> Teach Git to delete the current 'graph_head' file and the commit graph
> it references.
And will it leave other, non-important graph files behind? Looking at
the code it indeed does. What is the use case for keeping the
non-important graph files?
> This is a good safety valve if somehow the file is
> corrupted and needs to be recalculated. Since the commit graph is a
> summary of contents already in the ODB, it can be regenerated.
Wouldn't a simple 'git commit-graph --write --update-head' regenerate
it on it's own, without cleaning first? It appears, after running a
few tests, that a corrupt graph file can be recreated without
cleaning, which is great. However, if graph-head is corrupt, then the
command errors out with 'failed to read graph-head'. I don't
understand the rationale behind this, it would be overwritten anyway,
and its content is not necessary for recreating the graph. And
indeed, after commenting out that get_graph_head_hash() call in
cmd_commit_graph() it doesn't want to read my corrupted graph-head
file, and recreates both the graph and graph-head files just fine.
I think the requirement for explicitly cleaning a corrupt graph-head
before re-writing it is just unnecessary complication.
On second thought, what's the point of '--write' without
'--update-head', when consumers (thinking 'log --topo-order...) will
need the graph-head anyway? I think '--write' should create a
graph-head without requiring an additional option.
Hmph, another second thought: the word 'head' has a rather specific
meaning in Git, although it's usually capitalized. Using this word in
options and filenames may lead to confusion, especially the option
'--update-head'.
> Signed-off-by: Derrick Stolee <dsto...@microsoft.com>
> ---
> Documentation/git-commit-graph.txt | 16 ++++++++++++++--
> builtin/commit-graph.c | 32 +++++++++++++++++++++++++++++++-
> t/t5318-commit-graph.sh | 7 ++++++-
> 3 files changed, 51 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/git-commit-graph.txt
> b/Documentation/git-commit-graph.txt
> index 99ced16ddc..33d6567f11 100644
> --- a/Documentation/git-commit-graph.txt
> +++ b/Documentation/git-commit-graph.txt
> @@ -11,6 +11,7 @@ SYNOPSIS
> [verse]
> 'git commit-graph' --write <options> [--pack-dir <pack_dir>]
> 'git commit-graph' --read <options> [--pack-dir <pack_dir>]
> +'git commit-graph' --clear [--pack-dir <pack_dir>]
>
> OPTIONS
> -------
> @@ -18,16 +19,21 @@ OPTIONS
> Use given directory for the location of packfiles, graph-head,
> and graph files.
>
> +--clear::
> + Delete the graph-head file and the graph file it references.
> + (Cannot be combined with --read or --write.)
> +
> --read::
> Read a graph file given by the graph-head file and output basic
> - details about the graph file. (Cannot be combined with --write.)
> + details about the graph file. (Cannot be combined with --clear
> + or --write.)
>
> --graph-id::
> When used with --read, consider the graph file graph-<oid>.graph.
>
> --write::
> Write a new graph file to the pack directory. (Cannot be combined
> - with --read.)
> + with --clear or --read.)
All these "cannot be combined with --this and --that" remarks make
subcommands more and more appealing.
>
> --update-head::
> When used with --write, update the graph-head file to point to
> @@ -61,6 +67,12 @@ $ git commit-graph --write --update-head
> $ git commit-graph --read --graph-hash=<hash>
> ------------------------------------------------
>
> +* Delete <dir>/graph-head and the file it references.
