refactor(config): replace the hand-rolled AuthConfig secret lock with lazy val

[aglinxinyuan]

What changes were proposed in this PR?

AuthConfig.jwtSecretKey hand-rolls a double-checked-locking lazy initializer — a @volatile var, a null sentinel and a synchronized block — to compute one value once. Scala's lazy val is that exact pattern, generated by the compiler.

// before
@volatile private var secretKey: String = _

def jwtSecretKey: String = {
  synchronized {
    if (secretKey == null) {
      secretKey = conf.getString("auth.jwt.256-bit-secret").toLowerCase() match {
        case "random" => getRandomHexString
        case key      => key
      }
    }
  }
  secretKey
}

// after
lazy val jwtSecretKey: String = conf.getString("auth.jwt.256-bit-secret").toLowerCase() match {
  case "random" => getRandomHexString
  case key      => key
}

Behaviour is preserved on every axis I checked:

	hand-rolled	lazy val
initialized at most once	yes	yes
safe under concurrent first access	yes (synchronized)	yes (compiler-generated DCL)
safe publication of the result	yes (@volatile)	yes
behaviour if the initializer throws	leaves the field null, retries next call	initialized bit not set, retries next call
call-site shape	AuthConfig.jwtSecretKey	unchanged

The single caller, JwtAuth.scala:35 (final val TOKEN_SECRET = AuthConfig.jwtSecretKey), needs no change — def and lazy val are indistinguishable at the call site. getRandomHexString stays a private def, so AuthConfigSpec's reflective lookup of it still resolves.

−14 lines, +6.

Any related issues, documentation, discussions?

Closes #7039

How was this PR tested?

Existing tests only — this PR adds none, since it is a behaviour-preserving rewrite already covered by AuthConfigSpec (which pins both the configured-secret path and that the value is memoized across calls).

Locally, from the repo root with Java 17:

• sbt "scalafixAll --check" — clean.
• sbt scalafmtCheckAll — clean.
• sbt "Config/testOnly *AuthConfigSpec" — 3 tests, all pass, unmodified.

The whole-repo scalafix/scalafmt run also compiles common/auth, so the JwtAuth call site is covered.

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

Generated-by: Claude Code (Claude Opus 5)

[github-actions]

Automated Reviewer Suggestions

Based on the git blame history of the changed files, we recommend the following reviewers:

• Contributors with relevant context: @Ma77Ball
  You can notify them by mentioning @Ma77Ball in a comment.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 33.33333% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.09%. Comparing base (02ae12b) to head (8a81451).

Files with missing lines	Patch %	Lines
...a/org/apache/texera/common/config/AuthConfig.scala	33.33%	1 Missing and 1 partial ⚠️

❌ Your patch status has failed because the patch coverage (33.33%) is below the target coverage (60.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #7040      +/-   ##
============================================
- Coverage     79.27%   79.09%   -0.18%     
+ Complexity     3787     3786       -1     
============================================
  Files          1160     1160              
  Lines         46124    46053      -71     
  Branches       5114     5108       -6     
============================================
- Hits          36563    36424     -139     
- Misses         7942     8007      +65     
- Partials       1619     1622       +3     

Flag	Coverage Δ		*Carryforward flag
access-control-service	70.00% <ø> (ø)
agent-service	76.76% <ø> (ø)		Carriedforward from 9de1386
amber	72.60% <33.33%> (-0.01%)	⬇️
computing-unit-managing-service	20.49% <ø> (ø)
config-service	66.66% <ø> (ø)
file-service	67.21% <ø> (ø)
frontend	82.91% <ø> (-0.18%)	⬇️	Carriedforward from 9de1386
notebook-migration-service	78.94% <ø> (ø)
pyamber	95.38% <ø> (-0.97%)	⬇️	Carriedforward from 9de1386
workflow-compiling-service	26.31% <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

🟢 6 better · 🔴 3 worse · ⚪ 6 noise (<±5%) · 0 without baseline

Compared against main 02ae12b benchmarked on this same runner, so the delta is largely free of cross-runner hardware noise. The "7d avg" column still reflects the gh-pages dashboard. Treat <±5% as noise unless repeated.

Dashboard · Run

	config	throughput	MB/s	latency	max Δ latest / 7d
🔴	bs=10 sw=10 sl=64	577	0.352	17,089/23,879/23,879 us	🔴 +20.8% / 🔴 +51.4%
🟢	bs=100 sw=10 sl=64	1,444	0.881	68,098/94,967/94,967 us	🟢 -11.2% / 🟢 +44.4%
🟢	bs=1000 sw=10 sl=64	1,677	1.024	598,922/611,477/611,477 us	🟢 -15.5% / 🟢 +62.7%

Baseline details

Latest main 02ae12b from same runner

config	metric	PR	latest main	7d avg	Δ latest	Δ 7d
bs=10 sw=10 sl=64	throughput	577 tuples/sec	666 tuples/sec	786.12 tuples/sec	-13.4%	-26.6%
bs=10 sw=10 sl=64	MB/s	0.352 MB/s	0.407 MB/s	0.48 MB/s	-13.5%	-26.6%
bs=10 sw=10 sl=64	p50	17,089 us	14,146 us	12,305 us	+20.8%	+38.9%
bs=10 sw=10 sl=64	p95	23,879 us	26,267 us	15,774 us	-9.1%	+51.4%
bs=10 sw=10 sl=64	p99	23,879 us	26,267 us	18,978 us	-9.1%	+25.8%
bs=100 sw=10 sl=64	throughput	1,444 tuples/sec	1,416 tuples/sec	999.71 tuples/sec	+2.0%	+44.4%
bs=100 sw=10 sl=64	MB/s	0.881 MB/s	0.864 MB/s	0.61 MB/s	+2.0%	+44.4%
bs=100 sw=10 sl=64	p50	68,098 us	65,957 us	100,616 us	+3.2%	-32.3%
bs=100 sw=10 sl=64	p95	94,967 us	106,969 us	107,356 us	-11.2%	-11.5%
bs=100 sw=10 sl=64	p99	94,967 us	106,969 us	113,255 us	-11.2%	-16.1%
bs=1000 sw=10 sl=64	throughput	1,677 tuples/sec	1,609 tuples/sec	1,031 tuples/sec	+4.2%	+62.6%
bs=1000 sw=10 sl=64	MB/s	1.024 MB/s	0.982 MB/s	0.63 MB/s	+4.3%	+62.7%
bs=1000 sw=10 sl=64	p50	598,922 us	600,838 us	980,328 us	-0.3%	-38.9%
bs=1000 sw=10 sl=64	p95	611,477 us	723,719 us	1,027,528 us	-15.5%	-40.5%
bs=1000 sw=10 sl=64	p99	611,477 us	723,719 us	1,054,298 us	-15.5%	-42.0%

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
0,10,10,64,20,346.89,200,128000,577,0.352,17088.98,23878.89,23878.89
1,100,10,64,20,1384.93,2000,1280000,1444,0.881,68097.73,94967.34,94967.34
2,1000,10,64,20,11925.29,20000,12800000,1677,1.024,598921.70,611477.25,611477.25