diff --git a/doc/lua-api/_static/channel.fig b/doc/lua-api/_static/channel.fig
index 0838a37..8a6c0a1 100644
--- a/doc/lua-api/_static/channel.fig
+++ b/doc/lua-api/_static/channel.fig
@@ -8,12 +8,12 @@
 -2
 1200 2
 1 1 0 1 0 7 50 -1 -1 0.000 1 0.0000 4500 1620 1260 585 4500 1620 5760 2205
-2 3 0 1 0 7 50 -1 -1 0.000 0 0 -1 0 0 9
+2 3 0 1 0 7 50 -1 -1 0.000 0 0 -1 0 0 8
 	 1170 1350 1170 1890 2790 1890 2790 2070 3240 1620 2790 1170
-	 2790 1350 1170 1350 1170 1350
-2 3 0 1 0 7 50 -1 -1 0.000 0 0 -1 0 0 9
+	 2790 1350 1170 1350
+2 3 0 1 0 7 50 -1 -1 0.000 0 0 -1 0 0 8
 	 5760 1350 5760 1890 7380 1890 7380 2070 7830 1620 7380 1170
-	 7380 1350 5760 1350 5760 1350
+	 7380 1350 5760 1350
 2 1 1 1 0 7 50 -1 -1 1.000 0 0 -1 1 0 2
 	5 1 1.00 60.00 120.00
 	 6210 540 6210 1440
@@ -51,4 +51,5 @@
 4 0 0 50 -1 12 12 0.0000 4 150 720 6300 1110 send()\001
 4 0 0 50 -1 12 12 0.0000 4 165 1560 6255 2205 get_out_len()\001
 4 0 0 50 -1 16 12 0.0000 4 150 1230 6120 2520 read functions\001
-4 1 0 50 -1 16 12 0.0000 4 150 1650 4500 540 both side functions\001
+4 1 0 50 -1 16 12 0.0000 4 150 1650 4500 315 both side functions\001
+4 1 0 50 -1 12 12 0.0000 4 150 1080 4500 540 is_full()\001
diff --git a/doc/lua-api/_static/channel.png b/doc/lua-api/_static/channel.png
index 79eb6f7..e12a26e 100644
--- a/doc/lua-api/_static/channel.png
+++ b/doc/lua-api/_static/channel.png
Binary files differ
diff --git a/doc/lua-api/index.rst b/doc/lua-api/index.rst
index c42b2f3..77c2266 100644
--- a/doc/lua-api/index.rst
+++ b/doc/lua-api/index.rst
@@ -1070,6 +1070,11 @@
   :param class_channel channel: The manipulated Channel.
   :param integer int: The amount of data which will be forwarded.
 
+.. js:function:: Channel.is_full(channel)
+
+  This function returns true if the buffer channel is full.
+
+  :returns: a boolean
 
 .. _http_class: