content: /*
   * Copyright (C) 2017 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 com.android.server.locksettings.recoverablekeystore;
  
  import android.annotation.Nullable;
  import android.app.PendingIntent;
  import android.util.ArraySet;
  import android.util.Log;
  import android.util.SparseArray;
  
  import com.android.internal.annotations.GuardedBy;
  
  /**
   * In memory storage for listeners to be notified when new recovery snapshot is available. This
   * class is thread-safe. It is used on two threads - the service thread and the thread that runs the
   * {@link KeySyncTask}.
   *
   * @hide
   */
  public class RecoverySnapshotListenersStorage {
      private static final String TAG = "RecoverySnapshotLstnrs";
  
      @GuardedBy("this")
      private SparseArray<PendingIntent> mAgentIntents = new SparseArray<>();
  
      @GuardedBy("this")
      private ArraySet<Integer> mAgentsWithPendingSnapshots = new ArraySet<>();
  
      /**
       * Sets new listener for the recovery agent, identified by {@code uid}.
       *
       * @param recoveryAgentUid uid of the recovery agent.
       * @param intent PendingIntent which will be triggered when new snapshot is available.
       */
      public synchronized void setSnapshotListener(
              int recoveryAgentUid, @Nullable PendingIntent intent) {
          Log.i(TAG, "Registered listener for agent with uid " + recoveryAgentUid);
          mAgentIntents.put(recoveryAgentUid, intent);
  
          if (mAgentsWithPendingSnapshots.contains(recoveryAgentUid)) {
              Log.i(TAG, "Snapshot already created for agent. Immediately triggering intent.");
              tryToSendIntent(recoveryAgentUid, intent);
          }
      }
  
      /**
       * Returns {@code true} if a listener has been set for the recovery agent.
       */
      public synchronized boolean hasListener(int recoveryAgentUid) {
          return mAgentIntents.get(recoveryAgentUid) != null;
      }
  
      /**
       * Notifies recovery agent that new snapshot is available. If a recovery agent has not yet
       * registered a {@link PendingIntent}, remembers that a snapshot is pending for it, so that
       * when it does register, that intent is immediately triggered.
       *
       * @param recoveryAgentUid uid of recovery agent.
       */
      public synchronized void recoverySnapshotAvailable(int recoveryAgentUid) {
          PendingIntent intent = mAgentIntents.get(recoveryAgentUid);
          if (intent == null) {
              Log.i(TAG, "Snapshot available for agent " + recoveryAgentUid
                      + " but agent has not yet initialized. Will notify agent when it does.");
              mAgentsWithPendingSnapshots.add(recoveryAgentUid);
              return;
          }
  
          tryToSendIntent(recoveryAgentUid, intent);
      }
  
      /**
       * Attempts to send {@code intent} for the recovery agent. If this fails, remembers to notify
       * the recovery agent immediately if it registers a new intent.
       */
      private synchronized void tryToSendIntent(int recoveryAgentUid, PendingIntent intent) {
          try {
              intent.send();
              mAgentsWithPendingSnapshots.remove(recoveryAgentUid);
              Log.d(TAG, "Successfully notified listener.");
          } catch (PendingIntent.CanceledException e) {
              Log.e(TAG,
                      "Failed to trigger PendingIntent for " + recoveryAgentUid,
                      e);
              // As it failed to trigger, trigger immediately if a new intent is registered later.
              mAgentsWithPendingSnapshots.add(recoveryAgentUid);
          }
      }
  }
  