Consider initializing RateLimiter.mutex eagerly

[cowwoc]

Out of curiosity, what is gained by initializing RateLimiter.mutex() lazily? Effective Java Item 71 ("Use lazy initialization judiciously") strongly recommends against lazy initialization unless the object being initialized is expensive to construct. This is certainly not the case for you.

Consider:

• All RateLimiter's public methods require the use of mutex.
• Removing lazy initialization would simplify the code.
• Performance might improve slightly as you no longer need to check if mutex is null over and over again.

[cpovirk]

https://github.com/google/guava/blob/7f1defafe4155a4e14a9805cb6c14fa406b390f3/guava/src/com/google/common/util/concurrent/RateLimiter.java#L185

[cpovirk]

...which is a pretty crazy reason, but it solved the problem :)

[cowwoc]

@cpovirk Hmm... does this include private final Object mutex = new Object(); as a field (as opposed to inside the constructor)?

[cpovirk]

Yep. Inline field initialization is syntactic sugar for initializing from the constructor. Feel free to give it a shot; the tests should catch the problem, and you can peek at the bytecode with javap.

[cowwoc]

Okay, sad. Feel free to close this issue.