Simplified lr_perform()'s loop to prevent busy wait #144
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Calling curl_multi_perform() in a loop is actually busy waiting for data being available on the socket. The whole logic in lr_perform() can be simplified allowing more efficient processing. The function has to repeatedly do: 1) call curl_multi_perform() for curl to fetch data if needed/available 2) call check_transfer_statuses() to check download status 3) if curl needs more data, wait for the socket to have some Once there's no need for more data, and there's no other transfer pending, lr_perform() can return TRUE. The function can be further simplified by - assuming curl_multi_perform() is not returning CURLM_CALL_MULTI_PERFORM require cURL 7.20, https://curl.haxx.se/libcurl/c/curl_multi_perform.html - using curl_multi_wait() instead of select() require cURL 7.28, https://curl.haxx.se/libcurl/c/curl_multi_wait.html This fixes https://bugzilla.redhat.com/show_bug.cgi?id=1691856 Fixes: 208edbe ('Reduce download delays by using still_running correctly.')
ydroneaud
referenced
this pull request
Mar 22, 2019
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Thank you. Fix with nice simplification. |
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Calling curl_multi_perform() in a loop is actually
busy waiting for data being available on the socket.
The whole logic in lr_perform() can be simplified
allowing more efficient processing. The function has
to repeatedly do:
Once there's no need for more data, and there's no other
transfer pending, lr_perform() can return TRUE.
The function can be further simplified by
require cURL 7.20, https://curl.haxx.se/libcurl/c/curl_multi_perform.html
require cURL 7.28, https://curl.haxx.se/libcurl/c/curl_multi_wait.html
This fixes https://bugzilla.redhat.com/show_bug.cgi?id=1691856
Fixes: 208edbe ('Reduce download delays by using still_running correctly.')