From 8a6ac287b2ba5f75bb2d9409dd97e9b501daf253 Mon Sep 17 00:00:00 2001 From: Taylor Blau Date: Mon, 13 Apr 2020 22:04:17 -0600 Subject: builtin/commit-graph.c: introduce split strategy 'replace' When using split commit-graphs, it is sometimes useful to completely replace the commit-graph chain with a new base. For example, consider a scenario in which a repository builds a new commit-graph incremental for each push. Occasionally (say, after some fixed number of pushes), they may wish to rebuild the commit-graph chain with all reachable commits. They can do so with $ git commit-graph write --reachable but this removes the chain entirely and replaces it with a single commit-graph in 'objects/info/commit-graph'. Unfortunately, this means that the next push will have to move this commit-graph into the first layer of a new chain, and then write its new commits on top. Avoid such copying entirely by allowing the caller to specify that they wish to replace the entirety of their commit-graph chain, while also specifying that the new commit-graph should become the basis of a fresh, length-one chain. This addresses the above situation by making it possible for the caller to instead write: $ git commit-graph write --reachable --split=replace which writes a new length-one chain to 'objects/info/commit-graphs', making the commit-graph incremental generated by the subsequent push relatively cheap by avoiding the aforementioned copy. In order to do this, remove an assumption in 'write_commit_graph_file' that chains are always at least two incrementals long. Signed-off-by: Taylor Blau Signed-off-by: Junio C Hamano --- Documentation/git-commit-graph.txt | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'Documentation/git-commit-graph.txt') diff --git a/Documentation/git-commit-graph.txt b/Documentation/git-commit-graph.txt index a4c4a641e5..46f7f7c573 100644 --- a/Documentation/git-commit-graph.txt +++ b/Documentation/git-commit-graph.txt @@ -64,9 +64,10 @@ strategy and other splitting options. The new commits not already in the commit-graph are added in a new "tip" file. This file is merged with the existing file if the following merge conditions are met: * If `--split=no-merge` is specified, a merge is never performed, and -the remaining options are ignored. A bare `--split` defers to the -remaining options. (Note that merging a chain of commit graphs replaces -the existing chain with a length-1 chain where the first and only +the remaining options are ignored. `--split=replace` overwrites the +existing chain with a new one. A bare `--split` defers to the remaining +options. (Note that merging a chain of commit graphs replaces the +existing chain with a length-1 chain where the first and only incremental holds the entire graph). + * If `--size-multiple=` is not specified, let `X` equal 2. If the new -- cgit v1.2.3