"git clone" uses shortcuts when creating the initial set of
references:
* It writes them directly to packed-refs.
* It doesn't lock the individual references (though it does lock the
packed-refs file).
* It doesn't check for refname conflicts between two new references or
between one new reference and any hypothetical old ones.
* It doesn't create reflog entries for the reference creations.
This functionality was implemented in builtin/clone.c. But really that
file shouldn't have such intimate knowledge of how references are
stored. So provide a new function in the refs API,
initial_ref_transaction_commit(), which can be used for initial
reference creation. The new function is based on the ref_transaction
interface.
This means that we can make some other functions private to the refs
module. That will be done in a followup commit.
It would seem to make sense to add a test here that there are no
existing references, because that is how the function *should* be
used. But in fact, the "testgit" remote helper appears to call it
*after* having set up refs/remotes/<name>/HEAD and
refs/remotes/<name>/master, so we can't be so strict. For now, the
function trusts its caller to only call it when it makes sense. Future
commits will add some more limited sanity checks.
Signed-off-by: Michael Haggerty <mhagger@xxxxxxxxxxxx>
---
builtin/clone.c | 19 +++++++++++++++----
refs.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
refs.h | 14 ++++++++++++++
3 files changed, 76 insertions(+), 4 deletions(-)
diff --git a/builtin/clone.c b/builtin/clone.c
index b878252..bd2a50a 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -500,16 +500,27 @@ static void write_remote_refs(const struct ref *local_refs)
{
const struct ref *r;
- lock_packed_refs(LOCK_DIE_ON_ERROR);
+ struct ref_transaction *t;
+ struct strbuf err = STRBUF_INIT;
+
+ t = ref_transaction_begin(&err);
+ if (!t)
+ die(err.buf);
for (r = local_refs; r; r = r->next) {
if (!r->peer_ref)
continue;
- add_packed_ref(r->peer_ref->name, r->old_sha1);
+ if (ref_transaction_create(t, r->peer_ref->name, r->old_sha1,
+ 0, NULL, &err))
+ die(err.buf);
+ }
+
+ if (initial_ref_transaction_commit(t, &err)) {
+ die(err.buf);
}
- if (commit_packed_refs())
- die_errno("unable to overwrite old ref-pack file");
+ strbuf_release(&err);
+ ref_transaction_free(t);
}
static void write_followtags(const struct ref *refs, const char *msg)
diff --git a/refs.c b/refs.c
index 832d628..05e5d42 100644
--- a/refs.c
+++ b/refs.c
@@ -4045,6 +4045,53 @@ cleanup:
return ret;
}
+int initial_ref_transaction_commit(struct ref_transaction *transaction,
+ struct strbuf *err)
+{
+ int ret = 0, i;
+ int n = transaction->nr;
+ struct ref_update **updates = transaction->updates;
+
+ assert(err);
+
+ if (transaction->state != REF_TRANSACTION_OPEN)
+ die("BUG: commit called for transaction that is not open");
+
+ for (i = 0; i < n; i++) {
+ struct ref_update *update = updates[i];
+
+ if ((update->flags & REF_HAVE_OLD) &&
+ !is_null_sha1(update->old_sha1))
+ die("BUG: initial ref transaction with old_sha1 set");
+ }
+
+ if (lock_packed_refs(0)) {
+ strbuf_addf(err, "unable to lock packed-refs file: %s",
+ strerror(errno));
+ ret = TRANSACTION_GENERIC_ERROR;
+ goto cleanup;
+ }
+
+ for (i = 0; i < n; i++) {
+ struct ref_update *update = updates[i];
+
+ if ((update->flags & REF_HAVE_NEW) &&
+ !is_null_sha1(update->new_sha1))
+ add_packed_ref(update->refname, update->new_sha1);
+ }
+
+ if (commit_packed_refs()) {
+ strbuf_addf(err, "unable to commit packed-refs file: %s",
+ strerror(errno));
+ ret = TRANSACTION_GENERIC_ERROR;
+ goto cleanup;
+ }
+
+cleanup:
+ transaction->state = REF_TRANSACTION_CLOSED;
+ return ret;
+}
+
char *shorten_unambiguous_ref(const char *refname, int strict)
{
int i;
diff --git a/refs.h b/refs.h
index 5f3bea7..9602889 100644
--- a/refs.h
+++ b/refs.h
@@ -366,6 +366,20 @@ int ref_transaction_commit(struct ref_transaction *transaction,
struct strbuf *err);
/*
+ * Like ref_transaction_commit(), but optimized for creating
+ * references when originally initializing a repository (e.g., by "git
+ * clone"). It writes the new references directly to packed-refs
+ * without locking the individual references.
+ *
+ * It is a bug to call this function when there might be other
+ * processes accessing the repository or if there are existing
+ * references that might conflict with the ones being created. All
+ * old_sha1 values must either be absent or NULL_SHA1.
+ */
+int initial_ref_transaction_commit(struct ref_transaction *transaction,
+ struct strbuf *err);
+
+/*
* Free an existing transaction and all associated data.
*/
void ref_transaction_free(struct ref_transaction *transaction);
--
2.1.4
--
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