1/* 2 * Copyright (C) 2017 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 */ 16package com.android.server.am; 17 18import android.annotation.NonNull; 19import android.content.ComponentName; 20import android.content.Context; 21import android.content.Intent; 22import android.content.ServiceConnection; 23import android.os.Handler; 24import android.os.IBinder; 25import android.os.SystemClock; 26import android.os.UserHandle; 27import android.util.Slog; 28import android.util.TimeUtils; 29 30import com.android.internal.annotations.GuardedBy; 31import com.android.internal.annotations.VisibleForTesting; 32 33import java.io.PrintWriter; 34 35/** 36 * Connects to a given service component on a given user. 37 * 38 * - Call {@link #bind()} to create a connection. 39 * - Call {@link #unbind()} to disconnect. Make sure to disconnect when the user stops. 40 * 41 * Add onConnected/onDisconnected callbacks as needed. 42 * 43 * When the target process gets killed (by OOM-killer, etc), then the activity manager will 44 * re-connect the connection automatically, in which case onServiceDisconnected() gets called 45 * and then onServiceConnected(). 46 * 47 * However sometimes the activity manager just "kills" the connection -- like when the target 48 * package gets updated or the target process crashes multiple times in a row, in which case 49 * onBindingDied() gets called. This class handles this case by re-connecting in the time 50 * {@link #mRebindBackoffMs}. If this happens again, this class increases the back-off time 51 * by {@link #mRebindBackoffIncrease} and retry. The back-off time is capped at 52 * {@link #mRebindMaxBackoffMs}. 53 * 54 * The back-off time will never be reset until {@link #unbind()} and {@link #bind()} are called 55 * explicitly. 56 * 57 * NOTE: This class does *not* handle package-updates -- i.e. even if the binding dies due to 58 * the target package being updated, this class won't reconnect. This is because this class doesn't 59 * know what to do when the service component has gone missing, for example. If the user of this 60 * class wants to restore the connection, then it should call {@link #unbind()} and {@link #bind} 61 * explicitly. 62 */ 63public abstract class PersistentConnection<T> { 64 private final Object mLock = new Object(); 65 66 private final static boolean DEBUG = false; 67 68 private final String mTag; 69 private final Context mContext; 70 private final Handler mHandler; 71 private final int mUserId; 72 private final ComponentName mComponentName; 73 74 private long mNextBackoffMs; 75 76 private final long mRebindBackoffMs; 77 private final double mRebindBackoffIncrease; 78 private final long mRebindMaxBackoffMs; 79 80 private long mReconnectTime; 81 82 // TODO too many booleans... Should clean up. 83 84 @GuardedBy("mLock") 85 private boolean mBound; 86 87 /** 88 * Whether {@link #bind()} has been called and {@link #unbind()} hasn't been yet; meaning this 89 * is the expected bind state from the caller's point of view. 90 */ 91 @GuardedBy("mLock") 92 private boolean mShouldBeBound; 93 94 @GuardedBy("mLock") 95 private boolean mRebindScheduled; 96 97 @GuardedBy("mLock") 98 private boolean mIsConnected; 99 100 @GuardedBy("mLock") 101 private T mService; 102 103 private final ServiceConnection mServiceConnection = new ServiceConnection() { 104 @Override 105 public void onServiceConnected(ComponentName name, IBinder service) { 106 synchronized (mLock) { 107 if (!mBound) { 108 // Callback came in after PersistentConnection.unbind() was called. 