java.lang.ref.ReferenceQueue#remove ( )源码实例Demo

/**
 * Test that releasing the reference to the Cleaner service allows it to be
 * be freed.
 */
@Test
void testCleanerTermination() {
    ReferenceQueue<Object> queue = new ReferenceQueue<>();
    Cleaner service = Cleaner.create();

    PhantomReference<Object> ref = new PhantomReference<>(service, queue);
    System.gc();
    // Clear the Reference to the cleaning service and force a gc.
    service = null;
    System.gc();
    try {
        Reference<?> r = queue.remove(1000L);
        Assert.assertNotNull(r, "queue.remove timeout,");
        Assert.assertEquals(r, ref, "Wrong Reference dequeued");
    } catch (InterruptedException ie) {
        System.out.printf("queue.remove Interrupted%n");
    }
}
 

/** Collects items from GC and removes them from cache */
protected void runRefQueue(){
    try{
        final ReferenceQueue<?> queue = this.queue;
        if(queue == null)return;
        final LongConcurrentHashMap<CacheItem> items = this.items;

        while(true){
            CacheItem item = (CacheItem) queue.remove();
            items.remove(item.getRecid(), item);
            if(Thread.interrupted()) return;
        }
    }catch(InterruptedException e){
        //this is expected, so just silently exit thread
    }
}
 

@Override
public void run() {
    try {
        while (true) {
            ReferenceQueue<V> q = getQueue();
            if (q == null)
                break; // soft cache deallocated -- stop the thread
            if (q.remove(10000) == null)
                continue; // was there something deallocated?
            while (q.poll() != null) {
            } // pull all the deallocated references from the queue
            cleanDeallocated(); // clean the cache
        }
        sLogger.debug("cache terminated");
    } catch (Exception e) {
        sLogger.error("cleanup thread failed, reason:" + e.getMessage(), e);
    }
}
 

private void waitForRefToClear(Reference ref, ReferenceQueue queue)
    throws InterruptedException {
    Reference r;
    while ((r = queue.remove(20)) == null) {
        System.gc();
    }
    assertEquals(r, ref);
    assertNull(r.get());
}
 

public static final void main(String[] args) throws Exception {
        System.err.println("\n Regression test for bug 6232010\n");
        if (System.getSecurityManager() == null) {
                System.setSecurityManager(new SecurityManager());
        }

        ClassLoader systemLoader = ClassLoader.getSystemClassLoader();
        ClassLoader loader = new URLClassLoader(((URLClassLoader) systemLoader).getURLs(),
                                                                                systemLoader.getParent());
        Class<? extends ObjectOutputStream> cl =
                Class.forName(SubclassOfOOS.class.getName(), false,
                                          loader).asSubclass(ObjectOutputStream.class);

        Constructor<? extends ObjectOutputStream> cons =
                cl.getConstructor(OutputStream.class);

        OutputStream os = new ByteArrayOutputStream();
        ObjectOutputStream obj = cons.newInstance(os);

        final ReferenceQueue<Class<?>> queue = new ReferenceQueue<Class<?>>();
        WeakReference<Class<?>> ref = new WeakReference<Class<?>>(cl, queue);

        cl = null;
        obj = null;
        loader = null;
        cons = null;
        systemLoader = null;

        System.err.println("\nStart Garbage Collection right now");
        System.gc();

        Reference<? extends Class<?>> dequeued = queue.remove(TIMEOUT);
        if (dequeued == ref) {
                System.err.println("\nTEST PASSED");
        } else {
                throw new Error();
        }
}
 

public static final void main(String[] args) throws Exception {
        System.err.println("\n Regression test for bug 6232010\n");
        if (System.getSecurityManager() == null) {
                System.setSecurityManager(new SecurityManager());
        }

        ClassLoader systemLoader = ClassLoader.getSystemClassLoader();
        ClassLoader loader = new URLClassLoader(((URLClassLoader) systemLoader).getURLs(),
                                                                                systemLoader.getParent());
        Class<? extends ObjectOutputStream> cl =
                Class.forName(SubclassOfOOS.class.getName(), false,
                                          loader).asSubclass(ObjectOutputStream.class);

        Constructor<? extends ObjectOutputStream> cons =
                cl.getConstructor(OutputStream.class);

