2 != null) {
-                    // The handler from the factory must be given more
-                    // importance. Discard the default handler that
-                    // this thread created.
-                    handler = handler2;
-                }
+            if (handler2 != null) {
+                return handler2;
             }
 
-            // Insert this handler into the hashtable
-            if (handler != null) {
-                handlers.put(protocol, handler);
+            // Check with factory if another thread set a
+            // factory since our last check
+            if (!checkedWithFactory && (fac = factory) != null) {
+                handler2 = fac.createURLStreamHandler(protocol);
             }
+
+            if (handler2 != null) {
+                // The handler from the factory must be given more
+                // importance. Discard the default handler that
+                // this thread created.
+                handler = handler2;
+            }
+        }
+
+        // Insert this handler into the hashtable
+        if (handler != null) {
+            handlers.put(protocol, handler);
         }
 
         return handler;
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/jdk/java/net/URL/RacyHandler.java	Wed Nov 21 15:09:27 2018 +0000
@@ -0,0 +1,113 @@
+/*
+ * Copyright (c) 2018, 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 java.io.IOException;
+import java.lang.reflect.*;
+import java.net.URL;
+import java.net.URLConnection;
+import java.net.URLStreamHandler;
+import java.util.concurrent.CountDownLatch;
+
+/*
+ * @test
+ * @bug 8213942
+ * @summary URLStreamHandler initialization race
+ * @run main/othervm RacyHandler
+ * @run main/othervm RacyHandler
+ * @run main/othervm RacyHandler
+ */
+
+/*
+ * This test makes reasonable effort to reproduce the race.
+ * Run repeatedly to ensure correctness.
+ */
+public class RacyHandler {
+    static volatile boolean factorySet = false;
+    static int NUM_THREADS = 2;
+    static CountDownLatch cdl = new CountDownLatch(NUM_THREADS + 1);
+
+    public static void main(String[] args) {
+        RacyHandler tester = new RacyHandler();
+        tester.runTest();
+    }
+
+    public void runTest() {
+        new Thread(() -> {
+            try {
+                cdl.await();
+                URL.setURLStreamHandlerFactory(proto -> new CustomHttpHandler());
+                factorySet = true;
+            } catch (Exception ignore) { }
+        }).start();
+        cdl.countDown();
+
+        for (int i = 0; i < NUM_THREADS; i++) {
+            new Thread(() -> {
+                try {
+                    cdl.await();
+                    while (!factorySet) {
+                        // trigger URL class load
+                        getURLStreamHandler();
+                    }
+                } catch (Exception ignore) { }
+            }).start();
+            cdl.countDown();
+        }
+
+        // wait for the factory to be set
+        while (!factorySet) { }
+        // The sleep seems to help trigger the failure
+        try {
+            Thread.sleep(500);
+        } catch (InterruptedException ie) {
+        }
+
+        URLStreamHandler httpHandler = getURLStreamHandler();
+        System.out.println("After setting factory URL handlers: http " + httpHandler);
+        if (!(httpHandler instanceof CustomHttpHandler))
+            throw new RuntimeException("FAILED: Incorrect handler type");
+    }
+
+    /*
+     * This is just so we can see what we get for the URLStreamHandler back
+     * from the factory to verify whether it really is using our Handler
+     * or something else...
+     */
+    public URLStreamHandler getURLStreamHandler() {
+        try {
+            Method method = URL.class.getDeclaredMethod("getURLStreamHandler",
+                    String.class);
+            method.setAccessible(true);
+            return (URLStreamHandler) method.invoke(null, "http");
+        } catch (Exception e) {
+            return null;
+        }
+    }
+
+    class CustomHttpHandler extends URLStreamHandler {
+        @Override
+        protected URLConnection openConnection(URL u) throws IOException {
+            return null;
+        }
+    }
+}
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