109 // We just ignore this. 110 // (We've already called unbindService() already in unbind) 111 Slog.w(mTag, "Connected: " + mComponentName.flattenToShortString() 112 + " u" + mUserId + " but not bound, ignore."); 113 return; 114 } 115 Slog.i(mTag, "Connected: " + mComponentName.flattenToShortString() 116 + " u" + mUserId); 117 118 mIsConnected = true; 119 mService = asInterface(service); 120 } 121 } 122 123 @Override 124 public void onServiceDisconnected(ComponentName name) { 125 synchronized (mLock) { 126 Slog.i(mTag, "Disconnected: " + mComponentName.flattenToShortString() 127 + " u" + mUserId); 128 129 cleanUpConnectionLocked(); 130 } 131 } 132 133 @Override 134 public void onBindingDied(ComponentName name) { 135 // Activity manager gave up; we'll schedule a re-connect by ourselves. 136 synchronized (mLock) { 137 if (!mBound) { 138 // Callback came in late? 139 Slog.w(mTag, "Binding died: " + mComponentName.flattenToShortString() 140 + " u" + mUserId + " but not bound, ignore."); 141 return; 142 } 143 144 Slog.w(mTag, "Binding died: " + mComponentName.flattenToShortString() 145 + " u" + mUserId); 146 scheduleRebindLocked(); 147 } 148 } 149 }; 150 151 private final Runnable mBindForBackoffRunnable = () -> bindForBackoff(); 152 153 public PersistentConnection(@NonNull String tag, @NonNull Context context, 154 @NonNull Handler handler, int userId, @NonNull ComponentName componentName, 155 long rebindBackoffSeconds, double rebindBackoffIncrease, long rebindMaxBackoffSeconds) { 156 mTag = tag; 157 mContext = context; 158 mHandler = handler; 159 mUserId = userId; 160 mComponentName = componentName; 161 162 mRebindBackoffMs = rebindBackoffSeconds * 1000; 163 mRebindBackoffIncrease = rebindBackoffIncrease; 164 mRebindMaxBackoffMs = rebindMaxBackoffSeconds * 1000; 165 166 mNextBackoffMs = mRebindBackoffMs; 167 } 168 169 public final ComponentName getComponentName() { 170 return mComponentName; 171 } 172 173 /** 174 * @return whether {@link #bind()} has been called and {@link #unbind()} hasn't. 175 * 176 * Note when the AM gives up on connection, this class detects it and un-bind automatically, 177 * and schedule rebind, and {@link #isBound} returns false when it's waiting for a retry. 178 */ 179 public final boolean isBound() { 180 synchronized (mLock) { 181 return mBound; 182 } 183 } 184 185 /** 186 * @return whether re-bind is scheduled after the AM gives up on a connection. 187 */ 188 public final boolean isRebindScheduled() { 189 synchronized (mLock) { 190 return mRebindScheduled; 191 } 192 } 193 194 /** 195 * @return whether connected. 196 */ 197 public final boolean isConnected() { 198 synchronized (mLock) { 199 return mIsConnected; 200 } 201 } 202 203 /** 204 * @return the service binder interface. 205 */ 206 public final T getServiceBinder() { 207 synchronized (mLock) { 208 return mService; 209 } 210 } 211 212 /** 213 * Connects to the service. 214 */ 215 public final void bind() { 216 synchronized (mLock) { 217 mShouldBeBound = true; 218 219 bindInnerLocked(/* resetBackoff= */ true); 220 } 221 } 222 223 @GuardedBy("mLock") 224 public final void bindInnerLocked(boolean resetBackoff) { 225 unscheduleRebindLocked(); 226 227 if (mBound) { 228 return; 229 } 230 mBound = true; 231 232 if (resetBackoff) { 233 // Note this is the only place we reset the backoff time. 234 mNextBackoffMs = mRebindBackoffMs; 235 } 236 237 final Intent service = new Intent().setComponent(mComponentName); 238 239 if (DEBUG) { 