John Grossman | 3723783 | 2012-01-12 11:05:37 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2012 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | package android.os; |
| 17 | |
John Grossman | 3723783 | 2012-01-12 11:05:37 -0800 | [diff] [blame] | 18 | import java.net.InetSocketAddress; |
| 19 | import java.util.NoSuchElementException; |
John Grossman | 3723783 | 2012-01-12 11:05:37 -0800 | [diff] [blame] | 20 | import android.os.Binder; |
| 21 | import android.os.CommonTimeUtils; |
| 22 | import android.os.IBinder; |
| 23 | import android.os.Parcel; |
| 24 | import android.os.RemoteException; |
| 25 | import android.os.ServiceManager; |
John Grossman | 3723783 | 2012-01-12 11:05:37 -0800 | [diff] [blame] | 26 | |
| 27 | /** |
| 28 | * Used for accessing the android common time service's common clock and receiving notifications |
| 29 | * about common time synchronization status changes. |
| 30 | * @hide |
| 31 | */ |
| 32 | public class CommonClock { |
| 33 | /** |
| 34 | * Sentinel value returned by {@link #getTime()} and {@link #getEstimatedError()} when the |
| 35 | * common time service is not able to determine the current common time due to a lack of |
| 36 | * synchronization. |
| 37 | */ |
| 38 | public static final long TIME_NOT_SYNCED = -1; |
| 39 | |
| 40 | /** |
| 41 | * Sentinel value returned by {@link #getTimelineId()} when the common time service is not |
| 42 | * currently synced to any timeline. |
| 43 | */ |
| 44 | public static final long INVALID_TIMELINE_ID = 0; |
| 45 | |
| 46 | /** |
| 47 | * Sentinel value returned by {@link #getEstimatedError()} when the common time service is not |
| 48 | * currently synced to any timeline. |
| 49 | */ |
| 50 | public static final int ERROR_ESTIMATE_UNKNOWN = 0x7FFFFFFF; |
| 51 | |
| 52 | /** |
| 53 | * Value used by {@link #getState()} to indicate that there was an internal error while |
| 54 | * attempting to determine the state of the common time service. |
| 55 | */ |
| 56 | public static final int STATE_INVALID = -1; |
| 57 | |
| 58 | /** |
| 59 | * Value used by {@link #getState()} to indicate that the common time service is in its initial |
| 60 | * state and attempting to find the current timeline master, if any. The service will |
| 61 | * transition to either {@link #STATE_CLIENT} if it finds an active master, or to |
| 62 | * {@link #STATE_MASTER} if no active master is found and this client becomes the master of a |
| 63 | * new timeline. |
| 64 | */ |
| 65 | public static final int STATE_INITIAL = 0; |
| 66 | |
| 67 | /** |
| 68 | * Value used by {@link #getState()} to indicate that the common time service is in its client |
| 69 | * state and is synchronizing its time to a different timeline master on the network. |
| 70 | */ |
| 71 | public static final int STATE_CLIENT = 1; |
| 72 | |
| 73 | /** |
| 74 | * Value used by {@link #getState()} to indicate that the common time service is in its master |
| 75 | * state and is serving as the timeline master for other common time service clients on the |
| 76 | * network. |
| 77 | */ |
| 78 | public static final int STATE_MASTER = 2; |
| 79 | |
| 80 | /** |
| 81 | * Value used by {@link #getState()} to indicate that the common time service is in its Ronin |
| 82 | * state. Common time service instances in the client state enter the Ronin state after their |
| 83 | * timeline master becomes unreachable on the network. Common time services who enter the Ronin |
| 84 | * state will begin a new master election for the timeline they were recently clients of. As |
