On 30/09/2020 10:32, Dumitru Ceara wrote:
> On 9/30/20 11:21 AM, Dumitru Ceara wrote:
>> On 9/29/20 8:34 PM, Mark Gray wrote:
>>> Currently all functions of the type *_is_new() always return
>>> 'false'. This patch resolves this issue by using the
>>> 'OVSDB_IDL_CHANGE_INSERT' 'change_seqno' instead of the
>>> 'OVSDB_IDL_CHANGE_MODIFY' 'change_seqno' to determine if a row
>>> is new and by resetting the 'OVSDB_IDL_CHANGE_INSERT'
>>> 'change_seqno' on clear.
>>>
>>> Further to this, the code is also updated to match this
>>> behaviour:
>>>
>>> When a row is inserted, the 'OVSDB_IDL_CHANGE_INSERT'
>>> 'change_seqno' is updated to match the new database
>>> change_seqno. The 'OVSDB_IDL_CHANGE_MODIFY' 'change_seqno'
>>> is not set for inserted rows (only for updated rows).
>>>
>>> At the end of a run, ovsdb_idl_db_track_clear() should be
>>> called to clear all tracking information, this includes
>>> resetting all row 'change_seqno' to zero. This will ensure
>>> that subsequent runs will not see a previously 'new' row.
>>>
>>> add_tracked_change_for_references() is updated to only
>>> track rows that reference the current row.
>>>
>>> Signed-off-by: Mark Gray <[email protected]>
>>> Suggested-by: Dumitru Ceara <[email protected]>
>>> Reported-at: https://bugzilla.redhat.com/1883562
>>
>> Hi Mark,
>>
>> Thanks for working on this, it definitely looks like a nasty bug to me!
>>
>> We were lucky to not hit it in ovn-controller before. That's just
>> because all the "update" operations were handled there as "delete" +
>> "insert" but that is not mandatory and might change.
Very lucky!
>>
>>> ---
>>> lib/ovsdb-idl.c | 39 +++++++++++++++++++++++++++------------
>>> ovsdb/ovsdb-idlc.in | 2 +-
>>> 2 files changed, 28 insertions(+), 13 deletions(-)
>>>
>>> diff --git a/lib/ovsdb-idl.c b/lib/ovsdb-idl.c
>>> index d8f221ca6..3cfd73871 100644
>>> --- a/lib/ovsdb-idl.c
>>> +++ b/lib/ovsdb-idl.c
>>> @@ -1959,6 +1959,11 @@ ovsdb_idl_db_track_clear(struct ovsdb_idl_db *db)
>>> free(row->updated);
>>> row->updated = NULL;
>>> }
>>> +
>>> + row->change_seqno[OVSDB_IDL_CHANGE_INSERT] =
>>> + row->change_seqno[OVSDB_IDL_CHANGE_MODIFY] =
>>> + row->change_seqno[OVSDB_IDL_CHANGE_DELETE] = 0;
>>> +
>>> ovs_list_remove(&row->track_node);
>>> ovs_list_init(&row->track_node);
>>> if (ovsdb_idl_row_is_orphan(row) &&
>>> row->tracked_old_datum) {
>>> @@ -2684,24 +2689,27 @@ ovsdb_idl_process_update2(struct ovsdb_idl_table
>>> *table,
>>> return OVSDB_IDL_UPDATE_DB_CHANGED;
>>> }
>>>
>>> -/* Recursively add rows to tracked change lists for current row
>>> - * and the rows that reference this row. */
>>> +/* Recursively add rows to tracked change lists for all rows that reference
>>> + 'row'. */
>>> static void
>>> add_tracked_change_for_references(struct ovsdb_idl_row *row)
>>> {
>>> - if (ovs_list_is_empty(&row->track_node) &&
>>> - ovsdb_idl_track_is_set(row->table)) {
>>> - ovs_list_push_back(&row->table->track_list,
>>> - &row->track_node);
>>> - row->change_seqno[OVSDB_IDL_CHANGE_MODIFY]
>>> - = row->table->change_seqno[OVSDB_IDL_CHANGE_MODIFY]
>>> - = row->table->db->change_seqno + 1;
>>> -
>>> const struct ovsdb_idl_arc *arc;
>>> LIST_FOR_EACH (arc, dst_node, &row->dst_arcs) {
>>> - add_tracked_change_for_references(arc->src);
>>> + struct ovsdb_idl_row *ref = arc->src;
>>> +
>>> + if (ovs_list_is_empty(&ref->track_node) &&
>>> + ovsdb_idl_track_is_set(ref->table)) {
>>> + ovs_list_push_back(&ref->table->track_list,
>>> + &ref->track_node);
>>> +
>>> + ref->change_seqno[OVSDB_IDL_CHANGE_MODIFY]
>>> + = ref->table->change_seqno[OVSDB_IDL_CHANGE_MODIFY]
>>> + = ref->table->db->change_seqno + 1;
>>> +
>>> + add_tracked_change_for_references(ref);
>>> + }
>>> }
>>> - }
>>> }
>>>
>>>
>>> @@ -2767,7 +2775,14 @@ ovsdb_idl_row_change__(struct ovsdb_idl_row *row,
>>> const struct json *row_json,
>>> row->change_seqno[change]
>>> = row->table->change_seqno[change]
>>> = row->table->db->change_seqno + 1;
>>> +
>>> if (table->modes[column_idx] & OVSDB_IDL_TRACK) {
>>> + if (ovs_list_is_empty(&row->track_node) &&
>>> + ovsdb_idl_track_is_set(row->table)) {
>>> + ovs_list_push_back(&row->table->track_list,
>>> + &row->track_node);
>>> + }
>>> +
>>> add_tracked_change_for_references(row);
>>> if (!row->updated) {
>>> row->updated =
>>> bitmap_allocate(class->n_columns);
>>> diff --git a/ovsdb/ovsdb-idlc.in b/ovsdb/ovsdb-idlc.in
>>> index 698fe25f3..89c3eb682 100755
>>> --- a/ovsdb/ovsdb-idlc.in
>>> +++ b/ovsdb/ovsdb-idlc.in
>>> @@ -282,7 +282,7 @@ const struct %(s)s *%(s)s_table_track_get_first(const
>>> struct %(s)s_table *);
>>> /* Returns true if 'row' was inserted since the last change tracking
>>> reset. */
>>> static inline bool %(s)s_is_new(const struct %(s)s *row)
>>> {
>>> - return %(s)s_row_get_seqno(row, OVSDB_IDL_CHANGE_MODIFY) == 0;
>>> + return %(s)s_row_get_seqno(row, OVSDB_IDL_CHANGE_INSERT) > 0;
>>
>> This causes some issues with records created by the IDL client (e.g.,
>> ovn-controller). Those are created with ovsdb_idl_txn_insert() and we
>> don't set the OVSDB_IDL_CHANGE_INSERT change_seqno in that case.
>>
>> Essentially *_is_new() will never return true for rows inserted locally.
>>
>
> It would also be nice if we could add some OVS self tests in
> ovsdb-idl.at for all these changes.
Good idea, I will have a look at this suite of tests and see what can be
done. Thanks for the suggestion and review.
>
> Thanks,
> Dumitru
>
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