android lollipop internals and inferiority complex droidcon.hr 2015
TRANSCRIPT
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Android Lollipop Internalsand our inferiority complex
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+AleksanderPiotrowski@pelotasplus
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About presentation
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Inferiority complex
● mine but maybe yours as well?● gets better with each PR or a talk● … or look taken at others code
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History
● originally as “What’s new in Lollipop”● about new APIs● how it works under the hood● the devil is in the detail
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What to look for
● technical information - a bit● motivation - hopefully lot more
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Disclaimer
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Disclaimer
● nothing against the Google● actually make a living thanks to their
technologies
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Disclaimer
● don’t want to diminish their achievements● or suggest anything bad about their devs
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Disclaimer
● have never been recruited by them
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The APIs arms race
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The APIs arms race
● each new release thousands new APIs● iOS 8 includes over 4,000 new APIs● thousands of new Material Designs or new
Bluetooth stacks?
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The APIs arms race
● the more, the better● … or just a marketing?
● Android Weekly pressure ;-)
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Lollipop
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Significant changes
● Material Design
● WebView updated via Play Store
● FDE
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Significant changes
● Bluetooth stack changes
● Android Work/Multi-user - BYOD
● JobScheduler API
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One random change
● new package android.util.Range● immutable range
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android.util.Range
● check if a value is in a range● check if ranges are equal● get lower/upper values● intersect two ranges
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Range::contains(value)public boolean contains(T value) {
checkNotNull(value, "value must not be null");
boolean gteLower = value.compareTo(mLower) >= 0;
boolean lteUpper = value.compareTo(mUpper) <= 0;
return gteLower && lteUpper;
}
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The Projects
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Project Butter
● in JellyBean
● smoother UI60fps
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Other projects
● Svelte in KitKatrunning low-end on deviceswith 512MB or less
● Pi ;-)Google as a telecom
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Project Volta
● improve battery life
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Project Volta
● at platform level● at developers level● at users level
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Project Volta
● ART runtime● JobScheduler API and Battery Historian● Battery Saver
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JobScheduler API
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JobScheduler
Our App
Task
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JobInfo.Builder builder = new JobInfo.Builder(jobId, serviceComponent) .setMinimumLatency(4000) .setOverrideDeadline(5000) .setRequiredNetworkType( JobInfo.NETWORK_TYPE_UNMETERED) .setRequiresCharging(true) .setPersisted(true);JobInfo jobInfo = builder.build();
constraints
our task
task is now a job
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JobScheduler
Our App JobInfo
JobInfo.Builder
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JobScheduler
Our App JobInfo
JobInfo.Builder schedule()Job
Scheduler
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JobScheduler
SystemService
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JobScheduler
SystemService
BatteryService
android.content.Intent#ACTION_BATTERY_CHANGED
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JobScheduler
SystemService
BatteryService
android.content.Intent#ACTION_BATTERY_CHANGED
WebViewUpdateService
android.content.Intent #ACTION_PACKAGE_REPLACED
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JobScheduler
JobScheduler
JobInfo
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JobScheduler
JobScheduler
#1
JobInfo
#2
JobInfo
#3
JobInfo
/data/system/job/jobs.xml
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JobScheduler
JobScheduler
#1
JobInfo
#2
JobInfo
#3
JobInfo
/data/system/job/jobs.xml
Battery TimeNetwork ***
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BatteryControllerpublic class ChargingTracker extends BroadcastReceiver { private final AlarmManager mAlarm; private final PendingIntent mStableChargingTriggerIntent;
[...]
@Override public void onReceive(Context context, Intent intent) { onReceiveInternal(intent); }}
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BatteryControllerpublic void startTracking() { IntentFilter filter = new IntentFilter();
// Battery health. filter.addAction(Intent.ACTION_BATTERY_LOW); filter.addAction(Intent.ACTION_BATTERY_OKAY); // Charging/not charging. filter.addAction(Intent.ACTION_POWER_CONNECTED); filter.addAction(Intent.ACTION_POWER_DISCONNECTED); // Charging stable. filter.addAction(ACTION_CHARGING_STABLE); mContext.registerReceiver(this, filter);
[...]}
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BatteryControllerpublic void onReceiveInternal(Intent intent) { final String action = intent.getAction(); if (Intent.ACTION_BATTERY_LOW.equals(action)) { [...] // If we get this action, the battery is discharging => it isn't plugged in so // there's no work to cancel. We track this variable for the case where it is // charging, but hasn't been for long enough to be healthy.
