On Fri, Jan 8, 2021 at 12:04 AM Junio C Hamano <gitster@xxxxxxxxx> wrote:
>
> Patrick Steinhardt <ps@xxxxxx> writes:
>
> > static int s_update_ref(const char *action,
> > struct ref *ref,
> > + struct ref_transaction *transaction,
> > int check_old)
> > {
> > char *msg;
> > char *rla = getenv("GIT_REFLOG_ACTION");
> > - struct ref_transaction *transaction;
> > + struct ref_transaction *transaction_to_free = NULL;
> > struct strbuf err = STRBUF_INIT;
> > - int ret, df_conflict = 0;
> > + int ret, df_conflict = 0, commit = 0;
>
> > @@ -597,26 +598,38 @@ static int s_update_ref(const char *action,
> > rla = default_rla.buf;
> > msg = xstrfmt("%s: %s", rla, action);
> >
> > - transaction = ref_transaction_begin(&err);
> > - if (!transaction ||
> > - ref_transaction_update(transaction, ref->name,
> > + /*
> > + * If no transaction was passed to us, we manage the transaction
> > + * ourselves. Otherwise, we trust the caller to handle the transaction
> > + * lifecycle.
> > + */
> > + if (!transaction) {
> > + transaction = transaction_to_free = ref_transaction_begin(&err);
> > + if (!transaction)
> > + goto fail;
> > + commit = 1;
> > + }
>
> The idea is that we still allow the caller to pass NULL in which
> case we begin and commit a transaction ourselves, but if the caller
> is to pass an already initialized transaction to us, we obviously
> do not have to "begin" but also we won't commit.
>
> Which makes sense, but then do we still need the "commit" variable
> that reminds us "we are responsible for finishing the transaction we
> started"?
Yeah, I think we also don't need the df_conflict variable, and I don't
like the duplication of the following clean up code:
ref_transaction_free(transaction_to_free);
strbuf_release(&err);
free(msg);
Patrick's patch didn't introduce them, but we might still want to get
rid of them (see below).
> If we rename "transaction_to_free" to a name that makes it more
> clear that it is a transaction that we created and that we are
> responsible for seeing through to its end (after all, "to-free"
> captures only one half of that, i.e. before returning, we are
> responsible for calling ref_transation_free() on it), then we do not
> need such an extra variable that can go out of sync by mistake, no?
> The block that protects the call to ref_transaction_commit() can
> just check if the transaction_to_free variable (with a better name)
> is non-NULL, instead of looking at the commit variable.
>
> Just my attempt to come up with an alternative name for
> transaction_to_free:
>
> - "our_transaction" because it is ours?
>
> - "auto_transaction" because it is automatically started and
> committed without bothering the caller?
"our_transaction" looks fine.
Here is a suggested refactoring patch that could come before Patrick's patch:
-------------------------------------------------------------------------
diff --git a/builtin/fetch.c b/builtin/fetch.c
index ecf8537605..8017fc19da 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -581,6 +581,22 @@ static struct ref *get_ref_map(struct remote *remote,
#define STORE_REF_ERROR_OTHER 1
#define STORE_REF_ERROR_DF_CONFLICT 2
+static int do_s_update_ref(struct ref_transaction *transaction,
+ struct ref *ref,
+ int check_old,
+ struct strbuf *err,
+ char *msg)
+{
+ if (!transaction ||
+ ref_transaction_update(transaction, ref->name,
+ &ref->new_oid,
+ check_old ? &ref->old_oid : NULL,
+ 0, msg, err))
+ return TRANSACTION_GENERIC_ERROR;
+
+ return ref_transaction_commit(transaction, err);
+}
+
static int s_update_ref(const char *action,
struct ref *ref,
int check_old)
@@ -589,7 +605,7 @@ static int s_update_ref(const char *action,
char *rla = getenv("GIT_REFLOG_ACTION");
struct ref_transaction *transaction;
struct strbuf err = STRBUF_INIT;
- int ret, df_conflict = 0;
+ int ret = 0;
if (dry_run)
return 0;
@@ -598,30 +614,19 @@ static int s_update_ref(const char *action,
msg = xstrfmt("%s: %s", rla, action);
transaction = ref_transaction_begin(&err);
- if (!transaction ||
- ref_transaction_update(transaction, ref->name,
- &ref->new_oid,
- check_old ? &ref->old_oid : NULL,
- 0, msg, &err))
- goto fail;
- ret = ref_transaction_commit(transaction, &err);
+ ret = do_s_update_ref(transaction, ref, check_old, &err, msg);
if (ret) {
- df_conflict = (ret == TRANSACTION_NAME_CONFLICT);
- goto fail;
+ error("%s", err.buf);
+ ret = (ret == TRANSACTION_NAME_CONFLICT)
+ ? STORE_REF_ERROR_DF_CONFLICT
+ : STORE_REF_ERROR_OTHER;
}
ref_transaction_free(transaction);
strbuf_release(&err);
free(msg);
- return 0;
-fail:
- ref_transaction_free(transaction);
- error("%s", err.buf);
- strbuf_release(&err);
- free(msg);
- return df_conflict ? STORE_REF_ERROR_DF_CONFLICT
- : STORE_REF_ERROR_OTHER;
+ return ret;
}
static int refcol_width = 10;
-------------------------------------------------------------------------
After the above patch, Patrick's patch would become:
-------------------------------------------------------------------------
diff --git a/builtin/fetch.c b/builtin/fetch.c
index 8017fc19da..d58805c03d 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -584,6 +584,7 @@ static struct ref *get_ref_map(struct remote *remote,
static int do_s_update_ref(struct ref_transaction *transaction,
struct ref *ref,
int check_old,
+ int commit,
struct strbuf *err,
char *msg)
{
@@ -594,16 +595,17 @@ static int do_s_update_ref(struct
ref_transaction *transaction,
0, msg, err))
return TRANSACTION_GENERIC_ERROR;
- return ref_transaction_commit(transaction, err);
+ return (commit) ? ref_transaction_commit(transaction, err) : 0;
}
static int s_update_ref(const char *action,
+ struct ref_transaction *transaction,
struct ref *ref,
int check_old)
{
char *msg;
char *rla = getenv("GIT_REFLOG_ACTION");
- struct ref_transaction *transaction;
+ struct ref_transaction *our_transaction = NULL;
struct strbuf err = STRBUF_INIT;
int ret = 0;
@@ -613,9 +615,16 @@ static int s_update_ref(const char *action,
rla = default_rla.buf;
msg = xstrfmt("%s: %s", rla, action);
- transaction = ref_transaction_begin(&err);
+ /*
+ * If no transaction was passed to us, we manage the
+ * transaction ourselves. Otherwise, we trust the caller to
+ * handle the transaction lifecycle.
+ */
+ if (!transaction)
+ transaction = our_transaction = ref_transaction_begin(&err);
- ret = do_s_update_ref(transaction, ref, check_old, &err, msg);
+ ret = do_s_update_ref(transaction, ref, check_old, !!our_transaction,
+ &err, msg);
if (ret) {
error("%s", err.buf);
ret = (ret == TRANSACTION_NAME_CONFLICT)
@@ -623,7 +632,7 @@ static int s_update_ref(const char *action,
: STORE_REF_ERROR_OTHER;
}
- ref_transaction_free(transaction);
+ ref_transaction_free(our_transaction);
strbuf_release(&err);
free(msg);
return ret;
...
-------------------------------------------------------------------------
You can find these patches, with Patrick as the author, there:
https://gitlab.com/gitlab-org/gitlab-git/-/commits/cc-improve-s-update-ref/
