open_source.md

Navigating and Contributing to Large-Scale Open Source Projects

Beth Dakin, Apple

• Overview of the WebKit Code
• Getting Involved
  • Early Contributions
    • Report (good) bugs
      • The Anatomy of a Good Bug Report
    • Create reduced test cases
    • Track down regressions
    • Write test cases
  • Contributing Patches
    • Walk before you run
    • A patch is just the beginning
    • Communication is key
    • Add a test with your patch!

Overview of the WebKit Code

Stack:

• WebKit and WebKit2
• WebCore
  • Load, render, and interact with a webpage
  • The largest section
• JavaScriptCore
  • Compilers, garbage collection, JS as a language
• WTF
  • Lists, sets, etc.
• bmalloc

Clang and Swift → LLVM Optimizer → LLVM Code Generator → exec ↔ compiler-rt

Getting Involved

Early Contributions

Report (good) bugs

• Test against the latest version of software
• Safari Technology Preview (STP) – put out every two weeks

The Anatomy of a Good Bug Report

• Clear description of the problem
  • "Safari crashes in WebPage::dictionaryPopupInfo() clicking the comment button at http://mysneakywebsite.com/blog"
• Include the version of the browser and OS
• Series of steps that anyone can follow to reproduce the problem
• Description of expected and actual behavior
• Crash log (if applicable)

Create reduced test cases

A web page or small program that reduces the bug!

Track down regressions

Go to nightly builds and find when the bug occurred.

Write test cases

Tests are important!

Contributing Patches

Walk before you run

• Keywords or labels: GoodFirstBug, StarterBug, etc.
• Email or IRC
• Find the right people!

A patch is just the beginning

Code reviews, continuous integration, etc.

Communication is key

Get on IRC, chat rooms, etc.

Add a test with your patch!

The best way to show that you've fixed the bug :)