This document contains advice about developing patches for Flume.
This document will be updated as more infrastructure is put in place.
Getting the source
- Check out the code using SVN. The repository's root lives here. Most development happens under the 'trunk' so this command line can be used.
svn co http://svn.apache.org/repos/asf/incubator/flume/trunk flume-trunk
Alternately if you prefer using git
git clone git://git.apache.org/flume
Contributing changes
- Before you start, describe your proposed changes and check that they fit in with what others are doing and have planned for the project. Be patient, it may take folks a while to understand your requirements. This can be done by
- subscribing and sending a message to the <dev-flume AT SPAMFREE incubator DOT apache DOT org> Flume developer mailing list.
- getting an account and filing an issue in the Apache Flume issue tracker JIRA.
- Alternately, if you are interested in contributing you can find an existing issue one to work on. If you are just starting, we'd suggest you pick an "Easy" issue
- Assign the issue to yourself in the JIRA. If you cannot, ask one of the project administrators to add you as a contributor.
- Make your changes. Almost all patches should include unit tests or modifications to unit tests. Big cross-cutting changes should be discussed ahead of time, some up front design documentation and consideration for backwards compatibility may be necessary.
- Make sure your changes pass the required code quality metrics (see below)
- Create a single commit containing all your changes and a descriptive commit message (what files/classes did you add/remove; what tests did you add; what functionality does this include; etc). If you made multiple commits during your development process, squash them down to a single commit patch.
- Create a patch with your changes and commit message information.
- You can use
svn stat
to see which files have been modified,svn add
to add the files for commit, and thensvn diff > FLUME-###.patch
to generate a patchfile. - You can use
git status
to see which files have been modified,git add
to add files for commit, and thengit format-patch
to generate a git patchfile.
- You can use
- Post patch to Reviewboard for code review. (see below)
- Upload patch to JIRA granting license to Apache and put link to specific code review to the in the comments.
- Update the issue in JIRA to reflect status "patch available".
- Iterate with revised changes, (usually formatting, correctness review as well as request for docs or follow on issues).
- When it's ready, a committer will push it to the repository and mark the issue as "Resolved/Fixed" in JIRA.
Code Quality
Code added to Flume should meet the following code quality metrics:
- Findbugs should pass with zero warnings. See COMPILING.txt (in the root of the source repository) for instructions on running Findbugs.
- All existing unit tests must pass. New unit tests must be added for all non-trivial improvements.
- Public classes, methods, constants, etc. must have Javadoc comments. Additional Javadoc comments are encouraged.
- Code should be formatted according to the "Java Code Conventions":http://java.sun.com/docs/codeconv/html/CodeConvTOC.doc.html
with the following exceptions:
- All whitespace should be spaces (no tabs).
- Indent by two spaces
- All files must start with the Apache license header block (see any existing source file).
- No gratuitous reformatting of code please.
- Please fix any "broken windows" in your neighborhood. If you're modifying an existing method that does not comply with these standards, please update the method.
/** Holds some example code formatting. */ class ExampleClass { /** Does some thing. * @param someArg you are encouraged to document arguments with @param. * @returns is also an encouraged metadata tag in public methods. */ public void someMethod(int someArg) { // Note two spaces indenting each time. No tabs! someMethodCall(this, has, many, args); // Four space indent here. if (someCondition) { // Use a space after 'if' and before '('. // Use complete sentences in comments. // Do not use /* .. */ for text comments. Only use //-comments. } else { // If and else blocks are always surrounded by { .. }. // (i.e., follow the One True Brace Style.) } } }
Reviewboard
We use reviewboard for code reviews. It is highly encouraged for all patches – patches submitted to reviewboard are easier to review and comment on. Our reviewboard server is at http://reviews.apache.org.
- Create a new account for yourself.
- Sign up for the "Flume" review group if you would like to receive email when new patches are posted. (Reviews are also posted to the flume-dev mailing list.)
- SVN:
- Create a new review. This requires creating a diff against the master branch and then uploading the patch. The patch base path should usually be
/
- The repository should be set to "flume".
- Add the group "flume" to the Reviewer Groups list (otherwise we won't see it).
- Describe your changes and the test plan you implemented and executed.
- Put the JIRA issue number (e.g., "FLUME-10") in the "bugs" list.
- Make sure to hit "Publish" when you're ready.
- Create a new review. This requires creating a diff against the master branch and then uploading the patch. The patch base path should usually be
- Git:
- Create a new review. This requires creating a diff against the master branch and then uploading the patch.
- The repository should be set to "flume-git".
- Add the group "flume" to the Reviewer Groups list (otherwise we won't see it).
- Describe your changes and the test plan you implemented and executed.
- Put the JIRA issue number (e.g., "FLUME-10") in the "bugs" list.
- Make sure to hit "Publish" when you're ready.
Instructions for Committers
TODO