2021-06-27 21:25:29 +00:00
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/***
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Copyright (C) 2021 J Reece Wilson (a/k/a "Reece"). All rights reserved.
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File: RWLock.hpp
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Date: 2021-6-9
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Author: Reece
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***/
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#pragma once
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namespace Aurora::Threading::Primitives
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{
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class RWLock
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{
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public:
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virtual IWaitable *AsReadable() = 0;
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virtual IWaitable *AsWritable() = 0;
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2021-09-06 10:58:08 +00:00
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/**
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* Solves the problem of atomic write racing
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* Consider: Thread 1 | Thread 2
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* ReadLock() |
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* cmp internal_x, 0|
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* jmp not eq +1 |
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* ret |
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* ReadUnlock() |
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* | WriteLock()
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* | internal_x = 1
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* | WriteUnlock()
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* WriteLock() |
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* internal_x = 0 |
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* WriteUnlock()
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*
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* where 1 and 0 should have been decided on mutually exclusively, losing the 1 state while assuming a decision in the locked state would remain true
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* workaround: [1] check for the race conditions, implmeneting slow and inefficient branching and spurious checks
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* workaround: [2] upgrade from read to write
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*/
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virtual bool UpgradeReadToWrite(AuUInt64 timeout) = 0;
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2021-06-27 21:25:29 +00:00
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};
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AUKN_SHARED_API(RWLock, RWLock);
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}
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