README: update dependency information for xargs for sfeed_update - sfeed - RSS and Atom parser
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       ---
 (DIR) commit 89dbf565de7b980d2b336c58633b7a27681adaf5
 (DIR) parent cdb8f7feb135adf6f18e389b4bbf47886089474a
 (HTM) Author: Hiltjo Posthuma <hiltjo@codemadness.org>
       Date:   Tue, 26 Dec 2023 16:37:21 +0100
       
       README: update dependency information for xargs for sfeed_update
       
       Remove the parallel xargs example because it is now the default.
       
       Diffstat:
         M README                              |      58 ++-----------------------------
       
       1 file changed, 2 insertions(+), 56 deletions(-)
       ---
 (DIR) diff --git a/README b/README
       @@ -117,6 +117,8 @@ Optional dependencies
          used by sfeed_update(1). If the text in your RSS/Atom feeds are already UTF-8
          encoded then you don't need this. For a minimal iconv implementation:
          https://git.etalabs.net/cgit/noxcuse/tree/src/iconv.c
       +- xargs with support for the -P and -0 option,
       +  used by sfeed_update(1).
        - mandoc for documentation: https://mdocml.bsd.lv/
        - curses (typically ncurses), otherwise see minicurses.h,
          used by sfeed_curses(1).
       @@ -706,62 +708,6 @@ sfeedrc file and change the curl options "-L --max-redirs 0".
        
        - - -
        
       -Shellscript to update feeds in parallel more efficiently using xargs -P.
       -
       -It creates a queue of the feeds with its settings, then uses xargs to process
       -them in parallel using the common, but non-POSIX -P option. This is more
       -efficient than the more portable solution in sfeed_update which can stall a
       -batch of $maxjobs in the queue if one item is slow.
       -
       -sfeed_update_xargs shellscript:
       -
       -        #!/bin/sh
       -        # update feeds, merge with old feeds using xargs in parallel mode (non-POSIX).
       -        
       -        # include script and reuse its functions, but do not start main().
       -        SFEED_UPDATE_INCLUDE="1" . sfeed_update
       -        # load config file, sets $config.
       -        loadconfig "$1"
       -        
       -        # process a single feed.
       -        # args are: config, tmpdir, name, feedurl, basesiteurl, encoding
       -        if [ "${SFEED_UPDATE_CHILD}" = "1" ]; then
       -                sfeedtmpdir="$2"
       -                _feed "$3" "$4" "$5" "$6"
       -                exit $?
       -        fi
       -        
       -        # ...else parent mode:
       -        
       -        # feed(name, feedurl, basesiteurl, encoding)
       -        feed() {
       -                # workaround: *BSD xargs doesn't handle empty fields in the middle.
       -                name="${1:-$$}"
       -                feedurl="${2:-http://}"
       -                basesiteurl="${3:-${feedurl}}"
       -                encoding="$4"
       -        
       -                printf '%s\0%s\0%s\0%s\0%s\0%s\0' "${config}" "${sfeedtmpdir}" \
       -                        "${name}" "${feedurl}" "${basesiteurl}" "${encoding}"
       -        }
       -        
       -        # fetch feeds and store in temporary directory.
       -        sfeedtmpdir="$(mktemp -d '/tmp/sfeed_XXXXXX')" || exit 1
       -        mkdir -p "${sfeedtmpdir}/feeds"
       -        touch "${sfeedtmpdir}/ok" || exit 1
       -        # make sure path exists.
       -        mkdir -p "${sfeedpath}"
       -        # print feeds for parallel processing with xargs.
       -        feeds | SFEED_UPDATE_CHILD="1" xargs -r -0 -P "${maxjobs}" -L 6 "$(readlink -f "$0")"
       -        statuscode=$?
       -        # check error exit status indicator for parallel jobs.
       -        test -f "${sfeedtmpdir}/ok" || statuscode=1
       -        # cleanup temporary files etc.
       -        cleanup
       -        exit ${statuscode}
       -
       -- - -
       -
        Shellscript to handle URLs and enclosures in parallel using xargs -P.
        
        This can be used to download and process URLs for downloading podcasts,