a procmail rule with a dynamic timeout

[Francesco Potorti` <po...@potorti.it>]

Works on Sun.  Timeout is lower with greater load average.

TIMEOUT=250                     ## don't wait too long for children
SHELL=/usr/local/bin/bash       ## it was set to the user's shell

EX_TEMPFAIL=75                  # temporary failure: requeue
SPAMC=/usr/local/bin/spamc
SOCKETPATH=/var/spool/spamassassin/spamd-3.0.socket
SPAMCOPTS="-x -U $SOCKETPATH"
n="
"                               # newline, for LOG messages

  ## Compute a dynamic timeout depending on the one-minute load average
  timeout=60
  #timeout=`uptime|awk '{ x=$(NF-2); print x 15+int(200/(substr(x,1,length(x)-1)+0.1)) }'`
  timeout=`set - $(uptime) && shift $(($#-3)) && x=10#${1//[.,]/} && echo $((15+20000/(x+10))) || echo 50`

  maxsize=150000        # do not filter messages above this size

  :0 fW
  | $SPAMC $SPAMCOPTS -t $timeout -s $maxsize -u $LOGNAME

    :0 e        # failing because of timeout or system error
    * !> $maxsize
    {
      ## After an error or timeout we can either tell sendmail to requeue the
      ## message, by failing with EX_TEMPFAIL, or else give up and deliver an
      ## unfiltered message.
      #
      #timeout_behaviour=riaccoda       # requeue the message
      timeout_behaviour=consegna        # deliver the unfiltered message

      :0
      * timeout_behaviour ?? riaccoda
      # We want to requeue the message to sendmail for later processing
      {
        LOG="----> errore o timeout ($timeout s) per $LOGNAME: rinuncio e riaccodo$n"
        EXITCODE=$EX_TEMPFAIL   # Means: retry later; requeue
        :0
        #$INSPECTION.timeout    # inspection copy
        /dev/null               # discard
      }
        :0 E
        {
          # We want to get rid of the message immediately, so we deliver it unfiltered
        LOG="----> errore o timeout ($timeout s) per $LOGNAME: rinuncio e non filtro$n"
        }
    }