Re: using std::deque in multiple threads

"Scott McPhillips [MVP]" <org-dot-mvps-at-scottmcp>
Tue, 15 Aug 2006 17:42:49 -0400
Create a CRITICAL_SECTION object cs and initialize it
with InitializeCriticalSection(&cs);
Then see code inserted in-line...

PaulH wrote:

I have a thread that listens on a message queue and populates a
std::deque with events from that message queue, but only holds the
latest 100.
In my main thread, I want to populate a listbox with the information
from that deque. So, it ends up being that one thread can add/remove
items from the deque while another thread is trying to iterate through
them. How can I make this thread-safe?


The code looks a bit like this:

std::deque<MESSAGE_TYPE> m_dequeMessages;

  while (ReadMsgQueue(hMsgQueue, &msg,...))

---> EnterCriticalSection(&cs);

    if(m_dequeMessages.size() > 100)

---> LeaveCriticalSection(&cs);


CListCtrl c_MyList;


---> EnterCriticalSection(&cs);

  for (vector::iterator i = m_dequeMessages.begin(),
        i != m_vMessages.end()
    c_MyList.InsertItem(0, i->Message);

---> LeaveCriticalSection(&cs);


This will cause one thread to wait (at Enter...) if the other thread is
within the critical section.

Scott McPhillips [VC++ MVP]

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