Add car specific focus policy handler
The car specific focus policy installation accomplishes two things:
1) By giving car code control over which audio focus requests get
granted, it allows cars to concurrent audio focus for different types of
audio. We'll see if this ends up being a good thing or not once we
start experimenting in actual use cases.
2) By having the a focus policy installed, we bypass the built in
ducking logic, leaving that to the car to handle below the HAL.
Test: build and run KichenSink on Mojave and listen to radio in Jeep
Bug: 33352354
Change-Id: If2dfce9ad4620a4d840b95f9a2e2f67733f3b155
diff --git a/service/src/com/android/car/CarAudioFocus.java b/service/src/com/android/car/CarAudioFocus.java
new file mode 100644
index 0000000..c7c4e7c
--- /dev/null
+++ b/service/src/com/android/car/CarAudioFocus.java
@@ -0,0 +1,349 @@
+/*
+ * Copyright (C) 2015 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.car;
+
+import android.hardware.automotive.audiocontrol.V1_0.ContextNumber;
+import android.media.AudioAttributes;
+import android.media.AudioFocusInfo;
+import android.media.AudioManager;
+import android.media.audiopolicy.AudioPolicy;
+import android.util.Log;
+
+import java.io.PrintWriter;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.Iterator;
+
+
+public class CarAudioFocus extends AudioPolicy.AudioPolicyFocusListener {
+
+ private static final String TAG = "CarAudioFocus";
+
+ private final AudioManager mAudioManager;
+ private CarAudioService mCarAudioService; // Dynamically assigned just after construction
+ private AudioPolicy mAudioPolicy; // Dynamically assigned just after construction
+
+
+ // Values for the internal interaction matrix we use to make focus decisions
+ private static final int INTERACTION_REJECT = 0; // Focus not granted
+ private static final int INTERACTION_EXCLUSIVE = 1; // Focus granted, others loose focus
+ private static final int INTERACTION_CONCURRENT = 2; // Focus granted, others keep focus
+
+ // TODO: Make this an overlayable resource...
+ // MUSIC = 1, // Music playback
+ // NAVIGATION = 2, // Navigation directions
+ // VOICE_COMMAND = 3, // Voice command session
+ // CALL_RING = 4, // Voice call ringing
+ // CALL = 5, // Voice call
+ // ALARM = 6, // Alarm sound from Android
+ // NOTIFICATION = 7, // Notifications
+ // SYSTEM_SOUND = 8, // User interaction sounds (button clicks, etc)
+ private static int sInteractionMatrix[][] = {
+ // Row selected by playing sound (labels along the right)
+ // Column selected by incoming request (labels along the top)
+ // Cell value is one of INTERACTION_REJECT, INTERACTION_EXCLUSIVE, INTERACTION_CONCURRENT
+ // Invalid, Music, Nav, Voice, Ring, Call, Alarm, Notification, System
+ { 0, 0, 0, 0, 0, 0, 0, 0, 0 }, // Invalid
+ { 0, 1, 2, 1, 1, 1, 1, 2, 2 }, // Music
+ { 0, 2, 2, 1, 2, 1, 2, 2, 2 }, // Nav
+ { 0, 2, 0, 2, 1, 1, 0, 0, 0 }, // Voice
+ { 0, 0, 2, 2, 2, 2, 0, 0, 2 }, // Ring
+ { 0, 0, 2, 0, 2, 2, 2, 2, 0 }, // Context
+ { 0, 2, 2, 1, 1, 1, 2, 2, 2 }, // Alarm
+ { 0, 2, 2, 1, 1, 1, 2, 2, 2 }, // Notification
+ { 0, 2, 2, 1, 1, 1, 2, 2, 2 }, // System
+ };
+
+
+ private class FocusEntry {
+ // Requester info
+ final AudioFocusInfo mAfi; // never null
+
+ final int mAudioContext; // Which HAL level context does this affect
+ final ArrayList<FocusEntry> mBlockers; // List of requests that block ours
+
+ FocusEntry(AudioFocusInfo afi,
+ int context) {
+ mAfi = afi;
+ mAudioContext = context;
+ mBlockers = new ArrayList<FocusEntry>();
+ }
+
+ public String getClientId() {
+ return mAfi.getClientId();
+ }
+
+ public boolean wantsPauseInsteadOfDucking() {
+ return (mAfi.getFlags() & AudioManager.AUDIOFOCUS_FLAG_PAUSES_ON_DUCKABLE_LOSS) != 0;
+ }
+ }
+
+
+ // We keep track of all the focus requesters in this map, with their clientId as the key.
