upkeep: add a connection upkeep API: curl_easy_conn_upkeep()

Add functionality so that protocols can do custom keepalive on their
connections, when an external API function is called.

Add docs for the new options in 7.62.0

Closes #1641

1 files changed, 1 insertions, 0 deletions

diff --git a/lib/url.h b/lib/url.h
index 618309d38..089613abd 100644
--- a/lib/url.h
+++ b/lib/url.h
@@ -77,6 +77,7 @@ int Curl_removeHandleFromPipeline(struct Curl_easy *handle,
 void Curl_getoff_all_pipelines(struct Curl_easy *data,
                                struct connectdata *conn);
 
+CURLcode Curl_conn_upkeep(struct conncache *conn_cache, void *data);
 
 #define CURL_DEFAULT_PROXY_PORT 1080 /* default proxy port unless specified */
 #define CURL_DEFAULT_HTTPS_PROXY_PORT 443 /* default https proxy port unless