mBatteryHealthy = false; } else if (Intent.ACTION_BATTERY_OKAY.equals(action)) { [...] mBatteryHealthy = true; maybeReportNewChargingState(); } [...]}
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JobSchedulerCompat
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JobSchedulerFacebook
Google+
Ebay
JobScheduler
Service
System Service
Job
Battery
Time
Network
***
JobInfo
JobInfo
JobInfo
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JobSchedulerCompatFacebook
Google+
Ebay
Battery
Time
Network
***
JobInfo
JobInfo
JobScheduler
Service
JobScheduler
Service
JobScheduler
Service
JobInfo Battery
Time
Network
***
System Service
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The Idle mode
***
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https://www.youtube.com/watch?v=KzSKIpJepUw
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Idle mode
system has determinedthat phone is not being usedand is not likely to be used
anytime soon
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Idle mode example
Job criteria:idle state + charging
When:at night, when the phone is next to your bed
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Digression #1Many Googles
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Many Googles
● not the same Google for every one of us● different search results● different ads● fine-grained targeting of contents
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Almost there...
● strong technology marketingvideos, blog posts, APIs arms race
● bold statements about possibilitiesidle state, at night, next to the bed
● proven track recordsearch and ads tailored to our behaviour
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The idle state algorithmor is it “idle”?
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// Policy: we decide that we're "idle" if the device has been unused /// screen off or dreaming for at least this longprivate static final long INACTIVITY_IDLE_THRESHOLD = 71 * 60 * 1000;// millis; 71 min
private static final long IDLE_WINDOW_SLOP = 5 * 60 * 1000;// 5 minute window, to be nice
quotes are here ;-)
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The “idle” state algorithm
1. display turns off2. start the timer for 71 minutes +/- 5 minutes3. alarm goes off4. if screen still turned off
we are in the idle state
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@Overridepublic void onReceive(Context context, Intent intent) { final String action = intent.getAction();
if (action.equals(Intent.ACTION_SCREEN_ON) || action.equals(Intent.ACTION_DREAMING_STOPPED)) { // possible transition to not-idle if (mIdle) { [...] mAlarm.cancel(mIdleTriggerIntent); mIdle = false; reportNewIdleState(mIdle); } [...]
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@Overridepublic void onReceive(Context context, Intent intent) { final String action = intent.getAction();
[...]
} else if (action.equals(Intent.ACTION_SCREEN_OFF) || action.equals(Intent.ACTION_DREAMING_STARTED)) { // when the screen goes off or dreaming starts, we schedule the // alarm that will tell us when we have decided the device is // truly idle. final long nowElapsed = SystemClock.elapsedRealtime(); final long when = nowElapsed + INACTIVITY_IDLE_THRESHOLD; if (DEBUG) { Slog.v(TAG, "Scheduling idle : " + action + " now:" + nowElapsed + " when=" + when); } mAlarm.setWindow(AlarmManager.ELAPSED_REALTIME_WAKEUP, when, IDLE_WINDOW_SLOP, mIdleTriggerIntent); }
[...]
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@Overridepublic void onReceive(Context context, Intent intent) { final String action = intent.getAction();
[...]
} else if (action.equals(ACTION_TRIGGER_IDLE)) { // idle time starts now if (!mIdle) { if (DEBUG) { Slog.v(TAG, "Idle trigger fired @ " + SystemClock.elapsedRealtime()); } mIdle = true; reportNewIdleState(mIdle); } }}
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The “idle” state algorithm
● time is not a factorat night
● sensors not usedlying next to the bed
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The “idle” state algorithm
● display the only factorhow long is being turned off
● not tuned per usersame for everyonenot based on our own behaviour
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The “idle” state algorithm
● random 71 minutesor maybe there is some magic here?
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Takeaways
● don’t be afraid to look at the codenot a rocket science therecan cure from inferiority complex
● write code to get betterit always sucks with the first versiongets better which each commit or PR
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Thanks
● droidcon Zagreb
● YOU <3for attending my talkand others too ;-)