implement aggregate_locking design
[ikiwiki.git] / IkiWiki / Plugin / aggregate.pm
index cfc4ec955328e2dfa812b04b4cacd683ba336884..ba40ee6bcb42f57f2f3929db25a5f0fa75aeeb34 100644 (file)
@@ -33,33 +33,62 @@ sub getopt () { #{{{
 sub checkconfig () { #{{{
        if ($config{aggregate} && ! ($config{post_commit} && 
                                     IkiWiki::commit_hook_enabled())) {
-               if (! IkiWiki::lockwiki(0)) {
-                       debug("wiki is locked by another process, not aggregating");
-                       exit 1;
-               }
-       
+               # See if any feeds need aggregation.
                loadstate();
-               IkiWiki::loadindex();
-               aggregate();
-               expire();
-               savestate();
-               clearstate();
+               my @feeds=needsaggregate();
+               return unless @feeds;
+               if (! lockaggregate()) {
+                       debug("an aggregation process is already running");
+                       return;
+               }
+               # force a later rebuild of source pages
+               $IkiWiki::forcerebuild{$_->{sourcepage}}=1
+                       foreach @feeds;
+
+               # Fork a child process to handle the aggregation.
+               # The parent process will then handle building the
+               # result. This avoids messy code to clear state
+               # accumulated while aggregating.
+               defined(my $pid = fork) or error("Can't fork: $!");
+               if (! $pid) {
+                       IkiWiki::loadindex();
+
+                       # Aggregation happens without the main wiki lock
+                       # being held. This allows editing pages etc while
+                       # aggregation is running.
+                       aggregate(@feeds);
+
+                       IkiWiki::lockwiki;
+                       # Merge changes, since aggregation state may have
+                       # changed on disk while the aggregation was happening.
+                       mergestate();
+                       expire();
+                       savestate();
+                       IkiWiki::unlockwiki;
+                       exit 0;
+               }
+               waitpid($pid,0);
+               if ($?) {
+                       error "aggregation failed with code $?";
+               }
 
-               IkiWiki::unlockwiki();
+               clearstate();
+               unlockaggregate();
        }
 } #}}}
 
 sub needsbuild (@) { #{{{
        my $needsbuild=shift;
        
-       loadstate(); # if not already loaded
+       loadstate();
 
        foreach my $feed (values %feeds) {
                if (exists $pagesources{$feed->{sourcepage}} && 
                    grep { $_ eq $pagesources{$feed->{sourcepage}} } @$needsbuild) {
-                       # Mark all feeds originating on this page as removable;
-                       # preprocess will unmark those that still exist.
-                       remove_feeds($feed->{sourcepage});
+                       # Mark all feeds originating on this page as 
+                       # not yet seen; preprocess will unmark those that
+                       # still exist.
+                       markunseen($feed->{sourcepage});
                }
        }
 } # }}}
@@ -92,8 +121,7 @@ sub preprocess (@) { #{{{
        $feed->{updateinterval}=defined $params{updateinterval} ? $params{updateinterval} * 60 : 15 * 60;
        $feed->{expireage}=defined $params{expireage} ? $params{expireage} : 0;
        $feed->{expirecount}=defined $params{expirecount} ? $params{expirecount} : 0;
-       delete $feed->{remove};
-       delete $feed->{expired};
+       delete $feed->{unseen};
        $feed->{lastupdate}=0 unless defined $feed->{lastupdate};
        $feed->{numposts}=0 unless defined $feed->{numposts};
        $feed->{newposts}=0 unless defined $feed->{newposts};
@@ -123,16 +151,27 @@ sub delete (@) { #{{{
        # Remove feed data for removed pages.
        foreach my $file (@files) {
                my $page=pagename($file);
-               remove_feeds($page);
+               markunseen($page);
+       }
+} #}}}
+
+sub markunseen ($) { #{{{
+       my $page=shift;
+
+       foreach my $id (keys %feeds) {
+               if ($feeds{$id}->{sourcepage} eq $page) {
+                       $feeds{$id}->{unseen}=1;
+               }
        }
 } #}}}
 
 my $state_loaded=0;
+
 sub loadstate () { #{{{
        return if $state_loaded;
        $state_loaded=1;
        if (-e "$config{wikistatedir}/aggregate") {
-               open(IN, "<", "$config{wikistatedir}/aggregate") ||
+               open(IN, "$config{wikistatedir}/aggregate") ||
                        die "$config{wikistatedir}/aggregate: $!";
                while (<IN>) {
                        $_=IkiWiki::possibly_foolish_untaint($_);
@@ -166,32 +205,13 @@ sub loadstate () { #{{{
 
