memory pool and rb-tree

[Jarrett Billingsley]

"Jeff" <jeff.michels at gmx.net> wrote in message 
news:g90qs7$4gl$1 at digitalmars.com...
> Hi,
>
> i'm learning D and i'm trying to translate my C++ code to D. But i hit 
> some problems.
>
> My C++ code looks like:
>
> struct spot_rec
> {
> char id[20];
> int  value1;
> int  value2;
> int  value3;
> bool changed;
>
> spot_rec() {...}; //init
> const spot_rec& operator=(const spot_rec& r) {...}; //copy-operator
> };
>
> struct less_spot_record : public std::binary_function<spot_rec *,spot_rec 
> *,bool>
> {
>  bool operator()(const spot_rec *a, const spot_rec *b) const { return 
> stricmp(a->id, b->id); }
> };
>
> typedef set < spot_rec*, less_spot_record >  TableSpotRecords;
> typedef set < spot_rec*, less_spot_record >::iterator 
> TableSpotRecordsIter;
>
> boost::my_object_pool< spot_rec > pool_spot_rec;
> TableSpotRecords table_spot_rec;  //ordered RB-Tree
>
> bool shutdown = false;
> int thread_save_data()
> {
> while(!shutdown)
> {
> TableSpotRecordsIter iter = table_spot_rec.begin();
> while(iter != table_spot_rec.end())
> {
> spot_rec *r = *iter;
> if(r->changed)
> {
> mutex.lock();
> save_record(r);
> r->changed = false;
> mutex.unlock();
> }
> if(shutdown) return 0;
> ++iter; // is thread save
> }
> }
> return 0;
> }
>
> void update_spot(spot_rec *r)
> {
>    TableSpotRecordsIter iter = table_spot_rec.find(r);
>    if(iter==table_spot_rec.end())
> {   //add new record
> spot_rec *p = pool_spot_rec.construct();
> *p = *r;
> table_spot_rec.insert(p) // is thread save
> }
> else
> { //update record
> spot_rec *p = *iter;
> mutex.lock();
> *p = *r;
> mutex.unlock();
> }
> }
>
> main
> {
> create_thread(thread_save_data);
> ...
> //read from udp socket
> char buf[1024];
> while( recvfrom(socket,buf,sizeof(buf),from,fromlen)>0 )
> {
> spot_rec r;
> if(parse_record(buf,r))
> update_spot(&r);
> }
>
> shutdown=true;
> join_thread();
> table_spot_rec.purge_memory();
> ...
> }
>
> This program processes realtime data.
> I can't find a D replacement for boost::my_object_pool and stlport-set.
> I looked at tango and dcollections, but i can't find any example that use 
> RB-Trees and where i can set my own compare function.
>
> Can somebody help me?
>
>

I'm not sure there's a drop-in replacement for a memory pool, but there is 
tango.util.container.RedBlack.  Unfortunately the documentation generator 
seems not to like whatever they've done in that file (wow, another bug in 
Ddoc!) so you'll have to read the docs out of the source file here: 
http://www.dsource.org/projects/tango/docs/current/source/tango.util.container.RedBlack.html

Be warned that it is a bit low-level, but it allows you to use a custom 
comparator function on finds and such.

Or, if you wanted to make it rather simple, you could just have a dynamic 
array of spot_rec*, and overload opCmp in the spot_rec structure.  Then you 
can just append records as you allocate them (and of course you can 
preallocate space or make a small templated struct on top of it or 
whatever), and just call .sort on it when you're finished.  Unless you need 
them to be sorted on-the-fly?