ARROW-12287: [C++] Create enumerating generator #9945
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…r index as well as whether or not they were the last item in the sequence. This is needed for reassembly potentially out of order record batches during scan.
lidavidm
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LGTM, just one typo in the docstring.
pitrou
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pitrou
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pitrou
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pitrou
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pitrou
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Apr 13, 2021
cpp/src/arrow/util/async_generator.h
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| /// Wraps items from a source generator with positional information | ||
| /// | ||
| /// When reqsequencing items from multiple streams that have been merged into |
pitrou
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cpp/src/arrow/util/async_generator.h
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| /// | ||
| /// Note: Another potential use for this could be resequencing items from a | ||
| /// jittery source. However, the readahead generator will not emit items out of | ||
| /// order today so this is not needed. Furthermore, this generator would need to |
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I don't think this is very insightful. Also, the readahead generator isn't the only way of producing items out of order.
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cpp/src/arrow/util/async_generator.h
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| /// order today so this is not needed. Furthermore, this generator would need to | ||
| /// support async reentrancy which, while possible, is not done currently. | ||
| /// | ||
| /// Note: Since this generator is not actually taking in out-of-order sources it isn't |
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Why "not actually"? This reads confusing. Are you discussing this implementation or whatever use is made of it inside the code base?
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cpp/src/arrow/util/async_generator.h
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| /// Note: Since this generator is not actually taking in out-of-order sources it isn't | ||
| /// strictly neccesary to add the index, it could be added by a map generator. However, | ||
| /// since this generator is usually used as later input to the sequencing generator and | ||
| /// the sequencing generator needs the index we go ahead and add it for utility's sake |
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Again, I think sentences like this are confusing. Adding something "for utility's sake" while claiming it's not useful does not make sense.
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@pitrou I cleaned up the description so it doesn't ramble so much. The "it would be nice if" speculation I put in ARROW-12371. |
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R failure unrelated, ready for merge/additional review. |
lidavidm
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Apr 14, 2021
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Apr 14, 2021
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Adds an enumerating generator which tags items with their index as well as whether or not they were the last item in the sequence. This is needed for reassembly potentially out of order record batches during scan.