wifi_aware/snippet/CallbackUtils.java

/*
 * 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.google.snippet;

import static java.util.concurrent.TimeUnit.SECONDS;

import android.net.ConnectivityManager;
import android.net.Network;
import android.net.NetworkCapabilities;
import android.net.wifi.aware.AttachCallback;
import android.net.wifi.aware.DiscoverySessionCallback;
import android.net.wifi.aware.IdentityChangedListener;
import android.net.wifi.aware.PeerHandle;
import android.net.wifi.aware.PublishDiscoverySession;
import android.net.wifi.aware.SubscribeDiscoverySession;
import android.net.wifi.aware.WifiAwareSession;
import android.net.wifi.rtt.RangingResult;
import android.net.wifi.rtt.RangingResultCallback;
import android.util.Log;
import android.util.Pair;
import com.google.common.collect.ImmutableSet;
import java.util.ArrayDeque;
import java.util.List;
import java.util.Set;
import java.util.concurrent.CountDownLatch;

/** Blocking callbacks for Wi-Fi Aware and Connectivity Manager. */
public final class CallbackUtils {
  private static final String TAG = "CallbackUtils";

  public static final int CALLBACK_TIMEOUT_SEC = 15;

  /**
   * Utility AttachCallback - provides mechanism to block execution with the waitForAttach method.
   */
  public static class AttachCb extends AttachCallback {

    /** Callback codes. */
    public static enum CallbackCode {
      TIMEOUT,
      ON_ATTACHED,
      ON_ATTACH_FAILED
    };

    private final CountDownLatch blocker = new CountDownLatch(1);
    private CallbackCode callbackCode = CallbackCode.TIMEOUT;
    private WifiAwareSession wifiAwareSession = null;

    @Override
    public void onAttached(WifiAwareSession session) {
      callbackCode = CallbackCode.ON_ATTACHED;
      wifiAwareSession = session;
      blocker.countDown();
    }

    @Override
    public void onAttachFailed() {
      callbackCode = CallbackCode.ON_ATTACH_FAILED;
      blocker.countDown();
    }

    /**
     * Wait (blocks) for any AttachCallback callback or timeout.
     *
     * @return A pair of values: the callback constant (or TIMEOUT) and the WifiAwareSession created
     *     when attach successful - null otherwise (attach failure or timeout).
     */
    public Pair<CallbackCode, WifiAwareSession> waitForAttach() throws InterruptedException {
      if (blocker.await(CALLBACK_TIMEOUT_SEC, SECONDS)) {
        return new Pair<>(callbackCode, wifiAwareSession);
      }

      return new Pair<>(CallbackCode.TIMEOUT, null);
    }
  }

  /**
   * Utility IdentityChangedListener - provides mechanism to block execution with the
   * waitForIdentity method. Single shot listener - only listens for the first triggered callback.
   */
  public static class IdentityListenerSingleShot extends IdentityChangedListener {
    private final CountDownLatch blocker = new CountDownLatch(1);
    private byte[] mac = null;

    @Override
    public void onIdentityChanged(byte[] mac) {
      if (this.mac != null) {
        return;
      }

      this.mac = mac;
      blocker.countDown();
    }

    /**
     * Wait (blocks) for the onIdentityChanged callback or a timeout.
     *
     * @return The MAC address returned by the onIdentityChanged() callback, or null on timeout.
     */
    public byte[] waitForMac() throws InterruptedException {
      if (blocker.await(CALLBACK_TIMEOUT_SEC, SECONDS)) {
        return mac;
      }

      return null;
    }
  }

  /**
   * Utility NetworkCallback - provides mechanism for blocking/serializing access with the
   * waitForNetwork method.
   */
  public static class NetworkCb extends ConnectivityManager.NetworkCallback {
    private final CountDownLatch blocker = new CountDownLatch(1);
    private Network network = null;
    private NetworkCapabilities networkCapabilities = null;

    @Override
    public void onUnavailable() {
      networkCapabilities = null;
      blocker.countDown();
    }

    @Override
    public void onCapabilitiesChanged(Network network, NetworkCapabilities networkCapabilities) {
      this.network = network;
      this.networkCapabilities = networkCapabilities;
      blocker.countDown();
    }

    /**
     * Wait (blocks) for Capabilities Changed callback - or timesout.
     *
     * @return Network + NetworkCapabilities (pair) if occurred, null otherwise.
     */
    public Pair<Network, NetworkCapabilities> waitForNetworkCapabilities()
        throws InterruptedException {
      if (blocker.await(CALLBACK_TIMEOUT_SEC, SECONDS)) {
        return Pair.create(network, networkCapabilities);
      }
      return null;
    }
  }

