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curl_multi_wakeup - wakes up a sleeping curl_multi_poll call

Name

curl_multi_wakeup - wake up a sleeping curl_multi_poll call

Synopsis

#include <curl/curl.h>
 
CURLMcode curl_multi_wakeup(CURLM *multi_handle);

Description

This function can be called from any thread and it wakes up a sleeping curl_multi_poll call that is currently (or is about to be) waiting for activity or a timeout.

If the function is called when there is no curl_multi_poll call, it causes the next call to return immediately.

Calling this function only guarantees to wake up the current (or the next if there is no current) curl_multi_poll call, which means it is possible that multiple calls to this function wake up the same waiting operation.

This function has no effect on curl_multi_wait calls.

Protocols

This functionality affects all supported protocols

Example

extern int time_to_die(void);
extern int set_something_to_signal_thread_1_to_exit(void);
extern int decide_to_stop_thread1();
 
int main(void)
{
  CURL *easy;
  CURLM *multi = curl_multi_init();
  int still_running;
 
  easy = curl_easy_init();
 
  /* add the individual easy handle */
  curl_multi_add_handle(multi, easy);
 
  /* this is thread 1 */
  do {
    CURLMcode mc;
    int numfds;
 
    mc = curl_multi_perform(multi, &still_running);
 
    if(mc == CURLM_OK) {
      /* wait for activity, timeout or wakeup */
      mc = curl_multi_poll(multi, NULL, 0, 10000, &numfds);
    }
 
    if(time_to_die())
      return 1;
 
  } while(still_running);
 
  curl_multi_remove_handle(multi, easy);
 
  /* this is thread 2 */
 
  if(decide_to_stop_thread1()) {
 
    set_something_to_signal_thread_1_to_exit();
 
    curl_multi_wakeup(multi);
  }
}

Availability

Added in curl 7.68.0

Return value

This function returns a CURLMcode indicating success or error.

CURLM_OK (0) means everything was OK, non-zero means an error occurred, see libcurl-errors.