Kizingiti (tarakilishi)
Katika utarakilishi, kizingiti ni jinsi ya ulandanishi (kwa Kiingereza: barrier in computer science). Neno kizingiti linamaanisha kwamba amri ya tarakilishi haiwezi kuendelea ikiwa amri za awali hazifanyiki.
Mfano
[hariri | hariri chanzo]Amri hii ya C++ inatumia vizingiti :
struct barrier_type
{
// how many processors have entered the barrier
// initialize to 0
int arrive_counter;
// how many processors have exited the barrier
// initialize to p
int leave_counter;
int flag;
std::mutex lock;
};
// barrier for p processors
void barrier(barrier_type* b, int p)
{
b->lock.lock();
if (b->leave_counter == p)
{
if (b->arrive_counter == 0) // no other threads in barrier
{
b->flag = 0; // first arriver clears flag
}
else
{
b->lock.unlock();
while (b->leave_counter != p); // wait for all to leave before clearing
b->lock.lock();
b->flag = 0; // first arriver clears flag
}
}
b->arrive_counter++;
int arrived = b->arrive_counter;
b->lock.unlock();
if (arrived == p) // last arriver sets flag
{
b->arrive_counter = 0;
b->leave_counter = 1;
b->flag = 1;
}
else
{
while (b->flag == 0); // wait for flag
b->lock.lock();
b->leave_counter++;
b->lock.unlock();
}
}
Marejeo
[hariri | hariri chanzo]- Petzell, M. (2005). Expanding the Swahili vocabulary. Africa & Asia, 5, 85-107.
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