SoC-2014-Microprojects.md

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default	SoC 2014 Applicant Microprojects	false

Introduction

It is strongly recommended that students who want to apply to the Git project for the Summer of Code 2014 submit a small code-related patch to the Git project as part of their application. Think of these microprojects as the "Hello, world" of getting involved with the Git project; the coding aspect of the change can be almost trivial, but to make the change the student has to become familiar with many of the practical aspects of working on the Git project.

NOTE: Students who plan to work on libgit2, which is also under the Git umbrella in the Google Summer of Code, should refer to the libgit2 list of projects rather than the list below.

Consider a sample email thread, which shows how a developer proposed a change and a patch to implement it. The problem being solved, the design of the proposed solution, and the implementation of that design were all reviewed and discussed, and after several iterations an improved version of the patch was accepted into our codebase. As a GSoC student, you will be playing the role of the developer and engaging in a similar discussion. Get familar with the flow, need for clarity on both sides (i.e. you need to clearly defend your design, and need to ask clarifications when questions/suggestions you are offered are not clear enough), the pace at which the discussion takes place, and the general tone of the discussion, to learn what is expected of you.

To complete a microproject, you will have to go through approximately the following steps:

• Download the source code: clone the repository using the Git via Git instructions and read the README file.

• Build the source code: this is described in the file INSTALL.

• Glance over our coding guidelines in the file Documentation/CodingGuidelines. We take things like proper code formatting very seriously.

• Read about the process for submitting patches to Git: this is described in Documentation/SubmittingPatches.

• Make the actual change. (Funny, this is the only part they teach you about in college.)

• Run the test suite and make sure it passes 100%: this is described in the file t/README. (If you have added new functionality, you should also add new tests, but most microprojects will not add new functionality.)

• Commit your change. Surprise: we use Git for that, so you will need to gain at least a basic familiarity with using Git. Make sure to write a good commit message that explains the reason for the change and any ramifications. Remember to make sure that you agree with our "Developer's Certificate of Origin" (whose text is contained in Documentation/SubmittingPatches), and to signify your agreement by adding a Signed-off-by line.

• Submit your change to the Git mailing list. For this step you probably want to use the commands git format-patch and git send-email. Make sure that your email is formatted correctly: send a test version of the email to yourself and see if you can apply it to your repository using git am.

• Expect feedback, criticism, suggestions, etc. from the mailing list.

  Respond to it! and follow up with improved versions of your change. Even for a trivial patch you shouldn't be surprised if it takes two or more iterations before your patch is accepted. This is the best part of participating in the Git community; it is your chance to get personalized instruction from very experienced peers!

The coding part of the microproject should be very small (say, 10-30 minutes). We don't require that your patch be accepted into master by the time of your formal application; we mostly want to see that you have a basic level of competence and especially the ability to interact with the other Git developers.

When you submit your patch, please mention that you plan to apply for the GSoC. This will ensure that we take special care not to overlook your application among the large pile of others.

Students: Please attempt only ONE microproject. We want quality, not quantity! (Also, it takes work to collect the ideas, and it would be nice to have enough microprojects for everybody.) If you've already done a microproject and are itching to do more, then get involved in other ways, like finding and fixing other problems in the code, or improving the documentation or code comments, or helping to review other people's patches on the mailing list, or answering questions on the mailing list or in IRC, or writing new tests, etc., etc. In short, start doing things that other Git developers do!

Ideas for microprojects

The following are just ideas. Any small code-related change would be suitable. Just remember to keep the change small! It is much better for you to finish a small but complete change than to try something too ambitious and not get it done.

1. Rewrite git-compat-util.h:skip_prefix() as a loop, so that it doesn't have to scan through the prefix string twice. taken

2. Change branch.c:install_branch_config() to use skip_prefix(). taken

3. In branch.c:setup_tracking(), figure out where the magic number 1024 - 7 - 7 - 1 comes from. (Looking through the commit history might help.) If the check involving the number is still necessary, document where the number comes from. If the check is no longer necessary, explain why and delete the check. taken

4. Rewrite bulk-checkin.c:finish_bulk_checkin() to use a strbuf for handling packname, and explain why this is useful. Also check if the first argument of pack-write.c:finish_tmp_packfile() can be made const. taken

5. Change bundle.c:add_to_ref_list() to use hashcpy(). See if you can find other places where hashcpy() should be used instead of memcpy(). taken

6. Change bundle.c:add_to_ref_list() to use ALLOC_GROW(). See if you can find other places that would benefit from a similar change. taken

7. Write a function strbuf_write_or_die() and use it instead of write_or_die(fd, buf.buf, buf.len) in all of the places you can find. taken (and it turns out that the mailing list didn't like this idea)

8. In branch.c:install_branch_config(), can the long chain of if statements be simplified? Would it make sense to make the code table-driven? Don't forget that the strangely-named function _() is used for internationalization and limits the possibility of gluing strings together. taken

9. Could commit.c:commit_graft_pos() use one of the general-purpose bisection functions like sha1_pos() or sha1_entry_pos()? Are there other places that could do so? taken

10. Rewrite commit.c:record_author_date() to use skip_prefix(). Are there other places in this file where skip_prefix() would be more readable than starts_with()? taken

11. Find places where we scan a string twice unnecessarily, once with strchr() and then with strlen(), and rewrite these sites using strchrnul() when appropriate. taken

12. Currently in order to disallow the --[no]-xxx form of a command-line option, we have to initialize the option's full struct option explicitly. It'd be nice to have a set of OPT_* macros with PARSE_OPT_NONEG set. Find and update all struct option [] declarations with the new macros (including ones that should never accept --no-xxx form, but do anyway). Not recommended. This is more a milliproject than a microproject, and the mailing list wasn't so enthusiastic about the idea anyway.

13. Rewrite diff-no-index.c:read_directory() to use is_dot_or_dotdot(). Try to find other sites that can use that function. solved

14. Change fetch-pack.c:filter_refs() to use starts_with() instead of memcmp(). Try to find other sites that could be rewritten similarly.

15. Rewrite fsck.c:fsck_commit() to use starts_with() and/or skip_prefix().

16. Rewrite builtin/add.c:run_add_interactive() to use struct argv_array. taken

17. Find one or more bugs, inefficiencies, or unconventional code patterns in builtin/apply.c:fuzzy_matchlines() and fix them. (There are enough microprojects in this function for several students.)

18. "VAR=VAL command" is sufficient to run 'command' with environment variable VAR set to value VAL without affecting the environment of the shell itself. But the same does not work with a shell function (most notably, "test_must_fail"). So, in our test suite, we implement subshell invocations in multiple lines like this:

    ... &&
    (
            VAR=VAL &&
            export VAR &&
            test_must_fail git command
    ) &&
    ...
    

    But that could be expressed as

    ... &&
    test_must_fail env VAR=VAL git command &&
    ...
    

    Find and shorten such constructs in existing test scripts. solved