anyway to avoid to loop monitor multi handle in libcurl? - c

Question

I've read some examples from the libcurl homepage. It always uses loop monitoring the multi handle when download through curl_multi_perform like below:
curl_multi_add_handle(multi_handle, easy_handle);
do {
curl_multi_wait(…);
curl_multi_perform(multi_handle, &still_running);
} while (still_running);
that make me block on the section of program
I want the libcurl will do callback after the anyone of easy_handle is download finished
for example:
Server can receive requests and parse the requests to multi_handle to
download asynchronously.
Server still can receive requests while multi_handle is downloading.
Those are independent(asynchronous in other words)

Answer 1

Typically curl_multi_perform is called in a loop to complete all the curl related task, like http transaction.
The way you have put the code, you would not achieve the asynchronous way of using libcurl. There are ways to achieve it.
In a typical implementation you will have your main loop, where you might be dealing with number of task. For example
do
{
execute task1
execute task2
.............
execute taskn
}
while(condition)
In that loop, you can call curl_multi_perform.
So main loop looks like
do
{
execute task1
execute task2
.............
execute taskn
curl_multi_perform(curlm, &count);
}
while(condition)
That way you will do all your task and curl_multi_perform is called time to time and you will achieve asynchronous way of using libcurl.
Please check documentation, depending on some return value you may avoid calling curl_multi_perform (I remember reading it previously).