gix_merge/commit/
virtual_merge_base.rs

1/// The outcome produced by [`commit::merge_base()`](crate::commit::virtual_merge_base()).
2pub struct Outcome {
3    /// The commit ids of all the virtual merge bases we have produced in the process of recursively merging the merge-bases.
4    /// As they have been written to the object database, they are still available until they are garbage collected.
5    /// The last one is the most recently produced and the one returned as `commit_id`.
6    /// This is never empty.
7    pub virtual_merge_bases: Vec<gix_hash::ObjectId>,
8    /// The id of the commit that was created to hold the merged tree.
9    pub commit_id: gix_hash::ObjectId,
10    /// The hash of the merged tree.
11    pub tree_id: gix_hash::ObjectId,
12}
13
14/// The error returned by [`commit::merge_base()`](crate::commit::virtual_merge_base()).
15#[derive(Debug, thiserror::Error)]
16#[allow(missing_docs)]
17pub enum Error {
18    #[error(transparent)]
19    MergeTree(#[from] crate::tree::Error),
20    #[error("Failed to write tree for merged merge-base or virtual commit")]
21    WriteObject(gix_object::write::Error),
22    #[error("Failed to decode a commit needed to build a virtual merge-base")]
23    DecodeCommit(#[from] gix_object::decode::Error),
24    #[error(
25        "Conflicts occurred when trying to resolve multiple merge-bases by merging them. This is most certainly a bug."
26    )]
27    VirtualMergeBaseConflict,
28    #[error("Could not find commit to use as basis for a virtual commit")]
29    FindCommit(#[from] gix_object::find::existing_object::Error),
30}
31
32pub(super) mod function {
33    use gix_object::FindExt;
34
35    use super::Error;
36    use crate::{
37        blob::builtin_driver,
38        tree::{treat_as_unresolved, TreatAsUnresolved},
39    };
40
41    /// Create a single virtual merge-base by merging `first_commit`, `second_commit` and `others` into one.
42    /// Note that `first_commit` and `second_commit` are expected to have been popped off `others`, so `first_commit`
43    /// was the last provided merge-base of function that provides multiple merge-bases for a pair of commits.
44    ///
45    /// The parameters `graph`, `diff_resource_cache`, `blob_merge`, `objects`, `abbreviate_hash` and `options` are passed
46    /// directly to [`tree()`](crate::tree()) for merging the trees of two merge-bases at a time.
47    /// Note that most of `options` are overwritten to match the requirements of a merge-base merge.
48    #[allow(clippy::too_many_arguments)]
49    pub fn virtual_merge_base<'objects>(
50        first_commit: gix_hash::ObjectId,
51        second_commit: gix_hash::ObjectId,
52        mut others: Vec<gix_hash::ObjectId>,
53        graph: &mut gix_revwalk::Graph<'_, '_, gix_revwalk::graph::Commit<gix_revision::merge_base::Flags>>,
54        diff_resource_cache: &mut gix_diff::blob::Platform,
55        blob_merge: &mut crate::blob::Platform,
56        objects: &'objects (impl gix_object::FindObjectOrHeader + gix_object::Write),
57        abbreviate_hash: &mut dyn FnMut(&gix_hash::oid) -> String,
58        mut options: crate::tree::Options,
59    ) -> Result<super::Outcome, crate::commit::Error> {
60        let mut merged_commit_id = first_commit;
61        others.push(second_commit);
62
63        options.tree_conflicts = Some(crate::tree::ResolveWith::Ancestor);
64        options.blob_merge.is_virtual_ancestor = true;
65        options.blob_merge.text.conflict = builtin_driver::text::Conflict::ResolveWithOurs;
66        let favor_ancestor = Some(builtin_driver::binary::ResolveWith::Ancestor);
67        options.blob_merge.resolve_binary_with = favor_ancestor;
68        options.symlink_conflicts = favor_ancestor;
69        let labels = builtin_driver::text::Labels {
70            current: Some("Temporary merge branch 1".into()),
71            other: Some("Temporary merge branch 2".into()),
72            ancestor: None,
73        };
74        let mut virtual_merge_bases = Vec::new();
75        let mut tree_id = None;
76        while let Some(next_commit_id) = others.pop() {
77            options.marker_size_multiplier += 1;
78            let mut out = crate::commit(
79                merged_commit_id,
80                next_commit_id,
81                labels,
82                graph,
83                diff_resource_cache,
84                blob_merge,
85                objects,
86                abbreviate_hash,
87                crate::commit::Options {
88                    allow_missing_merge_base: false,
89                    tree_merge: options.clone(),
90                    use_first_merge_base: false,
91                },
92            )?;
93            // This shouldn't happen, but if for some buggy reason it does, we rather bail.
94            if out.tree_merge.has_unresolved_conflicts(TreatAsUnresolved {
95                content_merge: treat_as_unresolved::ContentMerge::Markers,
96                tree_merge: treat_as_unresolved::TreeMerge::Undecidable,
97            }) {
98                return Err(Error::VirtualMergeBaseConflict.into());
99            }
100            let merged_tree_id = out
101                .tree_merge
102                .tree
103                .write(|tree| objects.write(tree))
104                .map_err(Error::WriteObject)?;
105
106            tree_id = Some(merged_tree_id);
107            merged_commit_id = create_virtual_commit(objects, merged_commit_id, next_commit_id, merged_tree_id)?;
108
109            virtual_merge_bases.extend(out.virtual_merge_bases);
110            virtual_merge_bases.push(merged_commit_id);
111        }
112
113        Ok(super::Outcome {
114            virtual_merge_bases,
115            commit_id: merged_commit_id,
116            tree_id: tree_id.map_or_else(
117                || {
118                    let mut buf = Vec::new();
119                    objects.find_commit(&merged_commit_id, &mut buf).map(|c| c.tree())
120                },
121                Ok,
122            )?,
123        })
124    }
125
126    fn create_virtual_commit(
127        objects: &(impl gix_object::Find + gix_object::Write),
128        parent_a: gix_hash::ObjectId,
129        parent_b: gix_hash::ObjectId,
130        tree_id: gix_hash::ObjectId,
131    ) -> Result<gix_hash::ObjectId, Error> {
132        let mut buf = Vec::new();
133        let commit_ref = objects.find_commit(&parent_a, &mut buf)?;
134        let mut commit = commit_ref.to_owned()?;
135        commit.parents = vec![parent_a, parent_b].into();
136        commit.tree = tree_id;
137        objects.write(&commit).map_err(Error::WriteObject)
138    }
139}
gix_merge/commit/virtual_merge_base.rs

gix_merge/commit/
virtual_merge_base.rs