240 Slog.d(mTag, "Attempting to connect to " + mComponentName); 241 } 242 243 final boolean success = mContext.bindServiceAsUser(service, mServiceConnection, 244 Context.BIND_AUTO_CREATE | Context.BIND_FOREGROUND_SERVICE, 245 mHandler, UserHandle.of(mUserId)); 246 247 if (!success) { 248 Slog.e(mTag, "Binding: " + service.getComponent() + " u" + mUserId 249 + " failed."); 250 } 251 } 252 253 final void bindForBackoff() { 254 synchronized (mLock) { 255 if (!mShouldBeBound) { 256 // Race condition -- by the time we got here, unbind() has already been called. 257 return; 258 } 259 260 bindInnerLocked(/* resetBackoff= */ false); 261 } 262 } 263 264 @GuardedBy("mLock") 265 private void cleanUpConnectionLocked() { 266 mIsConnected = false; 267 mService = null; 268 } 269 270 /** 271 * Disconnect from the service. 272 */ 273 public final void unbind() { 274 synchronized (mLock) { 275 mShouldBeBound = false; 276 277 unbindLocked(); 278 } 279 } 280 281 @GuardedBy("mLock") 282 private final void unbindLocked() { 283 unscheduleRebindLocked(); 284 285 if (!mBound) { 286 return; 287 } 288 Slog.i(mTag, "Stopping: " + mComponentName.flattenToShortString() + " u" + mUserId); 289 mBound = false; 290 mContext.unbindService(mServiceConnection); 291 292 cleanUpConnectionLocked(); 293 } 294 295 @GuardedBy("mLock") 296 void unscheduleRebindLocked() { 297 injectRemoveCallbacks(mBindForBackoffRunnable); 298 mRebindScheduled = false; 299 } 300 301 @GuardedBy("mLock") 302 void scheduleRebindLocked() { 303 unbindLocked(); 304 305 if (!mRebindScheduled) { 306 Slog.i(mTag, "Scheduling to reconnect in " + mNextBackoffMs + " ms (uptime)"); 307 308 mReconnectTime = injectUptimeMillis() + mNextBackoffMs; 309 310 injectPostAtTime(mBindForBackoffRunnable, mReconnectTime); 311 312 mNextBackoffMs = Math.min(mRebindMaxBackoffMs, 313 (long) (mNextBackoffMs * mRebindBackoffIncrease)); 314 315 mRebindScheduled = true; 316 } 317 } 318 319 /** Must be implemented by a subclass to convert an {@link IBinder} to a stub. */ 320 protected abstract T asInterface(IBinder binder); 321 322 public void dump(String prefix, PrintWriter pw) { 323 synchronized (mLock) { 324 pw.print(prefix); 325 pw.print(mComponentName.flattenToShortString()); 326 pw.print(mBound ? " [bound]" : " [not bound]"); 327 pw.print(mIsConnected ? " [connected]" : " [not connected]"); 328 if (mRebindScheduled) { 329 pw.print(" reconnect in "); 330 TimeUtils.formatDuration((mReconnectTime - injectUptimeMillis()), pw); 331 } 332 pw.println(); 333 334 pw.print(prefix); 335 pw.print(" Next backoff(sec): "); 336 pw.print(mNextBackoffMs / 1000); 337 } 338 } 339 340 @VisibleForTesting 341 void injectRemoveCallbacks(Runnable r) { 342 mHandler.removeCallbacks(r); 343 } 344 345 @VisibleForTesting 346 void injectPostAtTime(Runnable r, long uptimeMillis) { 347 mHandler.postAtTime(r, uptimeMillis); 348 } 349 350 @VisibleForTesting 351 long injectUptimeMillis() { 352 return SystemClock.uptimeMillis(); 353 } 354 355 @VisibleForTesting 356 long getNextBackoffMsForTest() { 357 return mNextBackoffMs; 358 } 359 360 @VisibleForTesting 361 long getReconnectTimeForTest() { 362 return mReconnectTime; 363 } 364 365 @VisibleForTesting 366 ServiceConnection getServiceConnectionForTest() { 367 return mServiceConnection; 368 } 369 370 @VisibleForTesting 371 Runnable getBindForBackoffRunnableForTest() { 372 return mBindForBackoffRunnable; 373 } 374 375 @VisibleForTesting 376 boolean shouldBeBoundForTest() { 377 return mShouldBeBound; 378 } 379} 380