/*

 * 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

 * particular file as subject to the "Classpath" exception as provided

 *

 * 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.

 *

 */

package sun.rmi.server;

import java.io.IOException;

import java.lang.reflect.Constructor;

import java.lang.reflect.InvocationTargetException;

import java.net.ServerSocket;

import java.rmi.MarshalledObject;

import java.rmi.NoSuchObjectException;

import java.rmi.Remote;

import java.rmi.RemoteException;

import java.rmi.activation.Activatable;

import java.rmi.activation.ActivationDesc;

import java.rmi.activation.ActivationException;

import java.rmi.activation.ActivationGroup;

import java.rmi.activation.ActivationGroupID;

import java.rmi.activation.ActivationID;

import java.rmi.activation.UnknownObjectException;

import java.rmi.server.RMIClassLoader;

import java.rmi.server.RMIServerSocketFactory;

import java.rmi.server.RMISocketFactory;

import java.rmi.server.UnicastRemoteObject;

import java.security.AccessController;

import java.security.PrivilegedActionException;

import java.security.PrivilegedExceptionAction;

import java.util.ArrayList;

import java.util.Hashtable;

import java.util.List;

import sun.rmi.registry.RegistryImpl;

/**

 * The default activation group implementation.

 *

 * @author      Ann Wollrath

 * @since       1.2

 * @see         java.rmi.activation.ActivationGroup

 */

public class ActivationGroupImpl extends ActivationGroup {

    // use serialVersionUID from JDK 1.2.2 for interoperability

    private static final long serialVersionUID = 5758693559430427303L;

    /** maps persistent IDs to activated remote objects */

    private final Hashtable<ActivationID,ActiveEntry> active =

        new Hashtable<ActivationID,ActiveEntry>();

    private boolean groupInactive = false;

    private final ActivationGroupID groupID;

    private final List<ActivationID> lockedIDs = new ArrayList<ActivationID>();

    /**

     * Creates a default activation group implementation.

     *

     * @param id the group's identifier

     * @param data ignored

     */

    public ActivationGroupImpl(ActivationGroupID id, MarshalledObject<?> data)

        throws RemoteException

    {

        super(id);

        groupID = id;

        /*

         * Unexport activation group impl and attempt to export it on

         * an unshared anonymous port.  See 4692286.

         */

        unexportObject(this, true);

        RMIServerSocketFactory ssf = new ServerSocketFactoryImpl();

        UnicastRemoteObject.exportObject(this, 0, null, ssf);

        if (System.getSecurityManager() == null) {

            try {

                // Provide a default security manager.

                System.setSecurityManager(new SecurityManager());

            } catch (Exception e) {

                throw new RemoteException("unable to set security manager", e);

            }

        }

    }

    /**

     * Trivial server socket factory used to export the activation group

     * impl on an unshared port.

     */

    private static class ServerSocketFactoryImpl

        implements RMIServerSocketFactory

    {

        public ServerSocket createServerSocket(int port) throws IOException

        {

            RMISocketFactory sf = RMISocketFactory.getSocketFactory();

            if (sf == null) {

                sf = RMISocketFactory.getDefaultSocketFactory();

            }

            return sf.createServerSocket(port);

        }

    }

    /*

     * Obtains a lock on the ActivationID id before returning. Allows only one

     * thread at a time to hold a lock on a particular id.  If the lock for id

     * is in use, all requests for an equivalent (in the Object.equals sense)

     * id will wait for the id to be notified and use the supplied id as the

     * next lock. The caller of "acquireLock" must execute the "releaseLock"

     * method" to release the lock and "notifyAll" waiters for the id lock

     * obtained from this method.  The typical usage pattern is as follows:

     *

     * try {

     *    acquireLock(id);

     *    // do stuff pertaining to id...

     * } finally {

     *    releaseLock(id);

     *    checkInactiveGroup();

     * }

     */

    private void acquireLock(ActivationID id) {

        ActivationID waitForID;

        for (;;) {

            synchronized (lockedIDs) {

                int index = lockedIDs.indexOf(id);

                if (index < 0) {

                    lockedIDs.add(id);

                    return;

                } else {

                    waitForID = lockedIDs.get(index);

                }

            }

            synchronized (waitForID) {

                synchronized (lockedIDs) {

                    int index = lockedIDs.indexOf(waitForID);

                    if (index < 0) continue;

                    ActivationID actualID = lockedIDs.get(index);

                    if (actualID != waitForID)

                        /*

                         * don't wait on an id that won't be notified.

                         */

                        continue;

                }

                try {

                    waitForID.wait();

                } catch (InterruptedException ignore) {

                }

            }

        }

    }

    /*

     * Releases the id lock obtained via the "acquireLock" method and then

     * notifies all threads waiting on the lock.

