refs debug: add a wrapper for "read_symbolic_ref"

In cd475b3b038 (refs: add ability for backends to special-case reading
of symbolic refs, 2022-03-01) when the "read_symbolic_ref" callback
was added we'd fall back on "refs_read_raw_ref" if there wasn't any
backend implementation of "read_symbolic_ref".

As discussed in the preceding commit this would only happen if we were
running the "debug" backend, e.g. in the "setup for ref completion"
test in t9902-completion.sh with:

    GIT_TRACE_REFS=1 git fetch --no-tags other

Let's improve the trace output, but and also eliminate the
now-redundant refs_read_raw_ref() fallback case. As noted in the
preceding commit the "packed" backend will never call
refs_read_symbolic_ref() (nor is it ever going to). For any future
backend such as reftable it's OK to ask that they either implement
this (or a wrapper) themselves.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/refs.c b/refs.c
index 0b79bdd7c37d8a3f8da5f096b69a5e672cb5a60f..1a964505f92ad64da049439439f6da2656abe058 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -1676,18 +1676,7 @@ int refs_read_raw_ref(struct ref_store *ref_store, const char *refname,
 int refs_read_symbolic_ref(struct ref_store *ref_store, const char *refname,
                           struct strbuf *referent)
 {
-       struct object_id oid;
-       int ret, failure_errno = 0;
-       unsigned int type = 0;
-
-       if (ref_store->be->read_symbolic_ref)
-               return ref_store->be->read_symbolic_ref(ref_store, refname, referent);
-
-       ret = refs_read_raw_ref(ref_store, refname, &oid, referent, &type, &failure_errno);
-       if (ret || !(type & REF_ISSYMREF))
-               return -1;
-
-       return 0;
+       return ref_store->be->read_symbolic_ref(ref_store, refname, referent);
 }
 
 const char *refs_resolve_ref_unsafe(struct ref_store *refs,

diff --git a/refs/debug.c b/refs/debug.c
index b83b58171189b5df471765072f425b4b7d0aa942..eed8bc94b04f68125bb84eddfc26381ad86d3157 100644 (file)
--- a/refs/debug.c
+++ b/refs/debug.c
@@ -262,6 +262,24 @@ static int debug_read_raw_ref(struct ref_store *ref_store, const char *refname,
        return res;
 }
 
+static int debug_read_symbolic_ref(struct ref_store *ref_store, const char *refname,
+                                  struct strbuf *referent)
+{
+       struct debug_ref_store *drefs = (struct debug_ref_store *)ref_store;
+       struct ref_store *refs = drefs->refs;
+       int res;
+
+       res = refs->be->read_symbolic_ref(refs, refname, referent);
+       if (!res)
+               trace_printf_key(&trace_refs, "read_symbolic_ref: %s: (%s)\n",
+                                refname, referent->buf);
+       else
+               trace_printf_key(&trace_refs,
+                                "read_symbolic_ref: %s: %d\n", refname, res);
+       return res;
+
+}
+
 static struct ref_iterator *
 debug_reflog_iterator_begin(struct ref_store *ref_store)
 {
@@ -423,6 +441,13 @@ struct ref_storage_be refs_be_debug = {
        .name = "debug",
        .init = NULL,
        .init_db = debug_init_db,
+
+       /*
+        * None of these should be NULL. If the "files" backend (in
+        * "struct ref_storage_be refs_be_files" in files-backend.c)
+        * has a function we should also have a wrapper for it here.
+        * Test the output with "GIT_TRACE_REFS=1".
+        */
        .transaction_prepare = debug_transaction_prepare,
        .transaction_finish = debug_transaction_finish,
        .transaction_abort = debug_transaction_abort,
@@ -436,7 +461,7 @@ struct ref_storage_be refs_be_debug = {
 
        .iterator_begin = debug_ref_iterator_begin,
        .read_raw_ref = debug_read_raw_ref,
-       .read_symbolic_ref = NULL,
+       .read_symbolic_ref = debug_read_symbolic_ref,
 
        .reflog_iterator_begin = debug_reflog_iterator_begin,
        .for_each_reflog_ent = debug_for_each_reflog_ent,