changeset 472:f33c3846cecb

6725789: ScheduledExecutorService does not work as expected in jdk7/6/5 Reviewed-by: martin, dholmes, chegar
author dl
date Fri, 01 Aug 2008 00:42:43 -0700
parents 3a1325be2806
children e0dc076d99b8
files src/share/classes/java/util/concurrent/ScheduledThreadPoolExecutor.java test/java/util/concurrent/ScheduledThreadPoolExecutor/DelayOverflow.java
diffstat 2 files changed, 201 insertions(+), 15 deletions(-) [+]
line wrap: on
line diff
--- a/src/share/classes/java/util/concurrent/ScheduledThreadPoolExecutor.java	Fri Aug 01 00:38:02 2008 -0700
+++ b/src/share/classes/java/util/concurrent/ScheduledThreadPoolExecutor.java	Fri Aug 01 00:42:43 2008 -0700
@@ -223,8 +223,7 @@
         }
 
         public long getDelay(TimeUnit unit) {
-            long d = unit.convert(time - now(), TimeUnit.NANOSECONDS);
-            return d;
+            return unit.convert(time - now(), TimeUnit.NANOSECONDS);
         }
 
         public int compareTo(Delayed other) {
@@ -264,7 +263,7 @@
             if (p > 0)
                 time += p;
             else
-                time = now() - p;
+                time = triggerTime(-p);
         }
 
         public boolean cancel(boolean mayInterruptIfRunning) {
@@ -473,6 +472,38 @@
     }
 
