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| author |  Derrick Stolee <dstolee@microsoft.com> | 2019-06-18 11:14:31 -0700 |
|---|---|---|
| committer |  Junio C Hamano <gitster@pobox.com> | 2019-06-19 20:46:26 -0700 |
| commit | 8d84097f9655a954ea7e94ba08d93e5940ccb2ae (patch) | |
| tree | a03d339c93622614583625570967a94365add6b7 /Documentation/technical | |
| parent | commit-graph: allow cross-alternate chains (diff) | |
| download | tgif-8d84097f9655a954ea7e94ba08d93e5940ccb2ae.tar.xz | |
commit-graph: expire commit-graph files
As we merge commit-graph files in a commit-graph chain, we should clean
up the files that are no longer used.
This change introduces an 'expiry_window' value to the context, which is
always zero (for now). We then check the modified time of each
graph-{hash}.graph file in the $OBJDIR/info/commit-graphs folder and
unlink the files that are older than the expiry_window.
Since this is always zero, this immediately clears all unused graph
files. We will update the value to match a config setting in a future
change.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'Documentation/technical')
| -rw-r--r-- | Documentation/technical/commit-graph.txt | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/Documentation/technical/commit-graph.txt b/Documentation/technical/commit-graph.txt index 473032e476..aed4350a59 100644 --- a/Documentation/technical/commit-graph.txt +++ b/Documentation/technical/commit-graph.txt @@ -266,6 +266,21 @@ The merge strategy values (2 for the size multiple, 64,000 for the maximum number of commits) could be extracted into config settings for full flexibility. +## Deleting graph-{hash} files + +After a new tip file is written, some `graph-{hash}` files may no longer +be part of a chain. It is important to remove these files from disk, eventually. +The main reason to delay removal is that another process could read the +`commit-graph-chain` file before it is rewritten, but then look for the +`graph-{hash}` files after they are deleted. + +To allow holding old split commit-graphs for a while after they are unreferenced, +we update the modified times of the files when they become unreferenced. Then, +we scan the `$OBJDIR/info/commit-graphs/` directory for `graph-{hash}` +files whose modified times are older than a given expiry window. This window +defaults to zero, but can be changed using command-line arguments or a config +setting. + ## Chains across multiple object directories In a repo with alternates, we look for the `commit-graph-chain` file starting |