Removing volatile and synchronization in Text

[JaroslavTulach]

Pull Request Description

While investigating slowdown of lengthOfStrings benchmark I came to conclusion that our Text implementation can be simplified:

• no Lock
• no volatile
• use of switch (no semantic change)
• use of record (no semantic change)

I don't see much need for locking or using volatile as

• switching the value of contents field (and other simple fields) is always atomic
• the old and the new values are both valid
• the new value of contents field is String and String has all (important/non-idempotent) fields final
• according to Java memory model final fields set in constructor are going to be properly visible from all threads

Hence I think we can do this without any synchronization.

Checklist

Please ensure that the following checklist has been satisfied before submitting the PR:

• All code follows the
  Java,
• Unit tests continue to work
• Benchmarks are fine: engine run

[JaroslavTulach]

StringBenchmarks.lengthOfString seems to be slightly improved

which (I believe) is result of removing volatile.