bkietz commented on a change in pull request #8187:
URL: https://github.com/apache/arrow/pull/8187#discussion_r494537039
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File path: cpp/src/arrow/filesystem/filesystem.cc
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@@ -487,15 +489,27 @@ Status CopyFiles(const std::shared_ptr<FileSystem>&
source_fs,
internal::ConcatAbstractPath(destination_base_dir,
relative->to_string());
if (source_info.IsDirectory()) {
- destination_dirs.insert(destination_path);
+ dirs.push_back(destination_path);
} else if (source_info.IsFile()) {
sources.push_back({source_fs, source_info.path()});
destinations.push_back({destination_fs, destination_path});
}
}
- std::vector<std::string> dirs(destination_dirs.size());
- std::move(destination_dirs.begin(), destination_dirs.end(), dirs.begin());
+ // remove directories with descendants since recursive directory creation
will create
+ // them automatically
+ std::sort(dirs.begin(), dirs.end());
+ for (auto ancestor = dirs.begin(); ancestor != dirs.end(); ++ancestor) {
+ auto descendants_end = ancestor + 1;
+
+ while (descendants_end != dirs.end() &&
+ internal::IsAncestorOf(*ancestor, *descendants_end)) {
+ ++descendants_end;
+ }
+
+ dirs.erase(ancestor, descendants_end - 1);
Review comment:
> Perhaps `PathForest` can help. Though it's not obvious how to list the
leaves.
I don't think so; the intent of PathForest is to visit all ancestors
efficiently so getting a minimal set of descendants would not be efficient
> `internal::IsAncestorOf(*(descendants_end - 1), *descendants_end)`
You're right, thanks
> Another problem is that you're iterating on dirs while erasing from it.
That's not safe, I think, unless you write `ancestor = dirs.erase(ancestor,
descendants_end - 1)`.
You're right; vector::erase invalidates iterators *at* or after the
beginning of the range.
> Yet another issue is if you have {"a", "a/b/c"}, "a" won't be removed?
No, I'd expect `IsAncestorOf("a", "a/b/c") so "a" should be removed.
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