Re: [boost] Using std::list in a hard realtime environment

From: Matthew Towler (towler_at_[hidden])
Date: 2003-04-23 07:39:22

Andreas

Most RTOS provide something called a 'partition pool', effectively a 
fast deterministic heap of elements of a predefined size.

You then just have to write a custom allocator than just forwards to the 
pool you have already created - it saves writing any complicated 
allocation code.

An easier alternative if you know globally how many objects you will 
need (rather than just how many in a given list) is to instead add new 
and delete operators to the class you are going to hold, and make these 
forwarding functions to the partition pool.

Allocators are usually not too bad to write, just find one in the 
standard library source for your compiler and do a bit of cut and paste.

Matt

Andreas Huber wrote:

>Hi there
>
>I would like to use STL containers in a hard real-time environment. Hard
>real-time means that for all operations on the container it is possible to
>specify an upper duration limit. At some point containers have to allocate
>memory, which is notoriously non-deterministic. The usual solution is to
>preallocate for a certain maximum container-size *before* the software needs
>to react deterministically.
>
>With std::vector this is easy: Simply call vector::reserve(). However, there
>is no such function for all the other standard containers (deque, list, set,
>map) and I absolutely need a std::list-like container. The following
>solutions come to mind:
>- Use a custom allocator
>- Write your own list, which provides a reserve() function
>
>Neither is very appealing to me and I can't really believe that there is no
>easier solution within the standard library. What am I missing?
>
>Thanks,
>
>Andreas
>
>
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