development/git
development/git
1
0
Fork 0
mirror of https://github.com/git/git synced 2024-11-05 04:53:18 +00:00
Code Issues Projects Releases Packages Wiki Activity

refs/reftable: stop micro-optimizing refname allocations on copy

Browse source 
When copying refs, we execute `write_copy_table()` to write the new
table. As the names are given to us via `arg->newname` and
`arg->oldname`, respectively, we optimize away some allocations by
assigning those fields to the reftable records we are about to write
directly, without duplicating them. This requires us to cast the input
to `char *` pointers as they are in fact constant strings. Later on, we
then unset the refname for all of the records before calling
`reftable_log_record_release()` on them.

We also do this when assigning the "HEAD" constant, but here we do not
cast because its type is `char[]` by default. It's about to be turned
into `const char *` though once we enable `-Wwrite-strings` and will
thus cause another warning.

It's quite dubious whether this micro-optimization really helps. We're
about to write to disk anyway, which is going to be way slower than a
small handful of allocations. Let's drop the optimization altogther and
instead copy arguments to simplify the code and avoid the future warning
with `-Wwrite-strings`.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Patrick Steinhardt 2024-06-07 08:37:48 +02:00 committed by Junio C Hamano
parent c113c5df79
commit 23c32511b3
1 changed files with 16 additions and 12 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

28
refs/reftable-backend.c
View file

@ -1340,10 +1340,10 @@ static int write_copy_table(struct reftable_writer *writer, void *cb_data)
* old reference.
*/
refs[0] = old_ref;
refs[0].refname = (char *)arg->newname;
refs[0].refname = xstrdup(arg->newname);
refs[0].update_index = creation_ts;
if (arg->delete_old) {
refs[1].refname = (char *)arg->oldname;
refs[1].refname = xstrdup(arg->oldname);
refs[1].value_type = REFTABLE_REF_DELETION;
refs[1].update_index = deletion_ts;
}
@ -1366,7 +1366,7 @@ static int write_copy_table(struct reftable_writer *writer, void *cb_data)
ALLOC_GROW(logs, logs_nr + 1, logs_alloc);
memset(&logs[logs_nr], 0, sizeof(logs[logs_nr]));
fill_reftable_log_record(&logs[logs_nr], &committer_ident);
logs[logs_nr].refname = (char *)arg->newname;
logs[logs_nr].refname = xstrdup(arg->newname);
logs[logs_nr].update_index = deletion_ts;
logs[logs_nr].value.update.message =
xstrndup(arg->logmsg, arg->refs->write_options.block_size / 2);
@ -1387,7 +1387,13 @@ static int write_copy_table(struct reftable_writer *writer, void *cb_data)
if (append_head_reflog) {
ALLOC_GROW(logs, logs_nr + 1, logs_alloc);
logs[logs_nr] = logs[logs_nr - 1];
logs[logs_nr].refname = "HEAD";
logs[logs_nr].refname = xstrdup("HEAD");
logs[logs_nr].value.update.name =
xstrdup(logs[logs_nr].value.update.name);
logs[logs_nr].value.update.email =
xstrdup(logs[logs_nr].value.update.email);
logs[logs_nr].value.update.message =
xstrdup(logs[logs_nr].value.update.message);
logs_nr++;
}
}
@ -1398,7 +1404,7 @@ static int write_copy_table(struct reftable_writer *writer, void *cb_data)
ALLOC_GROW(logs, logs_nr + 1, logs_alloc);
memset(&logs[logs_nr], 0, sizeof(logs[logs_nr]));
fill_reftable_log_record(&logs[logs_nr], &committer_ident);
logs[logs_nr].refname = (char *)arg->newname;
logs[logs_nr].refname = xstrdup(arg->newname);
logs[logs_nr].update_index = creation_ts;
logs[logs_nr].value.update.message =
xstrndup(arg->logmsg, arg->refs->write_options.block_size / 2);
@ -1430,7 +1436,7 @@ static int write_copy_table(struct reftable_writer *writer, void *cb_data)
*/
ALLOC_GROW(logs, logs_nr + 1, logs_alloc);
logs[logs_nr] = old_log;
logs[logs_nr].refname = (char *)arg->newname;
logs[logs_nr].refname = xstrdup(arg->newname);
logs_nr++;
/*
@ -1439,7 +1445,7 @@ static int write_copy_table(struct reftable_writer *writer, void *cb_data)
if (arg->delete_old) {
ALLOC_GROW(logs, logs_nr + 1, logs_alloc);
memset(&logs[logs_nr], 0, sizeof(logs[logs_nr]));
logs[logs_nr].refname = (char *)arg->oldname;
logs[logs_nr].refname = xstrdup(arg->oldname);
logs[logs_nr].value_type = REFTABLE_LOG_DELETION;
logs[logs_nr].update_index = old_log.update_index;
logs_nr++;
@ -1462,13 +1468,11 @@ static int write_copy_table(struct reftable_writer *writer, void *cb_data)
reftable_iterator_destroy(&it);
string_list_clear(&skip, 0);
strbuf_release(&errbuf);
for (i = 0; i < logs_nr; i++) {
if (!strcmp(logs[i].refname, "HEAD"))
continue;
logs[i].refname = NULL;
for (i = 0; i < logs_nr; i++)
reftable_log_record_release(&logs[i]);
}
free(logs);
for (i = 0; i < ARRAY_SIZE(refs); i++)
reftable_ref_record_release(&refs[i]);
reftable_ref_record_release(&old_ref);
reftable_log_record_release(&old_log);
return ret;