FinalizerTest.java

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/**
 * @test
 * @bug 4272800 4274208 4392010
 * @summary Test debugger operations in finalize() methods
 * @author Gordon Hirsch  (modified for HotSpot by tbell & rfield)
 *
 * @run build TestScaffold VMConnection TargetListener TargetAdapter
 * @run compile -g FinalizerTest.java
 *
 * @run driver FinalizerTest -Xmx256M
 */
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;

import com.sun.jdi.StackFrame;
import com.sun.jdi.event.BreakpointEvent;
import com.sun.jdi.event.StepEvent;


/*
 * Debuggee which exercises a finalize() method. There's no guarantee
 * that this will work, but we need some way of attempting to test
 * the debugging of finalizers.
 * @author Gordon Hirsch  (modified for HotSpot by tbell & rfield)
 */
class FinalizerTarg {
    static final CountDownLatch finalizerDone = new CountDownLatch(1);
    static class BigObject {
        String name;
        byte[] foo = new byte[300000];

        public BigObject (String _name) {
            super();
            this.name = _name;
        }

        protected void finalize() throws Throwable {
            /*
             * JLS 2nd Ed. section 12.6 "Finalization of Class Instances" "[...]
             * invoke the finalize method for its superclass, [...] usually good
             * practice [...]"
             */
            super.finalize();
            //Thread.dumpStack();
            finalizerDone.countDown();
        }
    }

    static void waitForAFinalizer() {
        String s = Integer.toString(1);
        BigObject b = new BigObject (s);
        b = null; // Drop the object, creating garbage...
        System.gc();
        System.runFinalization();
        try {
            // finalize() is run in another lower priority Finalizer thread.
            // Wait for it to finish.
            finalizerDone.await(5, TimeUnit.SECONDS);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }

        // If System.gc() and System.runFinalization() did not trigger the
        // finalizer, then finalizerDone.await() will time out and the code
        // below will be needed as a second attempt to trigger finalization.
        List holdAlot = new ArrayList();
        for (int chunk=10000000; chunk > 10000; chunk = chunk / 2) {
            if (finalizerDone.getCount() == 0) {
                return;
            }
            try {
                while (finalizerDone.getCount() > 0) {
                    holdAlot.add(new byte[chunk]);
                    System.err.println("Allocated " + chunk);
                }
            } catch ( Throwable thrown ) {  // OutOfMemoryError
            } finally {
                holdAlot.clear();
                System.gc();
            }
            System.runFinalization();
        }
        System.out.println("The Debuggee should not reach here in theory!");
        return;
    }

    public static void main(String[] args) throws Exception {
        /*
         * Spin in waitForAFinalizer() while waiting for
         * another thread to run the finalizer on one of the
         * BigObjects ...
         */
        waitForAFinalizer();
    }
}
///// End of debuggee


public class FinalizerTest extends TestScaffold {

    public static void main(String args[])
        throws Exception {
        new FinalizerTest (args).startTests();
    }

    public FinalizerTest (String args[]) {
        super(args);
    }

    protected void runTests() throws Exception {
        try {
            BreakpointEvent event0 = startToMain("FinalizerTarg");

            BreakpointEvent event1 = resumeTo("FinalizerTarg$BigObject",
                                              "finalize", "()V");

            println("Breakpoint at " +
                    event1.location().method().name() + ":" +
                    event1.location().lineNumber() + " (" +
                    event1.location().codeIndex() + ")");

            /*
             * Record information about the current location
             */
            List frames = event1.thread().frames();
            List methodStack = new ArrayList(frames.size());
            Iterator iter = frames.iterator();
            while (iter.hasNext()) {
                StackFrame frame = (StackFrame) iter.next();
                methodStack.add(frame.location().declaringType().name() +
                                "." + frame.location().method().name());
            }
            println("Try a stepOverLine()...");
            StepEvent stepEvent = stepOverLine(event1.thread());

            println("Step Complete at " +
                               stepEvent.location().method().name() + ":" +
                               stepEvent.location().lineNumber() + " (" +
                               stepEvent.location().codeIndex() + ")");

            /*
             * Compare current location with recorded location
             */
            if (stepEvent.thread().frameCount() != methodStack.size()) {
                throw new Exception("Stack depths do not match: original=" +
                                    methodStack.size() +
                                    ", current=" +
                                    stepEvent.thread().frameCount());
            }
            iter = stepEvent.thread().frames().iterator();
            Iterator iter2 = methodStack.iterator();
            while (iter.hasNext()) {
                StackFrame frame = (StackFrame) iter.next();
                String name = (String) iter2.next();
                String currentName = frame.location().declaringType().name() +
                "." + frame.location().method().name();
                if (!name.equals(currentName)) {
                    throw new Exception("Stacks do not match at: original=" +
                                         name + ", current=" + currentName);

                }
            }
        } catch(Exception ex) {
            ex.printStackTrace();
            testFailed = true;
        } finally {
            // Allow application to complete and shut down
            listenUntilVMDisconnect();
        }
        if (!testFailed) {
            println("FinalizerTest: passed");
        } else {
            throw new Exception("FinalizerTest: failed");
        }
    }
}