diff options
Diffstat (limited to 'bcel-builder')
2 files changed, 29 insertions, 21 deletions
diff --git a/bcel-builder/src/main/java/org/aspectj/apache/bcel/classfile/LocalVariableTable.java b/bcel-builder/src/main/java/org/aspectj/apache/bcel/classfile/LocalVariableTable.java index 545227050..555e6bb2b 100644 --- a/bcel-builder/src/main/java/org/aspectj/apache/bcel/classfile/LocalVariableTable.java +++ b/bcel-builder/src/main/java/org/aspectj/apache/bcel/classfile/LocalVariableTable.java @@ -189,9 +189,16 @@ public class LocalVariableTable extends Attribute { return buf.toString(); } - @Override - public Object clone() throws CloneNotSupportedException { - return super.clone(); + /** + * Returns copy of this attribute using same packed state. Used in unit tests. + */ + public synchronized LocalVariableTable copyFromPackedState() { + if (!isInPackedState) throw new IllegalStateException("No in packed state"); + try { + return new LocalVariableTable(nameIndex, length, new DataInputStream(new ByteArrayInputStream(data)), getConstantPool()); + } catch (IOException e) { + throw new RuntimeException("Failed to unpack clone", e); + } } /** diff --git a/bcel-builder/src/test/java/org/aspectj/apache/bcel/classfile/tests/LocalVariableTableConcurrencyTest.java b/bcel-builder/src/test/java/org/aspectj/apache/bcel/classfile/tests/LocalVariableTableConcurrencyTest.java index da9b8c296..b62ffe380 100644 --- a/bcel-builder/src/test/java/org/aspectj/apache/bcel/classfile/tests/LocalVariableTableConcurrencyTest.java +++ b/bcel-builder/src/test/java/org/aspectj/apache/bcel/classfile/tests/LocalVariableTableConcurrencyTest.java @@ -7,7 +7,7 @@ * http://www.eclipse.org/legal/epl-v10.html * * Contributors: - * Andy Clement - initial implementation + * Dmitry Mikhaylov - initial implementation * ******************************************************************/ package org.aspectj.apache.bcel.classfile.tests; @@ -16,7 +16,6 @@ import org.aspectj.apache.bcel.classfile.Code; import org.aspectj.apache.bcel.classfile.JavaClass; import org.aspectj.apache.bcel.classfile.LocalVariableTable; import org.aspectj.apache.bcel.classfile.Method; -import org.aspectj.apache.bcel.classfile.tests.BcelTestCase; import java.util.concurrent.CountDownLatch; import java.util.concurrent.ExecutorService; @@ -35,29 +34,31 @@ public class LocalVariableTableConcurrencyTest extends BcelTestCase { protected void setUp() throws Exception { super.setUp(); + for (int i = 0; i < nThreads; i++) workers[i] = Executors.newSingleThreadExecutor(); JavaClass clazz = getClassFromJar("SimpleGenericsProgram"); - Method mainMethod = getMethod(clazz,"main"); Code codeAttr = (Code) findAttribute("Code",mainMethod.getAttributes()); - - reference = - (LocalVariableTable) findAttribute("LocalVariableTable",codeAttr.getAttributes()); - } - - private LocalVariableTable createReferenceCopy() { - try { - return (LocalVariableTable) reference.clone(); - } catch (CloneNotSupportedException e) { - throw new RuntimeException("Faileed to clone LocalVariableTable", e); - } + reference = (LocalVariableTable) findAttribute("LocalVariableTable",codeAttr.getAttributes()); } + /** + * Try to hit concurrency bug in org.aspectj.apache.bcel.classfile.LocalVariableTable.unpack(). + * We do so by running unpack() on same instance with multiple threads, and artificially + * delaying all threads but first so that they enter unpack() the moment first thread is about to leave it. + * + * Since this test relies on empirically obtained access pattern and number of iterations, + * it never has 100% probability of hitting the bug. If it fails - there is certainly a bug. + * If it passes, it could mean anything - fully correct code or slightly changed execution order preventing + * threads to collide at problematic location. + * + * As such, it is not really good for unit testing. + */ public void testLocalVariableTableAttributeConcurrency() throws RuntimeException, InterruptedException { final AtomicReference<RuntimeException> error = new AtomicReference<>(); - for (int i = 0; i < 100000; i++) { - LocalVariableTable sharedInstance = createReferenceCopy(); + for (int i = 0; i < 10000; i++) { + LocalVariableTable sharedInstance = reference.copyFromPackedState(); CountDownLatch preStart = new CountDownLatch(nThreads); Semaphore start = new Semaphore(0); CountDownLatch finish = new CountDownLatch(nThreads); @@ -67,8 +68,8 @@ public class LocalVariableTableConcurrencyTest extends BcelTestCase { workers[j].execute(() -> { preStart.countDown(); start.acquireUninterruptibly(); - // trying to trigger concurrent unpacking - one tread should enter unpack() when other is about to leave it - if (needsDelay) createReferenceCopy().getTableLength(); + // trying to trigger concurrent unpacking bug - one tread should enter unpack() when other is about to leave it + if (needsDelay) reference.copyFromPackedState().getTableLength(); try { sharedInstance.getTableLength(); } |