+ // This is used both for focus dispatch and death handling
+ // Note that the clientId reflects the AudioManager instance and listener object (if any)
+ // so that one app can have more than one unique clientId by setting up distinct listeners.
+ private HashMap<String, FocusEntry> mFocusHolders = new HashMap<String, FocusEntry>();
+ private HashMap<String, FocusEntry> mFocusLosers = new HashMap<String, FocusEntry>();
+
+
+ CarAudioFocus(AudioManager audioManager) {
+ mAudioManager = audioManager;
+ }
+
+
+ // This has to happen after the construction to avoid a chicken and egg problem when setting up
+ // the AudioPolicy which must depend on this object.
+ public void setOwningPolicy(CarAudioService audioService, AudioPolicy parentPolicy) {
+ mCarAudioService = audioService;
+ mAudioPolicy = parentPolicy;
+ }
+
+
+ // This sends a focus loss message to the targeted requester.
+ private void sendFocusLoss(FocusEntry loser, boolean permanent) {
+ int lossType = (permanent ? AudioManager.AUDIOFOCUS_LOSS :
+ AudioManager.AUDIOFOCUS_LOSS_TRANSIENT);
+ Log.i(TAG, "sendFocusLoss to " + loser.getClientId());
+ int result = mAudioManager.dispatchAudioFocusChange(loser.mAfi, lossType, mAudioPolicy);
+ if (result != AudioManager.AUDIOFOCUS_REQUEST_GRANTED) {
+ // TODO: Is this actually an error, or is it okay for an entry in the focus stack
+ // to NOT have a listener? If that's the case, should we even keep it in the focus
+ // stack?
+ Log.e(TAG, "Failure to signal loss of audio focus with error: " + result);
+ }
+ }
+
+
+ /** @see AudioManager#requestAudioFocus(AudioManager.OnAudioFocusChangeListener, int, int, int) */
+ // TODO: How should we handle focus requests from clients who are already in the focus stack?
+ // Especially if they're requesting with different AudioAttributes?
+ // The default audio framework's behavior is to remove the previous entry in the stack (no-op
+ // if the requester is already holding focus).
+ int evaluateFocusRequest(AudioFocusInfo afi) {
+ Log.i(TAG, "Evaluating focus request for client " + afi.getClientId());
+
+ // Is this a request for premanant focus?
+ // AUDIOFOCUS_GAIN_TRANSIENT_EXCLUSIVE -- Means Notifications should be denied
+ // AUDIOFOCUS_GAIN_TRANSIENT -- Means current focus holders should get transient loss
+ // AUDIOFOCUS_GAIN_TRANSIENT_MAY_DUCK -- Means other can duck (no loss message from us)
+ // NOTE: We expect that in practice it will be permanent for all media requests and
+ // transient for everything else, but that isn't currently an enforced requirement.
+ final boolean permanent =
+ (afi.getGainRequest() == AudioManager.AUDIOFOCUS_GAIN);
+ final boolean allowDucking =
+ (afi.getGainRequest() == AudioManager.AUDIOFOCUS_GAIN_TRANSIENT_MAY_DUCK);
+
+
+ // Convert from audio attributes "usage" to HAL level "context"
+ final int requestedContext = mCarAudioService.getContextForUsage(
+ afi.getAttributes().getUsage());
+
+
+ // Scan all active and pending focus requests. If any should cause rejection of
+ // this new request, then we're done. Keep a list of those against whom we're exclusive
+ // so we can update the relationships if/when we are sure we won't get rejected.
+ final ArrayList<FocusEntry> losers = new ArrayList<FocusEntry>();
+ for (FocusEntry entry : mFocusHolders.values()) {
+ // If this request is for Notifications and a current focus holder has specified
+ // AUDIOFOCUS_GAIN_TRANSIENT_EXCLUSIVE, then reject the request.
