Locks

• struct lock *lock_create(const char *name);
  • Name parameter for debug purposes!
  • Return NULL if out of memory -> Then panic
• void lock_destroy(struct lock *);
  • Destroy the lock
• void lock_acquire(struct lock *);
  • Enter the critical region
• void lock_release(struct lock *);
  • Exit the critical region

Semaphores

• struct semaphore *sem_create(const char *name, int initial_count);

• void sem_destroy(struct semaphore *);

• void P(struct semaphore *);

  • Wait

• void V(struct semaphore *);

  • Signal

Locks vs Semaphores

• Locks are binary || Semaphores are not.
• Semantic - intrinsic documentation -> Locks used for locks...

Condition Variables

• struct cv *cv_create(const char *name);
• void cv_destroy(struct cv *);
• void cv_wait(struct cv *cv, struct lock *lock);
  • Sleep and wakeup on an event
  • Sleeps thread and releases the lock
  • On wakeup, reacquires the lock
• void cv_signal(struct cv *cv, struct lock *lock);
  • Wake up one
• void cv_broadcast(struct cv *cv, struct lock *lock);
  • Wake up all

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