libcurl-share - how to use the share interface
This is an overview on how to use the libcurl share interface in your C
programs. There are specific man pages for each function mentioned in
All functions in the share interface are prefixed with curl_share.
The share interface was added to enable sharing of data between curl
ONE SET OF DATA - MANY TRANSFERS
You can have multiple easy handles share data between them. Have them
update and use the same cookie database or DNS cache! This way, each
single transfer will take advantage from data updates made by the other
You create a shared object with curl_share_init(3). It returns a handle
for a newly created one.
You tell the shared object what data you want it to share by using
curl_share_setopt(3). Currently you can only share DNS and/or COOKIE
Since you can use this share from multiple threads, and libcurl has no
internal thread synchronization, you must provide mutex callbacks if
you’re using this multi-threaded. You set lock and unlock functions
with curl_share_setopt(3) too.
Then, you make an easy handle to use this share, you set the
CURLOPT_SHARE option with curl_easy_setopt(3), and pass in share
handle. You can make any number of easy handles share the same share
To make an easy handle stop using that particular share, you set
CURLOPT_SHARE to NULL for that easy handle. To make a handle stop
sharing a particular data, you can CURLSHOPT_UNSHARE it.
When you’re done using the share, make sure that no easy handle is
still using it, and call curl_share_cleanup(3) on the handle.
curl_share_init(3), curl_share_setopt(3), curl_share_cleanup(3)