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"64k out to be enough for anyone"
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Michael Evans
October 29, 2014
Technology
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"64k out to be enough for anyone"
64k method limit talk @ DC Droids meetup
Michael Evans
October 29, 2014
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Transcript
Mike Evans LivingSocial @m_evans10
“640K ought to be enough for anybody.”
–Dalvik Developers “64K ought to be enough for anybody.”
Dalvik?
Dalvik?
Dalvik The VM that runs Android. Optimized for mobile devices.
Java/Scala/Clojure/etc Compiler (.jar) .class files JAVA ARCHITECTURE
.class files classes.dex Java/Scala/Clojure/etc Compiler dex (.apk) ANDROID ARCHITECTURE
Java/Scala/Clojure/etc Compiler dex optimizer (odex) zipalign proguard ANDROID ARCHITECTURE classes.dex
(.apk) .class files
Okay…what’s the problem?
Unable to execute dex: method ID not in [0, 0xffff]:
65536 ! Conversion to Dalvik format failed: Unable to execute dex: method ID not in [0, 0xffff]: 65536 PROBLEM:
https://source.android.com/devices/tech/dalvik/dex-format.html public final class IndexMap { … public final short[]
typeIds; public final short[] protoIds; public final short[] fieldIds; public final short[] methodIds; …
So what can we do?
SOLUTION #0:
ART? SOLUTION #1:
SOLUTION #2: Proguard Java class file shrinker, optimizer and obfuscator
! Detects and removes unused classes, fields, methods and attributes
SOLUTION #3: Refactor code so that code can be isolated
into 2nd dex Modify classpath during runtime Allow access to methods via reflection ! Facebook did this in 2011 Secondary DEX file
SOLUTION #3: Secondary DEX file Refactor code so that code
can be isolated into 2nd dex Modify classpath during runtime Allow access to methods via reflection ! Facebook did this in 2011
MultiDexApplication BRAND NEW
MultiDexApplication Native in Lollipop ! Part of support library (all
the way to Donut!) ! Not supported officially in developer tools…yet BRAND NEW
an egregious hack
a clever solution an egregious hack
None
$ ./dex-method-counts LivingSocial.apk ! Read in 65490 method IDs. <root>:
65490 : 3 android: 6837 accessibilityservice: 6 bluetooth: 2 … https://github.com/mihaip/dex-method-counts
GPS: 14K methods - collections, caching, primitives support, concurrency libraries,
common annotations, string processing, I/O, and so forth. 23k methods - Basically all of Google’s services. You’ll have a hard time making a compelling app that lives in the Google Play ecosystem without it. GUAVA:
$ gradle app:dependencies —configuration “compile” ! compile - Classpath for
compiling the main sources. +--- com.squareup.picasso:picasso:2.3.3 +--- com.jakewharton:butterknife:5.1.2 +--- com.squareup.retrofit:retrofit:1.6.1 | \--- com.google.code.gson:gson:2.2.4 -> 2.3 \--- de.hdodenhof:circleimageview:1.2.0 … ! BUILD SUCCESSFUL GUAVA:
ads analytics cast auth drive games push location maps wallet
wearable … A clever way for Google to provide support for its many services APIs, all the way back to Gingerbread Google Play Services: {
GAMES DRIVE ADS CAST
https://gist.github.com/MichaelEvans/71150c93577de6f5ab0a Custom Gradle Task - After compilation of .class files
Unzip the original google-play-services rm [plus|games|drive|cast] re-zip a new jar Inject new jar into dependency tree ??? Profit
$ ./dex-method-counts LivingSocial.apk ! Read in 40364 method IDs. <root>:
40364 : 3 android: 6837 accessibilityservice: 6 bluetooth: 2 …
Questions?