struct lfds610_freelist_element *lfds610_ringbuffer_get_current_write_element( struct lfds610_ringbuffer_state *rs, struct lfds610_freelist_element **fe, int *overwrite_flag );
struct lfds610_ringbuffer_state *rs
- A ringbuffer state as allocated by lfds610_ringbuffer_new.
struct lfds610_freelist_element **fe
- A pointer to a pointer which will be set to point to the freelist element obtained from the ringbuffer. This function never fails, so a NULL is never returned.
- A pointer to an integer, where the integer is set to 1 if the function consumed a data bearing element from the ringbuffer or is set to 0 if the function was able to use an existing, available element. This argument can be NULL.
Returns a pointer to the current ringbuffer write element. This function always succeeds.
The ringbuffer uses freelist elements and as such when obtaining elements from the ringbuffer, freelist elements are obtained. As such, to set the user data in these elements, use the appropriate freelist function, lfds610_freelist_set_user_data_in_element.
To permit concurrent readers and writers, there must be a way to protect an element which is being written from being read before it is fully written. The solution adopted is for a thread performing a write to detach, if one is available, an unused element from the ringbuffer, or, if there are no unused elements, the current read element (thus leading to the over-writing of its contents).