  /**
   * Utility DiscoverySessionCallback - provides mechanism to block/serialize Aware discovery
   * operations using the waitForCallbacks() method.
   */
  public static class DiscoveryCb extends DiscoverySessionCallback {
    /** Callback codes. */
    public static enum CallbackCode {
      TIMEOUT,
      ON_PUBLISH_STARTED,
      ON_SUBSCRIBE_STARTED,
      ON_SESSION_CONFIG_UPDATED,
      ON_SESSION_CONFIG_FAILED,
      ON_SESSION_TERMINATED,
      ON_SERVICE_DISCOVERED,
      ON_MESSAGE_SEND_SUCCEEDED,
      ON_MESSAGE_SEND_FAILED,
      ON_MESSAGE_RECEIVED,
      ON_SERVICE_DISCOVERED_WITH_RANGE,
    };

    /**
     * Data container for all parameters which can be returned by any DiscoverySessionCallback
     * callback.
     */
    public static class CallbackData {
      public CallbackData(CallbackCode callbackCode) {
        this.callbackCode = callbackCode;
      }

      public CallbackCode callbackCode;

      public PublishDiscoverySession publishDiscoverySession;
      public SubscribeDiscoverySession subscribeDiscoverySession;
      public PeerHandle peerHandle;
      public byte[] serviceSpecificInfo;
      public List<byte[]> matchFilter;
      public int messageId;
      public int distanceMm;
    }

    private CountDownLatch blocker = null;
    private Set<CallbackCode> waitForCallbackCodes = ImmutableSet.of();

    private final Object lock = new Object();
    private final ArrayDeque<CallbackData> callbackQueue = new ArrayDeque<>();

    private void processCallback(CallbackData callbackData) {
      synchronized (lock) {
        callbackQueue.addLast(callbackData);
        if (blocker != null && waitForCallbackCodes.contains(callbackData.callbackCode)) {
          blocker.countDown();
        }
      }
    }

    private CallbackData getAndRemoveFirst(Set<CallbackCode> callbackCodes) {
      synchronized (lock) {
        for (CallbackData cbd : callbackQueue) {
          if (callbackCodes.contains(cbd.callbackCode)) {
            callbackQueue.remove(cbd);
            return cbd;
          }
        }
      }

      return null;
    }

    private CallbackData waitForCallbacks(Set<CallbackCode> callbackCodes, boolean timeout)
        throws InterruptedException {
      synchronized (lock) {
        CallbackData cbd = getAndRemoveFirst(callbackCodes);
        if (cbd != null) {
          return cbd;
        }

        waitForCallbackCodes = callbackCodes;
        blocker = new CountDownLatch(1);
      }

      boolean finishedNormally = true;
      if (timeout) {
        finishedNormally = blocker.await(CALLBACK_TIMEOUT_SEC, SECONDS);
      } else {
        blocker.await();
      }
      if (finishedNormally) {
        CallbackData cbd = getAndRemoveFirst(callbackCodes);
        if (cbd != null) {
          return cbd;
        }

        Log.wtf(
            TAG,
            "DiscoveryCb.waitForCallback: callbackCodes="
                + callbackCodes
                + ": did not time-out but doesn't have any of the requested callbacks in "
                + "the stack!?");
        // falling-through to TIMEOUT
      }

      return new CallbackData(CallbackCode.TIMEOUT);
    }

    /**
     * Wait for the specified callbacks - a bitmask of any of the ON_* constants. Returns the
     * CallbackData structure whose CallbackData.callback specifies the callback which was
     * triggered. The callback may be TIMEOUT.
     *
     * <p>Note: other callbacks happening while while waiting for the specified callback(s) will be
     * queued.
     */
    public CallbackData waitForCallbacks(Set<CallbackCode> callbackCodes)
        throws InterruptedException {
      return waitForCallbacks(callbackCodes, true);
    }

    /**
     * Wait for the specified callbacks - a bitmask of any of the ON_* constants. Returns the
     * CallbackData structure whose CallbackData.callback specifies the callback which was
     * triggered.
     *
     * <p>This call will not timeout - it can be interrupted though (which results in a thrown
     * exception).
     *
     * <p>Note: other callbacks happening while while waiting for the specified callback(s) will be
     * queued.
     */
    public CallbackData waitForCallbacksNoTimeout(Set<CallbackCode> callbackCodes)
        throws InterruptedException {
      return waitForCallbacks(callbackCodes, false);
    }

