The language specification guarantees that reading or writing a variable is atomic unless the variable is of type long or double [jls, 17.4.7] } but i assume it's possible for that function to return the same value twice, right For example, thread a calls the function, increments the value, but then halts while thread b comes in and also increments the value, finally a and b both return the same value So using mutexes, the function might look like this: Note that atomic is contextual In this case, the upsert operation only needs to be atomic with respect to operations on the answers table in the database
The computer can be free to do other things as long as they don't affect (or are affected by) the result of what upsert is trying to do. Objects of atomic types are the only c++ objects that are free from data races Why the standard make that difference It seems as both designate, in the same way, an atomic type. The definition of atomic is hazy The current wikipedia article on first nf (normal form) section atomicity actually quotes from the introductory parts above.
I don't think it's possible to have a partially modified bool value When do i really need to use atomic<bool> instead of bool? I remember i came across certain types in the c language called atomic types, but we have never studied them So, how do they differ from regular types like int,float,double,long etc., and what are. Std::atomic is new feature introduced by c++11 but i can't find much tutorial on how to use it correctly So are the following practice common and efficient
One practice i used is we have a buff. Since std::atomic_init has been deprecated in c++20, here is a reimplementation which does not raise deprecation warnings, if you for some reason want to keep doing this.
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