     */

    private void releaseLock(ActivationID id) {

        synchronized (lockedIDs) {

            id = lockedIDs.remove(lockedIDs.indexOf(id));

        }

        synchronized (id) {

            id.notifyAll();

        }

    }

    /**

     * Creates a new instance of an activatable remote object. The

     * <code>Activator</code> calls this method to create an activatable

     * object in this group. This method should be idempotent; a call to

     * activate an already active object should return the previously

     * activated object.

     *

     * Note: this method assumes that the Activator will only invoke

     * newInstance for the same object in a serial fashion (i.e.,

     * the activator will not allow the group to see concurrent requests

     * to activate the same object.

     *

     * @param id the object's activation identifier

     * @param desc the object's activation descriptor

     * @return a marshalled object containing the activated object's stub

     */

    public MarshalledObject<? extends Remote>

                                      newInstance(final ActivationID id,

                                                  final ActivationDesc desc)

        throws ActivationException, RemoteException

    {

        RegistryImpl.checkAccess("ActivationInstantiator.newInstance");

        if (!groupID.equals(desc.getGroupID()))

            throw new ActivationException("newInstance in wrong group");

        try {

            acquireLock(id);

            synchronized (this) {

                if (groupInactive == true)

                    throw new InactiveGroupException("group is inactive");

            }

            ActiveEntry entry = active.get(id);

            if (entry != null)

                return entry.mobj;

            String className = desc.getClassName();

            final Class<? extends Remote> cl =

                RMIClassLoader.loadClass(desc.getLocation(), className)

                .asSubclass(Remote.class);

            Remote impl = null;

            final Thread t = Thread.currentThread();

            final ClassLoader savedCcl = t.getContextClassLoader();

            ClassLoader objcl = cl.getClassLoader();

            final ClassLoader ccl = covers(objcl, savedCcl) ? objcl : savedCcl;

            /*

             * Fix for 4164971: allow non-public activatable class

             * and/or constructor, create the activatable object in a

             * privileged block

             */

            try {

                /*

                 * The code below is in a doPrivileged block to

                 * protect against user code which code might have set

                 * a global socket factory (in which case application

                 * code would be on the stack).

                 */

                impl = AccessController.doPrivileged(

                      new PrivilegedExceptionAction<Remote>() {

                      public Remote run() throws InstantiationException,

                          NoSuchMethodException, IllegalAccessException,

                          InvocationTargetException

                      {

                          Constructor<? extends Remote> constructor =

                              cl.getDeclaredConstructor(

                                  ActivationID.class, MarshalledObject.class);

                          constructor.setAccessible(true);

                          try {

                              /*

                               * Fix for 4289544: make sure to set the

                               * context class loader to be the class

                               * loader of the impl class before

                               * constructing that class.

                               */

                              t.setContextClassLoader(ccl);

                              return constructor.newInstance(id,

                                                             desc.getData());

                          } finally {

                              t.setContextClassLoader(savedCcl);

                          }

                      }

                  });

            } catch (PrivilegedActionException pae) {

                Throwable e = pae.getException();

                // narrow the exception's type and rethrow it

                if (e instanceof InstantiationException) {

                    throw (InstantiationException) e;

                } else if (e instanceof NoSuchMethodException) {

                    throw (NoSuchMethodException) e;

                } else if (e instanceof IllegalAccessException) {

                    throw (IllegalAccessException) e;

                } else if (e instanceof InvocationTargetException) {

                    throw (InvocationTargetException) e;

                } else if (e instanceof RuntimeException) {

                    throw (RuntimeException) e;

                } else if (e instanceof Error) {

                    throw (Error) e;

                }

            }

            entry = new ActiveEntry(impl);

            active.put(id, entry);

            return entry.mobj;

        } catch (NoSuchMethodException e) {

            /* user forgot to provide activatable constructor? */

            throw new ActivationException

                ("Activatable object must provide an activation"+

                 " constructor", e);

        } catch (NoSuchMethodError e) {

            /* code recompiled and user forgot to provide

             *  activatable constructor?

             */

            throw new ActivationException

                ("Activatable object must provide an activation"+

                 " constructor", e );

        } catch (InvocationTargetException e) {

            throw new ActivationException("exception in object constructor",

                                          e.getTargetException());

        } catch (Exception e) {

            throw new ActivationException("unable to activate object", e);

        } finally {

            releaseLock(id);

            checkInactiveGroup();

        }

    }

   /**

    * The group's <code>inactiveObject</code> method is called

    * indirectly via a call to the <code>Activatable.inactive</code>

    * method. A remote object implementation must call

    * <code>Activatable</code>'s <code>inactive</code> method when

    * that object deactivates (the object deems that it is no longer

    * active). If the object does not call

    * <code>Activatable.inactive</code> when it deactivates, the

    * object will never be garbage collected since the group keeps

    * strong references to the objects it creates. <p>

    *

    * The group's <code>inactiveObject</code> method

    * unexports the remote object from the RMI runtime so that the

    * object can no longer receive incoming RMI calls. This call will

    * only succeed if the object has no pending/executing calls. If

    * the object does have pending/executing RMI calls, then false

    * will be returned.

