Those "set" methods in AtomicInteger

Asked Jul 19 '15 at 14:48

Active Jul 19 '15 at 15:17

Viewed 300 times

I am aware that compareAndSet() in AtomicInteger is a core method that takes a clever approach to atomically update the current value of the integer primitive that AtomicInteger encapsulates. It does so only after it has ascertained that another thread has not updated it already, and gives up if it detects otherwise.

Also, I know, the methods in AtomicInteger labelled "atomic" by the Java API documentation internally invoke compareAndSet().

Having expressed the indispensability of compareAndSet() in AtomicInteger, my questions are:

1. Why does weakCompareAndSet() exist in AtomicInteger? Why would I ever choose to use it while compareAndSet() is available for use? According to the Java API,
  
  it may fail spuriously and does not provide ordering guarantees, so is only rarely an appropriate alternative to compareAndSet.
1. Surprisingly, there is a raw set() method in AtomicInteger, which is not even labelled atomic! What is it doing in a class like AtomicInteger?!

edited Jul 19 '15 at 15:17

asked Jul 19 '15 at 14:48

softwarelover

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probably when one does not need the guarantee. – Subhrajyoti Majumder Jul 19 '15 at 14:51
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From http://docs.oracle.com/javase/7/docs/api/java/util/concurrent/atomic/package-summary.html: *set has the memory effects of writing (assigning) a volatile variable.* – JB Nizet Jul 19 '15 at 15:01
@JB Nizet: Thanks! It has got all in one place. I didn't know there was such a page. – softwarelover Jul 19 '15 at 15:11
It's linked to by the second sentence of the javadoc of AtomicInteger: * See the java.util.concurrent.atomic package specification for description of the properties of atomic variables* – JB Nizet Jul 19 '15 at 15:13
Excellent! Right on!.. – softwarelover Jul 19 '15 at 15:24

Those "set" methods in AtomicInteger

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