Recovery merge

[abudnik]

recovery: merge: removed obsolete Recovery code; used server-send, copy-iter everywhere

This PR sends greetings to PR #678

[noxiouz]

enumerate accepts optional parametr, which sets initial value of index. It's 0 by default.

enumerate(iterator, 1)

to remove index + 1

[abudnik]

fixed

[abudnik]

Fixed: 20e5376

[agend]

Hi all, do you have plans on merging this PR into master?

[agend]

@abudnik @shaitan Do you have plan to merge this? We really need this feature) May be we can help in some way?

[abudnik]

@agend You can merge both PR #679 and #681 into your local branch and test it on your test data. It would be very helpful for us.

[agend]

@abudnik Is it save for data?

[shaitan]

@agend It successfully passes our recovery tests but I wouldn't recommend you to test it on your production cluster until it is not tested on variety of test dataset or at least you have tested it on your test dataset that are close to your production.

PRs #679 and #681 are completed but before merging them we should fully test it to be sure that it is safe. Also we have one open question under discussion which doesn't affect to recovery correctness but defines recovery behaviour in case of error: "On which errors should copy-iterator stop?".

[bioothod]

I saw these fields in #668 pull request, why do you update them in two different places? Is this the same code as in #668 ?

[abudnik]

I've fixed distinction between _update_stats() code in both PRs (509bd3b). They are the same now.

[bioothod]

Should I merge this pull request?

[shaitan]

I will overlook and actualize it later today.

[shaitan]

It depends on #681 which has conflicts with current master.