java, c#, vb: Can we write thread safety functions without relying on native implementations
I'm wondering is it ever possible to write locking-features(for threading) with the language itself (this question is purely academic, I know no one will ever do it even if its possible (not me))?
Rephrasing the question:
A) In Java, is it possible to write thread safety functions with java alone, but without using any of the provided classes/language elements/syntax which offer this feature?
B) In C#, is it possible to write thread safety functions with C# alone, but without using any of the provided classes/language elements/syntax which offer this feature?
C) In Vb, is it possible to write thread safety functions with Vb alone, but without using any of the provided classes/language开发者_Python百科 elements/syntax which offer this feature?
If you have atomic reads and writes, which C# does for ints for example, you can use Dekker's algorithm to build thread-safe algorithms without support from any other primitives:
- Dekker's algorithm
Yes it is possible, all one really needs to form a mutex is a shared memory variable that is written in a single read-modify-write machine cycle. However, it is inefficient because all the threads in potential conflict have to busy-wait. A major point of the more advanced constructs in the thread contention avoidance classes in these languages is to allow a thread to quit executing until another thread is done with the conflicted resource and then be immediately put back into the execution train when the resource frees up.
I think maybe you are thinking about:
C# lock()
VB SyncLock
Java syncronized
Those are language elements, not library classes.
No. If you have a thread safe program, you must be using some of the provided classes/language elements/syntax which offer thread safety.
The semantics of volatile
in Java is defined in Java Language Spec Section 17, "Threads and Locks"
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