--- BayesStore.pm.post-793	2003-03-21 15:09:00.000000000 -0800
+++ BayesStore.pm.new	2003-03-21 15:10:42.000000000 -0800
@@ -19,7 +19,7 @@
   @DBNAMES @DB_EXTENSIONS
   $NSPAM_MAGIC_TOKEN $NHAM_MAGIC_TOKEN $LAST_EXPIRE_MAGIC_TOKEN
   $NTOKENS_MAGIC_TOKEN $OLDEST_TOKEN_AGE_MAGIC_TOKEN
-  $SCANCOUNT_BASE_MAGIC_TOKEN 
+  $SCANCOUNT_BASE_MAGIC_TOKEN $NOW_REBUILDING_MAGIC_TOKEN
 };
 
 @ISA = qw();
@@ -66,6 +66,7 @@
 $LAST_EXPIRE_MAGIC_TOKEN = '**LASTEXPIRE';
 $NTOKENS_MAGIC_TOKEN = '**NTOKENS';
 $SCANCOUNT_BASE_MAGIC_TOKEN = '**SCANBASE';
+$NOW_REBUILDING_MAGIC_TOKEN = '**NOWREBUILDING';
 
 use constant MAX_SIZE_FOR_SCAN_COUNT_FILE => 5000;
 
@@ -316,6 +317,7 @@
 	  || $tok eq $LAST_EXPIRE_MAGIC_TOKEN
 	  || $tok eq $NTOKENS_MAGIC_TOKEN
 	  || $tok eq $OLDEST_TOKEN_AGE_MAGIC_TOKEN
+	  || $tok eq $NOW_REBUILDING_MAGIC_TOKEN
 	  || $tok eq $SCANCOUNT_BASE_MAGIC_TOKEN);
 
     my ($ts, $th, $atime) = $self->tok_get ($tok);
@@ -341,8 +343,10 @@
       }
     }
 
-    if ($showdots && (($kept + $deleted) % 1000) == 0) {
-      print STDERR ".";
+    if ((($kept + $deleted) % 1000) == 0) {
+      # update "now expiring" token.
+      $self->{db_toks}->{$NOW_REBUILDING_MAGIC_TOKEN} = time();
+      if ($showdots) { print STDERR "."; }
     }
   }
 
@@ -374,6 +378,9 @@
   $new_toks{$NHAM_MAGIC_TOKEN} = $self->{db_toks}->{$NHAM_MAGIC_TOKEN};
   $new_toks{$NTOKENS_MAGIC_TOKEN} = $kept + $reprieved;
 
+  # ensure this is NOT set in the new db
+  delete $new_toks{$NOW_REBUILDING_MAGIC_TOKEN};
+
   # now untie so we can do renames
   untie %{$self->{db_toks}};
   untie %new_toks;
@@ -391,7 +398,6 @@
   # ok, once that's done we can re-tie.  Call untie_db() first so
   # we unlock correctly etc. first
   $self->untie_db();
-  $self->tie_db_writable();
 
   my $done = time();
 
@@ -427,6 +433,16 @@
   if (!$ntoks || $ntoks =~ /\D/) 
 		{ $ntoks = $self->{expiry_min_db_size} + 1; }
   if ($ntoks <= $self->{expiry_min_db_size}) {
+    dbg ("bayes: expiry not needed, db too small ($ntoks)");
+    return 0;
+  }
+
+  # is the database currently being expired, or did an expiry attempt
+  # fail for some reason in the last 300 seconds?
+  my $timenow = time();
+  my $amexping = $self->{db_toks}->{$NOW_REBUILDING_MAGIC_TOKEN};
+  if (defined ($amexping) && $timenow - $amexping < 300) { # TODO: conf item?
+    dbg ("bayes: expiry already in progress ($amexping)");
     return 0;
   }
 
@@ -441,6 +457,7 @@
     return 1;
   }
 
+  dbg ("bayes: expiry not needed, happened recently ($last, now=$now)");
   0;
 }
 
@@ -583,6 +600,12 @@
   my $showdots = $opts->{showdots};
   my $retirepath = $path.".old";
 
+  # Set this now.  Unset it at end of expire_old_tokens_trapped().
+  # NOTE: we do NOT unset it on error.   If something went
+  # wrong, give the server 300 secs to recover in case it was
+  # a system-level problem, or caused by load.
+  $self->{db_toks}->{$NOW_REBUILDING_MAGIC_TOKEN} = $started;
+
   # now read the retired journal
   if (!open (JOURNAL, "<$path")) {
     warn "bayes: cannot open read $path\n";
@@ -613,9 +636,11 @@
       warn "Bayes journal: gibberish entry found: $_";
     }
 
-#    if ($showdots && ($count % 1000) == 0) {
-#      print STDERR ".";
-#    }
+    if (($total_count % 1000) == 0) {
+      # update "now expiring" token.
+      $self->{db_toks}->{$NOW_REBUILDING_MAGIC_TOKEN} = time();
+#     if ($showdots) { print STDERR "."; }
+    }
   }
   close JOURNAL;
 
@@ -625,8 +650,10 @@
   while( my($k,$v) = each %tokens ) {
     $self->tok_touch_token ($v, $k);
 
-    if ($showdots && (++$count % 1000) == 0) {
-      print STDERR ".";
+    if ((++$count % 1000) == 0) {
+      # update "now expiring" token.
+      $self->{db_toks}->{$NOW_REBUILDING_MAGIC_TOKEN} = time();
+      if ($showdots) { print STDERR "."; }
     }
   }