> ++
> +------------------------------------------------
> +$ git commit-graph --clear --pack-dir=<dir>
> +------------------------------------------------
> +
> GIT
> ---
> Part of the linkgit:git[1] suite
> diff --git a/builtin/commit-graph.c b/builtin/commit-graph.c
> index d73cbc907d..4970dec133 100644
> --- a/builtin/commit-graph.c
> +++ b/builtin/commit-graph.c
> @@ -10,6 +10,7 @@
>
> static char const * const builtin_commit_graph_usage[] = {
> N_("git commit-graph [--pack-dir <packdir>]"),
> + N_("git commit-graph --clear [--pack-dir <packdir>]"),
> N_("git commit-graph --read [--graph-hash=<hash>]"),
> N_("git commit-graph --write [--pack-dir <packdir>] [--update-head]"),
> NULL
> @@ -17,6 +18,7 @@ static char const * const builtin_commit_graph_usage[] = {
>
> static struct opts_commit_graph {
> const char *pack_dir;
> + int clear;
> int read;
> const char *graph_hash;
> int write;
> @@ -25,6 +27,30 @@ static struct opts_commit_graph {
> struct object_id old_graph_hash;
> } opts;
>
> +static int graph_clear(void)
> +{
> + struct strbuf head_path = STRBUF_INIT;
> + char *old_path;
> +
> + if (!opts.has_existing)
> + return 0;
> +
> + strbuf_addstr(&head_path, opts.pack_dir);
> + strbuf_addstr(&head_path, "/");
> + strbuf_addstr(&head_path, "graph-head");
strbuf_addstr(&head_path, "/graph-head")
Although, considering that this is the third place assembling this
path, maybe a helper function would be worth it.
> + if (remove_path(head_path.buf))
> + die("failed to remove path %s", head_path.buf);
> + strbuf_release(&head_path);
> +
> + old_path = get_commit_graph_filename_hash(opts.pack_dir,
> + &opts.old_graph_hash);
> + if (remove_path(old_path))
> + die("failed to remove path %s", old_path);
> + free(old_path);
> +
> + return 0;
> +}
> +
> static int graph_read(void)
> {
> struct object_id graph_hash;
> @@ -105,6 +131,8 @@ int cmd_commit_graph(int argc, const char **argv, const
> char *prefix)
> { OPTION_STRING, 'p', "pack-dir", &opts.pack_dir,
> N_("dir"),
> N_("The pack directory to store the graph") },
> + OPT_BOOL('c', "clear", &opts.clear,
> + N_("clear graph file and graph-head")),
> OPT_BOOL('r', "read", &opts.read,
> N_("read graph file")),
> OPT_BOOL('w', "write", &opts.write,
> @@ -126,7 +154,7 @@ int cmd_commit_graph(int argc, const char **argv, const
> char *prefix)
> builtin_commit_graph_options,
> builtin_commit_graph_usage, 0);
>
> - if (opts.write + opts.read > 1)
> + if (opts.write + opts.read + opts.clear > 1)
> usage_with_options(builtin_commit_graph_usage,
> builtin_commit_graph_options);
>
> @@ -139,6 +167,8 @@ int cmd_commit_graph(int argc, const char **argv, const
> char *prefix)
>
> opts.has_existing = !!get_graph_head_hash(opts.pack_dir,
> &opts.old_graph_hash);
>
> + if (opts.clear)
> + return graph_clear();
> if (opts.read)
> return graph_read();
> if (opts.write)
> diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh
> index d1a23bcdaf..6e3b62b754 100755
> --- a/t/t5318-commit-graph.sh
> +++ b/t/t5318-commit-graph.sh
> @@ -101,6 +101,11 @@ test_expect_success 'write graph with merges' \
> _graph_read_expect "18" "${packdir}" &&
> cmp expect output'
>
> +test_expect_success 'clear graph' \
> + 'git commit-graph --clear &&
> + test_path_is_missing ${packdir}/graph-${graph2}.graph &&
> + test_path_is_missing ${packdir}/graph-head'
> +
> test_expect_success 'setup bare repo' \
> 'cd .. &&
> git clone --bare full bare &&
> @@ -110,7 +115,7 @@ test_expect_success 'setup bare repo' \
> baredir="./objects/pack"'
>
> test_expect_success 'write graph in bare repo' \
> - 'graphbare=$(git commit-graph --write) &&
> + 'graphbare=$(git commit-graph --write --update-head) &&
This should have been done in the previous patch.
> test_path_is_file ${baredir}/graph-${graphbare}.graph &&
> test_path_is_file ${baredir}/graph-head &&
> echo ${graphbare} >expect &&
> --
> 2.16.0.15.g9c3cf44.dirty