        OutputStream os = new ByteArrayOutputStream();
        ObjectOutputStream obj = cons.newInstance(os);

        final ReferenceQueue<Class<?>> queue = new ReferenceQueue<Class<?>>();
        WeakReference<Class<?>> ref = new WeakReference<Class<?>>(cl, queue);

        cl = null;
        obj = null;
        loader = null;
        cons = null;
        systemLoader = null;

        System.err.println("\nStart Garbage Collection right now");
        System.gc();

        Reference<? extends Class<?>> dequeued = queue.remove(TIMEOUT);
        if (dequeued == ref) {
                System.err.println("\nTEST PASSED");
        } else {
                throw new Error();
        }
}
 

public static final void main(String[] args) throws Exception {
        System.err.println("\n Regression test for bug 6232010\n");
        if (System.getSecurityManager() == null) {
                System.setSecurityManager(new SecurityManager());
        }

        ClassLoader systemLoader = ClassLoader.getSystemClassLoader();
        ClassLoader loader = new URLClassLoader(((URLClassLoader) systemLoader).getURLs(),
                                                                                systemLoader.getParent());
        Class<? extends ObjectOutputStream> cl =
                Class.forName(SubclassOfOOS.class.getName(), false,
                                          loader).asSubclass(ObjectOutputStream.class);

        Constructor<? extends ObjectOutputStream> cons =
                cl.getConstructor(OutputStream.class);

        OutputStream os = new ByteArrayOutputStream();
        ObjectOutputStream obj = cons.newInstance(os);

        final ReferenceQueue<Class<?>> queue = new ReferenceQueue<Class<?>>();
        WeakReference<Class<?>> ref = new WeakReference<Class<?>>(cl, queue);

        cl = null;
        obj = null;
        loader = null;
        cons = null;
        systemLoader = null;

        System.err.println("\nStart Garbage Collection right now");
        System.gc();

        Reference<? extends Class<?>> dequeued = queue.remove(TIMEOUT);
        if (dequeued == ref) {
                System.err.println("\nTEST PASSED");
        } else {
                throw new Error();
        }
}
 

private void waitForRefToClear(Reference ref, ReferenceQueue queue)
    throws InterruptedException {
    Reference r;
    while ((r = queue.remove(20)) == null) {
        System.gc();
    }
    assertEquals(r, ref);
    assertNull(r.get());
}
 

public static final void main(String[] args) throws Exception {
        System.err.println("\n Regression test for bug 6232010\n");
        if (System.getSecurityManager() == null) {
                System.setSecurityManager(new SecurityManager());
        }

        ClassLoader systemLoader = ClassLoader.getSystemClassLoader();
        ClassLoader loader = new URLClassLoader(((URLClassLoader) systemLoader).getURLs(),
                                                                                systemLoader.getParent());
        Class<? extends ObjectOutputStream> cl =
                Class.forName(SubclassOfOOS.class.getName(), false,
                                          loader).asSubclass(ObjectOutputStream.class);

        Constructor<? extends ObjectOutputStream> cons =
                cl.getConstructor(OutputStream.class);

        OutputStream os = new ByteArrayOutputStream();
        ObjectOutputStream obj = cons.newInstance(os);

        final ReferenceQueue<Class<?>> queue = new ReferenceQueue<Class<?>>();
        WeakReference<Class<?>> ref = new WeakReference<Class<?>>(cl, queue);

        cl = null;
        obj = null;
        loader = null;
        cons = null;
        systemLoader = null;

        System.err.println("\nStart Garbage Collection right now");
        System.gc();

        Reference<? extends Class<?>> dequeued = queue.remove(TIMEOUT);
        if (dequeued == ref) {
                System.err.println("\nTEST PASSED");
        } else {
                throw new Error();
        }
}
 

public static final void main(String[] args) throws Exception {
        System.err.println("\n Regression test for bug 6232010\n");
        if (System.getSecurityManager() == null) {
                System.setSecurityManager(new SecurityManager());
        }

        ClassLoader systemLoader = ClassLoader.getSystemClassLoader();
        ClassLoader loader = new URLClassLoader(((URLClassLoader) systemLoader).getURLs(),
                                                                                systemLoader.getParent());
        Class<? extends ObjectOutputStream> cl =
                Class.forName(SubclassOfOOS.class.getName(), false,
                                          loader).asSubclass(ObjectOutputStream.class);

