Non blocking socket keep blocking on read ?

[Serge Savoie]

Hello everyone,

I have a problem with a socket that block (and my process alt) when the
server stop send me stuff. The server send me a couple of things ( file
name and so on ) and after that it send me a file ( a jpeg ). Everything
works ok but I have to force the read loop to break. How can I detect
that the server dont send me nothing anymore and break ? I was sure that
it will do it with connect_non_block ?

My problem is in the
while( buf = socket.readline )
it is where it hang when the server stop sending...

Here is my complete code...


socket = Socket.new(AF_INET, SOCK_STREAM, 0)
sockaddr = Socket.sockaddr_in(9401, '10.2.4.92')

begin
socket.connect_nonblock(sockaddr)
rescue Errno::EINPROGRESS
IO.select(nil, [socket])
begin
socket.connect_nonblock(sockaddr)
rescue Errno::EISCONN
end
end

puts "sending..."

begin

socket.write("207\n")
socket.write("146316\n")
socket.write( "89c38b1b197162cae874e5274963633f" + "\n")

puts "receiving..."

i=0
while data = socket.readline
puts "data : " + data

if i == 0
puts "Return code : " + data
end

if i == 1
puts "Bytes to receive : " + data
nombre_bytes = data
end

if i == 2
puts "File name : " + data
end

if i == 2
break;
end

i = i+1

end

i = 0;
while( buf = socket.readline )
puts "here"
puts buf
puts " i = " + i.to_s;

if( @imageData == nil )
@imageData = buf
else
@imageData += buf
end

i = i + 1

#I Dont want to do this
#with this all works because I kow the the server ships
#me the test file in 26 chunk
#I wanna detect that readline read nothing instead !
if( i == 27 )
break;
end



end


socket.close

rescue Exception => exc
puts "erreur #{exc.message}"
puts exc.inspect
socket.close


end

end


Thx for your comments !

Seurdge

 

[Luis Parravicini]

Hi Sergey

The server sends you the size of the image, so you can use that to
check when the download completed. Also check the way you are reading
the image, you are using IO::readline which is generally used to read
lines of text. Take a look at IO::read to download the image.

 

[Serge Savoie]

Ths Luis !

But how do I know the weight of the received bytes ? I have think of
what you propose but can't find the way to "measure" the received stuff
!!!

I have to use readline or gets to receive because the server (a java
server) only offer me buffered stream and recv and read dont work in
this case...

Serge

 

[Luis Parravicini]

But how do I know the weight of the received bytes ? I have think of
what you propose but can't find the way to "measure" the received stuff
!!!

I have to use readline or gets to receive because the server (a java
server) only offer me buffered stream and recv and read dont work in
this case...

It doesn't matter if the server is using a buffered stream, you'll
get the bytes on the client anyway. Maybe something like this helps
(haven't tried it):

data = nil
left = nombre_bytes
while left > 0
# 8192 is an arbitrary buffer size
buf = socket.read( left > 8192 ? 8192 : left )
# eof reached
break unless buf

left -= buf.size
data += buf
end

@imageData = data


Why are you using a while to read return code, filename and size?
Three socket.readline should be enough.


Bye

 

[Serge Savoie]

Thx a lot Luis ;-)

The Java server now send me a signal for "end of transmission" so I do
not have the check the weight of the transfer...

"Why are you using a while to read return code, filename and size? Three
socket.readline should be enough."

yeah sure, but its just cheesy test code lol

Thx again for your rapid reply and have a nice day !