Stats plugin sample

This plugin allows to compute statistics about the types, fields and methods that are processed during the compilation.

This plugin introduces the following concepts of Jack:

• Plugin
• Schedulables
• Features
• Properties
• Statistics
• Tracer

Fetch the code

This plugin is hosted in the Jack development branch in AOSP. You can follow the instructions at http://source.android.com/source/downloading.html to setup your machine then execute the following commands

mkdir <jack_project_dir>
cd <jack_project_dir>
repo init -u https://android.googlesource.com/platform/manifest -b ub-jack
repo sync

where <jack_project_dir> is the directory where you want to download the Jack repository.

Build the plugin

First you need to initialize the plugin's local dependencies with the following commands

cd toolchain/jack
ant dist
cd jack-samples
ant

Then you can build the plugin using Gradle with the following commands

cd jack-stats-plugin
./gradlew

The plugin .jar file is located at build/libs/jack-stats-plugin.jar.

Execute the plugin

The plugin's name is com.android.jack.sample.stats.StatsPlugin. Here is an example of command-line to compile source files with this plugin.

java -jar dist/jack.jar
 --pluginpath jack-samples/jack-stats-plugin/build/libs/jack-stats-plugin.jar
 --plugin com.android.jack.sample.stats.StatsPlugin
 -D sched.tracer=stat-only
 -D sched.tracer.file=<stats_output_file>
 -D sched.tracer.format=text
 --output-dex=<dex_dir> <source_files>

where

• <stats_output_file> is the file where all statistics will be written into
• <dex_dir> is the directory where the classes.dex file is generated
• <source_files> are the source files to be compiled.

By default, the plugin will process types (classes or interfaces), fields and methods. It is possible to select them individually using the following properties:

• jack.sample.stats.class: enables/disables statistics about types
• jack.sample.stats.field: enables/disables statistics about fields
• jack.sample.stats.method: enables/disables statistics about methods

It is also possible to generate the statistics file in JSON. Simply change the value of the property sched.tracer.format=json in the previous command-line.

You can take a look at the Jack's command-line usage with

java -jar dist/jack.jar --help

You can also take a look at the list of Jack properties, including the ones from this plugin, with

java -jar dist/jack.jar
 --pluginpath jack-samples/jack-stats-plugin/build/libs/jack-stats-plugin.jar
 --plugin com.android.jack.sample.stats.StatsPlugin
 --help-properties

Tracer

The com.android.sched.util.log.Tracer interface is used to update statistics during the compilation.

At the end of the compilation, it generates an HTML report (index.html file) of these statistics in the directory provided by the --tracer-dir <tracer_dir> option of the Jack command-line.

In this report, you can look for the statistics of the plugin, prefixed by:

• jack.sample.stats.class.<...> for statistics about classes
• jack.sample.stats.field.<...> for statistics about fields
• jack.sample.stats.method.<...> for statistics about methods