Create LockFreeQueue.chpl #1
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example/LockFreeQueue.chpl
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| * Created by Garvit Dewan - | ||
| * https://github.com/dgarvit/epoch-based-manager/blob/master/src/LockFreeQueue.chpl | ||
| * | ||
| * Lock-Free Queue that uses ABA feature of Distributed Data Structures |
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Should probably say that it uses the ABA feature of LocalAtomicObject. Sure the LocalAtomicObject was created back in GSoC 2017, but you don't need to state that here.
example/LockFreeQueue.chpl
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| proc init(type eltType) { | ||
| this.eltType = eltType; | ||
| val = nil; |
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Do not initialize val with a value, leave it as is (it will be initialized to a default value automatically). If eltType is an integral (int,uint, etc.), a tuple or a record, this will result in a compiler error.
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Well, I think that would further require changes to peek() and dequeue() in terms that if queue is empty then cannot return nil for eltType int
example/LockFreeQueue.chpl
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| var curr_head = _head.readABA(); | ||
| var curr_tail = _tail.readABA(); | ||
| var next = curr_head.next.readABA(); | ||
| if (_head.read() == _tail.read()) { |
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Why do you read curr_head and curr_tail and then try to read them again? Are you sure you shouldn't do curr_head.getObject() == curr_tail.getObject()?
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My bad, fixed it. Thanks for pointing out!
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| iter these() : objType { | ||
| var ptr = _head.read().next.read(); |
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What happens if the queue is empty?
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When queue is empty, it will hold a dummy node, which will have a next, which will be a LocalAtomicObject, which will point to a nil value.
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So, nothing will happen, because, if ptr is nil. then the function will finish executing.
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Right, I forgot about the dummy node! That should work then.
example/LockFreeQueue.chpl
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| } | ||
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| proc peek() : objType { | ||
| return _head.read().next.read().val; |
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What happens if the queue is empty?
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Similar to the previous reason, this will return nil. There was a bug with it, which I have fixed now.
| var ptr = _head.read(); | ||
| while (ptr != nil) { | ||
| _head = ptr.next; | ||
| delete ptr.val; |
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Nope, don't assume the user will have classes. If they want to have their classes managed, they should use a shared or owned type.
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| } | ||
| } | ||
| } |
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Add a main function here that tests it, similar to what is done in LockFreeStack.chpl:
LocalAtomics/example/LockFreeStack.chpl
Lines 75 to 80 in 614410c
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Can you also make Then I can possibly run |
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I think that you should make |
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