Re: mod_perl, mod_gzip and connection->fileno

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Marcel Greter wrote:
[...]
>> How about we keep the original code using IO::Select and provide an 
>> example how to do it more efficiently? The IO::Select example is much 
>> more userfriendly :)
>>
> Maybe something like this? Don't know how much you want to annotate ??

I meant to explain what it does. Not everybody will understand how this 
code works by just reading it. And especially why you choose fd 0 and not 
fd 1.

> =head1 Detecting a Client Abort
> 
>  # IsClientConnected? Might already be disconnected for busy
>  # site, if a user hits stop/reload
> 
>  my $conn = $r->connection;
>  my $is_connected = $conn->aborted ? 0 : 1;
>  if($is_connected) {
>      if (defined(my $fileno = $conn->fileno(0))) {
>          my $s = IO::Select->new($fileno);
>          $is_connected = $s->can_read(0) ? 0 : 1;
>      } else { $is_connected = 0 }
>  }
> 
> You may also implement this without using the IO::Select module
> 
>  my $is_connected = 1;
>  my $conn = $r->connection;
>  # check Apache::Connection abort status
>  if($conn->aborted) { $is_connected = 0 }
>  else {
>      if (defined(my $fileno = $conn->fileno(0))) {
>          vec(my $rbit = '', $fileno, 1) = 1; # enable fd in vector table
>          select($rbit, undef, undef, 0); # select for readable handles
>          $is_connected = vec($rbit, $fileno, 1) ? 0 : 1; # check fd in
> vector table
>      } else { $is_connected = 0 }
>  }

looks good.

>>>> Also take a look at: 
>>>> http://perl.apache.org/docs/1.0/guide/debug.html#Handling_the__User_pressed_Stop_button__case 
>>>>
>>>> It's directly related and should probably be merged into one item. 
>>>> or at least xref each other.
>>>>
>>> I'm checking the return value of each print, so this should take care 
>>> of this case.
>>
>>
>>
>> Wow! But most people don't. So in mp2 you no longer need to do that, 
>> as print() as well as all other IO methods croak on failure.
>>
> I'm doing a bigger framework, so there is actually just one place to
> check the print function :-)

that's smart :)

>> So could you please adjust whatever needs to be adjusted in that 
>> section, and post here a patch to the POD source (or the section 
>> itself), while adding the discussion why one should use 0 and not 1, 
>> based on this thread?
>>
> Please see the addition above. I'll post a patch later, ss it might will
> change. By 0/1, do you mean the fileno call?

Yup.


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