[ovs-dev] [PATCH v2 4/9] ovsdb: row: Add support for xor-based row updates.

[Mark Gray]

On 12/06/2021 03:00, Ilya Maximets wrote:
> This will be used to apply update3 type updates to ovsdb tables
> while processing updates for future ovsdb 'relay' service model.
> 
> 'ovsdb_datum_apply_diff' is allowed to fail, so adding support
> to return this error.
> 
> Signed-off-by: Ilya Maximets <i.maximets at ovn.org>
> ---
>  ovsdb/execution.c   |  5 +++--
>  ovsdb/replication.c |  2 +-
>  ovsdb/row.c         | 30 +++++++++++++++++++++++++-----
>  ovsdb/row.h         |  6 ++++--
>  ovsdb/table.c       |  9 +++++----
>  ovsdb/table.h       |  2 +-
>  6 files changed, 39 insertions(+), 15 deletions(-)
> 
> diff --git a/ovsdb/execution.c b/ovsdb/execution.c
> index 3a0dad5d0..f6150e944 100644
> --- a/ovsdb/execution.c
> +++ b/ovsdb/execution.c
> @@ -483,8 +483,9 @@ update_row_cb(const struct ovsdb_row *row, void *ur_)
>  
>      ur->n_matches++;
>      if (!ovsdb_row_equal_columns(row, ur->row, ur->columns)) {
> -        ovsdb_row_update_columns(ovsdb_txn_row_modify(ur->txn, row),
> -                                 ur->row, ur->columns);
> +        ovsdb_error_assert(ovsdb_row_update_columns(
> +                               ovsdb_txn_row_modify(ur->txn, row),
> +                               ur->row, ur->columns, false));
>      }
>  
>      return true;
> diff --git a/ovsdb/replication.c b/ovsdb/replication.c
> index b755976b0..d8b56d813 100644
> --- a/ovsdb/replication.c
> +++ b/ovsdb/replication.c
> @@ -677,7 +677,7 @@ process_table_update(struct json *table_update, const char *table_name,
>          struct ovsdb_error *error;
>          error = (!new ? ovsdb_table_execute_delete(txn, &uuid, table)
>                   : !old ? ovsdb_table_execute_insert(txn, &uuid, table, new)
> -                 : ovsdb_table_execute_update(txn, &uuid, table, new));
> +                 : ovsdb_table_execute_update(txn, &uuid, table, new, false));
>          if (error) {
>              if (!strcmp(ovsdb_error_get_tag(error), "consistency violation")) {
>                  ovsdb_error_assert(error);
> diff --git a/ovsdb/row.c b/ovsdb/row.c
> index 755ab91a8..65a054621 100644
> --- a/ovsdb/row.c
> +++ b/ovsdb/row.c
> @@ -163,20 +163,40 @@ ovsdb_row_equal_columns(const struct ovsdb_row *a,
>      return true;
>  }
>  
> -void
> +struct ovsdb_error *
>  ovsdb_row_update_columns(struct ovsdb_row *dst,
>                           const struct ovsdb_row *src,
> -                         const struct ovsdb_column_set *columns)
> +                         const struct ovsdb_column_set *columns,
> +                         bool xor)
>  {
>      size_t i;
>  
>      for (i = 0; i < columns->n_columns; i++) {
>          const struct ovsdb_column *column = columns->columns[i];
> +        struct ovsdb_datum xor_datum;
> +        struct ovsdb_error *error;
> +
> +        if (xor) {
> +            error = ovsdb_datum_apply_diff(&xor_datum,
> +                                           &dst->fields[column->index],
> +                                           &src->fields[column->index],
> +                                           &column->type);
> +            if (error) {
> +                return error;
> +            }
> +        }
> +
>          ovsdb_datum_destroy(&dst->fields[column->index], &column->type);
> -        ovsdb_datum_clone(&dst->fields[column->index],
> -                          &src->fields[column->index],
> -                          &column->type);

