pack-refs: teach --exclude option to exclude refs from being packed

At GitLab, we have a system that creates ephemeral internal refs that
don't live long before getting deleted. Having an option to exclude
certain refs from a packed-refs file allows these internal references to
be deleted much more efficiently.

Add an --exclude option to the pack-refs builtin, and use the ref
exclusions API to exclude certain refs from being packed into the final
packed-refs file

Signed-off-by: John Cai <johncai86@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

4 files changed, 15 insertions, 10 deletions

diff --git a/refs/debug.c b/refs/debug.c
index adc34c836f..63f434ea26 100644
--- a/refs/debug.c
+++ b/refs/debug.c
@@ -122,10 +122,10 @@ static int debug_initial_transaction_commit(struct ref_store *refs,
 	return res;
 }
 
-static int debug_pack_refs(struct ref_store *ref_store, unsigned int flags)
+static int debug_pack_refs(struct ref_store *ref_store, struct pack_refs_opts *opts)
 {
 	struct debug_ref_store *drefs = (struct debug_ref_store *)ref_store;
-	int res = drefs->refs->be->pack_refs(drefs->refs, flags);
+	int res = drefs->refs->be->pack_refs(drefs->refs, opts);
 	trace_printf_key(&trace_refs, "pack_refs: %d\n", res);
 	return res;
 }
diff --git a/refs/files-backend.c b/refs/files-backend.c
index d0581ee41a..8620e01362 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -19,6 +19,7 @@
 #include "../worktree.h"
 #include "../wrapper.h"
 #include "../write-or-die.h"
+#include "../revision.h"
 
 /*
  * This backend uses the following flags in `ref_update::flags` for
@@ -1173,15 +1174,18 @@ static void prune_refs(struct files_ref_store *refs, struct ref_to_prune **refs_
  */
 static int should_pack_ref(const char *refname,
 			   const struct object_id *oid, unsigned int ref_flags,
-			   unsigned int pack_flags)
+			   struct pack_refs_opts *opts)
 {
 	/* Do not pack per-worktree refs: */
 	if (parse_worktree_ref(refname, NULL, NULL, NULL) !=
 	    REF_WORKTREE_SHARED)
 		return 0;
 
+	if (ref_excluded(opts->exclusions, refname))
+		return 0;
+
 	/* Do not pack non-tags unless PACK_REFS_ALL is set: */
-	if (!(pack_flags & PACK_REFS_ALL) && !starts_with(refname, "refs/tags/"))
+	if (!(opts->flags & PACK_REFS_ALL) && !starts_with(refname, "refs/tags/"))
 		return 0;
 
 	/* Do not pack symbolic refs: */
@@ -1195,7 +1199,8 @@ static int should_pack_ref(const char *refname,
 	return 1;
 }
 
-static int files_pack_refs(struct ref_store *ref_store, unsigned int flags)
+static int files_pack_refs(struct ref_store *ref_store,
+			   struct pack_refs_opts *opts)
 {
 	struct files_ref_store *refs =
 		files_downcast(ref_store, REF_STORE_WRITE | REF_STORE_ODB,
@@ -1220,8 +1225,7 @@ static int files_pack_refs(struct ref_store *ref_store, unsigned int flags)
 		 * in the packed ref cache. If the reference should be
 		 * pruned, also add it to refs_to_prune.
 		 */
-		if (!should_pack_ref(iter->refname, iter->oid, iter->flags,
-				     flags))
+		if (!should_pack_ref(iter->refname, iter->oid, iter->flags, opts))
 			continue;
 
 		/*
@@ -1235,7 +1239,7 @@ static int files_pack_refs(struct ref_store *ref_store, unsigned int flags)
 			    iter->refname, err.buf);
 
 		/* Schedule the loose reference for pruning if requested. */
-		if ((flags & PACK_REFS_PRUNE)) {
+		if ((opts->flags & PACK_REFS_PRUNE)) {
 			struct ref_to_prune *n;
 			FLEX_ALLOC_STR(n, name, iter->refname);
 			oidcpy(&n->oid, iter->oid);
diff --git a/refs/packed-backend.c b/refs/packed-backend.c
index 34c0c4e20f..87ba5f520e 100644
--- a/refs/packed-backend.c
+++ b/refs/packed-backend.c
@@ -1576,7 +1576,7 @@ static int packed_delete_refs(struct ref_store *ref_store, const char *msg,
 }
 
 static int packed_pack_refs(struct ref_store *ref_store UNUSED,
-			    unsigned int flags UNUSED)
+			    struct pack_refs_opts *pack_opts UNUSED)
 {
 	/*
 	 * Packed refs are already packed. It might be that loose refs
diff --git a/refs/refs-internal.h b/refs/refs-internal.h
index a85d113123..f72b7be894 100644
--- a/refs/refs-internal.h
+++ b/refs/refs-internal.h
@@ -547,7 +547,8 @@ typedef int ref_transaction_commit_fn(struct ref_store *refs,
 				      struct ref_transaction *transaction,
 				      struct strbuf *err);
 
-typedef int pack_refs_fn(struct ref_store *ref_store, unsigned int flags);
+typedef int pack_refs_fn(struct ref_store *ref_store,
+			 struct pack_refs_opts *opts);
 typedef int create_symref_fn(struct ref_store *ref_store,
 			     const char *ref_target,
 			     const char *refs_heads_master,