     /**
+     * Returns the trigger time of a delayed action.
+     */
+    private long triggerTime(long delay, TimeUnit unit) {
+        return triggerTime(unit.toNanos((delay < 0) ? 0 : delay));
+    }
+
+    /**
+     * Returns the trigger time of a delayed action.
+     */
+    long triggerTime(long delay) {
+        return now() +
+            ((delay < (Long.MAX_VALUE >> 1)) ? delay : overflowFree(delay));
+    }
+
+    /**
+     * Constrains the values of all delays in the queue to be within
+     * Long.MAX_VALUE of each other, to avoid overflow in compareTo.
+     * This may occur if a task is eligible to be dequeued, but has
+     * not yet been, while some other task is added with a delay of
+     * Long.MAX_VALUE.
+     */
+    private long overflowFree(long delay) {
+        Delayed head = (Delayed) super.getQueue().peek();
+        if (head != null) {
+            long headDelay = head.getDelay(TimeUnit.NANOSECONDS);
+            if (headDelay < 0 && (delay - headDelay < 0))
+                delay = Long.MAX_VALUE + headDelay;
+        }
+        return delay;
+    }
+
+    /**
      * @throws RejectedExecutionException {@inheritDoc}
      * @throws NullPointerException       {@inheritDoc}
      */
@@ -481,10 +512,9 @@
                                        TimeUnit unit) {
         if (command == null || unit == null)
             throw new NullPointerException();
-        if (delay < 0) delay = 0;
-        long triggerTime = now() + unit.toNanos(delay);
         RunnableScheduledFuture<?> t = decorateTask(command,
-            new ScheduledFutureTask<Void>(command, null, triggerTime));
+            new ScheduledFutureTask<Void>(command, null,
+                                          triggerTime(delay, unit)));
         delayedExecute(t);
         return t;
     }
@@ -498,10 +528,9 @@
                                            TimeUnit unit) {
         if (callable == null || unit == null)
             throw new NullPointerException();
-        if (delay < 0) delay = 0;
-        long triggerTime = now() + unit.toNanos(delay);
         RunnableScheduledFuture<V> t = decorateTask(callable,
-            new ScheduledFutureTask<V>(callable, triggerTime));
+            new ScheduledFutureTask<V>(callable,
+                                       triggerTime(delay, unit)));
         delayedExecute(t);
         return t;
     }
@@ -519,12 +548,10 @@
             throw new NullPointerException();
         if (period <= 0)
             throw new IllegalArgumentException();
-        if (initialDelay < 0) initialDelay = 0;
-        long triggerTime = now() + unit.toNanos(initialDelay);
         ScheduledFutureTask<Void> sft =
             new ScheduledFutureTask<Void>(command,
                                           null,
-                                          triggerTime,
+                                          triggerTime(initialDelay, unit),
                                           unit.toNanos(period));
         RunnableScheduledFuture<Void> t = decorateTask(command, sft);
         sft.outerTask = t;
@@ -545,12 +572,10 @@
             throw new NullPointerException();
         if (delay <= 0)
             throw new IllegalArgumentException();
-        if (initialDelay < 0) initialDelay = 0;
-        long triggerTime = now() + unit.toNanos(initialDelay);
         ScheduledFutureTask<Void> sft =
             new ScheduledFutureTask<Void>(command,
                                           null,
-                                          triggerTime,
+                                          triggerTime(initialDelay, unit),
                                           unit.toNanos(-delay));
         RunnableScheduledFuture<Void> t = decorateTask(command, sft);
         sft.outerTask = t;
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/java/util/concurrent/ScheduledThreadPoolExecutor/DelayOverflow.java	Fri Aug 01 00:42:43 2008 -0700
@@ -0,0 +1,161 @@
+/*
+ * 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/*
+ * @test
+ * @bug 6725789
+ * @summary Check for long overflow in task time comparison.
+ */
+
+import java.util.concurrent.*;
+
+public class DelayOverflow {
+    static void waitForNanoTimeTick() {
+        for (long t0 = System.nanoTime(); t0 == System.nanoTime(); )
+            ;
+    }
+
+    void scheduleNow(ScheduledThreadPoolExecutor pool,
+                     Runnable r, int how) {
+        switch (how) {
+        case 0:
+            pool.schedule(r, 0, TimeUnit.MILLISECONDS);
+            break;
+        case 1:
+            pool.schedule(Executors.callable(r), 0, TimeUnit.DAYS);
+            break;
+        case 2:
+            pool.scheduleWithFixedDelay(r, 0, 1000, TimeUnit.NANOSECONDS);
+            break;
+        case 3:
+            pool.scheduleAtFixedRate(r, 0, 1000, TimeUnit.MILLISECONDS);
+            break;
+        default:
+            fail(String.valueOf(how));
+        }
+    }
+
+    void scheduleAtTheEndOfTime(ScheduledThreadPoolExecutor pool,
+                                Runnable r, int how) {
+        switch (how) {
+        case 0:
+            pool.schedule(r, Long.MAX_VALUE, TimeUnit.MILLISECONDS);
+            break;
+        case 1:
+            pool.schedule(Executors.callable(r), Long.MAX_VALUE, TimeUnit.DAYS);
+            break;
+        case 2:
+            pool.scheduleWithFixedDelay(r, Long.MAX_VALUE, 1000, TimeUnit.NANOSECONDS);
+            break;
+        case 3:
+            pool.scheduleAtFixedRate(r, Long.MAX_VALUE, 1000, TimeUnit.MILLISECONDS);
+            break;
+        default:
+            fail(String.valueOf(how));
+        }
+    }
+
+    /**
+     * Attempts to test exhaustively and deterministically, all 20
+     * possible ways that one task can be scheduled in the maximal
+     * distant future, while at the same time an existing tasks's time
+     * has already expired.
+     */
+    void test(String[] args) throws Throwable {
+        for (int nowHow = 0; nowHow < 4; nowHow++) {
+            for (int thenHow = 0; thenHow < 4; thenHow++) {
+
+                final ScheduledThreadPoolExecutor pool
+                    = new ScheduledThreadPoolExecutor(1);
+                final CountDownLatch runLatch     = new CountDownLatch(1);
+                final CountDownLatch busyLatch    = new CountDownLatch(1);
+                final CountDownLatch proceedLatch = new CountDownLatch(1);
+                final Runnable notifier = new Runnable() {
+                        public void run() { runLatch.countDown(); }};
+                final Runnable neverRuns = new Runnable() {
+                        public void run() { fail(); }};
+                final Runnable keepPoolBusy = new Runnable() {
+                        public void run() {
+                            try {
+                                busyLatch.countDown();
+                                proceedLatch.await();
+                            } catch (Throwable t) { unexpected(t); }
+                        }};
+                pool.schedule(keepPoolBusy, 0, TimeUnit.SECONDS);
+                busyLatch.await();
+                scheduleNow(pool, notifier, nowHow);
+                waitForNanoTimeTick();
+                scheduleAtTheEndOfTime(pool, neverRuns, thenHow);
+                proceedLatch.countDown();
+
+                check(runLatch.await(10L, TimeUnit.SECONDS));
+                equal(runLatch.getCount(), 0L);
+
+                pool.setExecuteExistingDelayedTasksAfterShutdownPolicy(false);
+                pool.shutdown();
+            }
+
+            final int nowHowCopy = nowHow;
+            final ScheduledThreadPoolExecutor pool
+                = new ScheduledThreadPoolExecutor(1);
+            final CountDownLatch runLatch = new CountDownLatch(1);
+            final Runnable notifier = new Runnable() {
+                    public void run() { runLatch.countDown(); }};
+            final Runnable scheduleNowScheduler = new Runnable() {
+                    public void run() {
+                        try {
+                            scheduleNow(pool, notifier, nowHowCopy);
+                            waitForNanoTimeTick();
+                        } catch (Throwable t) { unexpected(t); }
+                    }};
+            pool.scheduleWithFixedDelay(scheduleNowScheduler,
+                                        0, Long.MAX_VALUE,
+                                        TimeUnit.NANOSECONDS);
+
+            check(runLatch.await(10L, TimeUnit.SECONDS));
+            equal(runLatch.getCount(), 0L);
+
+            pool.setExecuteExistingDelayedTasksAfterShutdownPolicy(false);
+            pool.shutdown();
+        }
+    }
+
+    //--------------------- Infrastructure ---------------------------
+    volatile int passed = 0, failed = 0;
+    void pass() {passed++;}
+    void fail() {failed++; Thread.dumpStack();}
+    void fail(String msg) {System.err.println(msg); fail();}
+    void unexpected(Throwable t) {failed++; t.printStackTrace();}
+    void check(boolean cond) {if (cond) pass(); else fail();}
+    void equal(Object x, Object y) {
+        if (x == null ? y == null : x.equals(y)) pass();
+        else fail(x + " not equal to " + y);}
+    public static void main(String[] args) throws Throwable {
+        Class<?> k = new Object(){}.getClass().getEnclosingClass();
+        try {k.getMethod("instanceMain",String[].class)
+                .invoke( k.newInstance(), (Object) args);}
+        catch (Throwable e) {throw e.getCause();}}
+    public void instanceMain(String[] args) throws Throwable {
+        try {test(args);} catch (Throwable t) {unexpected(t);}
+        System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
+        if (failed > 0) throw new AssertionError("Some tests failed");}
+}