core/java/android/os/CommonTimeConfig.java

/*
 * Copyright (C) 2012 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package android.os;

import java.net.InetSocketAddress;
import java.util.NoSuchElementException;

import android.os.CommonTimeUtils;
import android.os.IBinder;
import android.os.RemoteException;
import android.os.ServiceManager;

/**
 * Used for configuring and controlling the status of the android common time service.
 * @hide
 */
public class CommonTimeConfig {
    /**
     * Successful operation.
     */
    public static final int SUCCESS = 0;
    /**
     * Unspecified error.
     */
    public static final int ERROR = -1;
    /**
     * Operation failed due to bad parameter value.
     */
    public static final int ERROR_BAD_VALUE = -4;
    /**
     * Operation failed due to dead remote object.
     */
    public static final int ERROR_DEAD_OBJECT = -7;

    /**
     * Sentinel value returned by {@link #getMasterElectionGroupId()} when an error occurs trying to
     * fetch the master election group.
     */
    public static final long INVALID_GROUP_ID = -1;

    /**
     * Name of the underlying native binder service
     */
    public static final String SERVICE_NAME = "common_time.config";

    /**
     * Class constructor.
     * @throws android.os.RemoteException
     */
    public CommonTimeConfig()
    throws RemoteException {
        mRemote = ServiceManager.getService(SERVICE_NAME);
        if (null == mRemote)
            throw new RemoteException();

        mInterfaceDesc = mRemote.getInterfaceDescriptor();
        mUtils = new CommonTimeUtils(mRemote, mInterfaceDesc);
        mRemote.linkToDeath(mDeathHandler, 0);
    }

    /**
     * Handy class factory method.
     */
    static public CommonTimeConfig create() {
        CommonTimeConfig retVal;

        try {
            retVal = new CommonTimeConfig();
        }
        catch (RemoteException e) {
            retVal = null;
        }

        return retVal;
    }

    /**
     * Release all native resources held by this {@link android.os.CommonTimeConfig} instance.  Once
     * resources have been released, the {@link android.os.CommonTimeConfig} instance is
     * disconnected from the native service and will throw a {@link android.os.RemoteException} if
     * any of its methods are called.  Clients should always call release on their client instances
     * before releasing their last Java reference to the instance.  Failure to do this will cause
     * non-deterministic native resource reclamation and may cause the common time service to remain
     * active on the network for longer than it should.
     */
    public void release() {
        if (null != mRemote) {
            try {
                mRemote.unlinkToDeath(mDeathHandler, 0);
            }
            catch (NoSuchElementException e) { }
            mRemote = null;
        }
        mUtils = null;
    }

    /**
     * Gets the current priority of the common time service used in the master election protocol.
     *
     * @return an 8 bit value indicating the priority of this common time service relative to other
     * common time services operating in the same domain.
     * @throws android.os.RemoteException
     */
    public byte getMasterElectionPriority()
    throws RemoteException {
        throwOnDeadServer();
        return (byte)mUtils.transactGetInt(METHOD_GET_MASTER_ELECTION_PRIORITY, -1);
    }

    /**
     * Sets the current priority of the common time service used in the master election protocol.
     *
     * @param priority priority of the common time service used in the master election protocol.
     * Lower numbers are lower priority.
     * @return {@link #SUCCESS} in case of success,
     * {@link #ERROR} or {@link #ERROR_DEAD_OBJECT} in case of failure.
     */
    public int setMasterElectionPriority(byte priority) {
        if (checkDeadServer())
            return ERROR_DEAD_OBJECT;
        return mUtils.transactSetInt(METHOD_SET_MASTER_ELECTION_PRIORITY, priority);
    }

    /**
     * Gets the IP endpoint used by the time service to participate in the master election protocol.
     *
     * @return an InetSocketAddress containing the IP address and UDP port being used by the
     * system's common time service to participate in the master election protocol.
     * @throws android.os.RemoteException
     */
    public InetSocketAddress getMasterElectionEndpoint()
    throws RemoteException {
        throwOnDeadServer();
        return mUtils.transactGetSockaddr(METHOD_GET_MASTER_ELECTION_ENDPOINT);
    }

