Re: [Cppcms-users] Concurrent download question

[mawan s. <ma...@gm...>]

this is PHP method to download file step by step with limited speed.
how to write in cppcms?

$file1 = @fopen($filename,"rb");
$start = microtime (TRUE);
if ($file1) {
while(!feof($file1)) {
print(fread($file1, 1024));
flush();
$now = microtime (TRUE);
$count++;
$ms = (($count/$speed) - ($now-$start))*1000;
if (intval($ms)<10) {
                   $ms = 50;
               }

ob_flush();
if (connection_status()!=0) {
ob_flush();
@fclose($file1);
die();
}
usleep ($ms);
}
 @fclose($file1);
}
ob_flush();
die();



Thankyou




On Sun, Mar 27, 2016 at 6:38 PM, Shiv Shankar Dayal <
shi...@gm...> wrote:

> I think that I will start with a synchronous application with thread
> per connection and also have another version of asynchronous. I will
> let both run and decide after serious testing and real world usage.
>
> The answer to the questions varies. We will have to try combinations
> in real world before arriving at the solution. I think I will use FUSE
> so that I can do X-Send-File which seems to be optimal for me. But
> without real testing it is hard to say what approach will be final.
>
> Thanks a lot for all the help you have provided. I really appreciate it.
>
> On Sun, Mar 27, 2016 at 3:25 PM, Artyom Beilis <art...@gm...>
> wrote:
> >> The problem is that individual file will have rare downloads(usually
> >> one file will be downloaded once a month or two)
> >> and no. of downloads are large. So caching will not help.
> >> They have to be read asynchronously and concurrently. I am not sure
> >> that should I create booster::io::service or cppcms::service. Also,
> >> I find it hard to create booster::io::service as its example is not
> >> exhaustive. Even if I create booster::io::service the filesystem
> >> calls may block. I will be using GlusterFS for storage. But that is
> >> something not within CppCMS's domain so I will take care of
> >> that.
> >
> > Got it, sorry I was mislead by previous question regarding the uploads.
> >
> > Regarding downloads.
> >
> > 1st if you run behind lighttpd or nginx web server (which you probably
> > should do) I suggest
> > to use X-Send-File stuff
> > http://cppcms.com/wikipp/en/page/cppcms_1x_serving_static_files
> >
> > Also in such case you may need to mount GlusterFS via FUSE or NFS or
> > use a special plugin
> > (I've seen one for lighttpd)
> >
> > They do the best they can in serving static files - but you probably
> > check the solution explicitly
> > because maybe lighttpd or nginx are not optimized for GlusterFS as
> > normal file system.
> >
> > ---------------------------------------------------
> >
> > If you use CppCMS's internal file server it can work in both sync and
> async mode
> > starting from CppCMS 1.2 but you'll need to use stuff like FUSE or NFS
> > to mount file system.
> >
> > But in async mode if GlusterFS hangs in opening/reading file you may
> block
> > entire event loop.
> >
> > You can write your own application that does the job.
> >
> > Also note - if you don't have lots of concurrent downloads it may be
> > simpler just to use thread per connection - in standard synchronous
> > application as it would deal with both concurrency and "io optimization"
> >
> > if you do it asynchronously it can be tricky as if GlusterFS API may
> block
> > and it would stall entire event loop. So you need to handle it someway,
> > i.e. use booster::aio::io_service to handle such and events (I assyme
> > glusterfs API has some event driven handling)
> >
> > Also you should note that web server may read the request
> > faster than it sends it to the client - lighttpd in such a case would
> > put it into memory and nginx create its own temporary file
> > so it can be tricky stuff - neither of them would block you from
> > writing to client (AFAIR) - which can be bad for huge files.
> >
> > Bottom line several questions you need to answer:
> >
> > 1. Do you work with GlusterFS via FUSE/NFS or its own API?
> > 2. What concurrency level do you expect?
> > 3. What web server does when client does not read in same speed as you
> send?
> >
> >
> > Artyom
> >
> >
> ------------------------------------------------------------------------------
> > Transform Data into Opportunity.
> > Accelerate data analysis in your applications with
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>
>
>
> --
> Respect,
> Shiv Shankar Dayal
>
>
> ------------------------------------------------------------------------------
> Transform Data into Opportunity.
> Accelerate data analysis in your applications with
> Intel Data Analytics Acceleration Library.
> Click to learn more.
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