android_frameworks_base/docs/html/training/monitoring-device-state/doze-standby.jd

page.title=Optimizing for Doze and App Standby
page.metaDescription=Test and optimize your app for the power-saving features in Android 6.0.
page.tags=doze, app standby, marshmallow, alarms
meta.tags="battery", "marshmallow", "alarms"
page.image=images/cards/card-doze_16-9_2x.png


parent.link=index.html

trainingnavtop=true
next.title=Monitoring the Battery Level and Charging State
next.link=battery-monitoring.html
@jd:body

<div id="tb-wrapper">
<div id="tb">
    <h2>In this document</h2>
    <ol>
      <li><a href="#understand_doze">Understanding Doze</a>
      <ol>
        <li><a href="#restrictions">Doze restrictions</a></li>
        <li><a href="#assessing_your_app">Adapting your app to Doze</a></li>
      </ol>
      </li>
      <li><a href="#understand_app_standby">Understanding App Standby</a></li>
      <li><a href="#using_gcm">Using GCM to Interact with Your App</a></li>
      <li><a href="#support_for_other_use_cases">Support for Other Use Cases</a></li>
      <li><a href="#testing_doze_and_app_standby">Testing with Doze and App
Standby</a>
      <ol>
        <li><a href="#testing_doze">Testing your app with Doze</a></li>
        <li><a href="#testing_your_app_with_app_standby">Testing your app with App Standby</a></li>
      </ol>
      </li>
      <li><a href="#whitelisting-cases">Example Use Cases for Whitelisting</a></li>
    </ol>
  </div>
</div>

<p>
  Starting from Android 6.0 (API level 23), Android introduces two
  power-saving features that extend battery life for users by managing how apps behave when a
  device is not connected to a power source. <em>Doze</em> reduces battery consumption by deferring
  background CPU and network activity for apps when the device is unused for long periods
  of time. <em>App Standby</em> defers background network activity for apps
  with which the user has not recently interacted.
</p>

<p>
  Doze and App Standby manage the behavior of all apps running on Android 6.0
  or higher, regardless whether they are specifically targeting API level 23.
  To ensure the best experience for users, test your app in Doze and App
  Standby modes and make any necessary adjustments to your code. The sections
  below provide details.
</p>


<h2 id="understand_doze">Understanding Doze</h2>
<p>
  If a user leaves a device unplugged and stationary for a period of time, with
  the screen off, the device enters Doze mode. In Doze mode, the system
  attempts to conserve battery by restricting apps' access to network and
  CPU-intensive services. It also prevents apps from accessing the network and
  defers their jobs, syncs, and standard alarms.
</p>

<p>
  Periodically, the system exits Doze for a brief time to let apps complete
  their deferred activities. During this <em>maintenance window</em>, the
  system runs all pending syncs, jobs, and alarms, and lets apps access the
  network.
</p>

<div style="margin:1em 0em;">
  <img src="{@docRoot}images/training/doze.png">
  <p class="img-caption" style="text-align:center;">
    <strong>Figure 1.</strong> Doze provides a recurring maintenance window for apps to use the
    network and handle pending activities.
  </p>
</div>

<p>
  At the conclusion of each maintenance window, the system again enters Doze,
  suspending network access and deferring jobs, syncs, and alarms. Over time,
  the system schedules maintenance windows less and less frequently, helping to
  reduce battery consumption in cases of longer-term inactivity when the device is not
  connected to a charger.
</p>


<p>
  As soon as the user wakes the device by moving it, turning on the screen, or
  connecting a charger, the system exits Doze and all apps return to normal
  activity.
</p>


<h3 id="restrictions">Doze restrictions</h3>

<p>
  The following restrictions apply to your apps while in Doze:
</p>

<ul>
  <li>Network access is suspended.
  </li>

  <li>The system ignores <a href="{@docRoot}reference/android/os/PowerManager.WakeLock.html">
  wake locks</a>.
  </li>

  <li>Standard {@link android.app.AlarmManager} alarms (including {@link
  android.app.AlarmManager#setExact(int, long, android.app.PendingIntent) setExact()} and
  {@link android.app.AlarmManager#setWindow(int, long, long,
  android.app.PendingIntent) setWindow()}) are deferred to the next maintenance window.
  </li>

