GitCommitExtractor

This ComAnI plug-in realizes an extractor for extracting commits from Git repositories and providing them as input to a ComAnI analyzer. It supports the following extraction variants:

• Full repository extraction, which performs the extraction of all commits of a software repository. This requires the definition of the location of the target repository as part of the configuration file using the parameter extraction.input.
• Partial repository extraction, which performs the extraction of a predefined set of commits. Besides the location of the target repository, this requires the specification of an additional file, which contains a list of unique commit numbers, e.g., "b025911". Each line of this commit list file must contain exactly one commit number. Further, the author of the commit list file must ensure that the commit numbers specify commits of the target repository. The usage of a commit list file requires its definition in the configuration file as follows: extraction.commit_list = <path>/<to>/commitlist-file
• Single commit extraction, in which the content of a single commit can be passed on the command line as an input. Therefore, the infrastructure has to be executed using the -i option followed by the commit information, which is terminated by a last line containing the string “!q!”.

Depending on the extraction variant, this extractor executes the following Git commands:

• git log --oneline: Prints all commit numbers (SHAs)
• git show -s --format=%ci <SHA>: Prints the committer date for a particular commit; ; <SHA> will be replaced by a particular commit number, like "b025911"
• git show -U100000 --no-renames <SHA>: Prints the the entire commit information, the content of the changed files (100.000 lines of context including renamed files), and the changes to these files; <SHA> will be replaced by a particular commit number, like "b025911"

Main class name: net.ssehub.comani.extraction.git.GitCommitExtractor

Support:

• Operating system: all
• Version control system: “git”

For more information on how to use ComAnI and its plug-ins, we recommend reading the ComAnI Guide.

Installation

Download the GitCommitExtractor.jar file from the release directory and save it to the ComAnI plug-ins directory on your machine. This directory is the one specified as core.plugins_dir in the configuration file of a particular ComAnI instance.

Requirements:

• The ComAnI infrastructure has to be installed to execute this plug-in as the extractor of a particular ComAnI instance
• Git has to be installed and globally executable

Execution

This plug-in is not a standalone tool, but only executable as the extractor of a particular ComAnI instance. Therefore, it has to be defined in the configuration file via its fully qualified main class name as follows:

extraction.extractor = net.ssehub.comani.extraction.git.GitCommitExtractor

Plug-in-specific configuration parameter(s):

None

Single commit extraction:

The ComAnI infrastructure offers the single commit extraction as one of three different extraction variants (read the ComAnI Guide). When using the GitCommitExtractor, the required format of the string representing the single commit must be as illustrated by the following example:

commit 0123456789987654321001234567899876543210
Author: Some One <[email protected]>
Date:   Fri Mar 8 19:32:34 2019 -????

    A commit message.

diff --git a/some/path/readme.txt b/some/path/readme.txt
index 030745d5ab..504d71b4f5 100644
--- a/some/path/readme.txt
+++ b/some/path/readme.txt
@@ -1,5 +1,5 @@
 This repository hosts some files to check whether the GitCommitExtractor works as expected.
+These files neither represent a particular software nor do they have any relations.
-These files are only used for testing correct extraction of commits.

 This line was introduced on a new branch.
!q!

The example above shows the content of a commit as provided by the Git command git show –U100000 <SHA>, where <SHA> identifies the respective commit (the commit number). Note that the first line starts with commit <SHA>, which is required by the commit extractor to identify the commit id. If this line does not exist, the commit extractor throws an error and stops without further processing the given string.

The last line terminates the commit string as required by the infrastructure. This line must only contain !q!. All lines after this termination-string will be ignored.

License

This project is licensed under the Apache License 2.0.

Acknowledgments

This work is partially supported by the ITEA3 project REVaMP², funded by the BMBF (German Ministry of Research and Education) under grant 01IS16042H.

A special thanks goes to the developers of KernelHaven: Adam Krafczyk, Sascha El-Sharkawy, Moritz Flöter, Alice Schwarz, Kevin Stahr, Johannes Ude, Manuel Nedde, Malek Boukhari, and Marvin Forstreuter. Their architecture and core concepts significantly inspired the development of this project. In particular, the mechanisms for file-based configuration of the infrastructure and the plug-ins as well as loading and executing individual plug-ins are adopted in this work.