⚡️ Speed up method Util.toTimeStamp by 14%

[codeflash-ai]

📄 14% (0.14x) speedup for Util.toTimeStamp in client/src/com/aerospike/client/util/Util.java

⏱️ Runtime : 554 microseconds → 485 microseconds (best of 5 runs)

📝 Explanation and details

Runtime improvement: the optimized version reduces average call time from ~554µs to ~485µs (~14% faster) by avoiding repeated allocation and pattern parsing for SimpleDateFormat.

What changed

• Introduced a ThreadLocal<HashMap<String, SimpleDateFormat>> that caches one prototype SimpleDateFormat per pattern, per thread.
• On each call we lookup the prototype for the pattern, create it only once if missing, and then clone the prototype for actual use before passing it to the existing toTimeStamp(dateTime, format, timeZoneOffset) helper.

Why this speeds up the code

• Constructing a SimpleDateFormat parses the date pattern and builds internal state (format symbols, calendars, locale-sensitive objects). That work is relatively expensive compared to cloning an existing, already-initialized instance.
• Caching the prototype eliminates repeat pattern parsing and allocations for repeated patterns (the common case), so hot-call sites pay only the cost of a cheap lookup + clone instead of full construction.
• Using ThreadLocal avoids synchronization: SimpleDateFormat is not thread-safe, so a shared cache would need locking or pooling. The ThreadLocal approach gives per-thread cache without lock overhead, keeping concurrent access fast.
• Cloning preserves the original semantics (every call gets a fresh SimpleDateFormat instance) while remaining cheaper than reconstructing from the pattern.

Behavioral and workload impact

• Best case: many repeated calls with a small set of patterns (typical for logging, repeated timestamp parsing) — substantial wins, as shown by the 14% measured speedup.
• Neutral/slower case: if callers use a large number of unique patterns once each, the cache provides little benefit and uses more per-thread map entries (small memory cost). Still, correctness is unchanged.
• Concurrency: multi-threaded workloads benefit because there is no contention on a global cache and allocations are reduced per thread.
• Memory trade-off: small per-thread HashMap and cached prototype instances; acceptable for most workloads given the runtime improvement.

Correctness

• The optimization preserves behavior: we clone the cached SimpleDateFormat before use, so callers receive a fresh, unshared formatter like the original code did but with lower cost to obtain it.

In short: caching pattern-parsed prototypes in a ThreadLocal and cloning them on use reduces repeated expensive pattern parsing and avoids locking, which directly cuts the observed runtime (~14%) for typical, repeated-pattern use cases while keeping semantics intact.

✅ Correctness verification report:

Test	Status
⚙️ Existing Unit Tests	✅ 198 Passed
🌀 Generated Regression Tests	🔘 None Found
⏪ Replay Tests	🔘 None Found
🔎 Concolic Coverage Tests	🔘 None Found
📊 Tests Coverage	No coverage data found for toTimeStamp

⚙️ Click to see Existing Unit Tests

To edit these changes git checkout codeflash/optimize-Util.toTimeStamp-ml71jwav and push.