Implement refcounting for flocks

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).

diff --git a/src/PVE/Tools.pm b/src/PVE/Tools.pm
index 9f08aa6fbf0c08da62e2f17078684cc2136d5b14..60ba8aa5f62d01892ed2fd9189c77141d34ca74e 100644 (file)
--- a/src/PVE/Tools.pm
+++ b/src/PVE/Tools.pm
@@ -126,15 +126,16 @@ sub lock_file_full {
 
     my $lock_func = sub {
         if (!$lock_handles->{$$}->{$filename}) {
 
     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) {
             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;
                # try again on EINTR (see bug #273)
                if ($success || ($! != EINTR)) {
                    last;


@@ -146,6 +147,7 @@ sub lock_file_full {
             }
             print STDERR " OK\n";
         }
             }
             print STDERR " OK\n";
         }

+       $lock_handles->{$$}->{$filename}->{refcount}++;

     };
 
     my $res;
     };
 
     my $res;


@@ -159,9 +161,12 @@ sub lock_file_full {
        $err = $@;
     }
 
        $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) {
     }
 
     if ($err) {