Allow wquque to use callback to free an mbuf - so

mbufs can be reused/pooled

include/ucore/wqueue.h

@@ -67,6 +67,12 @@ typedef enum UC_WQ_RESULT (*wqueue_write_cb)(struct IOMux *mux,
 typedef enum UC_WQ_RESULT (*wqueue_read_cb)(struct IOMux *mux, 
                                             struct UCWQueue *wqueue);
 
+/**
+ * Callback to free a MBuf once it's fully written.
+ * @param the fd of the current wqueue
+ */
+typedef void (*wqueue_free_mbuf_cb)(struct MBuf *mbuf);
+
 /** 
  * Represents a queue of data to write.
  * UCWQueue replaces a raw IOMuxFD, and manages a queue
@@ -91,7 +97,8 @@ struct UCWQueue {
     /** Users callback for write events
      */
     wqueue_write_cb write_cb;
-
+    /** Function used to free an MBuf - default is uc_mbuf_free()*/
+    wqueue_free_mbuf_cb free_cb;
     /** Current number of queued struct MBuf
      */
     unsigned int queue_len;

src/wqueue.c

@@ -24,7 +24,7 @@ static int uc_wqueue_handle_write(struct UCWQueue *wqueue)
 
         mbuf = uc_mbuf_dequeue(&wqueue->queue);
         assert(mbuf != NULL);
-        uc_mbuf_free(mbuf);
+        wqueue->free_cb(mbuf);
         wqueue->queue_len--;
     }
 
@@ -71,7 +71,7 @@ void uc_wqueue_init(struct UCWQueue *wqueue, struct IOMux *mux)
     memset(wqueue, 0, sizeof *wqueue);
     wqueue->mux = mux;
     wqueue->fd.callback = uc_wqueue_cb;
-    
+    wqueue->free_cb = uc_mbuf_free;
     uc_tailq_init(&wqueue->queue);
 }
 
@@ -81,7 +81,7 @@ int uc_wqueue_clear(struct UCWQueue *wqueue)
     int rc = 0;
 
     while ((buf = uc_mbuf_dequeue(&wqueue->queue)) != NULL) {
-        uc_mbuf_free(buf);
+        wqueue->free_cb(buf);
         wqueue->queue_len--;
     }