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reftable/stack: simplify tracking of table locks

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When compacting tables, we store the locks of all tables we are about to
compact in the `table_locks` array. As we currently only ever compact
all tables in the user-provided range or none, we simply track those
locks via the indices of the respective tables in the merged stack.

This is about to change though, as we will introduce a mode where auto
compaction gracefully handles the case of already-locked files. In this
case, it may happen that we only compact a subset of the user-supplied
range of tables. In this case, the indices will not necessarily match
the lock indices anymore.

Refactor the code such that we track the number of locks via a separate
variable. The resulting code is expected to perform the same, but will
make it easier to perform the described change.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Patrick Steinhardt
2024-08-08 16:06:39 +02:00
committed by Junio C Hamano
parent 5f0ed603a1
commit 558f6fbeb1
1 changed files with 7 additions and 7 deletions
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14
reftable/stack.c
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@ -1016,7 +1016,7 @@ static int stack_compact_range(struct reftable_stack *st,
struct lock_file *table_locks = NULL; struct lock_file *table_locks = NULL;
struct tempfile *new_table = NULL; struct tempfile *new_table = NULL;
int is_empty_table = 0, err = 0; int is_empty_table = 0, err = 0;
size_t i; size_t i, nlocks = 0;
if (first > last || (!expiry && first == last)) { if (first > last || (!expiry && first == last)) {
err = 0; err = 0;
@ -1051,7 +1051,7 @@ static int stack_compact_range(struct reftable_stack *st,
for (i = first; i <= last; i++) { for (i = first; i <= last; i++) {
stack_filename(&table_name, st, reader_name(st->readers[i])); stack_filename(&table_name, st, reader_name(st->readers[i]));
err = hold_lock_file_for_update(&table_locks[i - first], err = hold_lock_file_for_update(&table_locks[nlocks],
table_name.buf, LOCK_NO_DEREF); table_name.buf, LOCK_NO_DEREF);
if (err < 0) { if (err < 0) {
if (errno == EEXIST) if (errno == EEXIST)
@ -1066,7 +1066,7 @@ static int stack_compact_range(struct reftable_stack *st,
* run into file descriptor exhaustion when we compress a lot * run into file descriptor exhaustion when we compress a lot
* of tables. * of tables.
*/ */
err = close_lock_file_gently(&table_locks[i - first]); err = close_lock_file_gently(&table_locks[nlocks++]);
if (err < 0) { if (err < 0) {
err = REFTABLE_IO_ERROR; err = REFTABLE_IO_ERROR;
goto done; goto done;
@ -1183,8 +1183,8 @@ static int stack_compact_range(struct reftable_stack *st,
* Delete the old tables. They may still be in use by concurrent * Delete the old tables. They may still be in use by concurrent
* readers, so it is expected that unlinking tables may fail. * readers, so it is expected that unlinking tables may fail.
*/ */
for (i = first; i <= last; i++) { for (i = 0; i < nlocks; i++) {
struct lock_file *table_lock = &table_locks[i - first]; struct lock_file *table_lock = &table_locks[i];
char *table_path = get_locked_file_path(table_lock); char *table_path = get_locked_file_path(table_lock);
unlink(table_path); unlink(table_path);
free(table_path); free(table_path);
@ -1192,8 +1192,8 @@ static int stack_compact_range(struct reftable_stack *st,
done: done:
rollback_lock_file(&tables_list_lock); rollback_lock_file(&tables_list_lock);
for (i = first; table_locks && i <= last; i++) for (i = 0; table_locks && i < nlocks; i++)
rollback_lock_file(&table_locks[i - first]); rollback_lock_file(&table_locks[i]);
reftable_free(table_locks); reftable_free(table_locks);
delete_tempfile(&new_table); delete_tempfile(&new_table);