undefect. CWE-407 — 63 sites patched across 27 ecosystems

Authors: russell@unturf.com · brackishbert@gmail.com · foxhop.net · TimeHexOn.com

Patches, unit tests, benchmarks, whitepaper, and outreach briefs.
Public domain — no copyright claimed. Use freely.

test/jdk/java/util/concurrent/locks/Lock/FlakyMutex.java

@@ -0,0 +1,180 @@
+/*
+ * Copyright (c) 2006, 2013, 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.
+ */
+
+/*
+ * @test
+ * @bug 6503247 6574123
+ * @summary Test resilience to tryAcquire methods that throw
+ * @author Martin Buchholz
+ */
+
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.concurrent.CyclicBarrier;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.AbstractQueuedLongSynchronizer;
+import java.util.concurrent.locks.Condition;
+import java.util.concurrent.locks.Lock;
+
+/**
+ * This uses a variant of the standard Mutex demo, except with a
+ * tryAcquire method that randomly throws various Throwable
+ * subclasses.
+ */
+@SuppressWarnings("serial")
+public class FlakyMutex implements Lock {
+    static class MyError extends Error {}
+    static class MyException extends Exception {}
+    static class MyRuntimeException extends RuntimeException {}
+
+    static void checkThrowable(Throwable t) {
+        if (!((t instanceof MyError) ||
+              (t instanceof MyException) ||
+              (t instanceof MyRuntimeException)))
+            unexpected(t);
+    }
+
+    static void realMain(String[] args) throws Throwable {
+        final ThreadLocalRandom rndMain = ThreadLocalRandom.current();
+        final int nCpus = Runtime.getRuntime().availableProcessors();
+        final int maxThreads = Math.min(4, nCpus);
+        final int nThreads = rndMain.nextInt(1, maxThreads + 1);
+        final int iterations = 10_000;
+        final CyclicBarrier startingGate = new CyclicBarrier(nThreads);
+        final ExecutorService es = Executors.newFixedThreadPool(nThreads);
+        final FlakyMutex mutex = new FlakyMutex();
+        final Runnable task = () -> {
+            try {
+                ThreadLocalRandom rnd = ThreadLocalRandom.current();
+                startingGate.await();
+                for (int i = 0; i < iterations; i++) {
+                    for (;;) {
+                        try {
+                            if (rnd.nextBoolean())
+                                mutex.lock();
+                            else
+                                mutex.lockInterruptibly();
+                            break;
+                        } catch (Throwable t) { checkThrowable(t); }
+                    }
+
+                    if (rnd.nextBoolean()) {
+                        try {
+                            check(! mutex.tryLock());
+                        } catch (Throwable t) { checkThrowable(t); }
+                    }
+
+                    if (rnd.nextInt(10) == 0) {
+                        try {
+                            check(! mutex.tryLock(1, TimeUnit.MICROSECONDS));
+                        } catch (Throwable t) { checkThrowable(t); }
+                    }
+
+                    if (rnd.nextBoolean()) {
+                        check(mutex.isLocked());
+                    }
+
+                    mutex.unlock();
+                }
+            } catch (Throwable t) { unexpected(t); }
+        };
+
+        for (int i = 0; i < nThreads; i++)
+            es.submit(task);
+        es.shutdown();
+        // Let test harness handle timeout
+        check(es.awaitTermination(Long.MAX_VALUE, TimeUnit.DAYS));
+    }
+
+    private static class FlakySync extends AbstractQueuedLongSynchronizer {
+        private static final long serialVersionUID = -1L;
+
+        public boolean isHeldExclusively() { return getState() == 1; }
+
+        public boolean tryAcquire(long acquires) {
+            // Sneak in some tests for queue state
+            if (hasQueuedPredecessors())
+                check(getFirstQueuedThread() != Thread.currentThread());
+            if (getFirstQueuedThread() == Thread.currentThread()) {
+                check(hasQueuedThreads());
+                check(!hasQueuedPredecessors());
+            } else {
+                // Might be true, but only transiently
+                do {} while (hasQueuedPredecessors() != hasQueuedThreads());
+            }
+
+            switch (ThreadLocalRandom.current().nextInt(10)) {
+            case 0: throw new MyError();
+            case 1: throw new MyRuntimeException();
+            case 2: FlakyMutex.<RuntimeException>uncheckedThrow(new MyException());
+                // fall through ... NOT!
+            default: return compareAndSetState(0, 1);
+            }
+        }
+
+        public boolean tryRelease(long releases) {
+            setState(0);
+            return true;
+        }
+
+        Condition newCondition() { return new ConditionObject(); }
+    }
+
+    private final FlakySync sync = new FlakySync();
+    public void lock() { sync.acquire(1); }
+    public boolean tryLock() { return sync.tryAcquire(1); }
+    public void lockInterruptibly() throws InterruptedException {
+        sync.acquireInterruptibly(1);
+    }
+    public boolean tryLock(long timeout, TimeUnit unit) throws InterruptedException {
+        return sync.tryAcquireNanos(1, unit.toNanos(timeout));
+    }
+    public void unlock() { sync.release(1); }
+    public Condition newCondition()   { return sync.newCondition(); }
+    public boolean isLocked()         { return sync.isHeldExclusively(); }
+    public boolean hasQueuedThreads() { return sync.hasQueuedThreads(); }
+
+    //--------------------- Infrastructure ---------------------------
+    static volatile int passed = 0, failed = 0;
+    static void pass() {passed++;}
+    static void fail() {failed++; Thread.dumpStack();}
+    static void fail(String msg) {System.out.println(msg); fail();}
+    static void unexpected(Throwable t) {failed++; t.printStackTrace();}
+    static void check(boolean cond) {if (cond) pass(); else fail();}
+    static 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 {
+        int runsPerTest = Integer.getInteger("jsr166.runsPerTest", 1);
+        try {
+            for (int i = runsPerTest; i--> 0; )
+                realMain(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");}
+    @SuppressWarnings("unchecked")
+    static <T extends Throwable> void uncheckedThrow(Throwable t) throws T {
+        throw (T)t; // rely on vacuous cast
+    }
+}