@matheusbsbs / matheus-bagliano / commits / 558f6fbeb1

reftable/stack: simplify tracking of table locks

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>

Patrick Steinhardt committed Aug 8, 2024 at 16:06 UTC 558f6fbeb1f194116231218b3e7496ceef4b9618
1 file changed +7 -7
reftable/stack.c
+7 -7
@@ -1016,7 +1016,7 @@ static int stack_compact_range(struct reftable_stack *st,
1016 struct lock_file *table_locks = NULL;
1017 struct tempfile *new_table = NULL;
1018 int is_empty_table = 0, err = 0;
1019 - size_t i;
1019 + size_t i, nlocks = 0;
1020
1021 if (first > last || (!expiry && first == last)) {
1022 err = 0;
@@ -1051,7 +1051,7 @@ static int stack_compact_range(struct reftable_stack *st,
1051 for (i = first; i <= last; i++) {
1052 stack_filename(&table_name, st, reader_name(st->readers[i]));
1053
1054 - err = hold_lock_file_for_update(&table_locks[i - first],
1054 + err = hold_lock_file_for_update(&table_locks[nlocks],
1055 table_name.buf, LOCK_NO_DEREF);
1056 if (err < 0) {
1057 if (errno == EEXIST)
@@ -1066,7 +1066,7 @@ static int stack_compact_range(struct reftable_stack *st,
1066 * run into file descriptor exhaustion when we compress a lot
1067 * of tables.
1068 */
1069 - err = close_lock_file_gently(&table_locks[i - first]);
1069 + err = close_lock_file_gently(&table_locks[nlocks++]);
1070 if (err < 0) {
1071 err = REFTABLE_IO_ERROR;
1072 goto done;
@@ -1183,8 +1183,8 @@ static int stack_compact_range(struct reftable_stack *st,
1183 * Delete the old tables. They may still be in use by concurrent
1184 * readers, so it is expected that unlinking tables may fail.
1185 */
1186 - for (i = first; i <= last; i++) {
1187 - struct lock_file *table_lock = &table_locks[i - first];
1186 + for (i = 0; i < nlocks; i++) {
1187 + struct lock_file *table_lock = &table_locks[i];
1188 char *table_path = get_locked_file_path(table_lock);
1189 unlink(table_path);
1190 free(table_path);
@@ -1192,8 +1192,8 @@ static int stack_compact_range(struct reftable_stack *st,
1192
1193 done:
1194 rollback_lock_file(&tables_list_lock);
1195 - for (i = first; table_locks && i <= last; i++)
1196 - rollback_lock_file(&table_locks[i - first]);
1195 + for (i = 0; table_locks && i < nlocks; i++)
1196 + rollback_lock_file(&table_locks[i]);
1197 reftable_free(table_locks);
1198
1199 delete_tempfile(&new_table);