Hi Sharath,I have answered your questions on GitHub, and referenced from the
comment on my blog:https://github.com/JCTools/JCTools/issues/179
I'll copy here for your convenience:1. It was a bug, fixed now by commit:
https://github.com/JCTools/JCTools/commit/56b5e58b07266bea077ab5aa2c6e6268696b4784#diff-b871020fbeb6c92660e34a22b41c2b7dL138This
check is not part of original algo, but required to support java.util.Queue
interface correctly where returning false indicated queue is full.
2. The queue can be non-full and still hit this case if a single consumer is
'stuck' between claiming the slot and moving the sequence. In this state other
consumers can make progress, clearing more slots, thus the queue is not full.I
hope this is clear enough.Regards,Nitsan
On Friday, May 26, 2017 10:51 AM, Sharath Gururaj <[email protected]>
wrote:
This question is regarding JCTools MPMC queue which is a java port of Dmitry
Vyukov's Mpmc C++ implementation
https://github.com/JCTools/JCTools/blob/011e1c3a6919a0fb641815c7429e0742911b9a79/jctools-core/src/main/java/org/jctools/queues/MpmcArrayQueue.java#L141
Everything inside the if condition of line 140 seems to be redundant. Here are
my questions: seems
1. the check pIndex - capacity >= (cIndex = lvConsumerIndex()) seems wrong to
me. The >= actually be <=
2. The inner else seems to be redundant. Under what conditions can it be that
seq < pIndex but array has free capacity?? If so then we can remove the inner
if..else and simply return false
ThanksSharath--
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