+ // This matches the hardwired behavior in the default audio policy engine which apps
+ // might expect (The interaction matrix doesn't have any provision for dealing with
+ // override flags like this).
+ if ((requestedContext == ContextNumber.NOTIFICATION) &&
+ (entry.mAfi.getGainRequest() ==
+ AudioManager.AUDIOFOCUS_GAIN_TRANSIENT_EXCLUSIVE)) {
+ return AudioManager.AUDIOFOCUS_REQUEST_FAILED;
+ }
+
+ // Check the interaction matrix for the relationship between this entry and the request
+ switch (sInteractionMatrix[entry.mAudioContext][requestedContext]) {
+ case INTERACTION_REJECT:
+ // This request is rejected, so nothing further to do
+ return AudioManager.AUDIOFOCUS_REQUEST_FAILED;
+ case INTERACTION_EXCLUSIVE:
+ // The new request will cause this existing entry to lose focus
+ losers.add(entry);
+ break;
+ default:
+ // If ducking isn't allowed by the focus requestor, then everybody else
+ // must get a LOSS.
+ // If a focus holder has set the AUDIOFOCUS_FLAG_PAUSES_ON_DUCKABLE_LOSS flag,
+ // they must get a LOSS message even if ducking would otherwise be allowed.
+ if ((!allowDucking) ||
+ (entry.mAfi.getFlags() &
+ AudioManager.AUDIOFOCUS_FLAG_PAUSES_ON_DUCKABLE_LOSS) != 0) {
+ // The new request will cause audio book to lose focus and pause
+ losers.add(entry);
+ }
+ }
+ }
+ final ArrayList<FocusEntry> blocked = new ArrayList<FocusEntry>();
+ for (FocusEntry entry : mFocusLosers.values()) {
+ // If this request is for Notifications and a pending focus holder has specified
+ // AUDIOFOCUS_GAIN_TRANSIENT_EXCLUSIVE, then reject the request
+ if ((requestedContext == ContextNumber.NOTIFICATION) &&
+ (entry.mAfi.getGainRequest() ==
+ AudioManager.AUDIOFOCUS_GAIN_TRANSIENT_EXCLUSIVE)) {
+ return AudioManager.AUDIOFOCUS_REQUEST_FAILED;
+ }
+
+ // Check the interaction matrix for the relationship between this entry and the request
+ switch (sInteractionMatrix[entry.mAudioContext][requestedContext]) {
+ case INTERACTION_REJECT:
+ // Even though this entry has currently lost focus, the fact that it is
+ // waiting to play means we'll reject this new conflicting request.
+ return AudioManager.AUDIOFOCUS_REQUEST_FAILED;
+ case INTERACTION_EXCLUSIVE:
+ // The new request is yet another reason this entry cannot regain focus (yet)
+ blocked.add(entry);
+ break;
+ default:
+ // If ducking is not allowed by the requester, or the pending focus holder had
+ // set the AUDIOFOCUS_FLAG_PAUSES_ON_DUCKABLE_LOSS flag,
+ // then the pending holder must stay "lost" until this requester goes away.
