| /* |
| * Copyright (c) 2017, 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.util.Calendar; |
| import java.util.Locale; |
| import java.util.SimpleTimeZone; |
| import java.util.TimeZone; |
| import java.util.function.Supplier; |
| |
| /* |
| * @test |
| * @bug 8191216 |
| * @summary test that provokes race between cloning and lazily initializing |
| * SimpleTimeZone cache fields |
| */ |
| public class SimpleTimeZoneCloneRaceTest { |
| |
| public static void main(String[] args) throws InterruptedException { |
| |
| // shared TZ user repeatedly samples sharedTZ and calculates offset |
| // using the shared instance |
| TimeZoneUser sharedTZuser = new TimeZoneUser(() -> sharedTZ); |
| |
| // cloned TZ user repeatedly samples sharedTZ then clones it and |
| // calculates offset using the clone... |
| TimeZoneUser clonedTZuser = new TimeZoneUser(() -> { |
| // sample shared TZ |
| TimeZone tz = sharedTZ; |
| // do some computation that takes roughly the same time as it takes |
| // sharedTZUser to start changing cache fields in shared TZ |
| cpuHogTZ.getOffset(time); |
| // now clone the sampled TZ and return it, hoping the clone is done |
| // at about the right time.... |
| return (TimeZone) tz.clone(); |
| }); |
| |
| // start threads |
| Thread t1 = new Thread(sharedTZuser); |
| Thread t2 = new Thread(clonedTZuser); |
| t1.start(); |
| t2.start(); |
| |
| // plant new SimpleTimeZone instances for 2 seconds |
| long t0 = System.currentTimeMillis(); |
| do { |
| TimeZone tz1 = createSTZ(); |
| TimeZone tz2 = createSTZ(); |
| cpuHogTZ = tz1; |
| sharedTZ = tz2; |
| } while (System.currentTimeMillis() - t0 < 2000L); |
| |
| sharedTZuser.stop = true; |
| clonedTZuser.stop = true; |
| t1.join(); |
| t2.join(); |
| |
| System.out.println( |
| String.format("shared TZ: %d correct, %d incorrect calculations", |
| sharedTZuser.correctCount, sharedTZuser.incorrectCount) |
| ); |
| System.out.println( |
| String.format("cloned TZ: %d correct, %d incorrect calculations", |
| clonedTZuser.correctCount, clonedTZuser.incorrectCount) |
| ); |
| if (clonedTZuser.incorrectCount > 0) { |
| throw new RuntimeException(clonedTZuser.incorrectCount + |
| " fatal data races detected"); |
| } |
| } |
| |
| static SimpleTimeZone createSTZ() { |
| return new SimpleTimeZone(-28800000, |
| "America/Los_Angeles", |
| Calendar.APRIL, 1, -Calendar.SUNDAY, |
| 7200000, |
| Calendar.OCTOBER, -1, Calendar.SUNDAY, |
| 7200000, |
| 3600000); |
| } |
| |
| static volatile TimeZone cpuHogTZ = createSTZ(); |
| static volatile TimeZone sharedTZ = createSTZ(); |
| static final long time; |
| static final long correctOffset; |
| |
| static { |
| TimeZone tz = createSTZ(); |
| Calendar cal = Calendar.getInstance(tz, Locale.ROOT); |
| cal.set(2000, Calendar.MAY, 1, 0, 0, 0); |
| time = cal.getTimeInMillis(); |
| correctOffset = tz.getOffset(time); |
| } |
| |
| static class TimeZoneUser implements Runnable { |
| private final Supplier<? extends TimeZone> tzSupplier; |
| |
| TimeZoneUser(Supplier<? extends TimeZone> tzSupplier) { |
| this.tzSupplier = tzSupplier; |
| } |
| |
| volatile boolean stop; |
| int correctCount, incorrectCount; |
| |
| @Override |
| public void run() { |
| while (!stop) { |
| TimeZone tz = tzSupplier.get(); |
| int offset = tz.getOffset(time); |
| if (offset == correctOffset) { |
| correctCount++; |
| } else { |
| incorrectCount++; |
| } |
| } |
| } |
| } |
| } |