| 85 | * clients detect they are not the winner and drop out of the election, they will transition to |
| 86 | * the {@link #STATE_WAIT_FOR_ELECTION} state. When there is only one client remaining in the |
| 87 | * election, it will assume ownership of the timeline and transition to the |
| 88 | * {@link #STATE_MASTER} state. During the election, all clients will allow their timeline to |
| 89 | * drift without applying correction. |
| 90 | */ |
| 91 | public static final int STATE_RONIN = 3; |
| 92 | |
| 93 | /** |
| 94 | * Value used by {@link #getState()} to indicate that the common time service is waiting for a |
| 95 | * master election to conclude and for the new master to announce itself before transitioning to |
| 96 | * the {@link #STATE_CLIENT} state. If no new master announces itself within the timeout |
| 97 | * threshold, the time service will transition back to the {@link #STATE_RONIN} state in order |
| 98 | * to restart the election. |
| 99 | */ |
| 100 | public static final int STATE_WAIT_FOR_ELECTION = 4; |
| 101 | |
| 102 | /** |
| 103 | * Name of the underlying native binder service |
| 104 | */ |
| 105 | public static final String SERVICE_NAME = "common_time.clock"; |
| 106 | |
| 107 | /** |
| 108 | * Class constructor. |
| 109 | * @throws android.os.RemoteException |
| 110 | */ |
| 111 | public CommonClock() |
| 112 | throws RemoteException { |
| 113 | mRemote = ServiceManager.getService(SERVICE_NAME); |
| 114 | if (null == mRemote) |
| 115 | throw new RemoteException(); |
| 116 | |
| 117 | mInterfaceDesc = mRemote.getInterfaceDescriptor(); |
| 118 | mUtils = new CommonTimeUtils(mRemote, mInterfaceDesc); |
| 119 | mRemote.linkToDeath(mDeathHandler, 0); |
| 120 | registerTimelineChangeListener(); |
| 121 | } |
| 122 | |
| 123 | /** |
| 124 | * Handy class factory method. |
| 125 | */ |
| 126 | static public CommonClock create() { |
| 127 | CommonClock retVal; |
| 128 | |
| 129 | try { |
| 130 | retVal = new CommonClock(); |
| 131 | } |
| 132 | catch (RemoteException e) { |
| 133 | retVal = null; |
| 134 | } |
| 135 | |
| 136 | return retVal; |
| 137 | } |
| 138 | |
| 139 | /** |
| 140 | * Release all native resources held by this {@link android.os.CommonClock} instance. Once |
| 141 | * resources have been released, the {@link android.os.CommonClock} instance is disconnected from |
| 142 | * the native service and will throw a {@link android.os.RemoteException} if any of its |
| 143 | * methods are called. Clients should always call release on their client instances before |
| 144 | * releasing their last Java reference to the instance. Failure to do this will cause |
| 145 | * non-deterministic native resource reclamation and may cause the common time service to remain |
| 146 | * active on the network for longer than it should. |
| 147 | */ |
| 148 | public void release() { |
| 149 | unregisterTimelineChangeListener(); |
| 150 | if (null != mRemote) { |
| 151 | try { |
| 152 | mRemote.unlinkToDeath(mDeathHandler, 0); |
| 153 | } |
| 154 | catch (NoSuchElementException e) { } |
| 155 | mRemote = null; |
| 156 | } |
| 157 | mUtils = null; |
| 158 | } |
| 159 | |
| 160 | /** |
| 161 | * Gets the common clock's current time. |
| 162 | * |
| 163 | * @return a signed 64-bit value representing the current common time in microseconds, or the |
| 164 | * special value {@link #TIME_NOT_SYNCED} if the common time service is currently not |
| 165 | * synchronized. |
| 166 | * @throws android.os.RemoteException |
| 167 | */ |
| 168 | public long getTime() |
| 169 | throws RemoteException { |
| 170 | throwOnDeadServer(); |
