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===== Low-level Functions =====

Eina offers low-level functions that are portable across the operating system,
such as locks, conditions, semaphores, barriers, and spinlocks. The functions
follow closely the logic of pthreads.

While these functions are useful, they are building blocks and not usually
useful in EFL applications considering the higher-level functions that are
available in Ecore.

For an introduction to threads and pthreads in particular, see:

   * [[http://www.ibm.com/developerworks/library/l-pthred/index.html|Basic use of pthreads]] (IBM developerWorks)
   * [[https://computing.llnl.gov/tutorials/pthreads/|POSIX Threads Programming]] (Lawrence Livermore National Laboratory)
   * [[http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/pthread.h.html|POSIX 2003 specification]] (opengroup)

If you are already familiar with threads, see the standard pthreads
documentation and the Eina reference documentation, or the following function
lists. Remember that the Eina functions map very closely to the pthreads
functions.

^    Lock (mutual exclusions)    ^^
|   **pthreads function**   |   **eina equivalent**     |
|''pthread_mutex_new()''|''eina_lock_new()''|
|''pthread_mutex_destroy()''|''eina_lock_free()''|
|''pthread_mutex_lock()''|''eina_lock_take()''|
|''pthread_mutex_trylock()''|''eina_lock_take_try()''|
|''pthread_mutex_unlock()''|''eina_lock_release()''|
|none (prints debug information on the lock)|''eina_lock_debug()''|

^     Conditions (notifications when condition objects change)    ^^
|   **pthreads function**   |   **eina equivalent**     |
|''pthread_cond_init()''      |''eina_condition_new()''           |
|''pthread_cond_destroy''     |''eina_condition_free()''          |
|''pthread_cond_wait()''      |''eina_condition_wait()''          |
|''pthread_cond_timedwait()'' |''eina_condition_timedwait()''     |
|''pthread_cond_broadcast()'' |''eina_condition_broadcast()''     |
|''pthread_cond_signal()''    |''eina_condition_signal()''        |

^      RWLocks (Read-write locks, for multiple-readers/single-writer scenarios)    ^^
|   **pthreads function**   |   **eina equivalent**     |
|''pthread_rwlock_init()''         |''eina_rwlock_new()''          |
|''pthread_rwlock_destroy()''      |''eina_rwlock_free()''         |
|''pthread_rwlock_rwlock_rdlock()''|''eina_rwlock_take_read()''    |
|''pthread_rwlock_rwlock_wrlock()''|''eina_rwlock_take_write()''   |
|''pthread_rwlock_unlock()''       |''eina_rwlock_release()''      |

^       TLS (Thread-Local Storage)    ^^
|   **pthreads function**   |   **eina equivalent**     |
|''pthread_key_create()''      |''eina_tls_new()''  |
|''pthread_key_delete()''      |''eina_tls_free()'' |
|''pthread_getspecific()''     |''eina_tls_get()''  |
|''pthread_setspecific()''     |''eina_tls_set()''  |

^        Semaphores (access restrictions for a set of resources)    ^^
|   **pthreads function**   |   **eina equivalent**     |
|''sem_init()''    |''eina_semaphore_new()''     |
|''sem_destroy()'' |''eina_semaphore_free()''    |
|''sem_wait()''    |''eina_semaphore_lock()''    |
|''sem_post()''    |''eina_semaphore_release()'' |

^        Barriers    ^^
|   **pthreads function**   |   **eina equivalent**     |
|''pthread_barrier_init()''   |''eina_barrier_new()''  |
|''pthread_barrier_destroy()''|''eina_barrier_free()'' |
|''pthread_barrier_wait()''   |''eina_barrier_wait()'' |

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