From b4eccdb413df6e434f04426759a5cfb40912424c Mon Sep 17 00:00:00 2001
From: Alex Schroeder <alex@gnu.org>
Date: Sat, 26 Jun 2004 00:00:31 +0000
Subject: [PATCH] (WriteLinkDb): Removed lock. (DoLinkDb): Added Lock.
 (RefreshLinkDb): Rewrite.  It was full of bugs. (NewNotFoundHandlerSave):
 Rewrite. (NotFoundHandlerCacheUpdate): Rewrite.

---
 modules/not-found-handler.pl | 54 ++++++++++++++++++++++++++++--------
 1 file changed, 42 insertions(+), 12 deletions(-)

diff --git a/modules/not-found-handler.pl b/modules/not-found-handler.pl
index bcdd852e..e649a561 100644
--- a/modules/not-found-handler.pl
+++ b/modules/not-found-handler.pl
@@ -16,7 +16,7 @@
 #    59 Temple Place, Suite 330
 #    Boston, MA 02111-1307 USA
 
-$ModulesDescription .= '<p>$Id: not-found-handler.pl,v 1.5 2004/06/13 14:46:50 as Exp $</p>';
+$ModulesDescription .= '<p>$Id: not-found-handler.pl,v 1.6 2004/06/26 00:00:31 as Exp $</p>';
 
 use vars qw($NotFoundHandlerDir, $LinkFile, %LinkDb, $LinkDbInit);
 
@@ -39,15 +39,14 @@ sub DoClearCache {
 sub ReadLinkDb {
   return if $LinkDbInit;
   $LinkDbInit = 1;
+  return if not -f $LinkFile;
   my $data = ReadFileOrDie($LinkFile);
   map { my ($id, @links) = split; $LinkDb{$id} = \@links } split(/\n/, $data);
 }
 
-sub WriteLinkDb {
+sub WriteLinkDb { # call within the main lock!
   my $str = join("\n", map { join(' ', $_, @{$LinkDb{$_}}) } keys %LinkDb);
-  RequestLockOrError(); # fatal
   WriteStringToFile($LinkFile, $str);
-  ReleaseLock();
   return $str;
 }
 
@@ -55,17 +54,36 @@ sub WriteLinkDb {
 
 sub DoLinkDb {
   print GetHeader('', QuoteHtml(T('Generating Link Database')), '');
+  RequestLockOrError(); # fatal
   %LinkDb = %{GetFullLinkList(1, 0, 0, 1)};
   print $q->pre(WriteLinkDb());
+  ReleaseLock();
   PrintFooter();
 }
 
 # refresh link database with data from the current open page
 
 sub RefreshLinkDb {
+  if (not defined(&GetLinkList)) {
+    ReportError(T('The 404 handler extension requires the link data extension (links.pl).'));
+    return;
+  }
+  if ($Page{revision} > 0 and not ($Page{blocks} && $Page{flags})) { #
+    # make sure we have a cache!  We just discard this output, because
+    # in a multilingual setting we would need to determine the correct
+    # filename in which to store it in order to get headers
+    # etc. right.
+    *P = STDOUT;
+    PrintWikiToHTML($Page{text}, 1, 0, 1); # revision 0, is already locked
+    *STDOUT = *P;
+  }
+  my @links = GetLinkList(1, 0, 0, 1); # works on cached blocks...
   ReadLinkDb();
-  my @links = GetLinkList(1, 0, 0, 1);
-  $LinkDb{$OpenPageName} = \@links;
+  if (@links) {
+    $LinkDb{$OpenPageName} = \@links;
+  } else {
+    delete $LinkDb{$OpenPageName};
+  }
   WriteLinkDb();
 }
 
@@ -79,8 +97,9 @@ sub NewNotFoundHandlerSave {
   my $id = $args[0];
   OldNotFoundHandlerSave(@args);
   RefreshLinkDb(); # for the open page
-  mkdir($NotFoundHandlerDir) unless -d $NotFoundHandlerDir;
-  if ($Page{revision} == 1) {
+  if (not -d $NotFoundHandlerDir) {
+    mkdir($NotFoundHandlerDir);
+  } elsif ($Page{revision} == 1) {
     NotFoundHandlerCacheUpdate($id);
   } else {
     # unlink PageName, PageName.en, PageName.de, etc.
@@ -93,14 +112,25 @@ sub NotFoundHandlerCacheUpdate {
   # new or deleted page: regenerate all pages that link to this page,
   # or to the permanent anchors defined on this page.
   ReadLinkDb();
-  my @pages = @{$LinkDb{$id}};
+  # we will check for the current page, and for all the anchors defined on it.
+  my @targets = ($id);
   if ($PermanentAnchors) {
     foreach ($Page{text} =~ m/\[::$FreeLinkPattern\]/g) {
-      push(@pages, @{$LinkDb{$1}}); # harmless: potentially adds duplicates
+      push(@targets, $1); # harmless: potentially adds duplicates
     }
   }
-  foreach my $page (@pages) {
-    unlink("$NotFoundHandlerDir/$page", glob("$NotFoundHandlerDir/$page.[a-z][a-z]"));
+  # if any of the potential targets is the target of a link in the
+  # link database, then the source page must be rendered anew.  in
+  # other words, delete the cached version of the source page.
+  my $target = '^(' . join('|', @targets) . ')$';
+  warn "Unlinking pages pointing to $target\n";
+  $target = qr($target);
+  foreach my $source (keys %LinkDb) {
+    warn "Examining $source\n";
+    if (grep(/$target/, @{$LinkDb{$source}})) {
+      unlink("$NotFoundHandlerDir/$source", glob("$NotFoundHandlerDir/$source.[a-z][a-z]"));
+      warn "Unlinking $source\n";
+    }
   }
 }