Re: Forcing curl_multi_perform() to return regularly

From: XSLT2.0 via curl-library <curl-library_at_cool.haxx.se>
Date: Wed, 20 Jan 2021 17:02:45 +0100

Indeed, that could the correct solution to "reverse" the control of the
loop and give it back to the application in a "read-like" manner.

You can look at my proposed PR on fcurl that is a "read-like" interface
designed by Daniel some years ago, where the application has control
over when it wants to read.

https://github.com/curl/fcurl/pull/2

Or the fork with the "pause-read-like" algorithm that served to the PR:

https://github.com/Bylon2/fcurl/blob/master/src/fcurl.c

That being said, unfortunately 'pause' has severe limitations on modern
system (not really multi-thread friendly) which should not bother you on
"vintage" systems.

IMHO

- curl_easy_pause feature is excellent since it corresponds to use case
where the application wants "full control of the read loop"

- It is so good that it should be better put forward in the documentation.

- Limitations about not-really multi-thread friendly should be ironed
and lifted (or at least better document in which case/O.S./protocol
"dead-locks" can happen)

Cheers

Alain



Date: Tue, 19 Jan 2021 22:55:10 +0000
> From: Jiahao XU <Jiahao_XU_at_outlook.com>
> To: libcurl development <curl-library_at_cool.haxx.se>
> Subject: Re: Forcing curl_multi_perform() to return regularly
> Message-ID:
> <SYBP282MB0202A691D5CBE453A0AF06FB8AA30_at_SYBP282MB0202.AUSP282.PROD.OUTLOOK.COM>
>
> Content-Type: text/plain; charset="utf-8"
>
> Perhaps you can use curl_easy_pause to pause a connection?
>
> Or you can return a special value CURL_READFUNC_PAUSE or CURL_WRITEFUNC_PAUSE in the callback function to paise the connection.
>
> Get Outlook for iOS<https://aka.ms/o0ukef>
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Received on 2021-01-20