docs/html/preview/features/power-mgmt.jd

page.title=Power-Saving Optimizations
page.keywords=preview,sdk,compatibility
sdk.platform.apiLevel=MNC
@jd:body

<div id="qv-wrapper">
<div id="qv">

<h2>In this document</h2>

<ol  class="hide-nested">
    <li><a href="#behavior-doze">Doze</a></li>
    <li><a href="#behavior-app-standby">App Standby</a></li>
</ol>

<h2>API Differences</h2>
<ol>
<li><a href="{@docRoot}preview/download.html">API level 22 to M Preview &raquo;</a> </li>
</ol>


<h2>See Also</h2>
<ol>
<li><a href="{@docRoot}preview/api-overview.html">M Developer Preview API Overview</a> </li>
</ol>

</div>
</div>

<p>Android M Preview helps prolong battery life by introducing new power-saving optimizations:
<em>Doze</em> mode improves the sleep efficiency of idle devices. <em>App Standby</em> prevents apps
from eating up power while idle.</p>

<h2 id="behavior-doze">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. Doze attempts to keep the system in a sleep state as long as the
device remains undisturbed. In this mode, devices periodically resume normal operations for brief periods of time so that the system can perform app syncing and any other pending operations.</p>

<p>The following restrictions apply to your apps while in Doze:</p>
<ul>
<li>Network access is disabled, unless your app receives a high-priority
<a href="https://developers.google.com/cloud-messaging/" class="external-link">
Google Cloud Messaging</a> tickle.</li>
<li>The system ignores <a href="{@docRoot}reference/android/os/PowerManager.WakeLock.html">
Wake locks</a>.</li>
<li>Alarms scheduled using the {@link android.app.AlarmManager} class are deferred, unless you have
exempted them using the
{@link android.app.AlarmManager#setAndAllowWhileIdle setAndAllowWhileIdle()} method.</li>
<li>The system does not perform Wi-Fi scans.</li>
<li>The system does not permit syncs or jobs for your sync adapters.</li>
<li>The system does not allow {@link android.app.job.JobScheduler} to run.</li>
</ul>
</p>
<p>When the device exits Doze mode, it executes any jobs and syncs that are pending.</p>

<h3>Testing apps with Doze</h3>

<p>You can test Doze mode by connecting your development host to a device running the M Preview,
and calling the following commands:
</p>
<pre class="no-prettyprint">
$ adb shell dumpsys battery unplug
$ adb shell dumpsys deviceidle step
$ adb shell dumpsys deviceidle -h
</pre>
<p class="note"><strong>Note</strong>: As of M Preview 3 release,
<a href="https://developers.google.com/cloud-messaging/" class="external-link">
Google Cloud Messaging</a> (GCM) lets you designate
<a href="https://developers.google.com/cloud-messaging/downstream#setting-the-priority-of-a-message">
high-priority messages</a>. If your app receives a high-priority GCM message</a>, the system grants
brief network access even when the device is dozing.
</p>

<p>See the
<a href="{@docRoot}preview/testing/guide.html#doze-standby">Testing Guide</a> for tips on how
to test Doze in your apps. </p>

<h2 id="behavior-app-standby">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>
<li>The user explicitly asks for the app to be exempt from optimizations,
via the Settings app.</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>

<h3>Testing apps with App Standby</h3>
<p>You can test App Standby by connecting your development host to a device running the M Preview,
and calling the following commands:
</p>
<pre class="no-prettyprint">
$ adb shell dumpsys battery unplug
$ adb shell am set-idle &lt;packageName&gt; true
$ adb shell am set-idle &lt;packageName&gt; false
$ adb shell am get-idle &lt;packageName&gt;
</pre>

<p class="note"><strong>Note</strong>:
As of M Preview 3 release,
<a href="https://developers.google.com/cloud-messaging/" class="external-link">
Google Cloud Messaging</a> (GCM) lets you
designate
<a href="https://developers.google.com/cloud-messaging/downstream#setting-the-priority-of-a-message">
high-priority messages</a>. If your app receives high-priority GCM messages, the system grants
brief network access even when the app is idle.
</p>

<p>See the
<a href="{@docRoot}preview/testing/guide.html#doze-standby">Testing Guide</a> for tips on how
to test App Standby in your apps. </p>