Challenges of Building HTC Sense (O'Reilly Android Open Conference 2011)

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Challenges of Building HTC Sense David Wu [email protected] O’Reilly Android Open Conference 2011 October 11, 2011 HTC Proprietary and Confidential – Internal use and strategic partner use only © 2010 HTC Corporation. All rights reserved.

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HTC Proprietary and Confidential 4 H , I’m D v d F l o @w m n

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HTC Proprietary and Confidential 9 Agenda •  Social Features in HTC Sense •  Challenge 1 - Seamlessness •  Challenge 2 – Sync •  Challenge 3 – Performance

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H C S n e HTC Proprietary and Confidential 10

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HTC Proprietary and Confidential 12 H C S n e

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HTC Proprietary and Confidential 13 S o k A d o d

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S c a E p r e c HTC Proprietary and Confidential 15

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C n a t S c a U d t s

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HTC Proprietary and Confidential 20 F i n C a n l

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HTC Proprietary and Confidential 21 F i n S r a

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HTC Proprietary and Confidential 22 S c a L c s r e

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HTC Proprietary and Confidential 23 S c a C o k

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HTC Proprietary and Confidential 24 S c a C l n a

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HTC Proprietary and Confidential 26 Agenda •  Social Features in HTC Sense •  Challenge 1 - Seamlessness •  Challenge 2 – Sync •  Challenge 3 – Performance

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S a l s n s HTC Proprietary and Confidential 27

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Host Host HTC Proprietary and Confidential 28 Host Plugin Plugin Plugin Query Request •  Aggregated data retrieval •  UI rendering •  Refresh •  Load more

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HTC Proprietary and Confidential 29 Broadcast Intent and Class Loading •  Request with callback: •  Host broadcast Intents •  Plugin registers an IntentReceiver •  Query: •  Dynamic class loading T y #1

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HTC Proprietary and Confidential 30 Problems •  Broadcast Intent problems: •  Overhead in receiving the Broadcast Intent •  Difficult synchronization between requests coming from different hosts •  Dynamic class loading problems: •  Host and plugins require the same UID •  Huge performance penalty due to dynamic class loading via Java Reflection •  Fat host processes •  Debugging difficulty •  Unintuitive control code for dynamic content filtering

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HTC Proprietary and Confidential 31 Binder IPC and ContentProvider •  Request with callback: •  Remote binder call with callback mechanism •  Query: •  ContentProvider with ContentObserver •  Standardized data types •  Limited UI rendering with markup languages T y #2

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HTC Proprietary and Confidential 32 Problems •  Database access performance issues •  Schema optimization via indexing •  Query optimization •  Prepared statements •  Transactions •  Reduce disk I/O by implementing a memcache layer •  Multiple ContentObservers may make the system unusually busy •  Use dirty flag and do lazy requery

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S n HTC Proprietary and Confidential 33

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HTC Proprietary and Confidential 34 Problems with Background Sync •  Bandwidth usage •  Battery usage

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HTC Proprietary and Confidential 35 Important Problem with Trade-Off Solutions •  Can’t disclose actual sales numbers, but to put things in perspective: •  2 out of every 5 Android phones sold is an HTC •  1 out of every 2 Windows phones sold is an HTC •  Every 0.68 sec there is a new HTC phone activated •  Who cares? •  Network operators •  Online services •  Users

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HTC Proprietary and Confidential 36 Improving Bandwidth and Battery Usage •  Monitor device states •  Partial sync •  Smart sync

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HTC Proprietary and Confidential 37 Monitoring Device States •  Network connectivity •  Online vs. Offline •  Roaming vs. Not Roaming •  WiFi vs. GPRS/EDGE •  Battery level •  Storage capacity •  The less free space left, the higher the disk latency •  AlarmManager intervals •  Best interval (sleep) vs. Minimum interval (wakeup) •  Check out Reto Meier’s “Android Protips” session at Google I/O 2011

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HTC Proprietary and Confidential 38 Partial Sync •  Sync only important data •  Only contacts explicitly marked as “favorite” or with frequent interactivities

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HTC Proprietary and Confidential 39 Partial Sync •  Sync only important data •  Only contacts explicitly marked as “favorite” or with frequent interactivities •  Only a limited number of most recent stream posts Current time

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HTC Proprietary and Confidential 40 Partial Sync •  Sync only important data •  Only contacts explicitly marked as “favorite” or with frequent interactivities •  Only a limited number of most recent stream posts Current time

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HTC Proprietary and Confidential 41 Partial Sync •  Sync only important data •  Only contacts explicitly marked as “favorite” or with frequent interactivities •  Only a limited number of most recent stream posts Current time Current time

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HTC Proprietary and Confidential 42 Partial Sync •  Avoid fetching or writing the same data more than once •  Use hash to speed up data comparisons

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HTC Proprietary and Confidential 43 Partial Sync •  Avoid fetching or writing the same data more than once •  Use hash to speed up data comparisons •  Deep integration with native clients •  Facebook vs. Facebook for HTC Sense

