fix(workflow-operator): set alreadyClosed before onClose

[justinsiek]

What changes were proposed in this PR?

AutoClosingIterator.hasNext only set alreadyClosed = true after calling onClose(), and so if onClose() throws, alreadyClosed would stay false, and so a subsequent hasNext would reinvoke onClose(), running cleanup a second time on a resource whose close already failed.

The change makes alreadyClosed = true run before onClose().

Any related issues, documentation, discussions?

Closes #5660

How was this PR tested?

Updated AutoClosingIteratorSpec — replaced the existing characterization test ("re-invoke onClose on a retry when the previous onClose threw") with a positive assertion that a second hasNext after a throwing close does NOT re-invoke onClose (closeCount stays at 1) and returns false.

sbt "WorkflowOperator/testOnly org.apache.texera.amber.operator.source.scan.AutoClosingIteratorSpec"

• 10/10 pass. sbt scalafmtCheckAll passes.

Was this PR authored or co-authored using generative AI tooling?

Generated-by: Claude Code (Claude Opus 4.8)

[Yicong-Huang]

LGTM, thanks

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 53.07%. Comparing base (7ae9b35) to head (ad1b3b9).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #5678      +/-   ##
============================================
- Coverage     53.23%   53.07%   -0.16%     
+ Complexity     2561     2541      -20     
============================================
  Files          1075     1075              
  Lines         42388    42191     -197     
  Branches       4640     4597      -43     
============================================
- Hits          22566    22394     -172     
+ Misses        18502    18480      -22     
+ Partials       1320     1317       -3     

Flag	Coverage Δ		*Carryforward flag
access-control-service	71.42% <ø> (-3.36%)	⬇️
agent-service	34.36% <ø> (ø)		Carriedforward from 7ae9b35
amber	53.89% <100.00%> (-0.32%)	⬇️
computing-unit-managing-service	1.65% <ø> (ø)
config-service	56.71% <ø> (-1.86%)	⬇️
file-service	57.06% <ø> (ø)
frontend	47.50% <ø> (ø)		Carriedforward from 7ae9b35
pyamber	90.79% <ø> (ø)		Carriedforward from 7ae9b35
python	90.74% <ø> (ø)		Carriedforward from 7ae9b35
workflow-compiling-service	58.69% <ø> (ø)

*This pull request uses carry forward flags. Click here to find out more.

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[github-actions]

⚠️ Benchmark changes need a look

🟢 5 better · 🔴 4 worse · ⚪ 6 noise (<±5%) · 0 without baseline

CI benchmark results are noisy; treat <±5% as noise unless repeated.

Dashboard · Run

	config	throughput	MB/s	latency	max Δ latest / 7d
🔴	bs=10 sw=10 sl=64	350	0.214	24,309/60,687/60,687 us	🔴 +58.3% / 🔴 +68.5%
🟢	bs=100 sw=10 sl=64	821	0.501	120,269/152,529/152,529 us	🟢 +12.6% / 🔴 +7.2%
⚪	bs=1000 sw=10 sl=64	946	0.577	1,053,355/1,103,324/1,103,324 us	⚪ within ±5% / 🔴 -6.4%

Baseline details

Latest main 7ae9b35 from 2026-06-13T00:44:28.840Z

config	metric	PR	latest main	7d avg	Δ latest	Δ 7d
bs=10 sw=10 sl=64	throughput	350 tuples/sec	394.18 tuples/sec	400.34 tuples/sec	-11.2%	-12.6%
bs=10 sw=10 sl=64	MB/s	0.214 MB/s	0.241 MB/s	0.244 MB/s	-11.1%	-12.4%
bs=10 sw=10 sl=64	p50	24,309 us	24,805 us	24,191 us	-2.0%	+0.5%
bs=10 sw=10 sl=64	p95	60,687 us	38,345 us	36,018 us	+58.3%	+68.5%
bs=10 sw=10 sl=64	p99	60,687 us	38,345 us	36,018 us	+58.3%	+68.5%
bs=100 sw=10 sl=64	throughput	821 tuples/sec	729.17 tuples/sec	867.19 tuples/sec	+12.6%	-5.3%
bs=100 sw=10 sl=64	MB/s	0.501 MB/s	0.445 MB/s	0.529 MB/s	+12.6%	-5.3%
bs=100 sw=10 sl=64	p50	120,269 us	133,219 us	114,874 us	-9.7%	+4.7%
bs=100 sw=10 sl=64	p95	152,529 us	173,178 us	142,264 us	-11.9%	+7.2%
bs=100 sw=10 sl=64	p99	152,529 us	173,178 us	142,264 us	-11.9%	+7.2%
bs=1000 sw=10 sl=64	throughput	946 tuples/sec	946.3 tuples/sec	1,010 tuples/sec	-0.0%	-6.3%
bs=1000 sw=10 sl=64	MB/s	0.577 MB/s	0.578 MB/s	0.616 MB/s	-0.1%	-6.4%
bs=1000 sw=10 sl=64	p50	1,053,355 us	1,059,718 us	995,071 us	-0.6%	+5.9%
bs=1000 sw=10 sl=64	p95	1,103,324 us	1,104,221 us	1,046,228 us	-0.1%	+5.5%
bs=1000 sw=10 sl=64	p99	1,103,324 us	1,104,221 us	1,046,228 us	-0.1%	+5.5%

Raw CSV

config_idx,batch_size,schema_width,string_len,num_batches,total_ms,total_tuples,total_bytes,tuples_per_sec,mb_per_sec,lat_p50_us,lat_p95_us,lat_p99_us
0,10,10,64,20,571.32,200,128000,350,0.214,24309.34,60687.35,60687.35
1,100,10,64,20,2437.23,2000,1280000,821,0.501,120269.28,152529.43,152529.43
2,1000,10,64,20,21150.51,20000,12800000,946,0.577,1053355.04,1103323.90,1103323.90