diff --git a/HISTORY b/HISTORY
index 075ff5b..0376c69 100644
--- a/HISTORY
+++ b/HISTORY
@@ -1,5 +1,5 @@
 
-Version 1.24  2016-01-14
+Version 1.24  2016-01-19
   * php extension compiled on PHP 7
   * add skiplist which support stable sort
   * make.sh: use sed to replace perl
diff --git a/src/fast_task_queue.c b/src/fast_task_queue.c
index 5f9483a..d5827fa 100644
--- a/src/fast_task_queue.c
+++ b/src/fast_task_queue.c
@@ -629,41 +629,45 @@ int task_queue_count(struct fast_task_queue *pQueue)
 	return count;
 }
 
-static int _get_new_buffer_size(struct fast_task_queue *pQueue,
-        const int expect_size, int *new_size)
+int task_queue_get_new_buffer_size(const int min_buff_size,
+        const int max_buff_size, const int expect_size, int *new_size)
 {
-    if (pQueue->min_buff_size == pQueue->max_buff_size)
+    if (min_buff_size == max_buff_size)
     {
         logError("file: "__FILE__", line: %d, "
                 "can't change buffer size because NOT supported", __LINE__);
         return EOPNOTSUPP;
     }
 
-    if (expect_size > pQueue->max_buff_size)
+    if (expect_size > max_buff_size)
     {
         logError("file: "__FILE__", line: %d, "
                 "can't change buffer size because expect buffer size: %d "
                 "exceeds max buffer size: %d", __LINE__, expect_size,
-                pQueue->max_buff_size);
+                max_buff_size);
         return EOVERFLOW;
     }
 
-    *new_size = pQueue->min_buff_size;
-    if (expect_size > pQueue->min_buff_size)
+    *new_size = min_buff_size;
+    if (expect_size > min_buff_size)
     {
         while (*new_size < expect_size)
         {
             *new_size *= 2;
         }
-        if (*new_size > pQueue->max_buff_size)
+        if (*new_size > max_buff_size)
         {
-            *new_size = pQueue->max_buff_size;
+            *new_size = max_buff_size;
         }
     }
 
     return 0;
 }
 
+#define  _get_new_buffer_size(pQueue, expect_size, new_size) \
+    task_queue_get_new_buffer_size(pQueue->min_buff_size, \
+            pQueue->max_buff_size, expect_size, new_size)
+
 int task_queue_set_buffer_size(struct fast_task_queue *pQueue,
         struct fast_task_info *pTask, const int expect_size)
 {
diff --git a/src/fast_task_queue.h b/src/fast_task_queue.h
index 8d29d76..4720e49 100644
--- a/src/fast_task_queue.h
+++ b/src/fast_task_queue.h
@@ -106,6 +106,9 @@ int task_queue_set_buffer_size(struct fast_task_queue *pQueue,
 int task_queue_realloc_buffer(struct fast_task_queue *pQueue,
         struct fast_task_info *pTask, const int expect_size);
 
+int task_queue_get_new_buffer_size(const int min_buff_size,
+        const int max_buff_size, const int expect_size, int *new_size);
+
 #ifdef __cplusplus
 }
 #endif