Ticket Locks

According to the following ticket lock implementation, fill out values for Turns and Tickets in the table AFTER each action finishes.

int FAA(int *ptr)

{

int old = *ptr;

*ptr = old + 1;

return old;

}

typedef struct __lock_t

{

int ticket;

int turn;

}

void lock_init(lock_t *lock)

{

lock->ticket = 0;

lock->turn = 0;

}

void acquire(lock_t *lock)

{

int myturn = FAA(&lock->ticket);

while (lock->turn != myturn); // spin

}

void release (lock_t *lock)

{

FAA(&lock->turn);

}

Actions	Turns	Tickets
A locks and runs
B locks
A unlocks
C locks
A locks
B runs
B unlocks
C runs
C unlocks
B locks