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Code Issues Releases Wiki Activity

curl_multi_fdset: clarify the max_fd == -1 case

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Elaborate what max_fd == -1 means

Remove the reference to CURLM_CALL_MULTI_PERFORM as modern libcurl
versions don't ever return that.
This commit is contained in:
Daniel Stenberg 2011-10-16 23:38:48 +02:00
parent 840eff44f2
commit 337252bdd4
1 changed files with 7 additions and 6 deletions
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13
docs/libcurl/curl_multi_fdset.3
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@ -40,14 +40,15 @@ but be sure to FD_ZERO them before calling this function as
otherwise remove any others. The \fIcurl_multi_perform(3)\fP function should be otherwise remove any others. The \fIcurl_multi_perform(3)\fP function should be
called as soon as one of them is ready to be read from or written to. called as soon as one of them is ready to be read from or written to.
To be sure to have up-to-date results, you should call
\fIcurl_multi_perform\fP until it does not return CURLM_CALL_MULTI_PERFORM
prior to calling \fIcurl_multi_fdset\fP. This will make sure that libcurl has
updated the handles' socket states.
If no file descriptors are set by libcurl, \fImax_fd\fP will contain -1 when If no file descriptors are set by libcurl, \fImax_fd\fP will contain -1 when
this function returns. Otherwise it will contain the higher descriptor number this function returns. Otherwise it will contain the higher descriptor number
libcurl set. libcurl set. When libcurl returns -1 in \fImax_fd\fP, it is because libcurl
currently does something that isn't possible for your application to monitor
with a socket and unfortunately you can then not know exactly when the current
action is completed using select(). When max_fd returns with -1, you need to
wait a while and then proceed and call \fIcurl_multi_perform\fP anyway. How
long to wait? I would suggest 100 milliseconds at least, but you may want to
test it out in your own particular conditions to find a suitable value.
When doing select(), you should use \fBcurl_multi_timeout\fP to figure out how When doing select(), you should use \fBcurl_multi_timeout\fP to figure out how
long to wait for action. Call \fIcurl_multi_perform\fP even if no activity has long to wait for action. Call \fIcurl_multi_perform\fP even if no activity has