    /**
     * Sets the IP endpoint used by the common time service to participate in the master election
     * protocol.
     *
     * @param ep The IP address and UDP port to be used by the common time service to participate in
     * the master election protocol.  The supplied IP address must be either the broadcast or
     * multicast address, unicast addresses are considered to be illegal values.
     * @return {@link #SUCCESS} in case of success,
     * {@link #ERROR}, {@link #ERROR_BAD_VALUE} or {@link #ERROR_DEAD_OBJECT} in case of failure.
     */
    public int setMasterElectionEndpoint(InetSocketAddress ep) {
        if (checkDeadServer())
            return ERROR_DEAD_OBJECT;
        return mUtils.transactSetSockaddr(METHOD_SET_MASTER_ELECTION_ENDPOINT, ep);
    }

    /**
     * Gets the current group ID used by the common time service in the master election protocol.
     *
     * @return The 64-bit group ID of the common time service.
     * @throws android.os.RemoteException
     */
    public long getMasterElectionGroupId()
    throws RemoteException {
        throwOnDeadServer();
        return mUtils.transactGetLong(METHOD_GET_MASTER_ELECTION_GROUP_ID, INVALID_GROUP_ID);
    }

    /**
     * Sets the current group ID used by the common time service in the master election protocol.
     *
     * @param id The 64-bit group ID of the common time service.
     * @return {@link #SUCCESS} in case of success,
     * {@link #ERROR}, {@link #ERROR_BAD_VALUE} or {@link #ERROR_DEAD_OBJECT} in case of failure.
     */
    public int setMasterElectionGroupId(long id) {
        if (checkDeadServer())
            return ERROR_DEAD_OBJECT;
        return mUtils.transactSetLong(METHOD_SET_MASTER_ELECTION_GROUP_ID, id);
    }

    /**
     * Gets the name of the network interface which the common time service attempts to bind to.
     *
     * @return a string with the network interface name which the common time service is bound to,
     * or null if the service is currently unbound.  Examples of interface names are things like
     * "eth0", or "wlan0".
     * @throws android.os.RemoteException
     */
    public String getInterfaceBinding()
    throws RemoteException {
        throwOnDeadServer();

        String ifaceName = mUtils.transactGetString(METHOD_GET_INTERFACE_BINDING, null);

        if ((null != ifaceName) && (0 == ifaceName.length()))
                return null;

        return ifaceName;
    }

    /**
     * Sets the name of the network interface which the common time service should attempt to bind
     * to.
     *
     * @param ifaceName The name of the network interface ("eth0", "wlan0", etc...) wich the common
     * time service should attempt to bind to, or null to force the common time service to unbind
     * from the network and run in networkless mode.
     * @return {@link #SUCCESS} in case of success,
     * {@link #ERROR}, {@link #ERROR_BAD_VALUE} or {@link #ERROR_DEAD_OBJECT} in case of failure.
     */
    public int setNetworkBinding(String ifaceName) {
        if (checkDeadServer())
            return ERROR_DEAD_OBJECT;

        return mUtils.transactSetString(METHOD_SET_INTERFACE_BINDING,
                                       (null == ifaceName) ? "" : ifaceName);
    }

    /**
     * Gets the amount of time the common time service will wait between master announcements when
     * it is the timeline master.
     *
     * @return The time (in milliseconds) between master announcements.
     * @throws android.os.RemoteException
     */
    public int getMasterAnnounceInterval()
    throws RemoteException {
        throwOnDeadServer();
        return mUtils.transactGetInt(METHOD_GET_MASTER_ANNOUNCE_INTERVAL, -1);
    }

    /**
     * Sets the amount of time the common time service will wait between master announcements when
     * it is the timeline master.
     *
     * @param interval The time (in milliseconds) between master announcements.
     * @return {@link #SUCCESS} in case of success,
     * {@link #ERROR}, {@link #ERROR_BAD_VALUE} or {@link #ERROR_DEAD_OBJECT} in case of failure.
     */
    public int setMasterAnnounceInterval(int interval) {
        if (checkDeadServer())
            return ERROR_DEAD_OBJECT;
        return mUtils.transactSetInt(METHOD_SET_MASTER_ANNOUNCE_INTERVAL, interval);
    }

    /**
     * Gets the amount of time the common time service will wait between time synchronization
     * requests when it is the client of another common time service on the network.
     *
     * @return The time (in milliseconds) between time sync requests.
     * @throws android.os.RemoteException
     */
    public int getClientSyncInterval()
    throws RemoteException {
        throwOnDeadServer();
        return mUtils.transactGetInt(METHOD_GET_CLIENT_SYNC_INTERVAL, -1);
    }