+ if ((!allowDucking) || entry.wantsPauseInsteadOfDucking()) {
+ // The new request is yet another reason this entry cannot regain focus yet
+ blocked.add(entry);
+ }
+ }
+ }
+
+
+ // Now that we've decided we'll grant focus, construct our new FocusEntry
+ FocusEntry newEntry = new FocusEntry(afi, requestedContext);
+
+
+ // Now that we're sure we'll accept this request, update any requests which we would
+ // block but are already out of focus but waiting to come back
+ for (FocusEntry entry : blocked) {
+ // If we're out of focus it must be because somebody is blocking us
+ assert !entry.mBlockers.isEmpty();
+
+ if (permanent) {
+ // This entry has now lost focus forever
+ sendFocusLoss(entry, permanent);
+ final FocusEntry deadEntry = mFocusLosers.remove(entry.mAfi.getClientId());
+ assert deadEntry != null;
+ } else {
+ // Note that this new request is yet one more reason we can't (yet) have focus
+ entry.mBlockers.add(newEntry);
+ }
+ }
+
+ // Notify and update any requests which are now losing focus as a result of the new request
+ for (FocusEntry entry : losers) {
+ // If we have focus (but are about to loose it), nobody should be blocking us yet
+ assert entry.mBlockers.isEmpty();
+
+ sendFocusLoss(entry, permanent);
+
+ // The entry no longer holds focus, so take it out of the holders list
+ mFocusHolders.remove(entry.mAfi.getClientId());
+
+ if (!permanent) {
+ // Add ourselves to the list of requests waiting to get focus back and
+ // note why we lost focus so we can tell when it's time to get it back
+ mFocusLosers.put(entry.mAfi.getClientId(), entry);
+ entry.mBlockers.add(newEntry);
+ }
+ }
+
+ // Finally, add the request we're granting to the focus holders' list
+ mFocusHolders.put(afi.getClientId(), newEntry);
+
+ return AudioManager.AUDIOFOCUS_REQUEST_GRANTED;
+ }
+
+
+ @Override
+ public synchronized void onAudioFocusRequest(AudioFocusInfo afi, int requestResult) {
+ Log.i(TAG, "onAudioFocusRequest " + afi);
+
+ int response = evaluateFocusRequest(afi);
+
+ // Post our reply for delivery to the original focus requester
+ mAudioManager.setFocusRequestResult(afi, response, mAudioPolicy);
+ }
+
+
+ /**
+ * @see AudioManager#abandonAudioFocus(AudioManager.OnAudioFocusChangeListener, AudioAttributes)
+ * Note that we'll get this call for a focus holder that dies while in the focus statck, so
+ * we don't need to watch for death notifications directly.
+ * */
+ @Override
+ public synchronized void onAudioFocusAbandon(AudioFocusInfo afi) {
+ Log.i(TAG, "onAudioFocusAbandon " + afi);
+
+ // Remove this entry from our active or pending list
+ FocusEntry deadEntry = mFocusHolders.remove(afi.getClientId());
+ if (deadEntry == null) {
+ deadEntry = mFocusLosers.remove(afi.getClientId());
+ if (deadEntry == null) {
+ // Caller is providing an unrecognzied clientId!?
+ Log.e(TAG, "Audio focus abandoned by unrecognzied client id: " + afi.getClientId());
+ // NOTE: We could choose to silently ignore this, but lets make it clear for now
+ throw new RuntimeException("Unrecognized client abandoning audio focus");
+ }
+ }
+
+ // Remove this entry from the blocking list of any pending requests
+ Iterator<FocusEntry> it = mFocusLosers.values().iterator();
+ while (it.hasNext()) {
+ FocusEntry entry = it.next();
+
+ // Remove the retiring entry from all blocker lists
+ entry.mBlockers.remove(deadEntry);
+
+ // Any entry whose blocking list becomes empty should regain focus
+ if (entry.mBlockers.isEmpty()) {
+ // Pull this entry out of the focus losers list
+ it.remove();
+
+ // Add it back into the focus holders list
+ mFocusHolders.put(entry.getClientId(), entry);
+
+ // Send the focus (re)gain notification
+ int result = mAudioManager.dispatchAudioFocusChange(
+ entry.mAfi,
+ entry.mAfi.getGainRequest(),
+ mAudioPolicy);
+ if (result != AudioManager.AUDIOFOCUS_REQUEST_GRANTED) {
+ // TODO: Is this actually an error, or is it okay for an entry in the focus
+ // stack to NOT have a listener? If that's the case, should we even keep
+ // it in the focus stack?
+ Log.e(TAG, "Failure to signal gain of audio focus with error: " + result);
+ }
+ }
+ }
+ }
+
+
+ public synchronized void dump(PrintWriter writer) {
+ writer.println("*CarAudioFocus*");
+
+ writer.println(" Current Focus Holders:");
+ for (String clientId : mFocusHolders.keySet()) {
+ System.out.println(clientId);
+ }
+
+ writer.println(" Transient Focus Losers:");
+ for (String clientId : mFocusLosers.keySet()) {
+ System.out.println(clientId);
+ }
+ }
+}