Getting Started with QNX Neutrino - QNX Software Systems

More on synchronization
© 2009, QNX Software Systems GmbH & Co. KG.
thread_pool_start (void *pool);
int
thread_pool_limits (thread_pool_t *pool,
int lowater,
int hiwater,
int maximum,
int increment,
unsigned flags);
int
thread_pool_control (thread_pool_t *pool,
thread_pool_attr_t *attr,
uint16_t lower,
uint16_t upper,
unsigned flags);
As you can see from the functions provided, you first create a thread pool definition
using thread_pool_create(), and then start the thread pool via thread_pool_start().
When you’re done with the thread pool, you can use thread_pool_destroy() to clean
up after yourself. Note that you might never call thread_pool_destroy(), as in the case
where the program is a server that runs “forever.” The thread_pool_limits() function is
used to specify thread pool behavior and adjust attributes of the thread pool, and the
thread_pool_control() function is a convenience wrapper for the thread_pool_limits()
function.
So, the first function to look at is thread_pool_create(). It takes two parameters, attr
and flags. The attr is an attributes structure that defines the operating characteristics of
the thread pool (from ):
typedef struct _thread_pool_attr {
// thread pool functions and handle
THREAD_POOL_HANDLE_T *handle;
THREAD_POOL_PARAM_T
*(*block_func)(THREAD_POOL_PARAM_T *ctp);
void
(*unblock_func)(THREAD_POOL_PARAM_T *ctp);
int
(*handler_func)(THREAD_POOL_PARAM_T *ctp);
THREAD_POOL_PARAM_T
*(*context_alloc)(THREAD_POOL_HANDLE_T *handle);
void
(*context_free)(THREAD_POOL_PARAM_T *ctp);
// thread pool parameters
pthread_attr_t
*attr;
unsigned short
lo_water;
unsigned short
increment;
unsigned short
hi_water;
unsigned short
maximum;
} thread_pool_attr_t;
I’ve broken the thread_pool_attr_t type into two sections, one that contains the
functions and handle for the threads in the thread pool, and another that contains the
operating parameters for the thread pool.
70 Chapter 1 • Processes and Threads April 30, 2009