mirror of https://github.com/curl/curl.git synced 2025-01-06 13:44:52 +08:00

Jay Satiro 573aaec3be easy: fix curl_easy_upkeep for shared connection caches

- Determine which connection cache is or will be used by the easy handle
  and perform connection upkeep on that cache.

This change allows curl_easy_upkeep to be effective on easy handles that
are using a shared connection cache, either from a user created shared
connection cache or a user created multi which has its own shared
connection cache.

Prior to this change curl_easy_upkeep would upkeep the connection cache
for the easy handle only if that cache was from the multi owned by the
easy handle (ie curl_easy_perform was previously called and there's a
connection cache exclusive to the easy handle in
data->multi_easy->conn_cache).

Ref: https://curl.se/mail/lib-2024-01/0016.html

Closes https://github.com/curl/curl/pull/12677

2024-08-04 18:41:18 -04:00

2.0 KiB

Raw Blame History

SPDX-License-Identifier

Title

Section

Source

See-also

Protocol

Added-in

curl

curl_easy_upkeep

libcurl

CURLOPT_TCP_KEEPALIVE (3)

CURLOPT_TCP_KEEPIDLE (3)

All

7.62.0

NAME

curl_easy_upkeep - keep existing connections alive

SYNOPSIS

#include <curl/curl.h>

CURLcode curl_easy_upkeep(CURL *handle);

DESCRIPTION

Some protocols have "connection upkeep" mechanisms. These mechanisms usually send some traffic on existing connections in order to keep them alive; this can prevent connections from being closed due to overzealous firewalls, for example.

Currently the only protocol with a connection upkeep mechanism is HTTP/2: when the connection upkeep interval is exceeded and curl_easy_upkeep(3) is called, an HTTP/2 PING frame is sent on the connection.

This function must be explicitly called in order to perform the upkeep work. The connection upkeep interval is set with CURLOPT_UPKEEP_INTERVAL_MS(3).

If you call this function on an easy handle that uses a shared connection cache then upkeep is performed on the connections in that cache, even if those connections were never used by the easy handle. (Added in 8.10.0)

%PROTOCOLS%

EXAMPLE

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    /* Make a connection to an HTTP/2 server. */
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");

    /* Set the interval to 30000ms / 30s */
    curl_easy_setopt(curl, CURLOPT_UPKEEP_INTERVAL_MS, 30000L);

    curl_easy_perform(curl);

    /* Perform more work here. */

    /* While the connection is being held open, curl_easy_upkeep() can be
       called. If curl_easy_upkeep() is called and the time since the last
       upkeep exceeds the interval, then an HTTP/2 PING is sent. */
    curl_easy_upkeep(curl);

    /* Perform more work here. */

    /* always cleanup */
    curl_easy_cleanup(curl);
  }
}

%AVAILABILITY%

RETURN VALUE

On success, returns CURLE_OK.

On failure, returns the appropriate error code.

2.0 KiB Raw Blame History