New httpd_monitor

[Jim Jagielski <ji...@jaguNET.com>]

I'd like to submit a patched version of httpd_monitor for inclusion
in the ./support area.

This version is a bit more generic, as well as slightly more streamlined.
It also supports the patch for scoreboard (i.e. the "Starting" status)
as well as fixing some, at least what looked to me like, bugs.

This is the full source, since it's small enough that a patch isn't
needed:

------------------>8 cut here START OF FILE---------------------
#!/usr/local/bin/perl

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# simple script to monitor the child Apache processes
#   Usage:
#      httpd_monitor N     
#                Will give you an update ever N seconds
#                If you choose 0, it might chew up lots of CPU time.
#
# Output explanation..
#
#  s = sleeping but "ready to go" child
#  R = active child
#  _ = dead child (no longer needed)
#  t = just starting
#
# Version History:
#  v1.0
#    Original release
#
#  v1.1
#    Modifications and "fixes":
#     o According to scoreboard.h, struct for short_score is:
#        { pid_t; char; }.
#       Now generally, pid_t is an int but some systems may have it
#       as a short. Also, we don't know whether we need to worry about
#       alignment before and after the read of the char. I'm sure we can
#       get Perl to figure this all out for us, but we'll take the lazy
#       approach and just make changable options. By default, we assume
#       we read 4 bytes (for the PID), skip 0 bytes, read 1 byte (for the
#       status) and then skip 1 byte for alignment.
#
#     o Added Status=3 condition (scoreboard patch) and folded it into
#       an easy-to-use list.
#
#     o Changed seek() from EOF (2) to SOF (0).
#

$PID_FILE = "/usr/local/httpd/logs/httpd.pid";
$SCOREB =   "/tmp/htstatus";
$MAX_PROC = 40;    # we never have (or are interested in) more than 40 children
@kidstat = ("_", "s", "R", "t");

#
# Here are those alignment parameters mentioned above:
$pid_size = 4;
$before_stat = 0;
$after_stat = 1;

#########################################################################
select STDOUT; $| = 1;

$delay = @ARGV[0];

if ($delay =~ /\-h/i) {
  print STDERR "usage:\n$0 [i]\n  i = interval in seconds (defaults to 1)\n";
  exit(0);
}

$delay = 1 unless $delay =~ /^[0-9]+$/;

open (P, "$PID_FILE") || die "Unable to open $PID_FILE";
$PID = <P>;
$ext = sprintf("a%05d", $PID);
close(P);
$SCOREB = "$SCOREB.$ext";

open (SB, $SCOREB) || die "Unable to open scoreboard file $SCOREB";

$last_len = 0;
while (1) {

  if ( ($last_mod = (stat("$SCOREB"))[9]) != $before) {
    open (SB, $SCOREB) || die "Unable to open scoreboard file $SCOREB";
    seek(SB, 0 , 0);
  
    $len = 0; $pad =""; $running = 0; $dead = 0;  $total=0;
    for ( $child=1; $child<=$MAX_PROC; $child++) {

       read(SB, $p, $pid_size);		# get to PID, which is 4 bytes (?)
       $p = unpack("I", $p);		# and get the int it refers to

       read(SB, $junk, $before_stat);	# alignment ??

       read(SB, $status, 1);		# next byte = status
       $status = unpack("C", $status);
     
       read(SB, $junk, $after_stat);	# skip to next entry
          
       $c = $kidstat[$status];
       
       if ($p != 0 && $p != $PID) {
         $total++;
         if ($c eq "R") {
            ++$running;
         }
         $printed .= "$pad$c";
         
         $pad = ""; 
         $dead = 0;
       } 
    }
    $printed .= " ($running/$total)";
    $len = length($printed);  
    
    if ($last_len > $len) {
       print "\010"x$last_len ;
       print " "x$last_len ;
       print "\010"x$last_len ;
    } else {
       print "\010"x$len ;
    }
    print $printed; $printed = "";

    $before = $last_mod;
    close(SB);
    $last_len = $len;
   }
   sleep($delay) if $delay >0;
}
------------------>8 cut here  END  OF FILE---------------------
-- 
Jim Jagielski  << jim@jaguNET.com >>   |           "Wind the frog!"
  **  jaguNET Access Services  **      |       - Woody (from Toy Story)
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