[Discuss-gnuradio] Problem with gr_head in simple graph

[Dominik Auras]

Hi!

I am encountering a problem with gr_head. For my testcase, I set up a
flow graph:

(...)
tcp_src = qtblocks.tcp_source (gr.sizeof_char, "127.0.0.1", 7777)
head = gr.head(gr.sizeof_char, 4)
vector_sink = gr.vector_sink_b()
self.fg.connect (tcp_src, head, vector_sink)
(...)

The logging in the single threaded scheduler is active. It outputs the
following:

--- snip ---
<gr_block tcp_source (5)> source
  noutput_items = 32767
  general_work: noutput_items = 32767 result = 0

<gr_block head (6)> regular 1:1
  max_items_avail = 0
  noutput_items = 32767
  BLKD_IN

<gr_block vector_sink_b (7)> sink
  max_items_avail = 0
  noutput_items = 0
  BLKD_IN

<gr_block tcp_source (5)> source
  noutput_items = 32767
  general_work: noutput_items = 32767 result = 12

<gr_block head (6)> regular 1:1
  max_items_avail = 12
  noutput_items = 32767
  general_work: noutput_items = 12 result = 4

<gr_block vector_sink_b (7)> sink
  max_items_avail = 4
  noutput_items = 4
  general_work: noutput_items = 4 result = 4

<gr_block tcp_source (5)>  Skipping source

<gr_block head (6)> regular 1:1
  max_items_avail = 8
  noutput_items = 32767
  general_work: noutput_items = 8 result = -1
  were_done

<gr_block vector_sink_b (7)> sink
  were_done

<gr_block tcp_source (5)> source
  noutput_items = 32759
  general_work: noutput_items = 32759 result = 0

<gr_block head (6)>
<gr_block vector_sink_b (7)>
<gr_block tcp_source (5)> source
  noutput_items = 32759
  general_work: noutput_items = 32759 result = 0
--- snip ---

The problem is that the graph does not stop. The source still outputs
items though its destination signaled done.

Greetings,
Dominik