Zero count of consumers/tail readers of CBUFF is handled now.

[ulut.git] / ulut / ul_cbuff.h

diff --git a/ulut/ul_cbuff.h b/ulut/ul_cbuff.h
index 29d662f49032e57b0516e2d507312cee7afd6a0b..a6fd8d8c06cc64a80d196cb6828bdbc58e1e803a 100644 (file)
--- a/ulut/ul_cbuff.h
+++ b/ulut/ul_cbuff.h
@@ -108,6 +108,7 @@ int ul_cbuff_tail_test(ul_cbuff_t *buff, ul_cbuff_tail_info_t *tail_info);
 int ul_cbuff_tail_release(ul_cbuff_t *buff, ul_cbuff_tail_info_t *tail_info);
 int ul_cbuff_tail_next(ul_cbuff_t *buff, ul_cbuff_tail_info_t *tail_info);
 int ul_cbuff_tail_state_update(ul_cbuff_t *buff, int release_result, ul_cbuff_loc_t loc, ul_cbuff_loc_t loc_next);
+int ul_cbuff_tail_detach_onestep(ul_cbuff_t *buff, ul_cbuff_tail_info_t *tail_info);
 void ul_cbuff_data_do_wrap(ul_cbuff_data_info_t *data_info);
 int ul_cbuff_data_at_once(ul_cbuff_data_info_t *data_info, void **pptr, int size);
 int ul_cbuff_put_data(ul_cbuff_data_info_t *data_info, const void *data, int size);
@@ -188,6 +189,8 @@ ul_cbuff_head_alloc(ul_cbuff_t *buff, ul_cbuff_put_info_t *put_info, unsigned in
   put_info->msg_head->flags|=flags;
   if(buff->state->readers>0)
     put_info->msg_head->flags+=buff->state->readers;
+  else if (buff->state->readers==0)
+    put_info->msg_head->flags+=1;
 
   put_info->msg_head->length=length;
 
@@ -261,7 +264,10 @@ ul_cbuff_tail_attach(ul_cbuff_t *buff, ul_cbuff_tail_info_t *tail_info, int mode
   ul_cbuff_state_t *state=buff->state;
   ul_cbuff_msg_head_t *msg_head;
 
-  msg_head=(ul_cbuff_msg_head_t *)(buff->buff_start+state->head);
+  if(state->readers>0)
+    msg_head=(ul_cbuff_msg_head_t *)(buff->buff_start+state->head);
+  else if(state->readers==0)
+    msg_head=(ul_cbuff_msg_head_t *)(buff->buff_start+state->lasttail);
   if(state->readers>=0)
     state->readers++;
   tail_info->msg_head=msg_head;
@@ -341,6 +347,39 @@ ul_cbuff_tail_state_update(ul_cbuff_t *buff, int release_result, ul_cbuff_loc_t
   }
 }
 
+ul_cbuff_inline int
+ul_cbuff_tail_detach_onestep(ul_cbuff_t *buff, ul_cbuff_tail_info_t *tail_info)
+{
+  ul_cbuff_state_t *state=buff->state;
+  ul_cbuff_loc_t loc;
+  ul_cbuff_loc_t loc_next;
+  unsigned msg_readers;
+
+  if(tail_info->msg_head==NULL)
+    return 0;
+
+  loc = ul_cbuff_head_loc(buff, tail_info->msg_head);
+
+  if(loc!=state->head) {
+    if(!ul_cbuff_is_ready(tail_info->msg_head))
+      return 2;
+    msg_readers=tail_info->msg_head->flags&UL_CBUFF_MSG_READERS;
+    loc_next=ul_cbuff_next_loc(buff, tail_info->msg_head);
+    if(msg_readers)
+      tail_info->msg_head->flags--;
+    tail_info->msg_head=(ul_cbuff_msg_head_t *)(buff->buff_start+loc_next);
+    ul_cbuff_tail_state_update(buff, msg_readers<=1? 1: 0, loc, loc_next);
+    return 1;
+  }
+
+  if(state->readers>0)
+    state->readers--;
+  tail_info->msg_head=NULL;
+  tail_info->data.ptr=NULL;
+  return 0;
+}
+
+
 ul_cbuff_inline void
 ul_cbuff_data_do_wrap(ul_cbuff_data_info_t *data_info)
 {