feat: add option to traverse commits from oldest to newest #1610
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nrdxp
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minimum viable diff take from: GitoxideLabs#1610
This change introduces an enum to control commit traversal order. Users can now choose between newest-first or oldest-first traversal. The default behavior remains newest-first, but it can be toggled by passing a CommitTimeOrder to a Sorting::ByCommitTime* variant. This feature is particularly useful for searching early repository history. The implementation remains largely agnostic to this change, with only minor logic adjustments in key areas as necessary. The reversed order is achieved by inverting the PriorityQueue key when an oldest-first traversal is requested.
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Thanks a lot for setting this up - it's great to see that this sorting mode along can make such a difference!
I will keep working on this PR until it's ready for merging, by adding some tests and probably fix one logic-issue I am seeing. But tests should say what's right or wrong here.
Tasks
- refactor
- see if topo-traversal should also implement this. That way the
CommitTimeOrdercould be shared and move up one level.- Yes, it can be done, but it's probably not useful. Git also doesn't have it, and it's better to wait for actual demand.
| @@ -61,11 +75,14 @@ pub enum Error { | |||
| ObjectDecode(#[from] gix_object::decode::Error), | |||
| } | |||
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| use Result as Either; | |||
| type QueueKey<T> = Either<T, Reverse<T>>; | |||
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It's a first for me to see this usage, and I kind of like it :).
It really does save a lot of boilerplate as well!
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That was the idea yes, also just wanted to make it clear that this is not an error condition.
| @@ -77,10 +94,13 @@ mod init { | |||
| use gix_date::SecondsSinceUnixEpoch; | |||
| use gix_hash::{oid, ObjectId}; | |||
| use gix_object::{CommitRefIter, FindExt}; | |||
| use std::cmp::Reverse; | |||
| @@ -77,10 +94,13 @@ mod init { | |||
| use gix_date::SecondsSinceUnixEpoch; | |||
| use gix_hash::{oid, ObjectId}; | |||
| use gix_object::{CommitRefIter, FindExt}; | |||
| use std::cmp::Reverse; | |||
| use Err as Oldest; | |||
gix-traverse/src/commit/simple.rs
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| state.queue.insert(ordered_time, commit_id); | ||
| } | ||
| (Some(cutoff_time), CommitTimeOrder::OldestFirst) if time <= cutoff_time => { | ||
| state.queue.insert(ordered_time, commit_id); |
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Did you invert the logic because it made sense or because it seemed right?
The reason I am curious is:
- there are no tests for this
- the way I think this could work with similar semantics is if the traversal would actually start from the back, and move forward in time, something that's not possible with a commitgraph.
My intuition here is to keep the cutoff logic the same, as the traversal direction is always from front to back, or newest to youngest.
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I was considering that as well, I actually wasn't 100% confident either way, so I'm happy to keep it simple unless something breaks. I have a real-world usecase for this, so I will let you know. But I can also devise some tests for this in a follow up PR as well
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I think that's the way to go, after removing the inverted cutoff logic essentially and adding tests.
Despite merging this, I am particularly interested to hear if this is the wrong way to go about it, and potential fixes are very welcome in follow-up PRs.
Thanks again for kicking off this feature!
…it-graph during traversals. It's implemented by sorting commits oldest first when choosing the next one to traverse, which can greatly reduce the time it takes to reach the first commit of a graph. Co-authored-by: Sebastian Thiel <[email protected]>
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minimum viable diff take from: GitoxideLabs#1610
This change introduces an enum to control commit traversal order for Simple. Users can now choose between newest-first or oldest-first traversal. The default behavior remains newest-first, but it can be toggled by passing a CommitTimeOrder to a Sorting::ByCommitTime* variant.
This feature is particularly useful for searching early repository history, which should be orders of magnitude faster with this variant. In my benchmarking I was able to identify the original commit in a large mono-repo source tree using the new OldestFirst variant in 12ms down from 2.6s with NewestFirst.
The implementation logic remains largely agnostic to this change, with only minor adjustments in key areas as necessary.
The reversed order is achieved by inverting the PriorityQueue key with std::cmp::Reverse when an oldest-first traversal is requested. This is what allows the bulk of the original logic to remain unchanged.