HTTP/2: fixed "task already active" with sendfile in threads. With sendfile in threads, "task already active" alerts might appear in logs if a write event happens on the main HTTP/2 connection, triggering a sendfile in threads while another thread operation is already running. Observed with "aio threads; aio_write on; sendfile on;" and with thread event handlers modified to post a write event to the main HTTP/2 connection (though can happen without any modifications). Similarly, sendfile() with AIO preloading on FreeBSD can trigger duplicate aio operation, resulting in "second aio post" alerts. This is, however, harder to reproduce, especially on modern FreeBSD systems, since sendfile() usually does not return EBUSY. Fix is to avoid starting a sendfile operation if other thread operation is active by checking r->aio in the thread handler (and, similarly, in aio preload handler). The added check also makes duplicate calls protection redundant, so it is removed.

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


NGX_MAKEFILE=$NGX_OBJS/Makefile
NGX_MODULES_C=$NGX_OBJS/ngx_modules.c

NGX_AUTO_HEADERS_H=$NGX_OBJS/ngx_auto_headers.h
NGX_AUTO_CONFIG_H=$NGX_OBJS/ngx_auto_config.h

NGX_AUTOTEST=$NGX_OBJS/autotest
NGX_AUTOCONF_ERR=$NGX_OBJS/autoconf.err

# STUBs
NGX_ERR=$NGX_OBJS/autoconf.err
MAKEFILE=$NGX_OBJS/Makefile


NGX_PCH=
NGX_USE_PCH=


# check the echo's "-n" option and "\c" capability

if echo "test\c" | grep c >/dev/null; then

    if echo -n test | grep n >/dev/null; then
        ngx_n=
        ngx_c=

    else
        ngx_n=-n
        ngx_c=
    fi

else
    ngx_n=
    ngx_c='\c'
fi


# create Makefile

cat << END > Makefile

default:	build

clean:
	rm -rf Makefile $NGX_OBJS

.PHONY:	default clean
END