Blocking reads from buffered reader (Bufio)

[Jirka Daněk]

Dear Gophers,

i am communicating with a server using net.Conn, which I get from net.Dial. To make my job easier, I wrapped it with bufio.NewReader(), so I can use convenience functions like ReadBytes.

My problem is that all functions I get with buffered reader are non-blocking. That becomes a problem when the server has nothing to say for a while and I keep getting EOFs from reads. I assume, once I call bufio.NewReader at an unbuffered reader, there is no way back. I cannot return to using the unbuffered reader directly.

So I want to ask: Is there a way to get a blocking read with bufio.Reader? Or function like SleepUntilDataAreAvailable? Otherwise, I would probably have to stick with unbuffered reader.

I use buffered reader mostly for the few convenience functions it provides. Is there a significant performance benefit from using it on a network socket as well? I kind of doubt it, because I think there are few buffers already in the OS and so on, so adding one more in my app does not help that much.

Thanks for your help

[Rémy Oudompheng]

On Wed 04 July 2012 at 13:43 -0700, Jirka Daněk wrote:
> Dear Gophers,
>

> i am communicating with a server using *net.Conn*, which I get from
> net.Dial. To make my job easier, I wrapped it with *bufio.NewReader*(), so
> I can use convenience functions like *ReadBytes*.

>
> My problem is that all functions I get with buffered reader are
> non-blocking. That becomes a problem when the server has nothing to say for

> a while and I keep getting EOFs from reads. I assume, once I call *
> bufio.NewReader* at an unbuffered reader, there is no way back. I cannot

> return to using the unbuffered reader directly.

Buffered readers have blocking behaviour. What is your problem about?
Maybe you should show some code with details about what you see.

Rémy.

[Jesse McNelis]

On Thu, Jul 5, 2012 at 6:43 AM, Jirka Daněk <jur...@gmail.com> wrote:
> non-blocking. That becomes a problem when the server has nothing to say for
> a while and I keep getting EOFs from reads.

If you're getting io.EOF returned from reading a network connection
then the connection has been closed.


--
=====================
http://jessta.id.au

[Jirka Daněk]

On Wednesday, July 4, 2012 10:53:14 PM UTC+2, Rémy Oudompheng wrote:

On Wed 04 July 2012 at 13:43 -0700, Jirka Daněk wrote: 

> Dear Gophers, 
> 
> i am communicating with a server using *net.Conn*, which I get from 
> net.Dial. To make my job easier, I wrapped it with *bufio.NewReader*(), so 
> I can use convenience functions like *ReadBytes*. 

> 
> My problem is that all functions I get with buffered reader are 

> non-blocking. That becomes a problem when the server has nothing to say for 

> a while and I keep getting EOFs from reads. I assume, once I call * 
> bufio.NewReader* at an unbuffered reader, there is no way back. I cannot 

> return to using the unbuffered reader directly. 

Buffered readers have blocking behaviour. What is your problem about? 
Maybe you should show some code with details about what you see. 

Rémy.

I tried to write an example (https://gist.github.com/3050053), which showed that buffered reads really block. 

On Thursday, July 5, 2012 12:41:46 AM UTC+2, Jesse McNelis wrote:

On Thu, Jul 5, 2012 at 6:43 AM, Jirka Daněk <***@gmail.com> wrote:
> non-blocking. That becomes a problem when the server has nothing to say for
> a while and I keep getting EOFs from reads.

If you're getting io.EOF returned from reading a network connection
then the connection has been closed. 

You are right. I forget to send a required parameter, which made the server close connection without warning.

When I was reading documentation, I was not sure what EOF means in case of network sockets, I thought it signalizes that data aren't momentarily ready.

Thanks for your help.