| 171 | return mUtils.transactGetLong(METHOD_GET_COMMON_TIME, TIME_NOT_SYNCED); |
| 172 | } |
| 173 | |
| 174 | /** |
| 175 | * Gets the current estimation of common clock's synchronization accuracy from the common time |
| 176 | * service. |
| 177 | * |
| 178 | * @return a signed 32-bit value representing the common time service's estimation of |
| 179 | * synchronization accuracy in microseconds, or the special value |
| 180 | * {@link #ERROR_ESTIMATE_UNKNOWN} if the common time service is currently not synchronized. |
| 181 | * Negative values indicate that the local server estimates that the nominal common time is |
| 182 | * behind the local server's time (in other words, the local clock is running fast) Positive |
| 183 | * values indicate that the local server estimates that the nominal common time is ahead of the |
| 184 | * local server's time (in other words, the local clock is running slow) |
| 185 | * @throws android.os.RemoteException |
| 186 | */ |
| 187 | public int getEstimatedError() |
| 188 | throws RemoteException { |
| 189 | throwOnDeadServer(); |
| 190 | return mUtils.transactGetInt(METHOD_GET_ESTIMATED_ERROR, ERROR_ESTIMATE_UNKNOWN); |
| 191 | } |
| 192 | |
| 193 | /** |
| 194 | * Gets the ID of the timeline the common time service is currently synchronizing its clock to. |
| 195 | * |
| 196 | * @return a long representing the unique ID of the timeline the common time service is |
| 197 | * currently synchronizing with, or {@link #INVALID_TIMELINE_ID} if the common time service is |
| 198 | * currently not synchronized. |
| 199 | * @throws android.os.RemoteException |
| 200 | */ |
| 201 | public long getTimelineId() |
| 202 | throws RemoteException { |
| 203 | throwOnDeadServer(); |
| 204 | return mUtils.transactGetLong(METHOD_GET_TIMELINE_ID, INVALID_TIMELINE_ID); |
| 205 | } |
| 206 | |
| 207 | /** |
| 208 | * Gets the current state of this clock's common time service in the the master election |
| 209 | * algorithm. |
| 210 | * |
| 211 | * @return a integer indicating the current state of the this clock's common time service in the |
| 212 | * master election algorithm or {@link #STATE_INVALID} if there is an internal error. |
| 213 | * @throws android.os.RemoteException |
| 214 | */ |
| 215 | public int getState() |
| 216 | throws RemoteException { |
| 217 | throwOnDeadServer(); |
| 218 | return mUtils.transactGetInt(METHOD_GET_STATE, STATE_INVALID); |
| 219 | } |
| 220 | |
| 221 | /** |
| 222 | * Gets the IP address and UDP port of the current timeline master. |
| 223 | * |
| 224 | * @return an InetSocketAddress containing the IP address and UDP port of the current timeline |
| 225 | * master, or null if there is no current master. |
| 226 | * @throws android.os.RemoteException |
| 227 | */ |
| 228 | public InetSocketAddress getMasterAddr() |
| 229 | throws RemoteException { |
| 230 | throwOnDeadServer(); |
| 231 | return mUtils.transactGetSockaddr(METHOD_GET_MASTER_ADDRESS); |
| 232 | } |
| 233 | |
| 234 | /** |
| 235 | * The OnTimelineChangedListener interface defines a method called by the |
| 236 | * {@link android.os.CommonClock} instance to indicate that the time synchronization service has |
| 237 | * either synchronized with a new timeline, or is no longer a member of any timeline. The |
| 238 | * client application can implement this interface and register the listener with the |
| 239 | * {@link #setTimelineChangedListener(OnTimelineChangedListener)} method. |
| 240 | */ |
| 241 | public interface OnTimelineChangedListener { |
| 242 | /** |