    /**
     * Sets the amount of time the common time service will wait between time synchronization
     * requests when it is the client of another common time service on the network.
     *
     * @param interval The time (in milliseconds) between time sync requests.
     * @return {@link #SUCCESS} in case of success,
     * {@link #ERROR}, {@link #ERROR_BAD_VALUE} or {@link #ERROR_DEAD_OBJECT} in case of failure.
     */
    public int setClientSyncInterval(int interval) {
        if (checkDeadServer())
            return ERROR_DEAD_OBJECT;
        return mUtils.transactSetInt(METHOD_SET_CLIENT_SYNC_INTERVAL, interval);
    }

    /**
     * Gets the panic threshold for the estimated error level of the common time service.  When the
     * common time service's estimated error rises above this level, the service will panic and
     * reset, causing a discontinuity in the currently synchronized timeline.
     *
     * @return The threshold (in microseconds) past which the common time service will panic.
     * @throws android.os.RemoteException
     */
    public int getPanicThreshold()
    throws RemoteException {
        throwOnDeadServer();
        return mUtils.transactGetInt(METHOD_GET_PANIC_THRESHOLD, -1);
    }

    /**
     * Sets the panic threshold for the estimated error level of the common time service.  When the
     * common time service's estimated error rises above this level, the service will panic and
     * reset, causing a discontinuity in the currently synchronized timeline.
     *
     * @param threshold The threshold (in microseconds) past which the common time service will
     * panic.
     * @return {@link #SUCCESS} in case of success,
     * {@link #ERROR}, {@link #ERROR_BAD_VALUE} or {@link #ERROR_DEAD_OBJECT} in case of failure.
     */
    public int setPanicThreshold(int threshold) {
        if (checkDeadServer())
            return ERROR_DEAD_OBJECT;
        return mUtils.transactSetInt(METHOD_SET_PANIC_THRESHOLD, threshold);
    }

    /**
     * Gets the current state of the common time service's auto disable flag.
     *
     * @return The current state of the common time service's auto disable flag.
     * @throws android.os.RemoteException
     */
    public boolean getAutoDisable()
    throws RemoteException {
        throwOnDeadServer();
        return (1 == mUtils.transactGetInt(METHOD_GET_AUTO_DISABLE, 1));
    }

    /**
     * Sets the current state of the common time service's auto disable flag.  When the time
     * service's auto disable flag is set, it will automatically cease all network activity when
     * it has no active local clients, resuming activity the next time the service has interested
     * local clients.  When the auto disabled flag is cleared, the common time service will continue
     * to participate the time synchronization group even when it has no active local clients.
     *
     * @param autoDisable The desired state of the common time service's auto disable flag.
     * @return {@link #SUCCESS} in case of success,
     * {@link #ERROR} or {@link #ERROR_DEAD_OBJECT} in case of failure.
     */
    public int setAutoDisable(boolean autoDisable) {
        if (checkDeadServer())
            return ERROR_DEAD_OBJECT;

        return mUtils.transactSetInt(METHOD_SET_AUTO_DISABLE, autoDisable ? 1 : 0);
    }

    /**
     * At startup, the time service enters the initial state and remains there until it is given a
     * network interface to bind to.  Common time will be unavailable to clients of the common time
     * service until the service joins a network (even an empty network).  Devices may use the
     * {@link #forceNetworklessMasterMode()} method to force a time service in the INITIAL state
     * with no network configuration to assume MASTER status for a brand new timeline in order to
     * allow clients of the common time service to operate, even though the device is isolated and
     * not on any network.  When a networkless master does join a network, it will defer to any
     * masters already on the network, or continue to maintain the timeline it made up during its
     * networkless state if no other masters are detected.  Attempting to force a client into master
     * mode while it is actively bound to a network will fail with the status code {@link #ERROR}
     *
     * @return {@link #SUCCESS} in case of success,
     * {@link #ERROR} or {@link #ERROR_DEAD_OBJECT} in case of failure.
     */
    public int forceNetworklessMasterMode() {
        android.os.Parcel data  = android.os.Parcel.obtain();
        android.os.Parcel reply = android.os.Parcel.obtain();

        try {
            data.writeInterfaceToken(mInterfaceDesc);
            mRemote.transact(METHOD_FORCE_NETWORKLESS_MASTER_MODE, data, reply, 0);

            return reply.readInt();
        }
        catch (RemoteException e) {
            return ERROR_DEAD_OBJECT;
        }
        finally {
            reply.recycle();
            data.recycle();
        }
    }

