ARROW-8354: [R] Fix segfault in Table to Array conversion #6871
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r/tests/testthat/test-dplyr.R
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This should not error: it should return a 0-row data.frame:
filter(mtcars,FALSE)
## [1] mpg cyl disp hp drat wt qsec vs am gear carb
## <0 rows> (or 0-length row.names)I'll pull the branch and try to special-case that.
r/src/array_to_vector.cpp
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To save us future pain, should we hunt for other places that assume >0 length vectors? grepping [0] in r/src hits a few places that look similarly suspect.
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I checked them all and found one bug, I'll add a test and the fix in the current PR.
r/src/array_to_vector.cpp
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This should accept the type of arrays explicitly; a Converter should not fail when arrays is empty. Instead the result of conversion should also be empty.
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I updated https://issues.apache.org/jira/browse/ARROW-7798 to include this. I tried to quickly refactor what you suggest but it bubbles to rewriting almost all methods/functions of the file.
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It also lead me to find a bug with handling Dictionary ChunkedArray, https://issues.apache.org/jira/browse/ARROW-8374
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#6878 may help give more visibility into the unexpected failures |
The Converter::Make did not like receiving empty ArrayVector. The bug was introduced in ARROW-8216 which could return an empty selection vector due to a randomly generated fixture in test-dplyr.R
nealrichardson
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Hmm, continuing to have |
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At least now it errors instead of segfaults, and I changed some of the choreography to keep away from the error. Agreed that we can do better, and I think what you say has been added to the scope of https://issues.apache.org/jira/browse/ARROW-7798. I'm going to merge this since we've at least fixed the issue and have a passing build. |
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The Converter::Make did not like receiving empty ArrayVector. The bug was exposed in ARROW-8216 which could return an empty selection vector due to a randomly generated fixture in test-dplyr.R