royvanrijn: Back to a single reader

[royvanrijn]

Minimal changes, back to a single reader, trying to get every single piece of performance from that atm, can't seem to crack feeding the CPU on x86.

Check List:

• You have run ./mvnw verify and the project builds successfully
• Tests pass (./test.sh <username> shows no differences between expected and actual outputs)
• All formatting changes by the build are committed
• Your launch script is named calculate_average_<username>.sh (make sure to match casing of your GH user name) and is executable
• Output matches that of calculate_average_baseline.sh
• For new entries, or after substantial changes: When implementing custom hash structures, please point to where you deal with hash collisions (line number)

• Execution time:
• Execution time of reference implementation:

[gunnarmorling]

No significant change:

Benchmark 1: timeout -v 300 ./calculate_average_royvanrijn.sh 2>&1
  Time (mean ± σ):      2.169 s ±  0.013 s    [User: 0.002 s, System: 0.004 s]
  Range (min … max):    2.146 s …  2.187 s    10 runs

Summary
  royvanrijn: trimmed mean 2.16988147611, raw times 2.14613909436,2.1594555573600003,2.16436538136,2.18173506736,2.1798577153600003,2.17423688136,2.17599544336,2.16450239736,2.15890336536,2.18652239336

Leaderboard

| # | Result (m:s.ms) | Implementation     | JDK | Submitter     | Notes     |
|---|-----------------|--------------------|-----|---------------|-----------|
|   | 00:02.169 | [link](https://github.com/gunnarmorling/1brc/blob/main/src/main/java/dev/morling/onebrc/CalculateAverage_royvanrijn.java)| 21.0.2-graal | [Roy van Rijn](https://github.com/royvanrijn) | GraalVM native binary, uses Unsafe |