Changeset 521

Timestamp:

06/12/13 16:58:14 (11 years ago)

Author:

Kris Deugau

Message:

/trunk

Finally commit a fix for the caching system so that it really
exports things properly. See #38.

File:

• trunk/DNSDB.pm (modified) (5 diffs)

trunk/DNSDB.pm

@@ -4895 +4895 @@
 #              still be followed.
 # but that doesn't help other platforms.  :/
-    sysopen(ZONECACHE, "$self->{exportcache}/$dom", O_RDWR|O_CREAT);
-    flock(ZONECACHE, LOCK_EX);
-    if ($changed || -s "$self->{exportcache}/$dom" == 0) {
-      $recsth->execute($domid);
-      while (my ($host,$type,$val,$dist,$weight,$port,$ttl,$recid,$loc) = $recsth->fetchrow_array) {
-        next if $recflags{$recid};
-
-        $loc = '' if !$loc;     # de-nullify - just in case
+    my $cachefile = "$self->{exportcache}/$dom";
+    my $tmpcache = "$self->{exportcache}/tmp.$dom.$$";
+    eval {
+
+      # only update the cache file if the zone has changed, or if the cache file has nothing in it.
+      if ($changed || !-e $cachefile || -z $cachefile) {
+        open ZONECACHE, ">$tmpcache" or die "Error creating temporary file $tmpcache: $!\n";
+
+        $recsth->execute($domid);
+        while (my ($host,$type,$val,$dist,$weight,$port,$ttl,$recid,$loc) = $recsth->fetchrow_array) {
+          next if $recflags{$recid};
+
+          $loc = '' if !$loc;   # de-nullify - just in case
 ##fixme:  handle case of record-with-location-that-doesn't-exist better.
 # note this currently fails safe (tested) - records with a location that
@@ -4912 +4917 @@
 # timestamps are TAI64
 # ~~ 2^62 + time()
-        my $stamp = '';
-
-        # support tinydns' auto-TTL
-        $ttl = '' if $ttl == -1;
-
-        # Spaces are evil.
-        $host =~ s/^\s+//;
-        $host =~ s/\s+$//;
-        if ($typemap{$type} ne 'TXT') {
-          # Leading or trailng spaces could be legit in TXT records.
-          $val =~ s/^\s+//;
-          $val =~ s/\s+$//;
-        }
-
-        _printrec_tiny(*ZONECACHE, 'n', \%recflags,
+          my $stamp = '';
+
+          # support tinydns' auto-TTL
+          $ttl = '' if $ttl == -1;
+
+          # Spaces are evil.
+          $host =~ s/^\s+//;
+          $host =~ s/\s+$//;
+          if ($typemap{$type} ne 'TXT') {
+            # Leading or trailng spaces could be legit in TXT records.
+            $val =~ s/^\s+//;
+            $val =~ s/\s+$//;
+          }
+
+          _printrec_tiny(*ZONECACHE, 'n', \%recflags,
                 $dom, $host, $type, $val, $dist, $weight, $port, $ttl, $loc, $stamp)
                 if *ZONECACHE;
 
-        # in case the zone shrunk, get rid of garbage at the end of the file.
-        truncate(ZONECACHE, tell(ZONECACHE));
-
-        $recflags{$recid} = 1;
-      } # while ($recsth)
-    }
-    # stream from cache, whether freshly created or existing
-    print $datafile $_ while <ZONECACHE>;
-    close ZONECACHE;
-    # mark domain as unmodified
-    $zonesth->execute($domid);
+          $recflags{$recid} = 1;
+
+        } # while ($recsth)
+
+        close ZONECACHE; # force the file to be written
+
+        # catch obvious write errors that leave an empty temp file
+        if (-s $tmpcache) {
+          rename $tmpcache, $cachefile
+            or die "Error overwriting cache file $cachefile with temporary file: $!\n";
+        }
+
+      } # if $changed or cache filesize is 0
+
+    };
+    if ($@) {
+      print "error writing new data for $dom: $@\n";
+      # error!  something borked, and we should be able to fall back on the old cache file
+      # report the error, somehow.
+    } else {
+      # mark domain as unmodified.  Only do this if no errors, that way
+      # export failures should recover a little more automatically.
+      $zonesth->execute($domid);
+    }
+    # Always stream the cache (even if stale or obsolete due to errors creating the new cache)
+    open CACHE, "<$cachefile";
+    print $datafile $_ while <CACHE>;
+    close CACHE;
+
   } # while ($domsth)
-
-  my $revsth = $dbh->prepare("SELECT rdns_id,revnet,status,changed FROM revzones WHERE status=1 ".
-        "ORDER BY masklen(revnet) DESC");
 
