Mercurial > hg > release > icedtea7-forest-2.2 > jdk
changeset 2408:fc7c38b2584c
6941130: Semaphore should throw if number of permits overflows or underflows
Summary: Check if release could make number of permits negative
Reviewed-by: dl, dholmes
author | martin |
---|---|
date | Wed, 07 Apr 2010 12:30:49 -0700 |
parents | 0b7f10901f30 |
children | 025f9e57566a 710c4493902f 6b641c576e77 |
files | src/share/classes/java/util/concurrent/Semaphore.java test/java/util/concurrent/Semaphore/PermitOverflow.java |
diffstat | 2 files changed, 109 insertions(+), 2 deletions(-) [+] |
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--- a/src/share/classes/java/util/concurrent/Semaphore.java Tue Apr 06 15:45:21 2010 -0700 +++ b/src/share/classes/java/util/concurrent/Semaphore.java Wed Apr 07 12:30:49 2010 -0700 @@ -191,8 +191,11 @@ protected final boolean tryReleaseShared(int releases) { for (;;) { - int p = getState(); - if (compareAndSetState(p, p + releases)) + int current = getState(); + int next = current + releases; + if (next < current) // overflow + throw new Error("Maximum permit count exceeded"); + if (compareAndSetState(current, next)) return true; } } @@ -201,6 +204,8 @@ for (;;) { int current = getState(); int next = current - reductions; + if (next > current) // underflow + throw new Error("Permit count underflow"); if (compareAndSetState(current, next)) return; }
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/test/java/util/concurrent/Semaphore/PermitOverflow.java Wed Apr 07 12:30:49 2010 -0700 @@ -0,0 +1,102 @@ +/* + * 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. + */ + +/* + * This file is available under and governed by the GNU General Public + * License version 2 only, as published by the Free Software Foundation. + * However, the following notice accompanied the original version of this + * file: + * + * Written by Doug Lea with assistance from members of JCP JSR-166 + * Expert Group and released to the public domain, as explained at + * http://creativecommons.org/licenses/publicdomain + */ + +/* + * @test + * @bug 6941130 + * @summary Numeric overflow/underflow of permits causes Error throw + */ + +import java.util.concurrent.Semaphore; + +public class PermitOverflow { + + public static void main(String[] args) throws Throwable { + for (boolean fair : new boolean[] { true, false }) { + Semaphore sem = new Semaphore(Integer.MAX_VALUE - 1, fair); + if (sem.availablePermits() != Integer.MAX_VALUE - 1) + throw new RuntimeException(); + try { + sem.release(2); + throw new RuntimeException(); + } catch (Error expected) { + } + sem.release(1); + if (sem.availablePermits() != Integer.MAX_VALUE) + throw new RuntimeException(); + try { + sem.release(1); + throw new RuntimeException(); + } catch (Error expected) { + } + try { + sem.release(Integer.MAX_VALUE); + throw new RuntimeException(); + } catch (Error expected) { + } + } + + class Sem extends Semaphore { + public Sem(int permits, boolean fair) { + super(permits, fair); + } + public void reducePermits(int reduction) { + super.reducePermits(reduction); + } + } + + for (boolean fair : new boolean[] { true, false }) { + Sem sem = new Sem(Integer.MIN_VALUE + 1, fair); + if (sem.availablePermits() != Integer.MIN_VALUE + 1) + throw new RuntimeException(); + try { + sem.reducePermits(2); + throw new RuntimeException(); + } catch (Error expected) { + } + sem.reducePermits(1); + if (sem.availablePermits() != Integer.MIN_VALUE) + throw new RuntimeException(); + try { + sem.reducePermits(1); + throw new RuntimeException(); + } catch (Error expected) { + } + try { + sem.reducePermits(Integer.MAX_VALUE); + throw new RuntimeException(); + } catch (Error expected) { + } + } + } +}