Re: List iterator assignment fails, assert iterator not dereferencable
David Bilsby schrieb:
snip
For a list, iterators are invalidated when the element of the list
that it refers to is erased. I don't see any glaring isses from a
Standard C++ standpoint. You did mention that you didn't see any
problems until you went multithreaded. Perhaps your mutexes aren't in
the right places.
Certainly from the debug code I added the list entry is valid right up
to the point I try and dereference the bad iterator. The debugger shows
the entry in the list OK.
Mutex wise, well I keep thinking this must be the issue, but I think I
have covered all bases here. The low level class protects the direct
list access by a mutex and I even added a mutex at the higher level
class around the call to the low level class function to protect the
iterator assignment to the array of iterators just incase the assignment
needs protecting and not just list access or iterator dereferencing.
Does that mean you lock the high level mutex, call the function that returns the
iterator, release the mutex, and then start using the returned iterator?
I yes, then this can bring you into trouble. As soon as you release the mutex,
another thread could manipulate the list and make your iterator invalid,
couldn't it?
Norbert
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