Destroys or initializes a spin lock object.
#include <pthread.h>
int pthread_spin_destroy(pthread_spinlock_t *lock);
int pthread_spin_init(pthread_spinlock_t *lock, int pshared); The pthread_spin_destroy subroutine destroys the spin lock referenced by lock and releases any resources used by the lock. The effect of subsequent use of the lock is undefined until the lock is reinitialized by another call to the pthread_spin_init subroutine. The results are undefined if the pthread_spin_destroy subroutine is called when a thread holds the lock, or if this function is called with an uninitialized thread spin lock.
The pthread_spin_init subroutine allocates any resources required to use the spin lock referenced by lock and initializes the lock to an unlocked state.
If the Thread Process-Shared Synchronization option is supported and the value of pshared is PTHREAD_PROCESS_SHARED, the implementation shall permit the spin lock to be operated upon by any thread that has access to the memory where the spin lock is allocated, even if it is allocated in memory that is shared by multiple processes.
If the Thread Process-Shared Synchronization option is supported and the value of pshared is PTHREAD_PROCESS_PRIVATE, or if the option is not supported, the spin lock shall only be operated upon by threads created within the same process as the thread that initialized the spin lock. If threads of differing processes attempt to operate on such a spin lock, the behavior is undefined.
The results are undefined if the pthread_spin_init subroutine is called specifying an already initialized spin lock. The results are undefined if a spin lock is used without first being initialized.
If the pthread_spin_init subroutine function fails, the lock is not initialized and the contents of lock are undefined.
Only the object referenced by lock may be used for performing synchronization.
The result of referring to copies of that object in calls to the pthread_spin_destroy subroutine, pthread_spin_lock subroutine, pthread_spin_trylock subroutine, or the pthread_spin_unlock subroutine is undefined.
Upon successful completion, these functions shall return zero; otherwise, an error number shall be returned to indicate the error.
| Item | Description |
|---|---|
| EBUSY | The implementation has detected an attempt to initialize or destroy a spin lock while it is in use (for example, while being used in a pthread_spin_lock call) by another thread. |
| EINVAL | The value specified by the lock parameter is invalid. |
| Item | Description |
|---|---|
| EAGAIN | The system lacks the necessary resources to initialize another spin lock. |
| ENOMEM | Insufficient memory exists to initialize the lock. |