Hi all,

I'm looking for a high performance 'wait-for'.

The situation:
There are m threads working in parallel on n chunks of work (n>=m).
The n chunks are indexed 0..n-1.
Sometimes one thread needs the result of some of the lower indexed chunks. For
example the chunk number 5 needs chunks 0..2.
So I have a function WaitForIndex(LowerIndex: integer) which should wait until
all chunks with less or equal to LowerIndex have finished.

My current approach is this:
EnterCriticalSection (try..finally)
Check if all lower chunks have finished, if yes then exit
LeaveCriticalSection
RTLeventWaitFor(AnEventOfTheCurrentThread);

And each time a thread has finished a chunk, it wakes all corresponding threads.

The problem is the gap between LeaveCriticalSection and RTLeventWaitFor. During
this time the other threads may finish. So there is no one left to wake up the
waiting thread.

Moving the RTLeventWaitFor into the CritialSection creates a deadlock.
I can use the timeout of RTLeventWaitFor and check in intervals, but
criticalsections and low response times don't fit together.


Mattias


