opt(recurse): Optimise recurse and bring range iterators from sroar

[ahsanbarkati]

Optimise recurse by using reached map with bitmap as the value, so a direct
bitmap AndNot can be done to get the list of unvisited edges. Also, use
range iterators and the fast iterator.

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This change is 

[manishrjain]

Very nice! Got a few comments.

Reviewed 9 of 9 files at r2, all commit messages.
Reviewable status: all files reviewed, 5 unresolved discussions (waiting on @ahsanbarkati)

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codec/codec.go, line 69 at r2 (raw file):

		return 0
	}
	// TODO: Update GetCardinality to handle nil Bitmap.

can you tackle this TODO?

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codec/codec.go, line 162 at r2 (raw file):

		return nil
	}
	return bm.ToBuffer()

bm.ToBuffer should deal with bm being empty. Can you make the change there? Then, we can just use ToBuffer or ToBufferWithCopy, I suppose.

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codec/codec.go, line 173 at r2 (raw file):

		iw.SetMany(l.SortedUids)
	}
	if len(l.Bitmap) > 0 {

move l.Bitmap above l.SortedUids, and return immediately, instead of doing check for l.SortedUids too. I can't imagine a case where both would be set.

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codec/codec.go, line 184 at r2 (raw file):

		return nil
	}
	if len(l.SortedUids) > 0 {

In my code, I had specifically moved this below l.Bitmap to avoid paying the code of check. The comment below says that we should optimize for l.Bitmap case. Can you move this below l.Bitmap? And add a comment to keep it that way.

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query/recurse.go, line 146 at r2 (raw file):

					if len(sg.uidMatrix[mIdx].SortedUids) > 0 {
						// we will have to keep the order, so using ApplyFilter
						algo.ApplyFilter(sg.uidMatrix[mIdx], func(uid uint64, i int) bool {

Did you find a case where this is needed?

[ahsanbarkati]

Reviewable status: 3 of 14 files reviewed, 5 unresolved discussions (waiting on @manishrjain)

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codec/codec.go, line 69 at r2 (raw file):

Previously, manishrjain (Manish R Jain) wrote…

can you tackle this TODO?

Done.

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codec/codec.go, line 162 at r2 (raw file):

Previously, manishrjain (Manish R Jain) wrote…

bm.ToBuffer should deal with bm being empty. Can you make the change there? Then, we can just use ToBuffer or ToBufferWithCopy, I suppose.

Done.

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codec/codec.go, line 173 at r2 (raw file):

Previously, manishrjain (Manish R Jain) wrote…

move l.Bitmap above l.SortedUids, and return immediately, instead of doing check for l.SortedUids too. I can't imagine a case where both would be set.

Done.

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codec/codec.go, line 184 at r2 (raw file):

Previously, manishrjain (Manish R Jain) wrote…

In my code, I had specifically moved this below l.Bitmap to avoid paying the code of check. The comment below says that we should optimize for l.Bitmap case. Can you move this below l.Bitmap? And add a comment to keep it that way.

Done.

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query/recurse.go, line 146 at r2 (raw file):

Previously, manishrjain (Manish R Jain) wrote…

Did you find a case where this is needed?

Yes for the case of recurse with order. Check TestRecurseQueryOrder.

[manishrjain]

Approved! Remember to add a task to also optimize AndNot.

Reviewed 11 of 11 files at r3, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @ahsanbarkati)

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codec/codec.go, line 139 at r3 (raw file):

	for _, m := range matrix {
		bmc := FromListNoCopy(m)
		if bmc != nil {

can be put together in one line.