On 2/1/2018 8:35 PM, SZEDER Gábor wrote:
It is possible to have multiple commit graph files in a pack directory,
but only one is important at a time. Use a 'graph_head' file to point
to the important file.
This implies that all those other files are ignored, right?
Yes. We do not use directory listings to find graph files.
Teach git-commit-graph to write 'graph_head' upon
writing a new commit graph file.
Signed-off-by: Derrick Stolee <dstolee@xxxxxxxxxxxxx>
---
Documentation/git-commit-graph.txt | 34 ++++++++++++++++++++++++++++++++++
builtin/commit-graph.c | 38 +++++++++++++++++++++++++++++++++++---
commit-graph.c | 25 +++++++++++++++++++++++++
commit-graph.h | 2 ++
t/t5318-commit-graph.sh | 12 ++++++++++--
5 files changed, 106 insertions(+), 5 deletions(-)
diff --git a/Documentation/git-commit-graph.txt b/Documentation/git-commit-graph.txt
index 09aeaf6c82..99ced16ddc 100644
--- a/Documentation/git-commit-graph.txt
+++ b/Documentation/git-commit-graph.txt
@@ -12,15 +12,49 @@ SYNOPSIS
'git commit-graph' --write <options> [--pack-dir <pack_dir>]
'git commit-graph' --read <options> [--pack-dir <pack_dir>]
+OPTIONS
+-------
Oh, look, the 'OPTIONS' section I missed in the previous patches! ;)
This should be split up and squashed into the previous patches where
the individual --options are first mentioned.
+--pack-dir::
+ Use given directory for the location of packfiles, graph-head,
+ and graph files.
+
+--read::
+ Read a graph file given by the graph-head file and output basic
+ details about the graph file. (Cannot be combined with --write.)
From the output of 'git commit-graph --read' it seems that it's not a
generally useful option to the user. Perhaps it should be mentioned
that it's only intended as a debugging aid? Or maybe it doesn't
really matter, because eventually this command will become irrelevant,
as other commands (clone, fetch, gc) will invoke it automagically...
I'll add some wording to make this clear.
+--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.)
I think this should also mention that it prints the generated graph
file's checksum.
+
+--update-head::
+ When used with --write, update the graph-head file to point to
+ the written graph file.
So it should be used with '--write', noted.
EXAMPLES
--------
+* Output the hash of the graph file pointed to by <dir>/graph-head.
++
+------------------------------------------------
+$ git commit-graph --pack-dir=<dir>
+------------------------------------------------
+
* Write a commit graph file for the packed commits in your local .git folder.
+
------------------------------------------------
$ git commit-graph --write
------------------------------------------------
+* Write a graph file for the packed commits in your local .git folder,
+* and update graph-head.
++
+------------------------------------------------
+$ git commit-graph --write --update-head
+------------------------------------------------
+
* Read basic information from a graph file.
+
------------------------------------------------
diff --git a/builtin/commit-graph.c b/builtin/commit-graph.c
index 218740b1f8..d73cbc907d 100644
--- a/builtin/commit-graph.c
+++ b/builtin/commit-graph.c
@@ -11,7 +11,7 @@
static char const * const builtin_commit_graph_usage[] = {
N_("git commit-graph [--pack-dir <packdir>]"),
N_("git commit-graph --read [--graph-hash=<hash>]"),
- N_("git commit-graph --write [--pack-dir <packdir>]"),
+ N_("git commit-graph --write [--pack-dir <packdir>] [--update-head]"),
NULL
};
@@ -20,6 +20,9 @@ static struct opts_commit_graph {
int read;
const char *graph_hash;
int write;
+ int update_head;
+ int has_existing;
+ struct object_id old_graph_hash;
} opts;
static int graph_read(void)
@@ -30,8 +33,8 @@ static int graph_read(void)
if (opts.graph_hash && strlen(opts.graph_hash) == GIT_MAX_HEXSZ)
get_oid_hex(opts.graph_hash, &graph_hash);
- else
- die("no graph hash specified");
+ else if (!get_graph_head_hash(opts.pack_dir, &graph_hash))
+ die("no graph-head exists");
graph_file = get_commit_graph_filename_hash(opts.pack_dir, &graph_hash);
graph = load_commit_graph_one(graph_file, opts.pack_dir);
@@ -62,10 +65,33 @@ static int graph_read(void)
return 0;
}
+static void update_head_file(const char *pack_dir, const struct object_id *graph_hash)
+{
+ struct strbuf head_path = STRBUF_INIT;
+ int fd;
+ struct lock_file lk = LOCK_INIT;
+
+ strbuf_addstr(&head_path, pack_dir);
+ strbuf_addstr(&head_path, "/");
+ strbuf_addstr(&head_path, "graph-head");
strbuf_addstr(&head_path, "/graph-head"); ?
+
+ fd = hold_lock_file_for_update(&lk, head_path.buf, LOCK_DIE_ON_ERROR);
+ strbuf_release(&head_path);
+
+ if (fd < 0)
+ die_errno("unable to open graph-head");
+
+ write_in_full(fd, oid_to_hex(graph_hash), GIT_MAX_HEXSZ);
+ commit_lock_file(&lk);
The new graph-head file will be writable. All other files in
.git/objects/pack are created read-only, including graph files. Just
pointing it out, but I don't think it's a bit deal; other than
consistency with the permissions of other files I don't have any
argument for making it read-only.
I don't have strong opinions on the permissions difference, except that
a graph-<hash>.graph file should not change contents (or the hash will
be wrong) but a user or external tool could change the graph-head
contents to point to a different file. I can't think of a case where
that is important.