 sub savestate () { #{{{
        return unless $state_loaded;
+       garbage_collect();
        eval q{use HTML::Entities};
        error($@) if $@;
        my $newfile="$config{wikistatedir}/aggregate.new";
        my $cleanup = sub { unlink($newfile) };
-       open (OUT, ">", $newfile) || error("open $newfile: $!", $cleanup);
+       open (OUT, ">$newfile") || error("open $newfile: $!", $cleanup);
        foreach my $data (values %feeds, values %guids) {
-               if ($data->{remove}) {
-                       if ($data->{name}) {
-                               foreach my $guid (values %guids) {
-                                       if ($guid->{feed} eq $data->{name}) {
-                                               $guid->{remove}=1;
-                                       }
-                               }
-                       }
-                       else {
-                               unlink pagefile($data->{page})
-                                       if exists $data->{page};
-                       }
-                       next;
-               }
-               elsif ($data->{expired} && exists $data->{page}) {
-                       unlink pagefile($data->{page});
-                       delete $data->{page};
-                       delete $data->{md5};
-               }
-
                my @line;
                foreach my $field (keys %$data) {
                        if ($field eq "name" || $field eq "feed" ||
@@ -212,6 +232,63 @@ sub savestate () { #{{{
                error("rename $newfile: $!", $cleanup);
 } #}}}
 
+sub garbage_collect () { #{{{
+       foreach my $name (keys %feeds) {
+               # remove any feeds that were not seen while building the pages
+               # that used to contain them
+               if ($feeds{$name}->{unseen}) {
+                       delete $feeds{$name};
+               }
+       }
+
+       foreach my $guid (values %guids) {
+               # any guid whose feed is gone should be removed
+               if (! exists $feeds{$guid->{feed}}) {
+                       unlink pagefile($guid->{page})
+                               if exists $guid->{page};
+                       delete $guids{$guid->{guid}};
+               }
+               # handle expired guids
+               elsif ($guid->{expired} && exists $guid->{page}) {
+                       unlink pagefile($guid->{page});
+                       delete $guid->{page};
+                       delete $guid->{md5};
+               }
+       }
+} #}}}
+
+sub mergestate () { #{{{
+       # Load the current state in from disk, and merge into it
+       # values from the state in memory that might have changed
+       # during aggregation.
+       my %myfeeds=%feeds;
+       my %myguids=%guids;
+       clearstate();
+       loadstate();
+
+       # All that can change in feed state during aggregation is a few
+       # fields.
+       foreach my $name (keys %myfeeds) {
+               if (exists $feeds{$name}) {
+                       foreach my $field (qw{message lastupdate numposts
+                                             newposts error}) {
+                               $feeds{$name}->{$field}=$myfeeds{$name}->{$field};
+                       }
+               }
+       }
+
+       # New guids can be created during aggregation.
+       # It's also possible that guids were removed from the on-disk state
+       # while the aggregation was in process. That would only happen if
+       # their feed was also removed, so any removed guids added back here
+       # will be garbage collected later.
+       foreach my $guid (keys %myguids) {
+               if (! exists $guids{$guid}) {
+                       $guids{$guid}=$myguids{$guid};
+               }
+       }
+} #}}}
+
 sub clearstate () { #{{{
        %feeds=();
        %guids=();
@@ -249,7 +326,12 @@ sub expire () { #{{{
        }
 } #}}}
 
-sub aggregate () { #{{{
+sub needsaggregate () { #{{{
+       return values %feeds if $config{rebuild};
+       return grep { time - $_->{lastupdate} >= $_->{updateinterval} } values %feeds;
+} #}}}
+
+sub aggregate (@) { #{{{
        eval q{use XML::Feed};
        error($@) if $@;
        eval q{use URI::Fetch};
@@ -257,15 +339,12 @@ sub aggregate () { #{{{
        eval q{use HTML::Entities};
        error($@) if $@;
 
-       foreach my $feed (values %feeds) {
-               next unless $config{rebuild} || 
-                       time - $feed->{lastupdate} >= $feed->{updateinterval};
+       foreach my $feed (@_) {
                $feed->{lastupdate}=time;
                $feed->{newposts}=0;
                $feed->{message}=sprintf(gettext("processed ok at %s"),
                        displaytime($feed->{lastupdate}));
                $feed->{error}=0;
-               $IkiWiki::forcerebuild{$feed->{sourcepage}}=1;
 
                debug(sprintf(gettext("checking feed %s ..."), $feed->{name}));
 
@@ -473,18 +552,6 @@ sub htmlabs ($$) { #{{{
        return $ret;
 } #}}}
 
-sub remove_feeds () { #{{{
-       my $page=shift;
-
-       my %removed;
-       foreach my $id (keys %feeds) {
-               if ($feeds{$id}->{sourcepage} eq $page) {
-                       $feeds{$id}->{remove}=1;
-                       $removed{$id}=1;
-               }
-       }
-} #}}}
-
 sub pagefile ($) { #{{{
        my $page=shift;