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Re: Different interface will affect each other while downloading?

From: Pahome Chen via curl-library <curl-library_at_cool.haxx.se>
Date: Thu, 3 Aug 2017 17:02:10 +0800

2017-08-03 14:12 GMT+08:00 Ray Satiro via curl-library <
curl-library_at_cool.haxx.se>:

> On 8/2/2017 4:45 AM, Pahome Chen via curl-library wrote:
> > Curl version: curl 7.54.0. libcurl/7.54.0 OpenSSL/1.0.2g zlib/1.2.8
> >
> > I use libcurl to download files from s3 bucket and apply two
> > interface: multi_socket and easy.
> >
> > Both interface download 1MB one time.
> >
> > Execution order in log is below:
> >
> > socket callback: s=16 e=0x7f4cb4020230 Adding data: OUT
> > socket callback: s=16 e=0x7f4cb4020230 Change action from OUT to IN.
> > easy_perform starte. Download 1MB. ->Download finished.
> > easy_perform starte. Download 1MB. -> Download finished.
> > socket callback: s=16 e=0x7f4cb4020230 Removing.
> > multi_socket download done.
> >
> > In code snippet the two interface use the same curl_easy_setopt() such
> > as CURLOPT_WRITEFUNCTION
> > CURLOPT_HTTPHEADER
> > CURLOPT_URL...etc.
> >
> > I have questions about that the two interface will affect each other?
> > I thought the multi_socket interface will download first that the
> > latter easy interface.
>
> You are using multi_socket_action and then in the middle of that you
> call easy_perform on some other handles? or (I really hope) is that
> happening in a separate thread?

I do it in different threads. I call easy_perform in one thread when I add
multi handle in another one thread.

> In any case if the easy_perform
> downloads have finished first any number of factors could contribute to
> that. You can only guarantee the order of synchronous downloads because
> libcurl would wait for one to finish before going on to the next one. In
> other words easy_perform(a); easy_perform(b); easy_perform(c);
> guaranteed order because the calls are blocking, a then b then c.
> curl_multi_add_handle(multi, a); curl_multi_add_handle(multi, b);
> curl_multi_add_handle(multi, c); no guaranteed order. bac, cba, acb, etc
>
>
Maybe the two interface won't affect each other?

-- 
Best Regards,
pahome

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Received on 2017-08-03