Re: Safe, regular or atomic registers

[fl <freder...@xxxxxxxxxxx>]

I think a trace of a safe register could look like this (1 writer, 1 reader, non-overlapping processes).

We have 4 variables Writer Reader Register Result.

Writer and Reader can take the values: None Start End

Register can take the value: 0, 1, 2

And Result can take the value: 0, 1 , 2 , 3

== Initial state ==

Writer = None

Reader = None

Register = 0

Result =  3

== State 1 ==

Writer = Start

Reader = None

Register = 0

Result =  3

== State 2 ==

Writer = Start

Reader = None

Register = 2

Result =  3

== State 3 ==

Writer = End

Reader = None

Register = 2

Result =  3

== State 4 ==

Writer = End

Reader = Start

Register = 2

Result =  3

== State 5 ==

Writer = End

Reader = Start

Register = 2

Result =  2

== Final State ==

Writer = End

Reader = End

Register = 2

Result =  2