Comparing Git And Gt

In this guide, you’ll learn some of the main differences between using gt and git, like fixup commits, working asynchronously, check pointing, syncing from remote, and restacking.

Once you learn more about gt and how it interacts with git, you can then re-integrate your previous git workflow into gt.

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Example of gt vs. git

Imagine you’re an engineer at a company that builds task management software (for example, Asana, Linear, or JIRA) and you want to build the ability to search across all task titles.

Let’s say this project has four parts:

1. Add an index to the task table on title so you can search through this field quickly

2. Add a helper function to query this table given a search query and returning tasks that match: searchTasks(string searchQuery) -> Task[]

3. Expose an endpoint on your webserver that allows the frontend to search for tasks

4. Query this endpoint and display results on the frontend

Here’s how this would look in git:

// Create new branch & check it out
$ git branch task_search && git checkout task_search
// Make index changes (~10 lines of code)
$ git add --all && git commit --message 'add index for searching tasks'
// Make helper function (~50 lines of code)
$ git add --all && git commit --message 'add helper function to search tasks'
// Make endpoint (~100 lines of code)
$ git add --all && git commit --message 'add endpoint to search tasks'
// Make UI (~200 lines of code)
$ git add --all && git commit --message 'addtUI to display searched tasks'
// Push changes to remote
$ git push origin task_search

Now you have a branch that implements search end to end. Next you want to get this reviewed by your teammates before it gets merged. There are a couple important issues here:

• This is a large PR! It has many lines of code changes for someone to review.

• The folks who own the UI are different from the folks who own the task table. You need multiple people on different teams to review your PR.

Here’s how this would look in gt:

// Make index changes (~10 lines of code)
$ gt create --all --message 'add index for searching tasks'
// Make helper function (~50 lines of code)
$ gt create --all --message 'add helper function to search tasks'
// Make endpoint (~100 lines of code)
$ gt create --all --message 'add endpoint to search tasks'
// Make UI (~200 lines of code) using aliases
$ gt create -a -m 'add UI to display searched tasks'
// Submit changes to remote
$ gt submit --stack

Now you have a stack that implements search end to end. A stack is made up of multiple branches stacked on top of each other.

Instead of creating a single PR to merge all these changes, Graphite creates four PRs for this stack (one per gt create command above). You can get each PR reviewed by a person who is familiar with that particular change.

This solves the two issues when using git: each PR with gt is small (and easier to review), and you can get reviews from different people for different parts of your change depending on their expertise.

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Fixup commits in gt

Continuing with the example above, let’s say you receive some comments about performance, related to the second part of your change “add helper function to search tasks”. You want to only search tasks within the last year—tasks older than that are out of scope for your search prototype.

How this looks with git:

// Make changes to limit the helper function's search scope to ~1 year
$ git add --all // stage changes
$ git commit --fixup=<commit hash of add helper function to search tasks> // Make the fixup commit
$ git rebase --interactive --autosquash=<commit hash of add helper function to search tasks>~1 // Merge fixup commit into previous commit

How this looks with gt:

$ gt checkout 'add helper function to search tasks'
// Make changes to limit the helper function's search scope to ~1 year
$ gt modify --all // Stage & amend these changes into "add helper function to search tasks"
// Push stack to remote
$ gt submit --stack

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Working asynchronously

The reason gt is so powerful is because it enables working asynchronously. Because each branch in the stack is independent, you can keep building on top of the existing changes without worrying about growing the size of your PR and making things a worse experience for reviewers.

Let’s say you’re waiting on your above PR(s) to be reviewed, when a colleague has a great idea that rather than just allowing people to search for tasks, you should also allow them to search for user profiles in the same UI.

In git, you now have three options:

• Wait until task_search is merged into main, pull main, then create a new branch profile_search and repeat the earlier steps

  • This isn’t great because you now need to wait for reviews and merging before you can work on profile_search

• Update task_search with all changes required to implement profile_search

  • This isn’t great because now you have to further pollute the task_search PR which was already large, and wait for reviews from new reviewers, and so on.

• Create a new branch profile_search on top of task_search, and make changes to that.

  • This works well, until you need to change task_search, and run a rebase. The gt workflow handles this for you automatically.

In gt, you can simply run:

$ gt checkout 'add UI to display searched tasks'
// Make changes to implement profile search
$ gt create --all --message 'implement profile search'
$ gt submit --stack

Now, implementing profile search is built on top of “add UI to display searched tasks”, but it creates a new PR that is independent of all the changes below it. You can keep building on top of this stack, while all PRs lower down the stack (”downstack”) are independent of these changes up the stack (”upstack”).

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Check pointing in gt

A common use case for git commit is to check point yourself in the process of development. An example commit history would look something like:

1. Initialize boilerplate

2. Fix copy paste bug in boilerplate

3. Fill out functions in boilerplate

4. …

If you want to do something similar in gt, just use gt create every time you would git commit. However, it is important to not gt submit the entire stack until some organization is done, otherwise each of your intermediate check points will create PRs, making for a really poor review experience for your reviewers. Instead, once you have your changes in a good place, use gt fold to fold a child branch into its parent. This will allow you to create checkpoints without submitting PRs for each checkpoint.

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Syncing from remote, restacking, and resubmitting

While you’re working on a piece of code, there is a chance that someone else touches the same code on main, or someone makes changes that you want to use. In git, to handle this you could do:

$ git checkout main
$ git pull
$ git checkout <my new branch>
$ git merge main

In gt, you would do the following instead:

$ gt sync
$ gt checkout <my new branch>
$ gt restack // This will rebase your stack onto main

Let’s assume you have a stack of PR#1 → PR#2 → PR#3.

gt restack tells Graphite to check if any rebases need to happen in order to correct your dependency list. For example, let’s say you make a change lower down in the stack, in PR #1. PR #3 doesn’t know about this until you dogt restack. Sogt restackis telling Graphite that you have made changes on a PR that could affect its children—to check the children for any conflicts, and perform a rebase if it finds them.