curl_multi_add_handle - Man Page

add an easy handle to a multi session

Synopsis

#include <curl/curl.h>

CURLMcode curl_multi_add_handle(CURLM *multi_handle, CURL *easy_handle);

Description

Adds the easy handle to the multi_handle.

While an easy handle is added to a multi stack, you cannot and you must not use curl_easy_perform(3) on that handle. After having removed the easy handle from the multi stack again, it is perfectly fine to use it with the easy interface again.

If the easy handle is not set to use a shared (CURLOPT_SHARE(3)) cache, it is made to use a DNS cache that is shared between all easy handles within the multi handle when curl_multi_add_handle(3) is called.

When an easy interface is added to a multi handle, it is set to use a shared connection cache owned by the multi handle. Removing and adding new easy handles does not affect the pool of connections or the ability to do connection reuse.

If you have CURLMOPT_TIMERFUNCTION(3) set in the multi handle (as you should if you are working event-based with curl_multi_socket_action(3) and friends), that callback is called from within this function to ask for an updated timer so that your main event loop gets the activity on this handle to get started.

The easy handle remains added to the multi handle until you remove it again with curl_multi_remove_handle(3) - even when a transfer with that specific easy handle is completed.

You should remove the easy handle from the multi stack before you terminate first the easy handle and then the multi handle:

1 - curl_multi_remove_handle(3)

2 - curl_easy_cleanup(3)

3 - curl_multi_cleanup(3)

Example

int main(void)
{
  /* init a multi stack */
  CURLM *multi = curl_multi_init();

  /* create two easy handles */
  CURL *http_handle = curl_easy_init();
  CURL *http_handle2 = curl_easy_init();

  /* add individual transfers */
  curl_multi_add_handle(multi, http_handle);
  curl_multi_add_handle(multi, http_handle2);
}

Availability

Added in 7.9.6

Return Value

CURLMcode type, general libcurl multi interface error code.

See Also

curl_multi_cleanup(3), curl_multi_get_handles(3), curl_multi_init(3), curl_multi_setopt(3), curl_multi_socket_action(3)

Referenced By

curl_easy_perform(3), curl_multi_get_handles(3), curl_multi_init(3), curl_multi_perform(3), curl_multi_remove_handle(3), libcurl-multi(3), libcurl-tutorial(3).

February 19 2024 libcurl