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Implement refcounting for flocks

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This was already implemented in PVE::LXC::lock_aquire() and
lock_release(). Enabling refcounting in the general
PVE::Tools::lock_file() and lock_file_full() methods allows
us to use one code base for flocking.

Furthermore, we could get rid of various xx_no_lock methods
that were required because the old non-refcounting version
did not support nested flocks (the inner most flock would
close the file handle and thus release the flock).
This commit is contained in:
Fabian Grünbichler 2016-02-10 08:25:23 +01:00 committed by Dietmar Maurer
parent 881eb75531
commit f127adaba5
1 changed files with 12 additions and 7 deletions
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19
src/PVE/Tools.pm
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@ -126,15 +126,16 @@ sub lock_file_full {
my $lock_func = sub {
if (!$lock_handles->{$$}->{$filename}) {
$lock_handles->{$$}->{$filename} = new IO::File (">>$filename") ||
die "can't open file - $!\n";
my $fh = new IO::File(">>$filename") ||
die "can't open file - $!\n";
$lock_handles->{$$}->{$filename} = { fh => $fh, refcount => 0};
}
if (!flock ($lock_handles->{$$}->{$filename}, $mode|LOCK_NB)) {
if (!flock($lock_handles->{$$}->{$filename}->{fh}, $mode|LOCK_NB)) {
print STDERR "trying to acquire lock...";
my $success;
while(1) {
$success = flock($lock_handles->{$$}->{$filename}, $mode);
$success = flock($lock_handles->{$$}->{$filename}->{fh}, $mode);
# try again on EINTR (see bug #273)
if ($success || ($! != EINTR)) {
last;
@ -146,6 +147,7 @@ sub lock_file_full {
}
print STDERR " OK\n";
}
$lock_handles->{$$}->{$filename}->{refcount}++;
};
my $res;
@ -159,9 +161,12 @@ sub lock_file_full {
$err = $@;
}
if (my $fh = $lock_handles->{$$}->{$filename}) {
$lock_handles->{$$}->{$filename} = undef;
close ($fh);
if (my $fh = $lock_handles->{$$}->{$filename}->{fh}) {
my $refcount = --$lock_handles->{$$}->{$filename}->{refcount};
if ($refcount <= 0) {
$lock_handles->{$$}->{$filename} = undef;
close ($fh);
}
}
if ($err) {