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Vinícius Ferrão
40409e854f
When a process releases a lock that another process waits for, the waiting process must take the lock. A third process must not take it while the waiting process holds it.
46 lines
1.4 KiB
Perl
46 lines
1.4 KiB
Perl
#!/usr/bin/env perl
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use strict;
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use warnings;
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use FindBin;
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use lib "$FindBin::Bin/../lib";
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use lib "$FindBin::Bin/../../perl-xCAT";
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use File::Temp qw(tempdir);
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use IO::Handle;
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use POSIX ();
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use Test::More;
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require xCAT::Utils;
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# The lock files live in /var/lock/xcat, so the test keeps them in a directory of its own.
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my $lock_dir = tempdir(CLEANUP => 1);
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{
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no warnings 'redefine';
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*xCAT::Utils::lock_dir = sub { return $lock_dir };
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}
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# A process holds a lock, a second one waits for it, and a third tries it after the release.
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my $holder = xCAT::Utils->acquire_lock('kit', 1);
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ok($holder, 'the first process takes the lock');
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pipe(my $from_waiter, my $to_parent) or die "cannot make a pipe: $!";
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my $pid = fork() // die "cannot fork: $!";
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if (!$pid) {
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close($from_waiter);
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my $lock = xCAT::Utils->acquire_lock('kit', 0);
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print {$to_parent} ($lock ? "held\n" : "failed\n");
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$to_parent->flush;
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sleep 60;
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POSIX::_exit(0);
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}
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close($to_parent);
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# The second process waits in flock on the file of the first one.
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sleep 2;
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xCAT::Utils->release_lock($holder, 1);
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my $waiter = <$from_waiter>;
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is($waiter, "held\n", 'the waiting process takes the lock after its release');
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my $third = xCAT::Utils->acquire_lock('kit', 1);
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ok(!$third, 'a third process cannot take the lock while the waiting process holds it');
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kill('KILL', $pid);
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waitpid($pid, 0);
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done_testing();
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