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HTC Proprietary and Confidential 44 Smart Sync •  Use application heuristics •  Sync if and only if •  At least one widget is installed on the Home screen •  It has been at least one hour since the last sync •  Do not sync if historically the stream timeline has sparse data

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P r o m n e HTC Proprietary and Confidential 45

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HTC Proprietary and Confidential 46 Outline for Improving Performance •  Aggregated content retrieval from multiple data sources •  Improving application launch time •  Scrolling performance •  General coding practices

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HTC Proprietary and Confidential 47 Aggregated Content Retrieval Host Host Application Data Source Data Source Data Source Sorted

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HTC Proprietary and Confidential 48 Aggregated Content Retrieval •  Aggregated content retrieval from multiple data sources •  Quick sort •  Need all content to be in memory •  Long startup delay

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HTC Proprietary and Confidential 49 Aggregated Content Retrieval •  Aggregated content retrieval from multiple data sources •  Quick sort •  Need all content to be in memory •  Long startup delay •  Merge sort •  Make use of SQLite indexed sorting capability •  Maintain a min/max heap and a set of position markers for each data source •  Minimal startup delay •  Amortized sorting cost, which is barely noticeable

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HTC Proprietary and Confidential 50 Aggregated Content Retrieval •  Aggregated content retrieval from multiple data sources •  Quick sort •  Need all content to be in memory •  Long startup delay •  Merge sort •  Make use of SQLite indexed sorting capability •  Maintain a min/max heap and a set of position markers for each data source •  Minimal startup delay •  Amortized sorting cost, which is barely noticeable •  Reduces application launch time from 1800ms to 600ms in FriendStream

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HTC Proprietary and Confidential 51 Aggregated Content Retrieval •  Aggregated content retrieval from multiple data sources •  Quick sort •  Need all content to be in memory •  Long startup delay •  Merge sort •  Make use of SQLite indexed sorting capability •  Maintain a min/max heap and a set of position markers for each data source •  Minimal startup delay •  Amortized sorting cost, which is barely noticeable •  Reduces application launch time from 1800ms to 600ms in FriendStream •  Same technique used in Contacts, Messages, Calendar, etc.

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HTC Proprietary and Confidential 52 Outline for Improving Performance •  Aggregated content retrieval from multiple data sources •  Improving application launch time •  Scrolling performance •  General coding practices

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HTC Proprietary and Confidential 53 Application Launch Times •  Perceived launch time (fake screen) • android:windowBackground=“@drawable/fakebg”!

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HTC Proprietary and Confidential 54 Application Launch Times •  Perceived launch time (fake screen) • android:windowBackground=“@drawable/fakebg”! • getWindow().setBackgroundDrawable(null);!

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HTC Proprietary and Confidential 55 Application Launch Times •  Perceived launch time (fake screen) • android:windowBackground=“@drawable/fakebg”! • getWindow().setBackgroundDrawable(null);! •  Reduce layout complexity

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HTC Proprietary and Confidential 56 Application Launch Times •  Perceived launch time (fake screen) • android:windowBackground=“@drawable/fakebg”! • getWindow().setBackgroundDrawable(null);! •  Reduce layout complexity •  Optimize database query •  Minimize fillWindow time •  Only select columns that are needed •  Use limits •  Profile SQLite queries

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HTC Proprietary and Confidential 57 Prepared Statements •  Precompiling frequently used SQL statements String sql = “INSERT INTO table VALUES (?, ?)”;! SQLiteStatement stmt = mDatabase.compileStatement(sql);! ! DatabaseUtils.bindObjectToProgram(stmt, 1, 1);! DatabaseUtils.bindObjectToProgram(stmt, 2, 2);! ! stmt.execute();! stmt.close();!

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HTC Proprietary and Confidential 58 Outline for Improving Performance •  Aggregated content retrieval from multiple data sources •  Improving application launch time •  Perceived launch time •  Database query optimization •  Prepared statements •  Transactions •  Scrolling performance •  General coding practices

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HTC Proprietary and Confidential 59 Improve Scrolling Performance •  Minimize getView() and draw() •  Check your ListAdapter.getView() •  Use convertViews •  Cache findViewById() results •  Do not set a Window background •  Avoid runtime scaling of images •  Reuse byte buffer in BitmapFactory.decodeStream() to avoid unnecessary GC

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HTC Proprietary and Confidential 60 Outline for Improving Performance •  Aggregated content retrieval from multiple data sources •  Improving application launch time •  Perceived launch time •  Database query optimization •  Prepared statements •  Transactions •  Scrolling performance •  General coding practices

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HTC Proprietary and Confidential 61 General Coding Tips •  Use System.arraycopy • for (int i = 0; i

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HTC Proprietary and Confidential 62 General Coding Tips •  Use System.arraycopy • for (int i = 0; i

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HTC Proprietary and Confidential 63 General Coding Tips •  Use System.arraycopy • for (int i = 0; i

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HTC Proprietary and Confidential 64 D v d W @w m n d v d@w -m n.c m b o .w -m n.c m

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