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curl_multi_timeout(3) [osx man page]

curl_multi_timeout(3)						  libcurl Manual					     curl_multi_timeout(3)

curl_multi_timeout - how long to wait for action before proceeding SYNOPSIS
#include <curl/curl.h> CURLMcode curl_multi_timeout(CURLM *multi_handle, long *timeout); DESCRIPTION
An application using the libcurl multi interface should call curl_multi_timeout(3) to figure out how long it should wait for socket actions - at most - before proceeding. Proceeding means either doing the socket-style timeout action: call the curl_multi_socket_action(3) function with the sockfd argument set to CURL_SOCKET_TIMEOUT, or call curl_multi_perform(3) if you're using the simpler and older multi interface approach. The timeout value returned in the long timeout points to, is in number of milliseconds at this very moment. If 0, it means you should pro- ceed immediately without waiting for anything. If it returns -1, there's no timeout at all set. An application that uses the multi_socket API SHOULD NOT use this function, but SHOULD instead use curl_multi_setopt(3) and its CURL- MOPT_TIMERFUNCTION option for proper and desired behavior. Note: if libcurl returns a -1 timeout here, it just means that libcurl currently has no stored timeout value. You must not wait too long (more than a few seconds perhaps) before you call curl_multi_perform() again. RETURN VALUE
The standard CURLMcode for multi interface error codes. TYPICAL USAGE
Call curl_multi_timeout(3), then wait for action on the sockets. You figure out which sockets to wait for by calling curl_multi_fdset(3) or by a previous call to curl_multi_socket(3). AVAILABILITY
This function was added in libcurl 7.15.4. SEE ALSO
curl_multi_fdset(3), curl_multi_info_read(3), curl_multi_socket(3), curl_multi_setopt(3) libcurl 7.16.0 2 Jan 2006 curl_multi_timeout(3)

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curl_multi_fdset(3)						  libcurl Manual					       curl_multi_fdset(3)

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 the read_fd_set argument is not a null pointer, it points to an object of type fd_set that on returns specifies the file descriptors to be checked for being ready to read. If the write_fd_set argument is not a null pointer, it points to an object of type fd_set that on return specifies the file descriptors to be checked for being ready to write. If the exc_fd_set argument is not a null pointer, it points to an object of type fd_set that on return specifies the file descriptors to be checked for error conditions pending. If no file descriptors are set by libcurl, max_fd will contain -1 when this function returns. Otherwise it will contain the highest descriptor 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(). You then need to wait a while before you proceed and call curl_multi_perform(3) anyway. How long to wait? We suggest 100 mil- liseconds 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(3) to figure out how long to wait for action. Call curl_multi_perform(3) even if no activity 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_wait(3), curl_multi_timeout(3), curl_multi_perform(3), select(2) libcurl 7.54.0 February 03, 2016 curl_multi_fdset(3)
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