| 243 | * Method called when the time service's timeline has changed. |
| 244 | * |
| 245 | * @param newTimelineId a long which uniquely identifies the timeline the time |
| 246 | * synchronization service is now a member of, or {@link #INVALID_TIMELINE_ID} if the the |
| 247 | * service is not synchronized to any timeline. |
| 248 | */ |
| 249 | void onTimelineChanged(long newTimelineId); |
| 250 | } |
| 251 | |
| 252 | /** |
| 253 | * Registers an OnTimelineChangedListener interface. |
| 254 | * <p>Call this method with a null listener to stop receiving server death notifications. |
| 255 | */ |
| 256 | public void setTimelineChangedListener(OnTimelineChangedListener listener) { |
| 257 | synchronized (mListenerLock) { |
| 258 | mTimelineChangedListener = listener; |
| 259 | } |
| 260 | } |
| 261 | |
| 262 | /** |
| 263 | * The OnServerDiedListener interface defines a method called by the |
| 264 | * {@link android.os.CommonClock} instance to indicate that the connection to the native media |
| 265 | * server has been broken and that the {@link android.os.CommonClock} instance will need to be |
| 266 | * released and re-created. The client application can implement this interface and register |
| 267 | * the listener with the {@link #setServerDiedListener(OnServerDiedListener)} method. |
| 268 | */ |
| 269 | public interface OnServerDiedListener { |
| 270 | /** |
| 271 | * Method called when the native media server has died. <p>If the native common time |
| 272 | * service encounters a fatal error and needs to restart, the binder connection from the |
| 273 | * {@link android.os.CommonClock} instance to the common time service will be broken. To |
| 274 | * restore functionality, clients should {@link #release()} their old visualizer and create |
| 275 | * a new instance. |
| 276 | */ |
| 277 | void onServerDied(); |
| 278 | } |
| 279 | |
| 280 | /** |
| 281 | * Registers an OnServerDiedListener interface. |
| 282 | * <p>Call this method with a null listener to stop receiving server death notifications. |
| 283 | */ |
| 284 | public void setServerDiedListener(OnServerDiedListener listener) { |
| 285 | synchronized (mListenerLock) { |
| 286 | mServerDiedListener = listener; |
| 287 | } |
| 288 | } |
| 289 | |
| 290 | protected void finalize() throws Throwable { release(); } |
| 291 | |
| 292 | private void throwOnDeadServer() throws RemoteException { |
| 293 | if ((null == mRemote) || (null == mUtils)) |
| 294 | throw new RemoteException(); |
| 295 | } |
| 296 | |
| 297 | private final Object mListenerLock = new Object(); |
| 298 | private OnTimelineChangedListener mTimelineChangedListener = null; |
| 299 | private OnServerDiedListener mServerDiedListener = null; |
| 300 | |
| 301 | private IBinder mRemote = null; |
| 302 | private String mInterfaceDesc = ""; |
| 303 | private CommonTimeUtils mUtils; |
| 304 | |
| 305 | private IBinder.DeathRecipient mDeathHandler = new IBinder.DeathRecipient() { |
| 306 | public void binderDied() { |
| 307 | synchronized (mListenerLock) { |
| 308 | if (null != mServerDiedListener) |
| 309 | mServerDiedListener.onServerDied(); |
| 310 | } |
| 311 | } |
| 312 | }; |
| 313 | |
| 314 | private class TimelineChangedListener extends Binder { |
| 315 | @Override |
| 316 | protected boolean onTransact(int code, Parcel data, Parcel reply, int flags) |
| 317 | throws RemoteException { |
| 318 | switch (code) { |
| 319 | case METHOD_CBK_ON_TIMELINE_CHANGED: |
| 320 | data.enforceInterface(DESCRIPTOR); |
| 321 | long timelineId = data.readLong(); |
| 322 | synchronized (mListenerLock) { |
