Difference between pages "r6:Function:ringbuffer delete" and "r6:Function:ringbuffer get read element"
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==Source Files== | ==Source Files== | ||
/src/ringbuffer/ | /src/ringbuffer/ringbuffer_get_and_put.c | ||
/inc/liblfds.h | /inc/liblfds.h | ||
==Prototype== | ==Prototype== | ||
struct freelist_element *ringbuffer_get_read_element( struct ringbuffer_state *rs, struct freelist_element **fe ); | |||
==Parameters== | ==Parameters== | ||
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: A ringbuffer state as allocated by ''[[r6:Function:ringbuffer_new|ringbuffer_new]]''. | : A ringbuffer state as allocated by ''[[r6:Function:ringbuffer_new|ringbuffer_new]]''. | ||
'' | ''struct freelist_element **fe'' | ||
: A | : A pointer to a pointer which will be set to point to the freelist element obtained from the ringbuffer. Set to NULL if there are no read elements. | ||
==Return Value== | ==Return Value== | ||
Returns a pointer to the current ringbuffer read element. Returns NULL if there are no read elements. | |||
==Notes== | ==Notes== | ||
The ringbuffer uses freelist elements and as such when obtaining elements from the ringbuffer, freelist elements are obtained. As such, to get the user data in these elements, use the appropriate freelist function, ''[[r6:Function:freelist_get_user_data_from_element|freelist_get_user_data_from_element]]''. | |||
To permit concurrent readers and writers, there must be a way to protect an element which is being read from being over-written while it is being read. The ringbuffer has no reference counting, so the solution adopted is for a thread performing a read to detach the current read element from the ringbuffer. This means that the element cannot be over-written while being read. It also means only one thread will read any one element, which may or may not be what you want, but it is what you've got :-) | |||
==See Also== | ==See Also== | ||
* [[r6:API:Ringbuffer|Ringbuffer]] | * [[r6:API:Ringbuffer|Ringbuffer]] | ||
* [[r6:Function: | * [[r6:Function:ringbuffer_put_read_element|ringbuffer_put_read_element]] | ||
* [[r6:Function:freelist_get_user_data_from_element|freelist_get_user_data_from_element]] | |||
Latest revision as of 14:07, 4 January 2015
Source Files
/src/ringbuffer/ringbuffer_get_and_put.c /inc/liblfds.h
Prototype
struct freelist_element *ringbuffer_get_read_element( struct ringbuffer_state *rs, struct freelist_element **fe );
Parameters
struct ringbuffer_state *rs
- A ringbuffer state as allocated by ringbuffer_new.
struct freelist_element **fe
- A pointer to a pointer which will be set to point to the freelist element obtained from the ringbuffer. Set to NULL if there are no read elements.
Return Value
Returns a pointer to the current ringbuffer read element. Returns NULL if there are no read elements.
Notes
The ringbuffer uses freelist elements and as such when obtaining elements from the ringbuffer, freelist elements are obtained. As such, to get the user data in these elements, use the appropriate freelist function, freelist_get_user_data_from_element.
To permit concurrent readers and writers, there must be a way to protect an element which is being read from being over-written while it is being read. The ringbuffer has no reference counting, so the solution adopted is for a thread performing a read to detach the current read element from the ringbuffer. This means that the element cannot be over-written while being read. It also means only one thread will read any one element, which may or may not be what you want, but it is what you've got :-)