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| author |  Junio C Hamano <gitster@pobox.com> | 2018-11-21 22:57:47 +0900 |
|---|---|---|
| committer | Junio C Hamano <gitster@pobox.com> | 2018-11-21 22:57:47 +0900 |
| commit | e60e38a15da202737790e2b2a9e613a9cf6ec092 (patch) | |
| tree | c91ed7a45574e4c543814e52daf7f72871aa6f89 /Documentation | |
| parent | Merge branch 'tg/range-diff-corner-case-fix' into maint (diff) | |
| parent | commit-graph: close_commit_graph before shallow walk (diff) | |
| download | tgif-e60e38a15da202737790e2b2a9e613a9cf6ec092.tar.xz | |
Merge branch 'ds/commit-graph-with-grafts' into maint
The recently introduced commit-graph auxiliary data is incompatible
with mechanisms such as replace & grafts that "breaks" immutable
nature of the object reference relationship. Disable optimizations
based on its use (and updating existing commit-graph) when these
incompatible features are in use in the repository.
* ds/commit-graph-with-grafts:
commit-graph: close_commit_graph before shallow walk
commit-graph: not compatible with uninitialized repo
commit-graph: not compatible with grafts
commit-graph: not compatible with replace objects
test-repository: properly init repo
commit-graph: update design document
refs.c: upgrade for_each_replace_ref to be a each_repo_ref_fn callback
refs.c: migrate internal ref iteration to pass thru repository argument
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/technical/commit-graph.txt | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/Documentation/technical/commit-graph.txt b/Documentation/technical/commit-graph.txt index c664acbd76..001395e950 100644 --- a/Documentation/technical/commit-graph.txt +++ b/Documentation/technical/commit-graph.txt @@ -112,12 +112,24 @@ Design Details - The file format includes parameters for the object ID hash function, so a future change of hash algorithm does not require a change in format. +- Commit grafts and replace objects can change the shape of the commit + history. The latter can also be enabled/disabled on the fly using + `--no-replace-objects`. This leads to difficultly storing both possible + interpretations of a commit id, especially when computing generation + numbers. The commit-graph will not be read or written when + replace-objects or grafts are present. + +- Shallow clones create grafts of commits by dropping their parents. This + leads the commit-graph to think those commits have generation number 1. + If and when those commits are made unshallow, those generation numbers + become invalid. Since shallow clones are intended to restrict the commit + history to a very small set of commits, the commit-graph feature is less + helpful for these clones, anyway. The commit-graph will not be read or + written when shallow commits are present. + Future Work ----------- -- The commit graph feature currently does not honor commit grafts. This can - be remedied by duplicating or refactoring the current graft logic. - - After computing and storing generation numbers, we must make graph walks aware of generation numbers to gain the performance benefits they enable. This will mostly be accomplished by swapping a commit-date-ordered |