        Constructor<? extends ObjectOutputStream> cons =
                cl.getConstructor(OutputStream.class);

        OutputStream os = new ByteArrayOutputStream();
        ObjectOutputStream obj = cons.newInstance(os);

        final ReferenceQueue<Class<?>> queue = new ReferenceQueue<Class<?>>();
        WeakReference<Class<?>> ref = new WeakReference<Class<?>>(cl, queue);

        cl = null;
        obj = null;
        loader = null;
        cons = null;
        systemLoader = null;

        System.err.println("\nStart Garbage Collection right now");
        System.gc();

        Reference<? extends Class<?>> dequeued = queue.remove(TIMEOUT);
        if (dequeued == ref) {
                System.err.println("\nTEST PASSED");
        } else {
                throw new Error();
        }
}
 

void removeAll(ReferenceQueue<?> q, int n) throws InterruptedException {
    for (int j = n; j--> 0; ) {
        if (q.poll() == null) {
            for (;;) {
                System.gc();
                if (q.remove(1000) != null)
                    break;
                System.out.printf(
                    "%d/%d unqueued references remaining%n", j, n);
            }
        }
    }
    check(q.poll() == null);
}
 

public static final void main(String[] args) throws Exception {
        System.err.println("\n Regression test for bug 6232010\n");
        if (System.getSecurityManager() == null) {
                System.setSecurityManager(new SecurityManager());
        }

        ClassLoader systemLoader = ClassLoader.getSystemClassLoader();
        URL testClassesURL = new File(System.getProperty("test.classes")).toURI().toURL();
        ClassLoader loader = new URLClassLoader(new URL[] { testClassesURL } ,
                                                systemLoader.getParent());
        Class<? extends ObjectOutputStream> cl =
                Class.forName(SubclassOfOOS.class.getName(), false,
                                          loader).asSubclass(ObjectOutputStream.class);

        Constructor<? extends ObjectOutputStream> cons =
                cl.getConstructor(OutputStream.class);

        OutputStream os = new ByteArrayOutputStream();
        ObjectOutputStream obj = cons.newInstance(os);

        final ReferenceQueue<Class<?>> queue = new ReferenceQueue<Class<?>>();
        WeakReference<Class<?>> ref = new WeakReference<Class<?>>(cl, queue);

        cl = null;
        obj = null;
        loader = null;
        cons = null;
        systemLoader = null;

        System.err.println("\nStart Garbage Collection right now");
        System.gc();

        Reference<? extends Class<?>> dequeued = queue.remove(TIMEOUT);
        if (dequeued == ref) {
                System.err.println("\nTEST PASSED");
        } else {
                throw new Error();
        }
}
 

public static final void main(String[] args) throws Exception {
        System.err.println("\n Regression test for bug 6232010\n");
        if (System.getSecurityManager() == null) {
                System.setSecurityManager(new SecurityManager());
        }

        ClassLoader systemLoader = ClassLoader.getSystemClassLoader();
        ClassLoader loader = new URLClassLoader(((URLClassLoader) systemLoader).getURLs(),
                                                                                systemLoader.getParent());
        Class<? extends ObjectOutputStream> cl =
                Class.forName(SubclassOfOOS.class.getName(), false,
                                          loader).asSubclass(ObjectOutputStream.class);

        Constructor<? extends ObjectOutputStream> cons =
                cl.getConstructor(OutputStream.class);

        OutputStream os = new ByteArrayOutputStream();
        ObjectOutputStream obj = cons.newInstance(os);

        final ReferenceQueue<Class<?>> queue = new ReferenceQueue<Class<?>>();
        WeakReference<Class<?>> ref = new WeakReference<Class<?>>(cl, queue);

        cl = null;
        obj = null;
        loader = null;
        cons = null;
        systemLoader = null;

        System.err.println("\nStart Garbage Collection right now");
        System.gc();

        Reference<? extends Class<?>> dequeued = queue.remove(TIMEOUT);
        if (dequeued == ref) {
                System.err.println("\nTEST PASSED");
        } else {
                throw new Error();
        }
}
 