    /**
     * The OnServerDiedListener interface defines a method called by the
     * {@link android.os.CommonTimeConfig} instance to indicate that the connection to the native
     * media server has been broken and that the {@link android.os.CommonTimeConfig} instance will
     * need to be released and re-created.  The client application can implement this interface and
     * register the listener with the {@link #setServerDiedListener(OnServerDiedListener)} method.
     */
    public interface OnServerDiedListener  {
        /**
         * Method called when the native common time service has died.  <p>If the native common time
         * service encounters a fatal error and needs to restart, the binder connection from the
         * {@link android.os.CommonTimeConfig} instance to the common time service will be broken.
         */
        void onServerDied();
    }

    /**
     * Registers an OnServerDiedListener interface.
     * <p>Call this method with a null listener to stop receiving server death notifications.
     */
    public void setServerDiedListener(OnServerDiedListener listener) {
        synchronized (mListenerLock) {
            mServerDiedListener = listener;
        }
    }

    protected void finalize() throws Throwable { release(); }

    private boolean checkDeadServer() {
        return ((null == mRemote) || (null == mUtils));
    }

    private void throwOnDeadServer() throws RemoteException {
        if (checkDeadServer())
            throw new RemoteException();
    }

    private final Object mListenerLock = new Object();
    private OnServerDiedListener mServerDiedListener = null;

    private IBinder mRemote = null;
    private String mInterfaceDesc = "";
    private CommonTimeUtils mUtils;

    private IBinder.DeathRecipient mDeathHandler = new IBinder.DeathRecipient() {
        public void binderDied() {
            synchronized (mListenerLock) {
                if (null != mServerDiedListener)
                    mServerDiedListener.onServerDied();
            }
        }
    };

    private static final int METHOD_GET_MASTER_ELECTION_PRIORITY = IBinder.FIRST_CALL_TRANSACTION;
    private static final int METHOD_SET_MASTER_ELECTION_PRIORITY = METHOD_GET_MASTER_ELECTION_PRIORITY + 1;
    private static final int METHOD_GET_MASTER_ELECTION_ENDPOINT = METHOD_SET_MASTER_ELECTION_PRIORITY + 1;
    private static final int METHOD_SET_MASTER_ELECTION_ENDPOINT = METHOD_GET_MASTER_ELECTION_ENDPOINT + 1;
    private static final int METHOD_GET_MASTER_ELECTION_GROUP_ID = METHOD_SET_MASTER_ELECTION_ENDPOINT + 1;
    private static final int METHOD_SET_MASTER_ELECTION_GROUP_ID = METHOD_GET_MASTER_ELECTION_GROUP_ID + 1;
    private static final int METHOD_GET_INTERFACE_BINDING = METHOD_SET_MASTER_ELECTION_GROUP_ID + 1;
    private static final int METHOD_SET_INTERFACE_BINDING = METHOD_GET_INTERFACE_BINDING + 1;
    private static final int METHOD_GET_MASTER_ANNOUNCE_INTERVAL = METHOD_SET_INTERFACE_BINDING + 1;
    private static final int METHOD_SET_MASTER_ANNOUNCE_INTERVAL = METHOD_GET_MASTER_ANNOUNCE_INTERVAL + 1;
    private static final int METHOD_GET_CLIENT_SYNC_INTERVAL = METHOD_SET_MASTER_ANNOUNCE_INTERVAL + 1;
    private static final int METHOD_SET_CLIENT_SYNC_INTERVAL = METHOD_GET_CLIENT_SYNC_INTERVAL + 1;
    private static final int METHOD_GET_PANIC_THRESHOLD = METHOD_SET_CLIENT_SYNC_INTERVAL + 1;
    private static final int METHOD_SET_PANIC_THRESHOLD = METHOD_GET_PANIC_THRESHOLD + 1;
    private static final int METHOD_GET_AUTO_DISABLE = METHOD_SET_PANIC_THRESHOLD + 1;
    private static final int METHOD_SET_AUTO_DISABLE = METHOD_GET_AUTO_DISABLE + 1;
    private static final int METHOD_FORCE_NETWORKLESS_MASTER_MODE = METHOD_SET_AUTO_DISABLE + 1;
}