Re: About task-safeness

["Peter C. Chapin" <PChapin@vtc.vsc.edu>]

On Wed, 2 Feb 2011, Shark8 wrote:

>> two tasks "only reading" values from the same container are *not* safe .
>
> Interesting! That is counter-intuitive; do you have a link to an 
> example/explaination?

Actually, in the absence of documentation to the contrary, I wouldn't expect 
simultaneous reads to be safe. Some data structures get modified internally 
in response to reads. For example splay trees[1] bring the last read item to 
the root. Thus looking up an item in a splay tree entails various 
transformations on the tree that would have to be reviewed for task safety 
(or otherwise protected).

By not guaranteeing task safety during simultaneous reads, the Ada reference 
manual is allowing implementors to keep their options open. That seems fair 
to me.

Peter

[1] http://en.wikipedia.org/wiki/Splay_tree