8299571: ZoneRulesProvider.registerProvider() can leave inconsistent state on failure

Reviewed-by: iris, rriggs, joehw

src/java.base/share/classes/java/time/zone/ZoneRulesProvider.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2023, 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
@@ -316,6 +316,10 @@ public abstract class ZoneRulesProvider {
             Objects.requireNonNull(zoneId, "zoneId");
             ZoneRulesProvider old = ZONES.putIfAbsent(zoneId, provider);
             if (old != null) {
+                // restore old state
+                ZONES.put(zoneId, old);
+                provider.provideZoneIds().stream()
+                    .forEach(id -> ZONES.remove(id, provider));
                 throw new ZoneRulesException(
                     "Unable to register zone as one already registered with that ID: " + zoneId +
                     ", currently loading from provider: " + provider);

test/jdk/java/time/test/java/time/zone/TestZoneRulesProvider.java

@@ -0,0 +1,94 @@
+/*
+ * Copyright (c) 2023, 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.
+ */
+
+package test.java.time.zone;
+
+import java.time.ZoneId;
+import java.time.zone.ZoneRules;
+import java.time.zone.ZoneRulesException;
+import java.time.zone.ZoneRulesProvider;
+import java.util.Arrays;
+import java.util.LinkedHashSet;
+import java.util.NavigableMap;
+import java.util.Set;
+
+import org.testng.annotations.Test;
+import static org.testng.Assert.assertFalse;
+import static org.testng.Assert.assertTrue;
+
+/**
+ * @summary Tests for ZoneRulesProvider class.
+ * @bug 8299571
+ */
+@Test
+public class TestZoneRulesProvider {
+    private static final Set<String> MY_ZONE_IDS =
+        new LinkedHashSet(Arrays.asList(new String[] {"MyID_1", "MyID_2", "CET", "MyID_3"}));
+
+    /**
+     * Tests whether partially registered zones are cleaned on a provider registration
+     * failure, in case a duplicated zone is detected.
+     */
+    @Test
+    public void test_registerDuplicatedZone() {
+        try {
+            ZoneRulesProvider.registerProvider(new ZoneRulesProvider() {
+                @Override
+                protected Set<String> provideZoneIds() {
+                    return MY_ZONE_IDS;
+                }
+
+                @Override
+                protected ZoneRules provideRules(String zoneId, boolean forCaching) {
+                    return null;
+                }
+
+                @Override
+                protected NavigableMap<String, ZoneRules> provideVersions(String zoneId) {
+                    return null;
+                }
+            });
+            throw new RuntimeException("Registering a provider that duplicates a zone should throw an exception");
+        } catch (ZoneRulesException e) {
+            // Ignore. Failure on registration is expected.
+        }
+
+        MY_ZONE_IDS.stream().forEach(id -> {
+            var isCET = id.equals("CET");
+
+            // availability check
+            var available = ZoneId.getAvailableZoneIds().contains(id);
+            if (available ^ isCET) {
+                throw new RuntimeException("Unexpected availability for " + id + ", availability: " + available);
+            }
+
+            // instantiation check
+            try {
+                ZoneId.of(id);
+                assertTrue(isCET, "ZoneId.of() for the custom id %s should throw ZoneRulesException.".formatted(id));
+            } catch (ZoneRulesException e) {
+                assertFalse(isCET, "Not possible to obtain a ZoneId for \"CET\".");
+            }
+        });
+    }
+}