Re: [PATCH/RFD 3/6] rev-list: list all heads with --all

[Duy Nguyen]

On Fri, Feb 26, 2016 at 11:39 PM, Michael J Gruber
 wrote:
> HEAD is a worktree specific sysmref, so that a repository with multiple
> worktrees can have multiple HEADs, or HEADs in a worktree different from
> the current worktree.
>
> So far, "rev-parse --all" adds only the HEAD from the current worktree
> to the list of refs (besides branches etc.). So, a detached HEAD from a
> different checkout would be missed unless a shared ref (or current HEAD)
> points to it (or descents from it). As a consequence, "git prune" can
> prune detached HEADs from worktrees and leave the repo in an
> inconsistent state.
>
> Make "rev-parse --all" add the HEADs from all worktrees. This results in
> a non-worktree-specific ref list and solves the pruning problem.
>
> Signed-off-by: Michael J Gruber 
> ---
>
> Notes:
> This patch solves the pruning problem with worktrees, but I feel quite
> uneasy about substituting the ref solving at the very heart of refs.c. So
> please consider this a mere poc and a request for discussion/input
> about how to do this the right way.
>
> In essence, I feel the worktree interface still has to evolve a bit: I'd
> rather for_each_worktree than loop myself, and if many call sites need to
> be aware of multiple heads or worktrees than get_worktrees() should be
> part of our init stuff, not here. [I may be out of sync of newer 
> progress.]

How about adding for_each_head_ref_submodule()  and make
handle_revision_pseudo_opt() use it with a new option, .e.g
--all-work-trees?

I looked over head_ref and head_ref_submodule call sites. I think
we're ok. Most of them only concern about "our head". for-each-ref may
need some improvement though.
-- 
Duy
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[PATCH/RFD 3/6] rev-list: list all heads with --all

[Michael J Gruber]

HEAD is a worktree specific sysmref, so that a repository with multiple
worktrees can have multiple HEADs, or HEADs in a worktree different from
the current worktree.

So far, "rev-parse --all" adds only the HEAD from the current worktree
to the list of refs (besides branches etc.). So, a detached HEAD from a
different checkout would be missed unless a shared ref (or current HEAD)
points to it (or descents from it). As a consequence, "git prune" can
prune detached HEADs from worktrees and leave the repo in an
inconsistent state.

Make "rev-parse --all" add the HEADs from all worktrees. This results in
a non-worktree-specific ref list and solves the pruning problem.

Signed-off-by: Michael J Gruber 
---

Notes:
This patch solves the pruning problem with worktrees, but I feel quite
uneasy about substituting the ref solving at the very heart of refs.c. So
please consider this a mere poc and a request for discussion/input
about how to do this the right way.

In essence, I feel the worktree interface still has to evolve a bit: I'd
rather for_each_worktree than loop myself, and if many call sites need to
be aware of multiple heads or worktrees than get_worktrees() should be
part of our init stuff, not here. [I may be out of sync of newer progress.]

 refs/files-backend.c | 15 +++
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/refs/files-backend.c b/refs/files-backend.c
index 81f68f8..5bdb568 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -4,6 +4,7 @@
 #include "../lockfile.h"
 #include "../object.h"
 #include "../dir.h"
+#include "../worktree.h"
 
 struct ref_lock {
char *ref_name;
@@ -1748,7 +1749,8 @@ static int do_for_each_ref(struct ref_cache *refs, const 
char *base,
 static int do_head_ref(const char *submodule, each_ref_fn fn, void *cb_data)
 {
struct object_id oid;
-   int flag;
+   struct worktree **worktrees;
+   int i, retval;
 
if (submodule) {
if (resolve_gitlink_ref(submodule, "HEAD", oid.hash) == 0)
@@ -1757,10 +1759,15 @@ static int do_head_ref(const char *submodule, 
each_ref_fn fn, void *cb_data)
return 0;
}
 
-   if (!read_ref_full("HEAD", RESOLVE_REF_READING, oid.hash, ))
-   return fn("HEAD", , flag, cb_data);
+   worktrees = get_worktrees();
+   retval = 0;
+   for (i=0; worktrees[i]; i++) {
+   hashcpy(oid.hash, worktrees[i]->head_sha1);
+   retval = retval || fn("HEAD", , worktrees[i]->is_detached ? 
0 : REF_ISSYMREF, cb_data);
+   }
 
-   return 0;
+   free_worktrees(worktrees);
+   return retval;
 }
 
 int head_ref(each_ref_fn fn, void *cb_data)
-- 
2.7.2.618.g7a61b68

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