On Thu, Jun 29, 2023 at 9:40 PM vignesh C <vignes...@gmail.com> wrote: > > On Thu, 29 Jun 2023 at 09:58, Zhijie Hou (Fujitsu) > <houzj.f...@fujitsu.com> wrote: > > > > On Thursday, June 29, 2023 12:06 PM vignesh C <vignes...@gmail.com> wrote: > > > > > > > Thanks for the patches. > > > > I tried to understand the following check: > > > > /* > > * If asked to skip empty transactions, we'll emit BEGIN at the > > point > > * where the first operation is received for this transaction. > > */ > > - if (data->skip_empty_xacts) > > + if (!(last_write ^ data->skip_empty_xacts) || > > txndata->xact_wrote_changes) > > return; > > > > I might miss something, but would you mind elaborating on why we use > > "last_write" in this check? > > last_write is used to indicate if it is begin/"begin > prepare"(last_write is true) or change/truncate/message(last_write is > false). > > We have specified logical XNOR which will be true for the following > conditions: > Condition1: last_write && data->skip_empty_xacts -> If it is > begin/begin prepare and user has specified skip empty transactions, we > will return from here, so that the begin message can be appended at > the point where the first operation is received for this transaction. > Condition2: !last_write && !data->skip_empty_xacts -> If it is > change/truncate or message and user has not specified skip empty > transactions, we will return from here as we would have appended the > begin earlier itself. > The txndata->xact_w6rote_changes will be set after the first operation > is received for this transaction during which we would have outputted > the begin message, this condition is to skip outputting begin message > if the begin message was already outputted. >
I feel the use of last_write has reduced the readability of this part of the code. It may be that we can add comments to make it clear but I feel your previous version was much easier to understand. -- With Regards, Amit Kapila.