  <li style="list-style: none; display: inline">
    <ul>
      <li>If you need to set alarms that fire while in Doze, use {@link
      android.app.AlarmManager#setAndAllowWhileIdle(int,long,android.app.PendingIntent)
      setAndAllowWhileIdle()}
      or {@link android.app.AlarmManager#setExactAndAllowWhileIdle(int, long,
      android.app.PendingIntent) setExactAndAllowWhileIdle()}.
      </li>

      <li>Alarms set with {@link
      android.app.AlarmManager#setAlarmClock(android.app.AlarmManager.AlarmClockInfo,
      android.app.PendingIntent) setAlarmClock()} continue to fire normally &mdash; the system
      exits Doze shortly before those alarms fire.
      </li>
    </ul>
  </li>

  <li>The system does not perform Wi-Fi scans.
  </li>

  <li>The system does not allow
  <a href="{@docRoot}reference/android/content/AbstractThreadedSyncAdapter.html">sync adapters</a>
  to run.
  </li>

  <li>The system does not allow {@link android.app.job.JobScheduler} to run.
  </li>
</ul>


<div id="qv-wrapper">
<div id="qv" style="width:300px">
<h2>Doze checklist</h2>
<ol>
<ul>
  <li>If possible, use GCM for <a href=
  "https://developers.google.com/cloud-messaging/downstream">downstream
  messaging</a>.
  </li>

  <li>If your users must see a notification right away, make sure to use a <a href=
  "https://developers.google.com/cloud-messaging/concept-options#setting-the-priority-of-a-message">GCM
  high priority message</a>.
  </li>

  <li>Provide sufficient information within the initial <a href=
  "https://developers.google.com/cloud-messaging/concept-options#payload">message
  payload</a>, so subsequent network access is unnecessary.
  </li>

  <li>Set critical alarms with {@link
  android.app.AlarmManager#setAndAllowWhileIdle(int, long,
  android.app.PendingIntent) setAndAllowWhileIdle()} and {@link
  android.app.AlarmManager#setExactAndAllowWhileIdle(int, long,
  android.app.PendingIntent) setExactAndAllowWhileIdle()}.
  </li>

  <li>
    <a href="#testing_doze">Test your app in Doze.</a>
  </li>
</ul>
</ol>
</div>
</div>

<h3 id="assessing_your_app">Adapting your app to Doze</h3>

<p>
  Doze can affect apps differently, depending on the capabilities they offer
  and the services they use. Many apps function normally across Doze
  cycles without modification. In some cases, you must optimize the way
  that your app manages network, alarms, jobs, and syncs. Apps should be able
  to efficiently manage activities during each maintenance window.
</p>
<p>
  Doze is particularly likely to affect activities that {@link android.app.AlarmManager} alarms and
  timers manage, because alarms in Android 5.1 (API level 22) or lower do not fire when the system
  is in Doze.
</p>

<p>
  To help with scheduling alarms, Android 6.0 (API level 23) introduces two new
  {@link android.app.AlarmManager} methods: {@link
  android.app.AlarmManager#setAndAllowWhileIdle(int, long,
  android.app.PendingIntent) setAndAllowWhileIdle()} and {@link
  android.app.AlarmManager#setExactAndAllowWhileIdle(int, long,
  android.app.PendingIntent) setExactAndAllowWhileIdle()}. With these methods,
  you can set alarms that will fire even if the device is in Doze.
</p>

<p class="note"><strong>Note:</strong> Neither
{@link
  android.app.AlarmManager#setAndAllowWhileIdle(int, long,
  android.app.PendingIntent) setAndAllowWhileIdle()} nor {@link
  android.app.AlarmManager#setExactAndAllowWhileIdle(int, long,
  android.app.PendingIntent) setExactAndAllowWhileIdle()} can fire alarms more than once per 15
minutes per app.</p>

<p>
  The Doze restriction on network access is also likely to affect your app,
  especially if the app relies on real-time messages such as tickles or
  notifications. If your app requires a persistent connection to the network to
  receive messages, you should use <a href="#using_gcm">Google Cloud Messaging (GCM)</a>
  if possible.
</p>

<p>
  To confirm that your app behaves as expected with Doze, you can use adb commands to force the
  system to enter and exit Doze and observe your app’s behavior. For details, see
  <a href="#testing_doze_and_app_standby">Testing with Doze and App Standby</a>.
</p>

