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Statistics tool for git repositories

Project description

Git Hammer

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NOTE: If you have been using Git Hammer prior to December 4th, 2019, your database is obsolete, and unfortunately you will need to rebuild it if you want to use the current version. This is because a necessary change in the database schema could not be automatically migrated from the old version. Git Hammer has now been set up to support database migrations better, and this situation hopefully won't happen again. My apologies for the inconvenience.

Git Hammer is a statistics tool for projects in git repositories. Its major feature is tracking the number of lines authored by each person for every commit, but it currently includes some other useful statistics as well, and the data that it collects could be used in multiple new ways as well.

Git Hammer is under active maintenance. New features appear when a need or desire for them exists. If Git Hammer lacks some feature you would like, all kinds of contributions are welcome, from simple feature suggestions to complete pull requests implementing the feature.


By default, Git Hammer stores the historical information from the repository in an SQLite database file in the current directory. If you wish to change this default, set the DATABASE_URL environment variable to a database URL according to the SQLAlchemy engine documentation. This database will be created if it does not already exist. Note that if you wish to use a database other than SQLite, you may need to install the appropriate Python module to connect to the database.

You will need Python 3, at least version 3.5. It is a good idea to set up a virtual environment, like this (run this wherever you have cloned Git Hammer):

python3 -m venv venv
source venv/bin/activate
pip install -r requirements.txt

The rest of the commands below assume that this has been done.

Creating a Project

Now pick some git repository to run Git Hammer on. The examples below use a hypothetical project called "baffle". You should replace the name with your own.

python -m githammer init-project baffle ~/projects/baffle

This will create the database containing the project baffle from the repository directory (here ~/projects/baffle; replace that with the path to your repository). Git Hammer will print out a progress report while it goes through all the commits in the repository.

(Incidentally, you should make sure that the main development branch is the one checked out in the repository. Currently, using Git Hammer really doesn't make sense otherwise.)

When the repository gets new development, first update the code in the repository to the latest version, and then run

python -m githammer update-project baffle

This will process all the new commits that were not yet seen into the database.

Showing Statistics

After the project has been initialized and the repository added, you can show some information on it. First try out

python -m githammer summary baffle

This will print out three tables: The number of commits for each person, the number of lines of code written by each person in the head version, and the number of tests written by each person in the head version. This last is only printed if the repository configuration includes test recognition (see below).

There are a few graphs that Git Hammer can display. To see the types of supported graphs, enter

python -m githammer graph --help

The graphs are

Type Description
line-count Number of lines in the project over time
line-author-count Same as above, except split per author
test-count Number of tests in the project over time
test-author-count Same as above, except split per author
day-of-week A histogram showing the number of commits for each day of the week
time-of-day A histogram showing the number of commits for each hour of the day

Configuring Sources and Tests

By default, Git Hammer assumes that every file in the repository is a source file and that there are no tests. This can be modified by creating a configuration file. The configuration file is JSON having some predefined keys:

  "sourceFiles": [
  "excludedSourceFiles": [
  "testFiles": [
  "testLineRegex": "def test_"

Here, sourceFiles is a list of patterns that match the source files. Any file not matching one of these patterns is not considered by Git Hammer. If sourceFiles captures too many files, for instance autogenerated sources, excludedSourceFiles is a list of patterns that will not be considered source even if they match some sourceFiles pattern.

To include test counts, testFiles needs to be specified. This is again, a list of patterns matching files that contain tests (it is up to you if you wish to define this to mean unit tests, integration tests, UI tests, etc.). Git Hammer will look inside each of the test files. Any line matching the Python regular expression testLineRegex is counted as one test. So testLineRegex should typically match whatever acts as the header of a test. Here, it is the definition of a function named starting with test_. Other projects, and especially other languages, will have different conventions.

All the file name patterns above (sourceFiles, excludedSourceFiles, testFiles) are glob patterns as defined by the globber library.

The configuration file can be given as an option to the init-project command:

python -m githammer init-project baffle ~/projects/baffle --configuration ./baffle-config.json

If the --configuration option is not given, but the repository contains a file named git-hammer-config.json, this file will be read as the configuration. This way you can keep the Git Hammer configuration for a repository in that repository.

Note: The configuration file path, as well as the repository path, will be stored in the database, so they should not be moved. If the configuration changes, data that was already in the database will not be reprocessed with the new configuration.

Multi-Repository Projects

Sometimes, a team works on multiple repositories that all still belong to the same project. For instance, a piece of functionality may be better to split off into a library in an independent repository. Git Hammer supports such projects by not limiting the project data to a single repository.

To add another repository to an existing project, just use add-repository:

python -m githammer add-repository baffle ~/projects/baffle-common

This will process the new repository, adding it to the project database. After this, any summary information will include data from all repositories of the project. Like init-project, add-repository also accepts the --configuration option to specify the configuration file for the new repository.


Git Hammer is licensed under the Apache Software License, version 2.0. See the LICENSE file for precise license terms and conditions.

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