[coverage] Conformance findings: CLOUDFETCH-018

[peco-engineer-bot]

Summary

Surfaced by the multi-language coverage fan-out while conformance-testing these SPEC-IDs against databricks/databricks-jdbc. Each finding is committed as an expected-failure (xfail) test in the coverage PR — the test asserts the CORRECT (post-fix) behavior and stays red until THIS driver (databricks/databricks-jdbc) is fixed, then flips green as a tripwire.

Findings

• CLOUDFETCH-018 [thrift]: Thrift chunk-ready timeout loses its TIMEOUT classification: AbstractRemoteChunkProvider.getChunk collapses ExecutionException|TimeoutException into DatabricksSQLException("Failed to ready chunk", e.getCause()), and TimeoutException has a null cause, so a stalled CloudFetch chunk surfaces an opaque internal error instead of a timeout (SEA's StreamingChunkProvider gets this right)
  • failing test: testStalledChunkDownloadIsBoundedByAnEndToEndDeadline (see the coverage PR diff under tests/)

Reproduce & Expected

CLOUDFETCH-018 — A CloudFetch chunk download that STALLS -- the cloud-storage GET is accepted but response headers/body never arrive -- must be abandoned under an ABSOLUTE end-to-end wall-clock budget for that chunk,…

Reproduce:

• Stall EVERY CloudFetch download: the proxy accepts each GET and holds it for
  180s, so no attempt ever completes and the chunk can only finish by the driver
  giving up.
• A result large enough to be delivered via CloudFetch external links; drain it
  and expect a terminal timeout rather than a multi-minute block.

Expected (per the shared spec):

• full assertion contract:

result:
- label: stalled_drain
  exception_thrown: true
- label: stalled_drain
  elapsed_seconds_range:
    max: 150
- label: stalled_drain
  error:
    contains:
    - timeout
    - timed out
    - deadline
protocol:
  thrift:
  - label: stalled_drain
    cloud_downloads_min: 1
  sea:
  - label: stalled_drain
    cloud_downloads_min: 1

Context

• The behavior was first fixed in a DIFFERENT driver — reference PR: https://github.com/databricks/databricks-sql-kernel/pull/323 — which seeded the shared language-neutral spec. This issue tracks the same conformance gap in databricks/databricks-jdbc; the reference PR is for cross-referencing the intended behavior, NOT a change to this repo.
• Coverage PR carrying the reproducing xfail test(s): https://github.com/databricks/databricks-driver-test/pull/1577