RWLock

The GRWLock struct is an opaque data structure to represent a reader-writer lock. It is similar to a #GMutex in that it allows multiple threads to coordinate access to a shared resource.

The difference to a mutex is that a reader-writer lock discriminates between read-only ('reader') and full ('writer') access. While only one thread at a time is allowed write access (by holding the 'writer' lock via g_rw_lock_writer_lock()), multiple threads can gain simultaneous read-only access (by holding the 'reader' lock via g_rw_lock_reader_lock()).

It is unspecified whether readers or writers have priority in acquiring the lock when a reader already holds the lock and a writer is queued to acquire it.

Here is an example for an array with access functions: |[ GRWLock lock; GPtrArray *array;

gpointer my_array_get (guint index) { gpointer retval = NULL;

if (!array)
  return NULL;

g_rw_lock_reader_lock (&lock);
if (index < array->len)
  retval = g_ptr_array_index (array, index);
g_rw_lock_reader_unlock (&lock);

return retval;

}

void my_array_set (guint index, gpointer data) { g_rw_lock_writer_lock (&lock);

if (!array)
  array = g_ptr_array_new ();

if (index >= array->len)
  g_ptr_array_set_size (array, index+1);
g_ptr_array_index (array, index) = data;

g_rw_lock_writer_unlock (&lock);

} ]| This example shows an array which can be accessed by many readers (the my_array_get() function) simultaneously, whereas the writers (the my_array_set() function) will only be allowed one at a time and only if no readers currently access the array. This is because of the potentially dangerous resizing of the array. Using these functions is fully multi-thread safe now.

If a #GRWLock is allocated in static storage then it can be used without initialisation. Otherwise, you should call g_rw_lock_init() on it and g_rw_lock_clear() when done.

A GRWLock should only be accessed with the g_rw_lock_ functions.

Skipped during bindings generation

• field p: Record field p is private

• field i: Record field i is private