curl_multi_wait(3) [osx man page]

curl_multi_wait(3)						  libcurl Manual						curl_multi_wait(3)

NAME

       curl_multi_wait - polls on all easy handles in a multi handle

SYNOPSIS

       #include <curl/curl.h>

       CURLMcode curl_multi_wait(CURLM *multi_handle,
				 struct curl_waitfd extra_fds[],
				 unsigned int extra_nfds,
				 int timeout_ms,
				 int *numfds);

DESCRIPTION

       This  function  polls  on  all file descriptors used by the curl easy handles contained in the given multi handle set.  It will block until
       activity is detected on at least one of the handles or timeout_ms has passed.

       The calling application may pass additional curl_waitfd structures which are similar to poll(2)'s pollfd structure to be waited on  in  the
       same call.

       On completion, if numfds is supplied, it will be populated with the number of file descriptors on which interesting events occured.

       If no extra file descriptors are provided and libcurl has no file descriptor to offer to wait for, this function will return immediately.

       This  function  is encouraged to be used instead of select(3) when using the multi interface to allow applications to easier circumvent the
       common problem with 1024 maximum file descriptors.

curl_waitfd
       struct curl_waitfd {
	 curl_socket_t fd;
	 short events;
	 short revents;
       };

       CURL_WAIT_POLLIN
	      Bit flag to curl_waitfd.events indicating the socket should poll on read events such as new data received.

       CURL_WAIT_POLLPRI
	      Bit flag to curl_waitfd.events indicating the socket should poll on high priority read events such as out of band data.

       CURL_WAIT_POLLOUT
	      Bit flag to curl_waitfd.events indicating the socket should poll on write events such as the socket being  clear	to  write  without
	      blocking.

RETURN VALUE

       CURLMcode type, general libcurl multi interface error code. See libcurl-errors(3)

AVAILABILITY

       This function was added in libcurl 7.28.0.

SEE ALSO

       curl_multi_fdset(3), curl_multi_perform(3)

libcurl 7.28.0							    12 Jul 2012 						curl_multi_wait(3)

curl_multi_fdset(3)						  libcurl Manual					       curl_multi_fdset(3)

NAME

       curl_multi_fdset - extracts file descriptor information from a multi handle

SYNOPSIS

       #include <curl/curl.h>

       CURLMcode curl_multi_fdset(CURLM *multi_handle,
				  fd_set *read_fd_set,
				  fd_set *write_fd_set,
				  fd_set *exc_fd_set,
				  int *max_fd);

DESCRIPTION

       This  function  extracts  file  descriptor information from a given multi_handle.  libcurl returns its fd_set sets. The application can use
       these to select() on, but be sure to FD_ZERO them before calling this function as curl_multi_fdset(3) only adds	its  own  descriptors,	it
       doesn't zero or otherwise remove any others. The curl_multi_perform(3) function should be called as soon as one of them is ready to be read
       from or written to.

       If no file descriptors are set by libcurl, max_fd will contain -1 when this function returns. Otherwise it will contain the higher descrip-
       tor  number  libcurl  set.  When  libcurl returns -1 in max_fd, 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 curl_multi_perform anyway. How long to wait? I would sug-
       gest 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 curl_multi_timeout to figure out how long to wait for action. Call curl_multi_perform even if no activ-
       ity has been seen on the fd_sets after the timeout expires as otherwise internal retries and timeouts may not work as you'd think and want.

       If  one	of  the sockets used by libcurl happens to be larger than what can be set in an fd_set, which on POSIX systems means that the file
       descriptor is larger than FD_SETSIZE, then libcurl will try to not set it. Setting a too large file descriptor in an fd_set implies an  out
       of  bounds  write which can cause crashes, or worse. The effect of NOT storing it will possibly save you from the crash, but will make your
       program NOT wait for sockets it should wait for...

RETURN VALUE

       CURLMcode type, general libcurl multi interface error code. See libcurl-errors(3)

SEE ALSO

       curl_multi_cleanup(3), curl_multi_init(3), curl_multi_timeout(3), curl_multi_perform(3)

libcurl 7.16.0							    2 Jan 2006						       curl_multi_fdset(3)