| 323 | if (null != mTimelineChangedListener) |
| 324 | mTimelineChangedListener.onTimelineChanged(timelineId); |
| 325 | } |
| 326 | return true; |
| 327 | } |
| 328 | |
| 329 | return super.onTransact(code, data, reply, flags); |
| 330 | } |
| 331 | |
| 332 | private static final String DESCRIPTOR = "android.os.ICommonClockListener"; |
| 333 | }; |
| 334 | |
| 335 | private TimelineChangedListener mCallbackTgt = null; |
| 336 | |
| 337 | private void registerTimelineChangeListener() throws RemoteException { |
| 338 | if (null != mCallbackTgt) |
| 339 | return; |
| 340 | |
| 341 | boolean success = false; |
| 342 | android.os.Parcel data = android.os.Parcel.obtain(); |
| 343 | android.os.Parcel reply = android.os.Parcel.obtain(); |
| 344 | mCallbackTgt = new TimelineChangedListener(); |
| 345 | |
| 346 | try { |
| 347 | data.writeInterfaceToken(mInterfaceDesc); |
| 348 | data.writeStrongBinder(mCallbackTgt); |
| 349 | mRemote.transact(METHOD_REGISTER_LISTENER, data, reply, 0); |
| 350 | success = (0 == reply.readInt()); |
| 351 | } |
| 352 | catch (RemoteException e) { |
| 353 | success = false; |
| 354 | } |
| 355 | finally { |
| 356 | reply.recycle(); |
| 357 | data.recycle(); |
| 358 | } |
| 359 | |
| 360 | // Did we catch a remote exception or fail to register our callback target? If so, our |
| 361 | // object must already be dead (or be as good as dead). Clear out all of our state so that |
| 362 | // our other methods will properly indicate a dead object. |
| 363 | if (!success) { |
| 364 | mCallbackTgt = null; |
| 365 | mRemote = null; |
| 366 | mUtils = null; |
| 367 | } |
| 368 | } |
| 369 | |
| 370 | private void unregisterTimelineChangeListener() { |
| 371 | if (null == mCallbackTgt) |
| 372 | return; |
| 373 | |
| 374 | android.os.Parcel data = android.os.Parcel.obtain(); |
| 375 | android.os.Parcel reply = android.os.Parcel.obtain(); |
| 376 | |
| 377 | try { |
| 378 | data.writeInterfaceToken(mInterfaceDesc); |
| 379 | data.writeStrongBinder(mCallbackTgt); |
| 380 | mRemote.transact(METHOD_UNREGISTER_LISTENER, data, reply, 0); |
| 381 | } |
| 382 | catch (RemoteException e) { } |
| 383 | finally { |
| 384 | reply.recycle(); |
| 385 | data.recycle(); |
| 386 | mCallbackTgt = null; |
| 387 | } |
| 388 | } |
| 389 | |
| 390 | private static final int METHOD_IS_COMMON_TIME_VALID = IBinder.FIRST_CALL_TRANSACTION; |
| 391 | private static final int METHOD_COMMON_TIME_TO_LOCAL_TIME = METHOD_IS_COMMON_TIME_VALID + 1; |
| 392 | private static final int METHOD_LOCAL_TIME_TO_COMMON_TIME = METHOD_COMMON_TIME_TO_LOCAL_TIME + 1; |
| 393 | private static final int METHOD_GET_COMMON_TIME = METHOD_LOCAL_TIME_TO_COMMON_TIME + 1; |
| 394 | private static final int METHOD_GET_COMMON_FREQ = METHOD_GET_COMMON_TIME + 1; |
| 395 | private static final int METHOD_GET_LOCAL_TIME = METHOD_GET_COMMON_FREQ + 1; |
| 396 | private static final int METHOD_GET_LOCAL_FREQ = METHOD_GET_LOCAL_TIME + 1; |
| 397 | private static final int METHOD_GET_ESTIMATED_ERROR = METHOD_GET_LOCAL_FREQ + 1; |
| 398 | private static final int METHOD_GET_TIMELINE_ID = METHOD_GET_ESTIMATED_ERROR + 1; |
| 399 | private static final int METHOD_GET_STATE = METHOD_GET_TIMELINE_ID + 1; |
| 400 | private static final int METHOD_GET_MASTER_ADDRESS = METHOD_GET_STATE + 1; |
| 401 | private static final int METHOD_REGISTER_LISTENER = METHOD_GET_MASTER_ADDRESS + 1; |
| 402 | private static final int METHOD_UNREGISTER_LISTENER = METHOD_REGISTER_LISTENER + 1; |
| 403 | |
| 404 | private static final int METHOD_CBK_ON_TIMELINE_CHANGED = IBinder.FIRST_CALL_TRANSACTION; |
| 405 | } |