    @Override
    public void onPublishStarted(PublishDiscoverySession session) {
      CallbackData callbackData = new CallbackData(CallbackCode.ON_PUBLISH_STARTED);
      callbackData.publishDiscoverySession = session;
      processCallback(callbackData);
    }

    @Override
    public void onSubscribeStarted(SubscribeDiscoverySession session) {
      CallbackData callbackData = new CallbackData(CallbackCode.ON_SUBSCRIBE_STARTED);
      callbackData.subscribeDiscoverySession = session;
      processCallback(callbackData);
    }

    @Override
    public void onSessionConfigUpdated() {
      CallbackData callbackData = new CallbackData(CallbackCode.ON_SESSION_CONFIG_UPDATED);
      processCallback(callbackData);
    }

    @Override
    public void onSessionConfigFailed() {
      CallbackData callbackData = new CallbackData(CallbackCode.ON_SESSION_CONFIG_FAILED);
      processCallback(callbackData);
    }

    @Override
    public void onSessionTerminated() {
      CallbackData callbackData = new CallbackData(CallbackCode.ON_SESSION_TERMINATED);
      processCallback(callbackData);
    }

    @Override
    public void onServiceDiscovered(
        PeerHandle peerHandle, byte[] serviceSpecificInfo, List<byte[]> matchFilter) {
      CallbackData callbackData = new CallbackData(CallbackCode.ON_SERVICE_DISCOVERED);
      callbackData.peerHandle = peerHandle;
      callbackData.serviceSpecificInfo = serviceSpecificInfo;
      callbackData.matchFilter = matchFilter;
      processCallback(callbackData);
    }

    @Override
    public void onServiceDiscoveredWithinRange(
        PeerHandle peerHandle,
        byte[] serviceSpecificInfo,
        List<byte[]> matchFilter,
        int distanceMm) {
      CallbackData callbackData = new CallbackData(CallbackCode.ON_SERVICE_DISCOVERED_WITH_RANGE);
      callbackData.peerHandle = peerHandle;
      callbackData.serviceSpecificInfo = serviceSpecificInfo;
      callbackData.matchFilter = matchFilter;
      callbackData.distanceMm = distanceMm;
      processCallback(callbackData);
    }

    @Override
    public void onMessageSendSucceeded(int messageId) {
      CallbackData callbackData = new CallbackData(CallbackCode.ON_MESSAGE_SEND_SUCCEEDED);
      callbackData.messageId = messageId;
      processCallback(callbackData);
    }

    @Override
    public void onMessageSendFailed(int messageId) {
      CallbackData callbackData = new CallbackData(CallbackCode.ON_MESSAGE_SEND_FAILED);
      callbackData.messageId = messageId;
      processCallback(callbackData);
    }

    @Override
    public void onMessageReceived(PeerHandle peerHandle, byte[] message) {
      CallbackData callbackData = new CallbackData(CallbackCode.ON_MESSAGE_RECEIVED);
      callbackData.peerHandle = peerHandle;
      callbackData.serviceSpecificInfo = message;
      processCallback(callbackData);
    }
  }

  /**
   * Utility RangingResultCallback - provides mechanism for blocking/serializing access with the
   * waitForRangingResults method.
   */
  public static class RangingCb extends RangingResultCallback {
    public static final int TIMEOUT = -1;
    public static final int ON_FAILURE = 0;
    public static final int ON_RESULTS = 1;

    private final CountDownLatch blocker = new CountDownLatch(1);
    private int status = TIMEOUT;
    private List<RangingResult> results = null;

    /**
     * Wait (blocks) for Ranging results callbacks - or times-out.
     *
     * @return Pair of status & Ranging results if succeeded, null otherwise.
     */
    public Pair<Integer, List<RangingResult>> waitForRangingResults() throws InterruptedException {
      if (blocker.await(CALLBACK_TIMEOUT_SEC, SECONDS)) {
        return new Pair<>(status, results);
      }
      return new Pair<>(TIMEOUT, null);
    }

    @Override
    public void onRangingFailure(int code) {
      status = ON_FAILURE;
      blocker.countDown();
    }

    @Override
    public void onRangingResults(List<RangingResult> results) {
      status = ON_RESULTS;
      this.results = results;
      blocker.countDown();
    }
  }

  private CallbackUtils() {}
}