 # For reasons unknown, we can't sanely UNION these statements.  Feh.
@@ -4963 +4983 @@
         "FROM records WHERE rdns_id=? AND not type=6 ".
         "ORDER BY masklen(CAST(val AS inet)) DESC, CAST(val AS inet)");
+  my $revsth = $dbh->prepare("SELECT rdns_id,revnet,status,changed FROM revzones WHERE status=1 ".
+        "ORDER BY masklen(revnet) DESC");
   $zonesth = $dbh->prepare("UPDATE revzones SET changed='n' WHERE rdns_id=?");
   $revsth->execute();
@@ -4973 +4995 @@
 # but that doesn't help other platforms.  :/
     my $tmpzone = NetAddr::IP->new($revzone);
-    sysopen(ZONECACHE, "$self->{exportcache}/".$tmpzone->network->addr, O_RDWR|O_CREAT);
-    flock(ZONECACHE, LOCK_EX);
-    if ($changed || -s "$self->{exportcache}/".$tmpzone->network->addr == 0) {
-      # need to fetch this separately since the rest of the records all (should) have real IPs in val
-      $soasth->execute($revid);
-      my (@zsoa) = $soasth->fetchrow_array();
-      _printrec_tiny(*ZONECACHE,'y',\%recflags,$revzone,
-        $zsoa[0],$zsoa[1],$zsoa[2],$zsoa[3],$zsoa[4],$zsoa[5],$zsoa[6],$zsoa[8],'');
-
-      $recsth->execute($revid);
-      while (my ($host,$type,$val,$dist,$weight,$port,$ttl,$recid,$loc) = $recsth->fetchrow_array) {
-        next if $recflags{$recid};
-
-        $loc = '' if !$loc;     # de-nullify - just in case
+##fixme:  locations/views?  subnet mask?  need to avoid possible collisions with zone/superzone
+##        (eg /20 vs /24, starting on .0.0)
+    my $cz = $tmpzone->network->addr."-".$tmpzone->masklen;
+    my $cachefile = "$self->{exportcache}/$cz";
+    my $tmpcache = "$self->{exportcache}/tmp.$cz.$$";
+    eval {
+
+      # only update the cache file if the zone has changed, or if the cache file has nothing in it.
+      if ($changed || !-e $cachefile || -z $cachefile) {
+        open ZONECACHE, ">$tmpcache" or die "Error creating temporary file $tmpcache: $!\n";
+
+        # need to fetch this separately since the rest of the records all (should) have real IPs in val
+        $soasth->execute($revid);
+        my (@zsoa) = $soasth->fetchrow_array();
+        _printrec_tiny(*ZONECACHE,'y',\%recflags,$revzone,
+          $zsoa[0],$zsoa[1],$zsoa[2],$zsoa[3],$zsoa[4],$zsoa[5],$zsoa[6],$zsoa[8],'');
+
+        $recsth->execute($revid);
+        while (my ($host,$type,$val,$dist,$weight,$port,$ttl,$recid,$loc) = $recsth->fetchrow_array) {
+          next if $recflags{$recid};
+
+          $loc = '' if !$loc;   # de-nullify - just in case
 ##fixme:  handle case of record-with-location-that-doesn't-exist better.
 # note this currently fails safe (tested) - records with a location that
@@ -4996 +5026 @@
 # timestamps are TAI64
 # ~~ 2^62 + time()
-        my $stamp = '';
-
-        # support tinydns' auto-TTL
-        $ttl = '' if $ttl == -1;
-
-        _printrec_tiny(*ZONECACHE, 'y', \%recflags, $revzone,
-                $host, $type, $val, $dist, $weight, $port, $ttl, $loc, $stamp)
+          my $stamp = '';
+
+          # support tinydns' auto-TTL
+          $ttl = '' if $ttl == -1;
+
+          _printrec_tiny(*ZONECACHE, 'y', \%recflags, $revzone,
+            $host, $type, $val, $dist, $weight, $port, $ttl, $loc, $stamp)
                 if *ZONECACHE;
 
-        # in case the zone shrunk, get rid of garbage at the end of the file.
-        truncate(ZONECACHE, tell(ZONECACHE));
-
-        $recflags{$recid} = 1;
-      } # while ($recsth)
-    }
-    # stream from cache, whether freshly created or existing
-    print $datafile $_ while <ZONECACHE>;
-    close ZONECACHE;
-    # mark zone as unmodified
-    $zonesth->execute($revid);
+          $recflags{$recid} = 1;
+
+        } # while ($recsth)
+
+        close ZONECACHE; # force the file to be written
+
+        # catch obvious write errors that leave an empty temp file
+        if (-s $tmpcache) {
+          rename $tmpcache, $cachefile
+            or die "Error overwriting cache file $cachefile with temporary file: $!\n";
+        }
+
+      } # if $changed or cache filesize is 0
+
+    };
+    if ($@) {
+      print "error writing new data for $revzone: $@\n";
+      # error!  something borked, and we should be able to fall back on the old cache file
+      # report the error, somehow.
+    } else {
+      # mark zone as unmodified.  Only do this if no errors, that way
+      # export failures should recover a little more automatically.
+      $zonesth->execute($revid);
+    }
+    # Always stream the cache (even if stale or obsolete due to errors creating the new cache)
+    open CACHE, "<$cachefile";
+    print $datafile $_ while <CACHE>;
+    close CACHE;
+
   } # while ($domsth)