(#4907) Replaced synchronized with ReentrantLock in PhCached

[AlexNetTie]

What does this PR do?

Replaces synchronized block with ReentrantLock in PhCached.take() method to avoid potential deadlocks and comply with qulice rules. Implements double-checked locking pattern for better performance.

Related issues

• Fixes 'Synchronized' in PhCached.java Risks Thread-Safety, Requires Replacement #4907

Changes

• Added ReentrantLock field
• Replaced synchronized (this.cached) with double-checked locking using lock.lock() / lock.unlock()
• Removed @SuppressWarnings("PMD.AvoidSynchronizedStatement")
• Removed corresponding @todo puzzle
• Fixed whitespace formatting issues found by qulice

How to test

Run mvn clean install -pl eo-runtime -am to verify compilation and tests.
Run mvn qulice:check -Pqulice -pl eo-runtime to verify code style.

Notes

Local Windows tests show known MjPrintTest failure unrelated to these changes. All CI checks on Linux are expected to pass.

Summary by CodeRabbit

• Refactor
  • Improved internal thread-safety mechanisms for better performance and reliability in the caching system.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 532d87bc-d2e9-4fb6-a077-be7f96fe4016

📥 Commits

Reviewing files that changed from the base of the PR and between 9250c27 and 3fb437e.

📒 Files selected for processing (1)

• eo-runtime/src/main/java/org/eolang/PhCached.java

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📝 Walkthrough

Walkthrough

Replaces the synchronized block in PhCached.java with an explicit ReentrantLock for cache lazy initialization. Implements a double-checked locking pattern to maintain thread safety while using modern lock-based synchronization instead of monitor-based synchronization.

Changes

Cohort / File(s)	Summary
Synchronization Mechanism Update eo-runtime/src/main/java/org/eolang/PhCached.java	Replaces synchronized block with ReentrantLock for cache initialization. Adds lock field, implements double-checked locking pattern, removes PMD suppression annotation, and updates necessary imports.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Suggested reviewers

• yegor256

Poem

🐰 A lock replaces sync's embrace,
No monitors in this space!
Double-checked, it guards the cache,
Thread-safe now—a swift dash! ✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 20.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically describes the main change: replacing synchronized with ReentrantLock in PhCached, directly matching the core modification in the changeset.
Linked Issues check	✅ Passed	The PR fully addresses issue #4907 by replacing the synchronized block with ReentrantLock, removing the puzzle annotation, implementing double-checked locking, and fixing qulice whitespace issues.
Out of Scope Changes check	✅ Passed	All changes are directly related to the stated objective: replacing synchronized with ReentrantLock in PhCached and removing the associated puzzle, with no extraneous modifications.

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[github-actions]

🚀 Performance Analysis

All benchmarks are within the acceptable range. No critical degradation detected (threshold is 100%). Please refer to the detailed report for more information.

Click to see the detailed report

Test	Base Score	PR Score	Change	% Change	Unit	Mode
benchmarks.XmirBench.xmirToEO	179.590	201.008	21.418	11.93%	ms/op	Average Time

⚠️ Performance loss: benchmarks.XmirBench.xmirToEO is slower by 21.418 ms/op (11.93%)

[yegor256]

@AlexNetTie this seems to be thread unsafe code