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marsadm: allow overrides of "marsadm secondary" in disconnected clusters 

When the communication is down in partitioned clusters, the command
"marsadm seconodary" would normally use the current timestamp of
the command execution for the Lamport update protocol.

Make an exception for the case that a concurrent "marsadm primary"
was given somewhere else on a disconnected / partitioned node: let
the "primary" always win over a "secondary" command.
This commit is contained in:
Thomas Schoebel-Theuer 2013-12-25 19:18:22 +01:00
parent c861a0d202
commit 767bb03060
1 changed files with 10 additions and 12 deletions
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userspace/marsadm
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@ -92,22 +92,20 @@ sub set_link {
sub finish_links {
return unless @link_list;
my $timestamp = time();
undef $/;
my $lamport = "";
if (open(my $fh, "<", "/proc/sys/mars/lamport_clock")) {
$lamport = <$fh>;
}
if ($lamport =~ m/lamport_now=([0-9.]+)/) {
$timestamp = $1;
lprint "using lamport timestamp $timestamp\n" if $verbose;
}
my $timestamp = mars_time();
lprint "using lamport timestamp $timestamp\n" if $verbose;
while (my $link = shift @link_list) {
my $link_tmp = to_tmp($link);
system("touch -h -d \"\@$timestamp\" $link_tmp") == 0 or ldie "cannot set mtime on symlink '$link_tmp'\n";
my $target = readlink($link_tmp);
my $this_timestamp = $timestamp;
# allow overriding of secondaries in partitioned clusters by use of small timestamps
if ($target eq "(none)") {
my @stat = lstat($link);
$this_timestamp = $stat[9] + 1 if @stat;
}
system("touch -h -d \"\@$this_timestamp\" $link_tmp") == 0 or ldie "cannot set mtime on symlink '$link_tmp'\n";
rename($link_tmp, $link) or ldie "cannot finalize symlink '$link'\n";
if ($verbose) {
my $target = readlink($link);
lprint "created symlink '$link' -> '$target'\n";
}
}