<p class="level0">The multi_socket API is designed to inform your application about which sockets libcurl is currently using and for what activities (read and/or write) on those sockets your application is expected to wait for.
<p class="level0">Your application must make sure to receive all sockets informed about in the CURLMOPT_SOCKETFUNCTION callback and make sure it reacts on the given activity on them. When a socket has the given activity, you call <a Class="emphasis" href="./curl_multi_socket_action.html">curl_multi_socket_action</a> specifying which socket and action there are.
<p class="level0">The CURLMOPT_TIMERFUNCTION callback is called to set a timeout. When that timeout expires, your application should call the <a Class="emphasis" href="./curl_multi_socket_action.html">curl_multi_socket_action</a> function saying it was due to a timeout.
-<p class="level0">This API is typically used with an event-driven underlying functionality (like libevent, libev, kqueue, epoll or similar) which which the application "subscribes" on socket changes. This allows applications and libcurl to much better scale upward and beyond thousands of simultaneous transfers without losing performance.
+<p class="level0">This API is typically used with an event-driven underlying functionality (like libevent, libev, kqueue, epoll or similar) with which the application "subscribes" on socket changes. This allows applications and libcurl to much better scale upward and beyond thousands of simultaneous transfers without losing performance.
<p class="level0">When you've added your initial set of handles, you call <a Class="emphasis" href="./curl_multi_socket_action.html">curl_multi_socket_action</a> with CURL_SOCKET_TIMEOUT set in the sockfd argument, and you'll get callbacks call that sets you up and you then continue to call <a Class="emphasis" href="./curl_multi_socket_action.html">curl_multi_socket_action</a> accordingly when you get activity on the sockets you've been asked to wait on, or if the timeout timer expires.
<p class="level0">You can poll <a Class="emphasis" href="./curl_multi_info_read.html">curl_multi_info_read</a> to see if any transfer has completed, as it then has a message saying so. <a name="BLOCKING"></a><h2 class="nroffsh">BLOCKING</h2>
<p class="level0">A few areas in the code are still using blocking code, even when used from the multi interface. While we certainly want and intend for these to get fixed in the future, you should be aware of the following current restrictions:
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