<h2 id="understand_app_standby">Understanding App Standby</h2>

<p>
  App Standby allows the system to determine that an app is idle when the user
  is not actively using it. The system makes this determination when the user
  does not touch the app for a certain period of time and none of the following
  conditions applies:
</p>

<ul>
  <li>The user explicitly launches the app.
  </li>

  <li>The app has a process currently in the foreground (either as an activity
  or foreground service, or in use by another activity or foreground service).
  </li>

  <li>The app generates a notification that users see on the lock screen or in
  the notification tray.
  </li>
</ul>

<p>
  When the user plugs the device into a power supply, the system releases apps
  from the standby state, allowing them to freely access the network and to
  execute any pending jobs and syncs. If the device is idle for long periods of
  time, the system allows idle apps network access around once a day.
</p>

<h2 id="using_gcm">Using GCM to Interact with Your App While the Device is Idle</h2>

<p>
  <a href="https://developers.google.com/cloud-messaging/">Google Cloud
  Messaging (GCM)</a> is a cloud-to-device service that lets you support
  real-time downstream messaging between backend services and apps on
  Android devices. GCM provides a single, persistent connection to the cloud; all apps needing
  real-time messaging can share this connection. This shared
  connection significantly optimizes battery consumption by making it unnecessary for
  multiple apps to maintain their own, separate persistent connections, which can
  deplete the battery rapidly. For this reason, if your app requires messaging integration with a
  backend service, we strongly recommend that you <strong>use GCM if possible</strong>, rather than
  maintaining your own persistent network connection.
</p>

<p>
  GCM is optimized to work with Doze and App Standby idle modes by means of
  <a href="https://developers.google.com/cloud-messaging/concept-options#setting-the-priority-of-a-message">
  high-priority GCM messages</a>. GCM high-priority messages let you reliably wake your app to
  access the network, even if the user’s device is in Doze or the app is in App Standby mode.
  In Doze or App Standby mode, the system delivers the message and gives the
  app temporary access to network services and partial wakelocks, then returns the device or app
  to idle state.
</p>

<p>
  High-priority GCM messages do not otherwise affect Doze mode, and they don’t
  affect the state of any other app. This means that your app can use them to communicate
  efficiently while minimizing battery impacts across the system and device.
</p>

<p>
  As a general best practice, if your app requires downstream messaging, it
  should use GCM. If your server and client already uses GCM, make sure that your service uses
  high-priority messages for critical messages, since this will reliably
  wake apps even when the device is in Doze.
</p>

<h2 id="support_for_other_use_cases">Support for Other Use Cases</h2>

<p>
  Almost all apps should be able to support Doze by managing network connectivity, alarms,
  jobs, and syncs properly, and using GCM high-priority messages. For a narrow
  set of use cases, this might not be sufficient. For such cases, the system
  provides a configurable whitelist of apps that are <strong>partially
  exempt</strong> from Doze and App Standby optimizations.
</p>

<p>
  An app that is whitelisted can use the network and hold

  <a href="{@docRoot}reference/android/os/PowerManager.html#PARTIAL_WAKE_LOCK">
  partial wake locks</a> during Doze and
  App Standby. However, <strong>other restrictions still apply</strong> to the
  whitelisted app, just as they do to other apps. For example, the whitelisted
  app’s jobs and syncs are deferred, and its regular {@link android.app.AlarmManager} alarms do not
  fire. An app can check whether it is currently on the exemption whitelist by
  calling {@link
  android.os.PowerManager#isIgnoringBatteryOptimizations(java.lang.String)
  isIgnoringBatteryOptimizations()}.
  </li>
</p>

<p>
  Users can manually configure the whitelist in <strong>Settings &gt; Battery
  &gt; Battery Optimization.</strong> Alternatively, the system provides
  ways for apps to ask users to whitelist them.

