#!/usr/bin/perl -w
use strict;            # Amen
use threads;
use threads::shared;


#--------------------------------------------------
# Application includes
#--------------------------------------------------
use person;


#--------------------------------------------------
# Forward declarations
#--------------------------------------------------
sub doTemp1;
sub doTemp2;
sub doQuit;


#--------------------------------------------------
# Local variables
#--------------------------------------------------
our $intDelay : shared;            # One-wire delay
our $blnRunning : shared;        # Signal boolean
our $intThreadCount : shared;    # Holds the number of threads active
our %hshSensors : shared;        # Sensor hash
our $OWFS : shared;                # Main application
our $OWFS_MOUNT : shared;        # Mounting point

$SIG{HUP} = \&doQuit;
$SIG{INT} = \&doQuit;
$SIG{TERM} = \&doQuit;
$SIG{CHLD} = 'IGNORE';        # Ignore child processes to prevent zomb
+ies

$OWFS = "/opt/owfs/bin/owfs";
$OWFS_MOUNT = "/var/1-wire";


#--------------------------------------------------
# Start application
#--------------------------------------------------
$intDelay = 5;
$intThreadCount = 0;
$blnRunning = 1;

# Start polling
`echo 1 > $OWFS_MOUNT/simultaneous/voltage`;
`echo 1 > $OWFS_MOUNT/simultaneous/temperature`;


# Start thread for monitoring
threads->new(\&doTemp, "Temperature 1", "10.D76B5A010800", 30, 0.2, ""
+);
threads->new(\&doTemp, "Temperature 2", "10.FB865A010800", 25, 0.2, ""
+);

# Just something to keep the script rolling in the background
while (1) {
    sleep 3600;
};


#--------------------------------------------------


# Thread sub
sub doTemp {
    my ($strTitle, $strDevice, $dblNominal, $dblHysteris, $strStatus) 
+= @_;
    my ($dblCurrent, $dblHigh, $dblLow);

    # Increment thread count
    $intThreadCount++;

    # Initialize values
    $dblCurrent = 0;
    $dblHigh = ($dblNominal + $dblHysteris);
    $dblLow = ($dblNominal - $dblHysteris);

    # Start main loop
    while ($blnRunning) {
        # Poll sensor
        $dblCurrent = `cat /var/1-wire/uncached/$strDevice/temperature
+`;
        $dblCurrent =~ s/^\s+//;
        $dblCurrent =~ s/\s+$//;
        if ($dblCurrent) {
            if ($dblCurrent >= $dblHigh) {
                $strStatus = "TOO HOT ($dblCurrent / $dblHigh)";
            } elsif ($dblCurrent <= $dblLow) {
                $strStatus = "TOO COLD ($dblCurrent / $dblLow)";
            } else {
                $strStatus = "WITHIN RANGE ($dblCurrent)";
            }

            # Dump data
            print "-> ($intThreadCount) $strTitle: $strStatus\n";
        }
        sleep $intDelay;
    }

    # Decrement thread count
    $intThreadCount--;

    # Bail thread
    print "-> Polling of $strTitle stopped.\n";
}

# Closes current server and bails out
sub doQuit() {
    $blnRunning = 0;

    # Close threads which are running
    print "-> Waiting for destruction\n";
    while ($intThreadCount > 0) {
        sleep 1;
    }

    print "-> Server destroyed\n";
    exit;
}
[download]

I would question the need to use threads for this project. As far as I can see, the threads merely read what appears to be a 1-line file, and print, for each loop. There does not seem to be any "event" the thread waits on, other than a pre-specified timer.

If this is an exercise (which is a laudable goal), I would approach using the threads differently.

Avoid shared variables unless absolutely necessary. The only thing the threads need to be told is when to quit. You can pass that information using a Thread::Queue. Any data collected by the thread can be returned by the same mechanism. Working thread code using Queues, is available here.

Each thread would read the queue in NON-BLOCKING mode, and quit if a message is received.

The main thread would queue in THREADCOUNT messages, when it was time to quit.

You also had additional requirements (in a separate post). If thresholds are breached, you can use the same thread to communicate the breach back to the main thread. That would then perform the appropriate action. This way, the thread code can be clean, and minimal.

I would also suggest you let perl read the files, instead of doing "CAT".

     "How many times do I have to tell you again and again .. not to be repetitive?"

You might want to check out POE. This is the sort of task it is really great at.

Of course POE isn't usually the first thing one throws at a Perl newbie. But you seem to be handling threads OK...


TGI says moo