xref: /aosp_15_r20/external/curl/docs/libcurl/opts/CURLOPT_PIPEWAIT.md (revision 6236dae45794135f37c4eb022389c904c8b0090d)

---
c: Copyright (C) Daniel Stenberg, <[email protected]>, et al.
SPDX-License-Identifier: curl
Title: CURLOPT_PIPEWAIT
Section: 3
Source: libcurl
See-also:
  - CURLMOPT_MAX_HOST_CONNECTIONS (3)
  - CURLMOPT_PIPELINING (3)
  - CURLOPT_FORBID_REUSE (3)
  - CURLOPT_FRESH_CONNECT (3)
Protocol:
  - HTTP
Added-in: 7.43.0
---

# NAME

CURLOPT_PIPEWAIT - wait for multiplexing

# SYNOPSIS

~~~c
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PIPEWAIT, long wait);
~~~

# DESCRIPTION

Set *wait* to 1L to tell libcurl to prefer to wait for a connection to
confirm or deny that it can do multiplexing before continuing.

When about to perform a new transfer that allows multiplexing, libcurl checks
for existing connections to use. If no such connection exists it immediately
continues and creates a fresh new connection to use.

By setting this option to 1 - and having CURLMOPT_PIPELINING(3) enabled
for the multi handle this transfer is associated with - libcurl instead waits
for the connection to reveal if it is possible to multiplex on before it
continues. This enables libcurl to much better keep the number of connections
to a minimum when using multiplexing protocols.

With this option set, libcurl prefers to wait and reuse an existing connection
for multiplexing rather than the opposite: prefer to open a new connection
rather than waiting.

The waiting time is as long as it takes for the connection to get up and for
libcurl to get the necessary response back that informs it about its protocol
and support level.

# DEFAULT

0 (off)

# %PROTOCOLS%

# EXAMPLE

~~~c
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
    curl_easy_setopt(curl, CURLOPT_PIPEWAIT, 1L);

    /* now add this easy handle to the multi handle */
  }
}
~~~

# %AVAILABILITY%

# RETURN VALUE

Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.