iv_work(3)						    ivykis programmer's manual							iv_work(3)

NAME

       IV_WORK_POOL_INIT, iv_work_pool_create, iv_work_pool_put, IV_WORK_ITEM_INIT, iv_work_pool_submit_work - ivykis worker thread management

SYNOPSIS

       #include <iv_work.h>

       struct iv_work_pool {
	       int	       max_threads;
	       void	       *cookie;
	       void	       (*thread_start)(void *cookie);
	       void	       (*thread_stop)(void *cookie);
       };

       struct iv_work_item {
	       void	       *cookie;
	       void	       (*work)(void *cookie);
	       void	       (*completion)(void *cookie);
       };

       void IV_WORK_POOL_INIT(struct iv_work_pool *this);
       int iv_work_pool_create(struct iv_work_pool *this);
       int iv_work_pool_put(struct iv_work_pool *this);
       void IV_WORK_ITEM_INIT(struct iv_work_item *work);
       int iv_work_pool_submit_work(struct iv_work_pool *this, struct iv_work_item *work);

DESCRIPTION

       Calling	iv_work_pool_create  on  a struct iv_work_pool object previously initialised by IV_WORK_POOL_INIT creates a pool of worker threads
       that can be used to offload CPU intensive tasks to, so as to prevent negatively influencing event handling latency in the  calling  thread,
       and to enable the use of multiple host CPUs for CPU intensive tasks.

       iv_work	dynamically  adjusts  the  number of threads in the pool to the amount of work there is to do.	The ->max_threads member of struct
       iv_work_pool specifies the maximum number of threads that will be created in this pool.

       Calling iv_work_pool_submit_work on a struct iv_work_item object previously initialised by IV_WORK_ITEM_INIT submits a work item to a pool.
       The  ->work  member of struct iv_work_item specifies the function that will be called in one of the worker threads in the pool specified by
       ->this, with ->cookie as its sole argument.  When the work function has completed, iv_work will call the ->completion callback to  indicate
       this, also with ->cookie as its sole argument, in the thread that iv_work_pool_create was called in for this pool object.

       As  a  special  case,  calling iv_work_pool_submit_work with a NULL work pool pointer will cause the work item to be processed in the local
       thread, from an iv_task(3) callback.

       If the ->thread_start function pointer specified in struct iv_work_pool is not NULL, it will be	called	upon  creation	of  a  new  worker
       thread,	in the context of the created worker thread, with ->cookie as its sole argument.  Calls to ->thread_start are not explicitly seri-
       alised, which should be kept in mind when manipulating state shared between threads from within that callback function.

       Similarly, if iv_work decides to terminate a worker thread, for example due to inactivity, ->thread_stop will be called in the  context	of
       the terminating thread, with ->cookie as its sole argument.  Calls to ->thread_stop are also not explicitly serialised.

       iv_work_pool_submit_work can only be called from the thread that iv_work_pool_create for this pool object was called in.

       There is no way to cancel submitted work items.

       There is no guaranteed order, FIFO or otherwise, between different work items submitted to the same worker thread pool.

       When the user has no more work items to submit to the pool, its reference to the pool can be dropped by calling iv_work_pool_put.

       If  there  are still pending or running work items assigned to this pool when iv_work_pool_put is called, those work items will not be can-
       celed, but will be allowed to run to completion, and their ->completion callbacks will be called as usual.  A similar thing holds  for  the
       ->thread_start  and  ->thread_stop  callbacks  -- they can also still be called after iv_work_pool_put returns.	Even so, the memory corre-
       sponding to the struct iv_work_pool can immediately be freed or reused by the user upon return of the iv_work_pool_put call.

       Internally, iv_work uses iv_thread(3) for its thread management.

SEE ALSO

       ivykis(3), iv_thread(3)

ivykis								    2010-09-14								iv_work(3)