With '--split', the commit-graph machinery writes new commits in another
incremental commit-graph which is part of the existing chain, and
optionally decides to condense the chain into a single commit-graph.
This is done to ensure that the asymptotic behavior of looking up a
commit in an incremental chain is not dominated by the number of
incrementals in that chain. It can be controlled by the '--max-commits'
and '--size-multiple' options.
In the next two commits, we will introduce additional splitting
strategies that can exert additional control over:
- when a split commit-graph is and isn't written, and
- when the existing commit-graph chain is discarded completely and
replaced with another graph
To prepare for this, make '--split' take an optional strategy (as in
'--split[=<strategy>]'), and add a new enum to describe which strategy
is being used. For now, no strategies are given, and the only enumerated
value is 'COMMIT_GRAPH_SPLIT_UNSPECIFIED', indicating the absence of a
strategy.
Signed-off-by: Taylor Blau <me@xxxxxxxxxxxx>
---
Documentation/git-commit-graph.txt | 11 ++++++-----
builtin/commit-graph.c | 26 ++++++++++++++++++++++----
commit-graph.h | 5 +++++
3 files changed, 33 insertions(+), 9 deletions(-)
diff --git a/Documentation/git-commit-graph.txt b/Documentation/git-commit-graph.txt
index 28d1fee505..10d757c5cc 100644
--- a/Documentation/git-commit-graph.txt
+++ b/Documentation/git-commit-graph.txt
@@ -57,11 +57,12 @@ or `--stdin-packs`.)
With the `--append` option, include all commits that are present in the
existing commit-graph file.
+
-With the `--split` option, write the commit-graph as a chain of multiple
-commit-graph files stored in `<dir>/info/commit-graphs`. 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:
+With the `--split[=<strategy>]` option, write the commit-graph as a
+chain of multiple commit-graph files stored in
+`<dir>/info/commit-graphs`. Commit-graph layers are merged based on the
+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 `--size-multiple=<X>` is not specified, let `X` equal 2. If the new
tip file would have `N` commits and the previous tip has `M` commits and
diff --git a/builtin/commit-graph.c b/builtin/commit-graph.c
index d1ab6625f6..342094fc77 100644
--- a/builtin/commit-graph.c
+++ b/builtin/commit-graph.c
@@ -9,7 +9,9 @@
static char const * const builtin_commit_graph_usage[] = {
N_("git commit-graph verify [--object-dir <objdir>] [--shallow] [--[no-]progress]"),
- N_("git commit-graph write [--object-dir <objdir>] [--append|--split] [--reachable|--stdin-packs|--stdin-commits] [--[no-]progress] <split options>"),
+ N_("git commit-graph write [--object-dir <objdir>] [--append] "
+ "[--split[=<strategy>]] [--reachable|--stdin-packs|--stdin-commits] "
+ "[--[no-]progress] <split options>"),
NULL
};
@@ -19,7 +21,9 @@ static const char * const builtin_commit_graph_verify_usage[] = {
};
static const char * const builtin_commit_graph_write_usage[] = {
- N_("git commit-graph write [--object-dir <objdir>] [--append|--split] [--reachable|--stdin-packs|--stdin-commits] [--[no-]progress] <split options>"),
+ N_("git commit-graph write [--object-dir <objdir>] [--append] "
+ "[--split[=<strategy>]] [--reachable|--stdin-packs|--stdin-commits] "
+ "[--[no-]progress] <split options>"),
NULL
};
@@ -114,6 +118,18 @@ static int graph_verify(int argc, const char **argv)
extern int read_replace_refs;
static struct split_commit_graph_opts split_opts;
+static int write_option_parse_split(const struct option *opt, const char *arg,
+ int unset)
+{
+ opts.split = 1;
+ if (!arg)
+ return 0;
+
+ die(_("unrecognized --split argument, %s"), arg);
+
+ return 0;
+}
+
static int graph_write(int argc, const char **argv)
{
struct string_list *pack_indexes = NULL;
@@ -136,8 +152,10 @@ static int graph_write(int argc, const char **argv)
OPT_BOOL(0, "append", &opts.append,
N_("include all commits already in the commit-graph file")),
OPT_BOOL(0, "progress", &opts.progress, N_("force progress reporting")),
- OPT_BOOL(0, "split", &opts.split,
- N_("allow writing an incremental commit-graph file")),
+ OPT_CALLBACK_F(0, "split", &split_opts.flags, NULL,
+ N_("allow writing an incremental commit-graph file"),
+ PARSE_OPT_OPTARG | PARSE_OPT_NONEG,
+ write_option_parse_split),
OPT_INTEGER(0, "max-commits", &split_opts.max_commits,
N_("maximum number of commits in a non-base split commit-graph")),
OPT_INTEGER(0, "size-multiple", &split_opts.size_multiple,
diff --git a/commit-graph.h b/commit-graph.h
index e87a6f6360..e799008ff4 100644
--- a/commit-graph.h
+++ b/commit-graph.h
@@ -82,10 +82,15 @@ enum commit_graph_write_flags {
COMMIT_GRAPH_WRITE_CHECK_OIDS = (1 << 3)
};
+enum commit_graph_split_flags {
+ COMMIT_GRAPH_SPLIT_UNSPECIFIED = 0
+};
+
struct split_commit_graph_opts {
int size_multiple;
int max_commits;
timestamp_t expire_time;
+ enum commit_graph_split_flags flags;
};
/*
--
2.26.0.106.g9fadedd637
