Migrate async client to unified checksum options

[v-pratap]

Migrates the Async client (connection_impl.cc, object_descriptor_impl.cc) to use the newly introduced unified checksum options. Also includes the necessary fallback logic to support users who are still using the deprecated options.

[gemini-code-assist]

Code Review

This pull request transitions the asynchronous connection implementation and object descriptors to use the new UploadChecksumValidationOption and DownloadChecksumValidationOption instead of the deprecated EnableCrc32cValidationOption and EnableMD5ValidationOption. Feedback on the changes highlights several issues in the test suite, including redundant duplicate test cases and an incorrect test case expecting an invalid argument when validation is disabled. Additionally, the reviewer noted that the logic for resolving checksum validation options is duplicated across multiple non-test files, violating the repository style guide's recommendation to factor out code duplicated three or more times.

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[gemini-code-assist]

These three test cases are completely duplicated and identical to the three test cases immediately following them (lines 181-195). Please remove this redundant block.

[gemini-code-assist]

This block of kInvalidArgument test cases contains several issues:

1. The test case with storage::ChecksumAlgorithm::kNone (lines 208-212) expects StatusCode::kInvalidArgument. However, when validation is disabled (kNone), no validation is performed, so it should succeed with StatusCode::kOk (which is already tested in the kOk section). This test case is incorrect and will fail.
2. The test cases for kCrc32c and kMD5 are duplicated (lines 213-217 and 218-222 are duplicates of lines 203-207 and 198-202 respectively).

Please simplify this block to only include the two unique and correct test cases for kMD5 and kCrc32c validation failures.

        HashTestCase{StatusCode::kInvalidArgument,
                     Options{}
                         .set<storage::DownloadChecksumValidationOption>(
                             storage::ChecksumAlgorithm::kMD5),
                     kQuickFoxCrc32cChecksumBad, kQuickFoxMD5HashBad},
        HashTestCase{StatusCode::kInvalidArgument,
                     Options{}
                         .set<storage::DownloadChecksumValidationOption>(
                             storage::ChecksumAlgorithm::kCrc32c),
                     kQuickFoxCrc32cChecksumBad, kQuickFoxMD5HashBad},

[gemini-code-assist]

The logic to resolve the checksum validation options is duplicated here and in CreateHashValidator (lines 132-142), as well as in object_descriptor_impl.cc. According to the repository style guide (lines 28-29), we should prefer to factor out duplicated code if it appears 3 or more times in non-test files. Consider defining a helper function template to handle both upload and download options:

template <typename Option>
std::pair<bool, bool> GetChecksumSettings(Options const& options) {
  if (options.has<Option>()) {
    auto const algo = options.get<Option>();
    return {algo == storage::ChecksumAlgorithm::kCrc32c,
            algo == storage::ChecksumAlgorithm::kMD5};
  }
  return {options.get<storage::EnableCrc32cValidationOption>(),
          options.get<storage::EnableMD5ValidationOption>()};
}

And then use structured bindings:

auto const [enable_crc32c, enable_md5] = GetChecksumSettings<storage::UploadChecksumValidationOption>(options);

References

1. Prefer to factor out duplicated code if it appears 3 or more times in non-test files. ^(link)

[gemini-code-assist]

The logic to resolve the download checksum validation options is duplicated here and in CreateHashValidator (lines 266-275), as well as in connection_impl.cc. According to the repository style guide (lines 28-29), we should prefer to factor out duplicated code if it appears 3 or more times in non-test files. Consider factoring this out into a helper function (e.g., in an anonymous namespace or as a private helper method):

std::pair<bool, bool> GetDownloadChecksumSettings(Options const& options) {
  if (options.has<storage::DownloadChecksumValidationOption>()) {
    auto const algo = options.get<storage::DownloadChecksumValidationOption>();
    return {algo == storage::ChecksumAlgorithm::kCrc32c,
            algo == storage::ChecksumAlgorithm::kMD5};
  }
  return {options.get<storage::EnableCrc32cValidationOption>(),
          options.get<storage::EnableMD5ValidationOption>()};
}

And then use structured bindings:

auto const [enable_crc32c, enable_md5] = GetDownloadChecksumSettings(options_);

References

1. Prefer to factor out duplicated code if it appears 3 or more times in non-test files. ^(link)