/** Collects items from GC and removes them from cache */
protected void runRefQueue(){
    try{
        final ReferenceQueue<?> queue = this.queue;
        final LongConcurrentHashMap<CacheItem> items = this.items;

        while(true){
            CacheItem item = (CacheItem) queue.remove();
            items.remove(item.getRecid(), item);
            if(Thread.interrupted()) return;
        }
    }catch(InterruptedException e){
        //this is expected, so just silently exit thread
    }
}
 

public static final void main(String[] args) throws Exception {
        System.err.println("\n Regression test for bug 6232010\n");
        if (System.getSecurityManager() == null) {
                System.setSecurityManager(new SecurityManager());
        }

        ClassLoader systemLoader = ClassLoader.getSystemClassLoader();
        ClassLoader loader = new URLClassLoader(((URLClassLoader) systemLoader).getURLs(),
                                                                                systemLoader.getParent());
        Class<? extends ObjectOutputStream> cl =
                Class.forName(SubclassOfOOS.class.getName(), false,
                                          loader).asSubclass(ObjectOutputStream.class);

        Constructor<? extends ObjectOutputStream> cons =
                cl.getConstructor(OutputStream.class);

        OutputStream os = new ByteArrayOutputStream();
        ObjectOutputStream obj = cons.newInstance(os);

        final ReferenceQueue<Class<?>> queue = new ReferenceQueue<Class<?>>();
        WeakReference<Class<?>> ref = new WeakReference<Class<?>>(cl, queue);

        cl = null;
        obj = null;
        loader = null;
        cons = null;
        systemLoader = null;

        System.err.println("\nStart Garbage Collection right now");
        System.gc();

        Reference<? extends Class<?>> dequeued = queue.remove(TIMEOUT);
        if (dequeued == ref) {
                System.err.println("\nTEST PASSED");
        } else {
                throw new Error();
        }
}
 

public static final void main(String[] args) throws Exception {
        System.err.println("\n Regression test for bug 6232010\n");
        if (System.getSecurityManager() == null) {
                System.setSecurityManager(new SecurityManager());
        }

        ClassLoader systemLoader = ClassLoader.getSystemClassLoader();
        ClassLoader loader = new URLClassLoader(((URLClassLoader) systemLoader).getURLs(),
                                                                                systemLoader.getParent());
        Class<? extends ObjectOutputStream> cl =
                Class.forName(SubclassOfOOS.class.getName(), false,
                                          loader).asSubclass(ObjectOutputStream.class);

        Constructor<? extends ObjectOutputStream> cons =
                cl.getConstructor(OutputStream.class);

        OutputStream os = new ByteArrayOutputStream();
        ObjectOutputStream obj = cons.newInstance(os);

        final ReferenceQueue<Class<?>> queue = new ReferenceQueue<Class<?>>();
        WeakReference<Class<?>> ref = new WeakReference<Class<?>>(cl, queue);

        cl = null;
        obj = null;
        loader = null;
        cons = null;
        systemLoader = null;

        System.err.println("\nStart Garbage Collection right now");
        System.gc();

        Reference<? extends Class<?>> dequeued = queue.remove(TIMEOUT);
        if (dequeued == ref) {
                System.err.println("\nTEST PASSED");
        } else {
                throw new Error();
        }
}
 

public static final void main(String[] args) throws Exception {
        System.err.println("\n Regression test for bug 6232010\n");
        if (System.getSecurityManager() == null) {
                System.setSecurityManager(new SecurityManager());
        }

        ClassLoader systemLoader = ClassLoader.getSystemClassLoader();
        ClassLoader loader = new URLClassLoader(((URLClassLoader) systemLoader).getURLs(),
                                                                                systemLoader.getParent());
        Class<? extends ObjectOutputStream> cl =
                Class.forName(SubclassOfOOS.class.getName(), false,
                                          loader).asSubclass(ObjectOutputStream.class);

        Constructor<? extends ObjectOutputStream> cons =
                cl.getConstructor(OutputStream.class);

        OutputStream os = new ByteArrayOutputStream();
        ObjectOutputStream obj = cons.newInstance(os);

        final ReferenceQueue<Class<?>> queue = new ReferenceQueue<Class<?>>();
        WeakReference<Class<?>> ref = new WeakReference<Class<?>>(cl, queue);

        cl = null;
        obj = null;
        loader = null;
        cons = null;
        systemLoader = null;

        System.err.println("\nStart Garbage Collection right now");
        System.gc();

