This variable must only be accessed through these functions. All lock functions require an argument that has a pointer to omp_lock_t type for lock functions and omp_nest_lock_t for nestable lock functions.
•omp_init_lock and omp_init_nest_lock
•omp_destroy_lock and omp_destroy_nest_lock
•omp_set_lock and omp_set_nest_lock
•omp_unset_lock and omp_unset_nest_lock
•omp_test_lock and omp_test_nest_lock
omp_init_lock and omp_init_nest_lock
#include <omp.h>
void omp_init_lock(omp_lock_t *lock);
void omp_init_nest_lock(omp_nest_lock_t *lock);
These functions provide the only means of initializing a lock. Each function initializes the lock associated with the parameter lock for use in subsequent calls. The initial state is unlocked (that is, no thread owns the lock). For a nestable lock, the initial nesting count is zero
omp_destroy_lock and omp_destroy_nest_lock
#include <omp.h>
void omp_destroy_lock(omp_lock_t *lock);
void omp_destroy_nest_lock(omp_nest_lock_t *lock);
These functions ensure that the pointed to lock variable lock is uninitialized. The argument to these functions must point to an initialized lock variable that is locked.
omp_set_lock and omp_set_nest_lock
#include <omp.h>
void omp_set_lock(omp_lock_t *lock);
void omp_set_nest_lock(omp_nest_lock_t *lock);
Each of these functions blocks the thread executing the function until the specified lock is available and then sets the lock. A simple lock is available if it is unlocked. A nestable lock is available if it is unlocked or if it is already owned by the thread executing the function. For a simple lock, the argument to the omp_set_lock function must point to an initialized lock variable. Ownership of the lock is granted to the thread executing the function.
For a nestable lock, the argument to the omp_set_nest_lock function must point to an initialized lock variable. The nesting count is incremented, and the thread is granted, or retains, ownership of the lock.
omp_unset_lock and omp_unset_nest_lock
#include <omp.h>
void omp_unset_lock(omp_lock_t *lock);
void omp_unset_nest_lock(omp_nest_lock_t *lock);
These functions provide the means of releasing ownership of a lock. The argument to each of these functions must point to an initialized lock variable owned by the thread executing the function. The behavior is undefined if the thread does not own that lock.
For a simple lock, the omp_unset_lock function releases the thread executing the function from ownership of the lock.
Parallel Programming Using OpenMP 173