Bisect
So we know how to fix problems in our code. We can either:
- Revert the commit with the bug (this is more common on large teams)
- "Fail forward" by just writing a new commit that fixes the bug (this is more common on small teams)
But there's another question:
How do we find out when a bug was introduced?
That's where the git bisect command comes in. Instead of manually checking all the commits (O(n) for Big O nerds), git bisect allows us to do a binary search (O(log n) for Big O nerds) to find the commit that introduced the bug.
For example, if you have 100 commits that might contain the bug, with git bisect you only need to check 7 commits to find the one that introduced the bug.
| commits to check | max checks to find |
|---|---|
| 1 | 1 |
| ---------------- | -------------------- |
| 2 | 1 |
| ---------------- | -------------------- |
| 10 | 4 |
| ---------------- | -------------------- |
| 100 | 7 |
| ---------------- | -------------------- |
| 1000 | 10 |
| ---------------- | -------------------- |
| 10000 | 14 |
git bisect isn't just for bugs, it can be used to find the commit that introduced any change, but issues like bugs and performance regressions are a common use case.
The most common purpose of 'git bisect' is to...