thread_pool_limits()

Convenience wrapper function for thread_pool_control()

Synopsis:

#include <sys/iofunc.h>
#include <sys/dispatch.h>

int thread_pool_limits( thread_pool_t * pool, 
                        int lowater,
                        int hiwater,
                        int maximum,
                        int increment,
                        unsigned flags );

Arguments:

pool

A thread pool handle that was returned by thread_pool_create().

lowater

The minimum number of threads that the pool should keep in the blocked state (i.e. threads that are ready to do work), or a negative number if you don't want to change the current value.

hiwater

The maximum number of threads that the pool should keep in the blocked state, or a negative number if you don't want to change the current value.

maximum

The maximum number of threads that the pool can create, or a negative number if you don't want to change the current value.

increment

The number of new threads created at one time, or a negative number if you don't want to change the current value.

flags

The only flag that's accepted is THREAD_POOL_CONTROL_NONBLOCK. For more information, see the documentation for thread_pool_control().

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The thread_pool_limits() function is a wrapper function for thread_pool_control(). If the value of lowater, hiwater, maximum or increment is ≥0 then that value is adjusted in the thread pool according to the handle pool.

If you don't set THREAD_POOL_CONTROL_NONBLOCK, the upper and lower bounds for waiting are:

• lower = (lowater != -1) : lowater ? 0;
• upper = (maximum != -1) : maximum ? USHRT_MAX;

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Having several threads call this function with the same thread pool handle isn't recommended.

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Returns:

-1 if an error occurs (errno is set).

Classification:

QNX Neutrino

See also:

thread_pool_control(), thread_pool_create(), thread_pool_destroy(), thread_pool_start()

Processes and Threads chapter of Getting Started with QNX Neutrino