Lingering close for connections with pipelined requests. This is expected to help with clients using pipelining with some constant depth, such as apt[1][2]. When downloading many resources, apt uses pipelining with some constant depth, a number of requests in flight. This essentially means that after receiving a response it sends an additional request to the server, and this can result in requests arriving to the server at any time. Further, additional requests are sent one-by-one, and can be easily seen as such (neither as pipelined, nor followed by pipelined requests). The only safe approach to close such connections (for example, when keepalive_requests is reached) is with lingering. To do so, now nginx monitors if pipelining was used on the connection, and if it was, closes the connection with lingering. [1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=973861#10 [2] https://mailman.nginx.org/pipermail/nginx-devel/2023-January/ZA2SP5SJU55LHEBCJMFDB2AZVELRLTHI.html

# Copyright (C) Igor Sysoev
# Copyright (C) Nginx, Inc.


echo $ngx_n "checking for uintptr_t ...$ngx_c"

cat << END >> $NGX_AUTOCONF_ERR

----------------------------------------
checking for uintptr_t

END

found=no

cat << END > $NGX_AUTOTEST.c

#include <sys/types.h>
$NGX_INCLUDE_INTTYPES_H

int main(void) {
    uintptr_t i = 0;
    return (int) i;
}

END

ngx_test="$CC $CC_TEST_FLAGS $CC_AUX_FLAGS \
          -o $NGX_AUTOTEST $NGX_AUTOTEST.c $NGX_LD_OPT"

eval "$ngx_test >> $NGX_AUTOCONF_ERR 2>&1"

if [ -x $NGX_AUTOTEST ]; then
    echo " uintptr_t found"
    found=yes
else
    echo $ngx_n " uintptr_t not found" $ngx_c
fi

rm -rf $NGX_AUTOTEST*


if [ $found = no ]; then
    found="uint`expr 8 \* $ngx_ptr_size`_t"
    echo ", $found used"

    echo "typedef $found  uintptr_t;"                   >> $NGX_AUTO_CONFIG_H
    echo "typedef $found  intptr_t;" | sed -e 's/u//g'  >> $NGX_AUTO_CONFIG_H
fi