ustream: tweak ustream_prepare_buf() a bit.

No functional change.

 - Reuse existing NULL check on buf.
 - Add some comments for ease of reading the code.

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>

diff --git a/ustream.c b/ustream.c
index fc93bc21dd334de315e1849a9f8e478fe33c249e..e7ee9f07c5952057bb2bc558ae9330af180bc753 100644 (file)
--- a/ustream.c
+++ b/ustream.c
@@ -145,21 +145,26 @@ static bool ustream_should_move(struct ustream_buf_list *l, struct ustream_buf *
        int maxlen;
        int offset;
 
+       /* nothing to squeeze */
        if (buf->data == buf->head)
                return false;
 
        maxlen = buf->end - buf->head;
        offset = buf->data - buf->head;
 
+       /* less than half is available */
        if (offset > maxlen / 2)
                return true;
 
+       /* less than 32 bytes data but takes more than 1/4 space */
        if (buf->tail - buf->data < 32 && offset > maxlen / 4)
                return true;
 
+       /* more buf is already in list or can be allocated */
        if (buf != l->tail || ustream_can_alloc(l))
                return false;
 
+       /* no need to move if len is available at the tail */
        return (buf->end - buf->tail < len);
 }
 
@@ -255,13 +260,14 @@ static bool ustream_prepare_buf(struct ustream *s, struct ustream_buf_list *l, i
                        if (l == &s->r)
                                ustream_fixup_string(s, buf);
                }
+               /* some chunks available at the tail */
                if (buf->tail != buf->end)
                        return true;
-       }
-
-       if (buf && buf->next) {
-               l->data_tail = buf->next;
-               return true;
+               /* next buf available */
+               if (buf->next) {
+                       l->data_tail = buf->next;
+                       return true;
+               }
        }
 
        if (!ustream_can_alloc(l))