Do "nothing" while "condition"

do-while, java, while-loop

Solution

If you read the comments at top of the file, just below the class declaration, there is a section which explains the use of this construct:

Style notes

===========

[...]

There are several occurrences of the unusual "do {} while
(!cas...)"  which is the simplest way to force an update of a
CAS'ed variable. There are also other coding oddities (including
several unnecessary-looking hoisted null checks) that help
some methods perform reasonably even when interpreted (not
compiled).

Problem

While browsing the code for the Java 8 version of ForkJoinPool(which has a few interesting changes from Java 7) I ran across this construct (here): ``` do {} while (!blocker.isReleasable() && !blocker.block()); ``` I'm struggling with why you would write it like this instead of just ``` while (!blocker.isReleasable() && !blocker.block()); ``` Is it just a semantics/readability choice, since you could read the first construct as `do "nothing" while "conditions"`? Or is there some additional benefit I'm missing?

Original source