Re: Refactor pg_rewind code and make it work against a standby

I wrote:
> Not sure if you noticed, but piculet has twice failed the
> 007_standby_source.pl test that was added by 9c4f5192f:
> ...
> Now, I'm not sure what to make of that, but I can't help noticing that
> piculet uses --disable-atomics while francolin uses --disable-spinlocks.
> That leads the mind towards some kind of low-level synchronization
> bug ...

Or, maybe it's less mysterious than that.  The failure looks like we
have not waited long enough for the just-inserted row to get replicated
to node C.  That wait is implemented as

    $lsn = $node_a->lsn('insert');
    $node_b->wait_for_catchup('node_c', 'write', $lsn);

which looks fishy ... shouldn't wait_for_catchup be told to
wait for replay of that LSN, not just write-the-WAL?

            regards, tom lane