</p>

<ul>
  <li>An app can fire the {@link
  android.provider.Settings#ACTION_IGNORE_BATTERY_OPTIMIZATION_SETTINGS} intent
  to take the user directly to the <strong>Battery Optimization</strong>, where they can
  add the app.
  </li>

  <li>An app holding the {@link
  android.Manifest.permission#REQUEST_IGNORE_BATTERY_OPTIMIZATIONS} permission
  can trigger a system dialog to let the user add the app to the whitelist
  directly, without going to settings. The app fires a {@link
  android.provider.Settings#ACTION_REQUEST_IGNORE_BATTERY_OPTIMIZATIONS} Intent
  to trigger the dialog.
  </li>

  <li>The user can manually remove apps from the whitelist as needed.
  </li>
</ul>

<p>Before asking the user to add your app to the whitelist, make sure the app

matches the <a href="#whitelisting-cases">acceptable use cases</a> for whitelisting.</p>


<p class="caution">
  <strong>Note:</strong> Google Play policies prohibit apps from requesting
  direct exemption from Power Management features in Android 6.0+ (Doze and App
  Standby) unless the core function of the app is adversely affected.
</p>

<h2 id="testing_doze_and_app_standby">Testing with Doze and App Standby</h2>

<p>
  To ensure a great experience for your users, you should test your app fully
  in Doze and App Standby.
</p>

<h3 id="testing_doze">Testing your app with Doze</h4>

<p>You can test Doze mode by following these steps:</p>
<ol>
  <li>Configure a hardware device or virtual device with an Android 6.0 (API
  level 23) or higher system image.
  </li>

  <li>Connect the device to your development machine and install your app.
  </li>

  <li>Run your app and leave it active.
  </li>

  <li>Shut off the device screen. (The app remains active.)
  </li>

  <li>Force the system to cycle through Doze modes by running the following
  commands:

  <pre class="no-pretty-print">
$ adb shell dumpsys battery unplug
$ adb shell dumpsys deviceidle step</pre>

  <p>You may need to run the second command more than once. Repeat it until
  the device state changes to idle.</p>
  </li>

  <li> Observe the behavior of your app after you reactivate the device. Make
  sure the app recovers gracefully when the device exits Doze.
  </li>
</ol>

<h3 id="testing_your_app_with_app_standby">Testing your app with App Standby</h4>

<p>To test the App Standby mode with your app:</p>

<ol>
  <li> Configure a hardware device or virtual device with an Android 6.0 (API level
  23) or higher system image.
  </li>
  <li> Connect the device to your development machine and install your app.</li>
  <li> Run your app and leave it active.</li>
  <li> Force the app into App Standby mode by running the following commands:

  <pre class="no-pretty-print">$ adb shell dumpsys battery unplug
$ adb shell am set-inactive &lt;packageName&gt; true</pre>
  <li>Simulate waking your app using the following commands:

  <pre class="no-pretty-print">$ adb shell am set-inactive &lt;packageName&gt; false
$ adb shell am get-inactive &lt;packageName&gt;</pre>
  </li>
  <li>Observe the behavior of your app after waking it. Make sure the app recovers gracefully
    from standby mode. In particular, you should check if your app's Notifications and background
    jobs continue to function as expected.
  </li>
</ol>


<h2 id="whitelisting-cases">Example Use Cases for Whitelisting</h2>

<p>The table below highlights the acceptable use cases for requesting or being on
   the Battery Optimizations exceptions whitelist. In general, your app should not be on the
   whitelist unless Doze or App Standby break the core function of the app or there is a
   technical reason why your app cannot use GCM high-priority messages.</p>

   <p>For more information, see <a href="#support_for_other_use_cases">Support for Other Use Cases
   </a>.</p>

<table>
 <tr>
    <th>Type</td>
    <th>Use-case</td>
    <th>Can use GCM?</td>
    <th>Whitelisting acceptable?</td>
    <th>Notes</td>
 </tr>

 <tr>
    <td rowspan="2">Instant messaging, chat, or calling app. </td>
    <td rowspan="3">Requires delivery of real-time messages to users while device is in Doze or app
    is in App Standby.</td>
    <td>Yes, using GCM</td>
    <td rowspan="2" style="color:red">Not Acceptable</td>
    <td rowspan="2">Should use GCM high-priority messages to wake the app and access the network.</td>
 </tr>

 <tr>
    <td>Yes, but is not using GCM high-priority messages.</td>
 </tr>

 <tr>
    <td rowspan="1">Instant messaging, chat, or calling app;
    enterprise VOIP apps</td>
    <td>No, can not use GCM because of technical dependency on another messaging
    service or Doze and App Standby break the core function of the app.</td>
    <td style="color:green">Acceptable</td>
    <td></td>
 </tr>

</table>