#!/usr/bin/perl
use strict;
use warnings;
use IPC::Open2;
use IO::Select; # for select

#my $cmd = "sqlplus -S apps/******"; # This is the query I really want
                                     # to run
my $cmd = "ssh oraprod\@remote_server './x 100'"; # "x" executes 
                                                  # sleep $1 to 
                                                  # simulate a process
                                                  # hunging on the 
                                                  # remote server
                    
my $timeout=1;
my $infh;
my $outfh;

my @output;

my $pid;

eval{
  $pid = open2($outfh, $infh, $cmd);
};
die "open2: $@\n" if $@;
print "PID was $pid\n"; #-------------------------- DEBUG ------------
#print "Timeout was $timeout\n";

my $sel = new IO::Select; # create a select object to notify
                          # us on write ready.
$sel->add($infh);         # add the std input file handle
if ($sel->can_write($timeout)){

# I will base my "DB alive" test off of this query's output
#print $infh "set feedback off pages 0\nselect sysdate from dual;\n";

} else {
   die "Timed out while waiting for the \"Write OK\" to send the query\n";
}
print "PID was $pid\n"; #-------------------------- DEBUG ------------

$sel->add($outfh);        # add the std output file handle

while ($sel->can_read($timeout)) { # Returns the std output file 
                                   # handle even while the sleep is 
                                   # being x. 
                                   # Would it do the same if "x" were
                                   # a truly hung process?
                                   # My hope is it won't so the 
                                   # while's condition would be false
                                   # after timeout causing the script
                                   # to skip the while.

   chomp(my $line=<$outfh>); # There is nothing on "x" std output to 
                             # be read so $line does not get defined.
   push(@output,$line);
}
close $infh;
print "PID was $pid\n"; #-------------------------- DEBUG ------------
waitpid $pid,0;
$sel->remove($infh,$outfh); # remove std output f handle from the list

unless (@output) {
   die "Timed out while waiting for query output\n";
}

print "$_\n" for @output;