    *

    * If the object has no pending/executing calls, the object is

    * removed from the RMI runtime and the group informs its

    * <code>ActivationMonitor</code> (via the monitor's

    * <code>inactiveObject</code> method) that the remote object is

    * not currently active so that the remote object will be

    * re-activated by the activator upon a subsequent activation

    * request.

    *

    * @param id the object's activation identifier

    * @returns true if the operation succeeds (the operation will

    * succeed if the object in currently known to be active and is

    * either already unexported or is currently exported and has no

    * pending/executing calls); false is returned if the object has

    * pending/executing calls in which case it cannot be deactivated

    * @exception UnknownObjectException if object is unknown (may already

    * be inactive)

    * @exception RemoteException if call informing monitor fails

    */

    public boolean inactiveObject(ActivationID id)

        throws ActivationException, UnknownObjectException, RemoteException

    {

        try {

            acquireLock(id);

            synchronized (this) {

                if (groupInactive == true)

                    throw new ActivationException("group is inactive");

            }

            ActiveEntry entry = active.get(id);

            if (entry == null) {

                // REMIND: should this be silent?

                throw new UnknownObjectException("object not active");

            }

            try {

                if (Activatable.unexportObject(entry.impl, false) == false)

                    return false;

            } catch (NoSuchObjectException allowUnexportedObjects) {

            }

            try {

                super.inactiveObject(id);

            } catch (UnknownObjectException allowUnregisteredObjects) {

            }

            active.remove(id);

        } finally {

            releaseLock(id);

            checkInactiveGroup();

        }

        return true;

    }

    /*

     * Determines if the group has become inactive and

     * marks it as such.

     */

    private void checkInactiveGroup() {

        boolean groupMarkedInactive = false;

        synchronized (this) {

            if (active.size() == 0 && lockedIDs.size() == 0 &&

                groupInactive == false)

            {

                groupInactive = true;

                groupMarkedInactive = true;

            }

        }

        if (groupMarkedInactive) {

            try {

                super.inactiveGroup();

            } catch (Exception ignoreDeactivateFailure) {

            }

            try {

                UnicastRemoteObject.unexportObject(this, true);

            } catch (NoSuchObjectException allowUnexportedGroup) {

            }

        }

    }

    /**

     * The group's <code>activeObject</code> method is called when an

     * object is exported (either by <code>Activatable</code> object

     * construction or an explicit call to

     * <code>Activatable.exportObject</code>. The group must inform its

     * <code>ActivationMonitor</code> that the object is active (via

     * the monitor's <code>activeObject</code> method) if the group

     * hasn't already done so.

     *

     * @param id the object's identifier

     * @param obj the remote object implementation

     * @exception UnknownObjectException if object is not registered

     * @exception RemoteException if call informing monitor fails

     */

    public void activeObject(ActivationID id, Remote impl)

        throws ActivationException, UnknownObjectException, RemoteException

    {

        try {

            acquireLock(id);

            synchronized (this) {

                if (groupInactive == true)

                    throw new ActivationException("group is inactive");

            }

            if (!active.contains(id)) {

                ActiveEntry entry = new ActiveEntry(impl);

                active.put(id, entry);

                // created new entry, so inform monitor of active object

                try {

                    super.activeObject(id, entry.mobj);

                } catch (RemoteException e) {

                    // daemon can still find it by calling newInstance

                }

            }

        } finally {

            releaseLock(id);

            checkInactiveGroup();

        }

    }

    /**

     * Entry in table for active object.

     */

    private static class ActiveEntry {

        Remote impl;

        MarshalledObject<Remote> mobj;

        ActiveEntry(Remote impl) throws ActivationException {

            this.impl =  impl;

            try {

                this.mobj = new MarshalledObject<Remote>(impl);

            } catch (IOException e) {

                throw new

                    ActivationException("failed to marshal remote object", e);

            }

        }

    }

    /**

     * Returns true if the first argument is either equal to, or is a

     * descendant of, the second argument.  Null is treated as the root of

     * the tree.

     */

    private static boolean covers(ClassLoader sub, ClassLoader sup) {

        if (sup == null) {

            return true;

        } else if (sub == null) {

            return false;

        }

        do {

            if (sub == sup) {

                return true;

            }

            sub = sub.getParent();

        } while (sub != null);

        return false;

    }

}