        Reference<? extends Class<?>> dequeued = queue.remove(TIMEOUT);
        if (dequeued == ref) {
                System.err.println("\nTEST PASSED");
        } else {
                throw new Error();
        }
}
 

public static final void main(String[] args) throws Exception {
        System.err.println("\n Regression test for bug 6232010\n");
        if (System.getSecurityManager() == null) {
                System.setSecurityManager(new SecurityManager());
        }

        ClassLoader systemLoader = ClassLoader.getSystemClassLoader();
        ClassLoader loader = new URLClassLoader(((URLClassLoader) systemLoader).getURLs(),
                                                                                systemLoader.getParent());
        Class<? extends ObjectOutputStream> cl =
                Class.forName(SubclassOfOOS.class.getName(), false,
                                          loader).asSubclass(ObjectOutputStream.class);

        Constructor<? extends ObjectOutputStream> cons =
                cl.getConstructor(OutputStream.class);

        OutputStream os = new ByteArrayOutputStream();
        ObjectOutputStream obj = cons.newInstance(os);

        final ReferenceQueue<Class<?>> queue = new ReferenceQueue<Class<?>>();
        WeakReference<Class<?>> ref = new WeakReference<Class<?>>(cl, queue);

        cl = null;
        obj = null;
        loader = null;
        cons = null;
        systemLoader = null;

        System.err.println("\nStart Garbage Collection right now");
        System.gc();

        Reference<? extends Class<?>> dequeued = queue.remove(TIMEOUT);
        if (dequeued == ref) {
                System.err.println("\nTEST PASSED");
        } else {
                throw new Error();
        }
}
 

public static final void main(String[] args) throws Exception {
        System.err.println("\n Regression test for bug 6232010\n");
        if (System.getSecurityManager() == null) {
                System.setSecurityManager(new SecurityManager());
        }

        ClassLoader systemLoader = ClassLoader.getSystemClassLoader();
        ClassLoader loader = new URLClassLoader(((URLClassLoader) systemLoader).getURLs(),
                                                                                systemLoader.getParent());
        Class<? extends ObjectOutputStream> cl =
                Class.forName(SubclassOfOOS.class.getName(), false,
                                          loader).asSubclass(ObjectOutputStream.class);

        Constructor<? extends ObjectOutputStream> cons =
                cl.getConstructor(OutputStream.class);

        OutputStream os = new ByteArrayOutputStream();
        ObjectOutputStream obj = cons.newInstance(os);

        final ReferenceQueue<Class<?>> queue = new ReferenceQueue<Class<?>>();
        WeakReference<Class<?>> ref = new WeakReference<Class<?>>(cl, queue);

        cl = null;
        obj = null;
        loader = null;
        cons = null;
        systemLoader = null;

        System.err.println("\nStart Garbage Collection right now");
        System.gc();

        Reference<? extends Class<?>> dequeued = queue.remove(TIMEOUT);
        if (dequeued == ref) {
                System.err.println("\nTEST PASSED");
        } else {
                throw new Error();
        }
}
 

public static void main(String[] args) throws Exception {

        TestLibrary.suggestSecurityManager(null);

        Permissions perms = new Permissions();
        perms.add(new SocketPermission("*:1024-", "listen"));
        AccessControlContext acc =
            new AccessControlContext(new ProtectionDomain[] {
                new ProtectionDomain(
                    new CodeSource(null, (Certificate[]) null), perms) });

        Remote impl = new DGCImplInsulation();;

        try {
            Remote stub = (Remote) java.security.AccessController.doPrivileged(
                new ExportAction(impl));
            System.err.println("exported remote object; local stub: " + stub);

            MarshalledObject mobj = new MarshalledObject(stub);
            stub = (Remote) mobj.get();
            System.err.println("marshalled/unmarshalled stub: " + stub);

            ReferenceQueue refQueue = new ReferenceQueue();
            Reference weakRef = new WeakReference(impl, refQueue);
            impl = null;
            System.gc();
            if (refQueue.remove(TIMEOUT) == weakRef) {
                throw new RuntimeException(
                    "TEST FAILED: remote object garbage collected");
            } else {
                System.err.println("TEST PASSED");
                stub = null;
                System.gc();
                Thread.sleep(2000);
                System.gc();
            }
        } finally {
            try {
                UnicastRemoteObject.unexportObject(impl, true);
            } catch (Exception e) {
            }
        }
    }