Could you move ovsdb_datum_destroy(&dst->fields[column->index],
&column->type) into the "else" clause below and then merge the "if"
clause below into the "if" clause above?
> +
> +        if (xor) {
> +            ovsdb_datum_swap(&dst->fields[column->index], &xor_datum);
> +        } else {
> +            ovsdb_datum_clone(&dst->fields[column->index],
> +                              &src->fields[column->index],
> +                              &column->type);
> +        }
>      }
> +    return NULL;
>  }
>  
>  /* Appends the string form of the value in 'row' of each of the columns in
> diff --git a/ovsdb/row.h b/ovsdb/row.h
> index 2c441b5a4..394ac8eb4 100644
> --- a/ovsdb/row.h
> +++ b/ovsdb/row.h
> @@ -82,8 +82,10 @@ bool ovsdb_row_equal_columns(const struct ovsdb_row *,
>  int ovsdb_row_compare_columns_3way(const struct ovsdb_row *,
>                                     const struct ovsdb_row *,
>                                     const struct ovsdb_column_set *);
> -void ovsdb_row_update_columns(struct ovsdb_row *, const struct ovsdb_row *,
> -                              const struct ovsdb_column_set *);
> +struct ovsdb_error *ovsdb_row_update_columns(struct ovsdb_row *,
> +                                             const struct ovsdb_row *,
> +                                             const struct ovsdb_column_set *,
> +                                             bool xor);
>  void ovsdb_row_columns_to_string(const struct ovsdb_row *,
>                                   const struct ovsdb_column_set *, struct ds *);
>  struct ovsdb_error *ovsdb_row_from_json(struct ovsdb_row *,
> diff --git a/ovsdb/table.c b/ovsdb/table.c
> index 2935bd897..455a3663f 100644
> --- a/ovsdb/table.c
> +++ b/ovsdb/table.c
> @@ -384,7 +384,8 @@ ovsdb_table_execute_delete(struct ovsdb_txn *txn, const struct uuid *row_uuid,
>  
>  struct ovsdb_error *
>  ovsdb_table_execute_update(struct ovsdb_txn *txn, const struct uuid *row_uuid,
> -                           struct ovsdb_table *table, struct json *json_row)
> +                           struct ovsdb_table *table, struct json *json_row,
> +                           bool xor)
>  {
>      const struct ovsdb_row *row = ovsdb_table_get_row(table, row_uuid);
>      if (!row) {
> @@ -399,9 +400,9 @@ ovsdb_table_execute_update(struct ovsdb_txn *txn, const struct uuid *row_uuid,
>      struct ovsdb_error *error = ovsdb_row_from_json(update, json_row,
>                                                      NULL, &columns);
>  
> -    if (!error && !ovsdb_row_equal_columns(row, update, &columns)) {
> -        ovsdb_row_update_columns(ovsdb_txn_row_modify(txn, row),
> -                                 update, &columns);
> +    if (!error && (xor || !ovsdb_row_equal_columns(row, update, &columns))) {
> +        error = ovsdb_row_update_columns(ovsdb_txn_row_modify(txn, row),
> +                                         update, &columns, xor);
>      }
>  
>      ovsdb_column_set_destroy(&columns);
> diff --git a/ovsdb/table.h b/ovsdb/table.h
> index e21ec7b31..ce69a5d13 100644
> --- a/ovsdb/table.h
> +++ b/ovsdb/table.h
> @@ -82,6 +82,6 @@ struct ovsdb_error *ovsdb_table_execute_delete(struct ovsdb_txn *txn,
>  struct ovsdb_error *ovsdb_table_execute_update(struct ovsdb_txn *txn,
>                                                 const struct uuid *row_uuid,
>                                                 struct ovsdb_table *table,
> -                                               struct json *new);
> +                                               struct json *new, bool xor);
>  
>  #endif /* ovsdb/table.h */
>