finalized POOL_resize()

POOL_ctx* POOL_resize(POOL_ctx* ctx, size_t numThreads)

The function may fail, and returns a NULL pointer in this case.

lib/common/pool.h

@@ -38,6 +38,16 @@ POOL_ctx* POOL_create_advanced(size_t numThreads, size_t queueSize,
  */
 void POOL_free(POOL_ctx* ctx);
 
+/*! POOL_resize() :
+ *  Expands or shrinks pool's number of threads.
+ *  This is more efficient than releasing and creating a new context.
+ * @return : a new pool context on success, NULL on failure
+ *    note : new pool context might have same address as original one, but it's not guaranteed.
+ *           consider starting context as consumed, only rely on returned one.
+ *    note 2 : only numThreads can be resized, queueSize is unchanged.
+ */
+POOL_ctx* POOL_resize(POOL_ctx* ctx, size_t numThreads);
+
 /*! POOL_sizeof() :
  * @return threadpool memory usage
  *  note : compatible with NULL (returns 0 in this case)