Add Iterator::Refresh() #2621
Add Iterator::Refresh() #2621
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Summary: Add and implement Iterator::Refresh(). When this function is called, if the super version doesn't change, update the sequence number of the iterator to the latest one and invalidate the iterator. If the super version changed, recreated the whole iterator. This can help users reuse the iterator more easily. Test Plan:Add a unit test.
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@siying updated the pull request - view changes |
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HISTORY.md
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| @@ -1,4 +1,8 @@ | |||
| # Rocksdb Change Log | |||
| ## Unreleased | |||
| ### New Features | |||
| * Add Iterator::Refresh(), which also users to bring the iterator state up-to-date and avoid some initialization costs of the iterator. | |||
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may be rephrase this as: "... which allows users to update the iterator state ... "
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@siying updated the pull request - view changes - changes since last import |
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@siying has imported this pull request. If you are a Facebook employee, you can view this diff on Phabricator. |
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@siying updated the pull request - view changes - changes since last import |
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@siying has imported this pull request. If you are a Facebook employee, you can view this diff on Phabricator. |
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| InternalIterator* internal_iter = db_impl_->NewInternalIterator( | ||
| read_options_, cfd_, sv, &arena_, db_iter_->GetRangeDelAggregator()); | ||
| SetIterUnderDBIter(internal_iter); |
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This feels like not the duty of DBIter and feels to me could lead to future bugs if the db_impl called SetIterUnderDBIter in a different way and then we called it in our way.
If we are sure that we will always call SetIterUnderDBIter with an InternalIterator that looks like this
db_impl_->NewInternalIterator(read_options_, cfd_, sv, &arena_, db_iter_->GetRangeDelAggregator());
Then maybe we should have something like
DBIter::SetDBUnderIter(DBImpl* db_impl) {
InternalIterator* internal_iter = db_impl_->NewInternalIterator(read_options_, cfd_, sv, &arena_, db_iter_->GetRangeDelAggregator());
SetIterUnderDBIter(internal_iter);
}
And always use this function in db_impl.cc and make SetIterUnderDBIter private
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Good suggestion. Let me try that.
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I am trying this approach. SetDBUnderIter() needs to pass read_options, cfd, sv, etc. I'm feeling I'm getting things even more complicated.
Summary: Add and implement Iterator::Refresh(). When this function is called, if the super version doesn't change, update the sequence number of the iterator to the latest one and invalidate the iterator. If the super version changed, recreated the whole iterator. This can help users reuse the iterator more easily.
Test Plan:Add a unit test.