src/threads/synch.h

   1 #ifndef THREADS_SYNCH_H
   2 #define THREADS_SYNCH_H
   3
   4 #include <list.h>
   5 #include <stdbool.h>
   6
   7 /* A counting semaphore. */
   8 struct semaphore
   9   {
  10     unsigned value;             /* Current value. */
  11     struct list waiters;        /* List of waiting threads. */
  12   };
  13
  14 void sema_init (struct semaphore *, unsigned value);
  15 void sema_down (struct semaphore *);
  16 bool sema_try_down (struct semaphore *);
  17 void sema_up (struct semaphore *);
  18 void sema_self_test (void);
  19
  20 /* Lock. */
  21 struct lock
  22   {
  23     struct thread *holder;      /* Thread holding lock (for debugging). */
  24     struct semaphore semaphore; /* Binary semaphore controlling access. */
  25   };
  26
  27 void lock_init (struct lock *);
  28 void lock_acquire (struct lock *);
  29 bool lock_try_acquire (struct lock *);
  30 void lock_release (struct lock *);
  31 bool lock_held_by_current_thread (const struct lock *);
  32
  33 /* Condition variable. */
  34 struct condition
  35   {
  36     struct list waiters;        /* List of waiting threads. */
  37   };
  38
  39 void cond_init (struct condition *);
  40 void cond_wait (struct condition *, struct lock *);
  41 void cond_signal (struct condition *, struct lock *);
  42 void cond_broadcast (struct condition *, struct lock *);
  43
  44 /* Optimization barrier.
  45
  46    The compiler will not reorder operations across an
  47    optimization barrier.  See "Optimization Barriers" in the
  48    reference guide for more information.*/
  49 #define barrier() asm volatile ("" : : : "memory")
  50
  51 #endif /* threads/synch.h */