bkietz commented on a change in pull request #10566:
URL: https://github.com/apache/arrow/pull/10566#discussion_r655503062
##########
File path: cpp/src/arrow/dataset/file_parquet.cc
##########
@@ -270,24 +279,29 @@ ParquetFileFormat::ParquetFileFormat(const
parquet::ReaderProperties& reader_pro
}
Result<bool> ParquetFileFormat::IsSupported(const FileSource& source) const {
- try {
- ARROW_ASSIGN_OR_RAISE(auto input, source.Open());
- ARROW_ASSIGN_OR_RAISE(auto parquet_scan_options,
- GetFragmentScanOptions<ParquetFragmentScanOptions>(
- kParquetTypeName, nullptr,
default_fragment_scan_options));
- auto reader = parquet::ParquetFileReader::Open(
- std::move(input), MakeReaderProperties(*this,
parquet_scan_options.get()));
- std::shared_ptr<parquet::FileMetaData> metadata = reader->metadata();
- return metadata != nullptr && metadata->can_decompress();
- } catch (const ::parquet::ParquetInvalidOrCorruptedFileException& e) {
- ARROW_UNUSED(e);
- return false;
- } catch (const ::parquet::ParquetException& e) {
- return Status::IOError("Could not open parquet input source '",
source.path(),
- "': ", e.what());
- }
-
- return true;
+ auto maybe_is_supported = [&]() -> Result<bool> {
Review comment:
Please move this to `IsSupportedImpl` or so, then
```suggestion
auto maybe_is_supported = IsSupportedImpl(*this, source);
```
##########
File path: cpp/src/arrow/dataset/file_parquet.cc
##########
@@ -307,14 +321,17 @@ Result<std::unique_ptr<parquet::arrow::FileReader>>
ParquetFileFormat::GetReader
auto properties = MakeReaderProperties(*this, parquet_scan_options.get(),
pool);
ARROW_ASSIGN_OR_RAISE(auto input, source.Open());
- std::unique_ptr<parquet::ParquetFileReader> reader;
- try {
- reader = parquet::ParquetFileReader::Open(std::move(input),
std::move(properties));
- } catch (const ::parquet::ParquetException& e) {
- return Status::IOError("Could not open parquet input source '",
source.path(),
- "': ", e.what());
- }
+ auto maybe_reader = [&]() ->
Result<std::unique_ptr<parquet::ParquetFileReader>> {
Review comment:
Less fragile than macros would be:
```c++
auto maybe_reader = parquet::CatchNotOk([&] {
return parquet::ParquetFileReader::Open(std::move(input),
std::move(properties));
});
```
Could be implemented like:
```c++
template <typename Fn, typename Ret>
struct CatchNotOkImpl {
static typename EnsureResult<Ret>::type Call(Fn&& fn) { return
std::forward<Fn>(fn)(); }
};
template <typename Fn>
struct CatchNotOkImpl<Fn, Status> {
static Status Call(Fn&& fn) { return std::forward<Fn>(fn)(); }
};
template <typename Fn>
struct CatchNotOkImpl<Fn, void> {
static Status Call(Fn&& fn) {
std::forward<Fn>(fn)();
return Status::OK();
}
};
template <typename Fn, typename Impl = CatchNotOkImpl<Fn,
decltype(std::declval<Fn>()())>>
auto CatchNotOk(Fn&& fn) -> decltype(Impl::Call(std::forward<Fn>(fn))) try {
return Impl::Call(std::forward<Fn>(fn));
} catch (const ParquetStatusException& e) {
return e.status();
} catch (const ParquetException& e) {
return Status::IOError(e.what());
}
```
What do you think?
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