Customize the stack size of the threads used by pupnp through the new THREAD_STACK_SIZE variable

This patch allows a user to customize the stack size of the threads used by
pupnp through the new THREAD_STACK_SIZE variable. This is especially useful
on embedded systems with limited memory where the user can set THREAD_STACK_SIZE
to ITHREAD_STACK_MIN.

However, as this modification can have side effects, I set 0 as the default
value, so threads will continue to use the default stack size of the system
(which varies greatly as stated in
https://computing.llnl.gov/tutorials/pthreads/).
(cherry picked from commit 467f9987a1)

threadutil/inc/ThreadPool.h

@@ -115,6 +115,10 @@ typedef enum priority {
 #define DEFAULT_MAX_THREADS 10
 
 
+/*! default stack size used by TPAttrInit */
+#define DEFAULT_STACK_SIZE 0
+
+
 /*! default jobs per thread used by TPAttrInit */
 #define DEFAULT_JOBS_PER_THREAD 10
 
@@ -182,6 +186,10 @@ typedef struct THREADPOOLATTR
 	/* maxThreads, ThreadPool will never have more than this number of threads */
 	int maxThreads;
 
+	/* stackSize (in bytes), this is the minimum stack size allocated for each
+	 * thread */
+	size_t stackSize;
+
 	/* maxIdleTime (in milliseconds) this is the maximum time a thread will
 	 * remain idle before dying */
 	int maxIdleTime;
@@ -522,6 +530,20 @@ int TPAttrSetMaxThreads(ThreadPoolAttr *attr, int maxThreads);
 int TPAttrSetMinThreads(ThreadPoolAttr *attr, int minThreads);
 
 
+/****************************************************************************
+ * Function: TPAttrSetStackSize
+ *
+ *  Description:
+ *      Sets the stack size for the thread pool attributes.
+ *  Parameters:
+ *      attr - must be valid thread pool attributes.
+ *      stackSize - value to set
+ *  Returns:
+ *      Always returns 0.
+ *****************************************************************************/
+int TPAttrSetStackSize(ThreadPoolAttr *attr, size_t stackSize);
+
+
 /****************************************************************************
  * Function: TPAttrSetIdleTime
  *

threadutil/inc/ithread.h

@@ -85,7 +85,10 @@ extern "C" {
 
 #define ITHREAD_CANCELED PTHREAD_CANCELED
 
-  
+
+#define ITHREAD_STACK_MIN PTHREAD_STACK_MIN
+
+
 /***************************************************************************
  * Name: ithread_t
  *
@@ -726,6 +729,49 @@ static UPNP_INLINE int ithread_cleanup_thread(void) {
    ***************************************************************************/
 #define ithread_cond_destroy pthread_cond_destroy
 
+  /****************************************************************************
+   * Function: ithread_attr_init
+   *
+   *  Description:
+   *      Initialises thread attribute object.
+   *  Parameters:
+   *      ithread_attr_t *attr (must be valid non NULL pointer to
+   *      ithread_attr_t)
+   *  Returns:
+   *      0 on success. Nonzero on failure.
+   *      See man page for pthread_attr_init
+   ***************************************************************************/
+#define ithread_attr_init pthread_attr_init
+
+  /****************************************************************************
+   * Function: ithread_attr_destroy
+   *
+   *  Description:
+   *      Destroys thread attribute object.
+   *  Parameters:
+   *      ithread_attr_t *attr (must be valid non NULL pointer to
+   *      ithread_attr_t)
+   *  Returns:
+   *      0 on success. Nonzero on failure.
+   *      See man page for pthread_attr_destroy
+   ***************************************************************************/
+#define ithread_attr_destroy pthread_attr_destroy
+
+  /****************************************************************************
+   * Function: ithread_attr_setstacksize
+   *
+   *  Description:
+   *      Sets stack size of a thread attribute object.
+   *  Parameters:
+   *      ithread_attr_t *attr (must be valid non NULL pointer to
+   *      ithread_attr_t)
+   *      size_t stacksize (value of stacksize must be greater than
+   *      ITHREAD_STACK_MIN and lower than system-imposed limits
+   *  Returns:
+   *      0 on success. Nonzero on failure.
+   *      See man page for pthread_attr_setstacksize
+   ***************************************************************************/
+#define ithread_attr_setstacksize pthread_attr_setstacksize
 
   /****************************************************************************
    * Function: ithread_create
@@ -735,7 +781,7 @@ static UPNP_INLINE int ithread_cleanup_thread(void) {
    *      and argument.
    *  Parameters:
    *      ithread_t * thread (must be valid non NULL pointer to pthread_t)
-   *      ithread_attr_t *attr, IGNORED
+   *      ithread_attr_t *attr
    *      void * (start_routine) (void *arg) (start routine)
    *      void * arg - argument.
    *  Returns: