Once again. Multiple threads, a root thread, and multiple processing threads (looking at emails). I am trying to define a shared Cache::MemoryCache object that holds Message-Ids for all the threads.

Running the supplied prototype code, shows that when it compiles and runs; each thread has a thread-local copy of the cache. I see each thread testing if '2' exists and then setting it's own value.

I have tried 'use vars', 'our', sharing a reference to the object; generally resulting in syntax errors, blessing errors, or local objects.

I have read 'man threads::shared", but won't claim to understand
"Due to problems with Perl’s prototyping, if you want to share a newly created reference, you need to use the "&share([])" and "&share({})" syntax." 

#!/usr/bin/perl

use threads;
use threads::shared;
use Cache::MemoryCache;

# the history cache
my $lockCache:shared;   #marks critical section

## Shotgun grammar follows ... hoping something works.

#use vars qw($cacheRef);    #

use vars qw($cache);    
  $cache = new Cache::MemoryCache( );

#our $cache = new Cache::MemoryCache( );
#my $cacheRef =\$cache;
#my $cacheRefShar = share($cacheRef);

# to tell when all threads are complete
#  keep from blocking in a join,  so we can accept signals
my $threadTerm :shared =0;

sub checkCache ($);
sub setCache ($$);

$thr1 = threads->new(\&t,1);
$thr2 = threads->new(\&t,10);
$thr3 = threads->new(\&t,20);

#t (1);

sub t
{
    my $id=shift;
    sleep (int rand(3));
    foreach $i (1...10) {
        print "T$id-$i\n"; 
        my $key = $i + int (rand 3);
        my $val = checkCache($key);
        #print "check  returned ($val)\n";
        if (! defined $val ) {
            $val = $id+rand(10);
            #print "T%id-$i  $key=$val\n";
            setCache ($key, $val);
        }
        sleep (int rand (3)); 
    }
    $threadTerm++;
}

# to allow future signals to be recognized
while ($threadTerm <3) { sleep 2; }


$thr1->join;
$thr2->join;
$thr3->join;

### fini ####

sub checkCache ($)
{
    my $key = shift;
    my $val;
    { lock $lockCache;
      #$val= $$cacheRefShar->get( $key );
      #Thread 1 terminated abnormally: Can't call method "get" on an u
+ndefined value at testCache.pl line 65.

      $val= $cacheRefShar->get( $key );
      #Thread 1 terminated abnormally: Can't call method "get" on unbl
+essed reference at testCache.pl line 65.

      $val= $cache->get( $key );

      print "checking $key  = ($val)\n";
    }
    return $val;
}

sub setCache ($$)
{
    my($key, $newval) = @_;
    {
        printf "setting $key=$newval\n";
        lock $lockCache;
        $$cacheRefShar->set( $key, $newval, "3 minutes" );
    }
}


sub testAndSet ($$)
{
    #not yet
}

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In reply to Threads sharing a Cache::MemoryCache object?? by Wiggins

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