Adopt OpenJDK

Hackathon, 11 Dec. 2014

Agenda of the hackathon

Build OpenJDK

Improve OpenJDK

Write some tests

Create patch

Submit patch

Agenda of the hackathon

Build OpenJDK

Improve OpenJDK

Write some tests

Create patch

Submit patch

While building…

◦ Intro to OpenJDK

Let’s get it going

Import VM and login

Change to openjdk directory

cd $SOURCE_CODE/jdk9

Get the sources

bash get_sources.sh

Configure

bash configure

Make images

make clean images

OpenJDK overview

Free and open-source implementation of the Java Platform, Standard Edition

Base for the Oracle VM

GPL v2 for the VMs and GPL v2 + classpath exception for class libraries

Major contributors:◦ IBM

◦ Apple

◦ RedHat

◦ SAP

◦ A lot of JUGs

Why bother?

Move Java forward

Give back something to the platform

Help our JUG gain its own identity and

focus

Acquire new knowledge

Have some fun and socialize

How can we help?

Introductory level

◦ Fix compiler warnings

◦ Generify, coinify and labdify internal APIs

◦ Add new tests, convert existing tests

◦ Fix typos, add javadoc

Next level

◦ Affiliate with an existing project (Jigsaw,

Nashorn)

◦ Help with new stuff in project Valhalla

Development process

Sign OCA

Find interesting bug or enhancement

Discuss with sponsoring project

mailing list

Get together and create a patch

◦ Don’t forget the tests!

Upload the patch and contact ML

again

Be proud of yourself!

Task selection (1)

Add getStackTraceString() to Throwable

Usually people do:catch (MyException e) {

StringWriter sw = new StringWriter();e.printStackTrace(

new PrintWriter(sw));}

Look at existing solutions (Apache Commons)

https://bugs.openjdk.java.net/browse/JDK-5050783

Task selection (2)

Generic support to Collection bulk methods

addAll, containsAll, removeAll, retainAll can only receive other collections

You have to an intermediate Arrays.asList:

collection.addAll(Arrays.asList("a", "b", "c"));

Consider using default methods

https://bugs.openjdk.java.net/browse/JDK-6201180

Task selection (3)

Replace array parameters with

varargs

Look throughout all internal APIs

Supported since JDK 1.5

Discuss with Joe Darcy and team

https://bugs.openjdk.java.net/browse/J

DK-4974893

Write some tests

JTreg: the legacy◦ Java program with main method

◦ If test fails, testcase should throw an exception

◦ If it succeeds, testcase should return normally

/* @test

* @summary StringBuffer.isEmpty();

* @run main IsEmptyTest

*/

public class IsEmptyTest {

public static void main(String[] args) {

StringBuffer buffer = new StringBuffer();

if (!buffer.isEmpty()) {

throw new RuntimeException("StringBuffer isEmpty on newobject failed");

}

}

}

Test “docklets”

@test – defines a test. Mandatory.

@run – tells how to perform a test.

@summary – text description.

@library – reference library source files.

@build – compile class or library before running test

@bug – bug number reference

@key – keywords

TestNG support

TestNG is cool and nicely supported

TestNG test cases are run through jtreg

Two types of tests

Type 1◦ Describe the test in JTreg “docklets”

◦ No main method required/* @test

* @summary comments about your test;

* @run testng YourTest

*/

Type 2◦ Describe the test in TEST.ROOT or TESTS.properties

TestNG.dirs = .

othervm.dirs = tck/java/time/chronotest/java/time/chrono test/java/time/format

Create a patch

Let’s contribute

cd $SOURCE_CODE/jdk9

Commit in Mercurial

hg status

hg commit

Run webrev

ksh ../webrev.ksh

Upload to web server

$SOURCE_CODE/jdk9/webrev