git/Documentation
Taylor Blau 8a6ac287b2 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 <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-15 09:20:28 -07:00
..
2019-05-09 00:37:27 +09:00
2018-06-25 13:22:36 -07:00
2019-12-06 16:31:39 +01:00
2019-08-07 12:37:33 -07:00
2019-01-23 11:37:29 -08:00
2019-08-11 17:40:07 -07:00
2019-08-11 17:40:07 -07:00
2019-04-02 13:57:00 +09:00
2019-08-11 17:40:07 -07:00
2019-01-23 11:37:29 -08:00
2019-03-18 14:45:21 +09:00
2019-04-02 13:57:00 +09:00
2018-12-26 14:59:37 -08:00
2019-05-07 13:04:48 +09:00
2019-05-07 13:04:48 +09:00
2019-05-07 13:04:48 +09:00
2019-04-02 13:57:00 +09:00
2019-11-10 18:02:11 +09:00
2019-10-21 12:02:39 +09:00