IkiWiki/Plugin/aggregate.pm

   1 #!/usr/bin/perl
   2 # Feed aggregation plugin.
   3 package IkiWiki::Plugin::aggregate;
   4
   5 use warnings;
   6 use strict;
   7 use IkiWiki 2.00;
   8 use HTML::Parser;
   9 use HTML::Tagset;
  10 use HTML::Entities;
  11 use URI;
  12 use open qw{:utf8 :std};
  13
  14 my %feeds;
  15 my %guids;
  16
  17 sub import { #{{{
  18         hook(type => "getopt", id => "aggregate", call => \&getopt);
  19         hook(type => "checkconfig", id => "aggregate", call => \&checkconfig);
  20         hook(type => "needsbuild", id => "aggregate", call => \&needsbuild);
  21         hook(type => "preprocess", id => "aggregate", call => \&preprocess);
  22         hook(type => "delete", id => "aggregate", call => \&delete);
  23         hook(type => "savestate", id => "aggregate", call => \&savestate);
  24         if (exists $config{aggregate_webtrigger} && $config{aggregate_webtrigger}) {
  25                 hook(type => "cgi", id => "aggregate", call => \&cgi);
  26         }
  27 } # }}}
  28
  29 sub getopt () { #{{{
  30         eval q{use Getopt::Long};
  31         error($@) if $@;
  32         Getopt::Long::Configure('pass_through');
  33         GetOptions(
  34                 "aggregate" => \$config{aggregate},
  35                 "aggregateinternal!" => \$config{aggregateinternal},
  36         );
  37 } #}}}
  38
  39 sub checkconfig () { #{{{
  40         if ($config{aggregate} && ! ($config{post_commit} &&
  41                                      IkiWiki::commit_hook_enabled())) {
  42                 launchaggregation();
  43         }
  44 } #}}}
  45
  46 sub cgi ($) { #{{{
  47         my $cgi=shift;
  48
  49         if (defined $cgi->param('do') &&
  50             $cgi->param("do") eq "aggregate_webtrigger") {
  51                 $|=1;
  52                 print "Content-Type: text/plain\n\n";
  53                 $config{cgi}=0;
  54                 $config{verbose}=1;
  55                 $config{syslog}=0;
  56                 print gettext("Aggregation triggered via web.")."\n\n";
  57                 if (launchaggregation()) {
  58                         IkiWiki::lockwiki();
  59                         IkiWiki::loadindex();
  60                         require IkiWiki::Render;
  61                         IkiWiki::refresh();
  62                         IkiWiki::saveindex();
  63                 }
  64                 else {
  65                         print gettext("Nothing to do right now, all feeds are up-to-date!")."\n";
  66                 }
  67                 exit 0;
  68         }
  69 } #}}}
  70
  71 sub launchaggregation () { #{{{
  72         # See if any feeds need aggregation.
  73         loadstate();
  74         my @feeds=needsaggregate();
  75         return unless @feeds;
  76         if (! lockaggregate()) {
  77                 debug("an aggregation process is already running");
  78                 return;
  79         }
  80         # force a later rebuild of source pages
  81         $IkiWiki::forcerebuild{$_->{sourcepage}}=1
  82                 foreach @feeds;
  83
  84         # Fork a child process to handle the aggregation.
  85         # The parent process will then handle building the
  86         # result. This avoids messy code to clear state
  87         # accumulated while aggregating.
  88         defined(my $pid = fork) or error("Can't fork: $!");
  89         if (! $pid) {
  90                 IkiWiki::loadindex();
  91                 # Aggregation happens without the main wiki lock
  92                 # being held. This allows editing pages etc while
  93                 # aggregation is running.
  94                 aggregate(@feeds);
  95
  96                 IkiWiki::lockwiki;
  97                 # Merge changes, since aggregation state may have
  98                 # changed on disk while the aggregation was happening.
  99                 mergestate();
 100                 expire();
 101                 savestate();
 102                 IkiWiki::unlockwiki;
 103                 exit 0;
 104         }
 105         waitpid($pid,0);
 106         if ($?) {
 107                 error "aggregation failed with code $?";
 108         }
 109
 110         clearstate();
 111         unlockaggregate();
 112
 113         return 1;
 114 } #}}}
 115
 116 sub migrate_to_internal { #{{{
 117
 118         if (! lockaggregate()) {
 119                 error("an aggregation process is already running");
 120                 return;
 121         }
 122
 123         IkiWiki::lockwiki();
 124         loadstate();
 125
 126         foreach my $data (values %guids) {
 127                 next unless $data->{page};
 128
 129                 $config{aggregateinternal} = 0;
 130                 my $oldname = pagefile($data->{page});
 131
 132                 $config{aggregateinternal} = 1;
 133                 my $newname = pagefile($data->{page});
 134
 135                 print "I: $oldname -> $newname\n";
 136                 if (-e $newname) {
 137                         if (-e $oldname) {
 138                                 error("$newname already exists");
 139                         }
 140                         else {
 141                                 print STDERR
 142                                         "W: already renamed to $newname?\n";
 143                         }
 144                 }
 145                 elsif (-e $oldname) {
 146                         rename($oldname, $newname) || error("$!");
 147                 }
 148                 else {
 149                         print "W: $oldname not found\n";
 150                 }
 151         }
 152
 153         savestate();
 154         IkiWiki::unlockwiki;
 155
 156         unlockaggregate();
 157 } #}}}
 158
 159 sub needsbuild (@) { #{{{
 160         my $needsbuild=shift;
 161
 162         loadstate();
 163
 164         foreach my $feed (values %feeds) {
 165                 if (exists $pagesources{$feed->{sourcepage}} &&
 166                     grep { $_ eq $pagesources{$feed->{sourcepage}} } @$needsbuild) {
 167                         # Mark all feeds originating on this page as
 168                         # not yet seen; preprocess will unmark those that
 169                         # still exist.
 170                         markunseen($feed->{sourcepage});
 171                 }
 172         }
 173 } # }}}
 174
 175 sub preprocess (@) { #{{{
 176         my %params=@_;
 177
 178         foreach my $required (qw{name url}) {
 179                 if (! exists $params{$required}) {
 180                         error sprintf(gettext("missing %s parameter"), $required)
 181                 }
 182         }
 183
 184         my $feed={};
 185         my $name=$params{name};
 186         if (exists $feeds{$name}) {
 187                 $feed=$feeds{$name};
 188         }
 189         else {
 190                 $feeds{$name}=$feed;
 191         }
 192         $feed->{name}=$name;
 193         $feed->{sourcepage}=$params{page};
 194         $feed->{url}=$params{url};
 195         my $dir=exists $params{dir} ? $params{dir} : $params{page}."/".IkiWiki::titlepage($params{name});
 196         $dir=~s/^\/+//;
 197         ($dir)=$dir=~/$config{wiki_file_regexp}/;
 198         $feed->{dir}=$dir;
 199         $feed->{feedurl}=defined $params{feedurl} ? $params{feedurl} : "";
 200         $feed->{updateinterval}=defined $params{updateinterval} ? $params{updateinterval} * 60 : 15 * 60;
 201         $feed->{expireage}=defined $params{expireage} ? $params{expireage} : 0;
 202         $feed->{expirecount}=defined $params{expirecount} ? $params{expirecount} : 0;
 203         if (exists $params{template}) {
 204                 $params{template}=~s/[^-_a-zA-Z0-9]+//g;
 205         }
 206         else {
 207                 $params{template} = "aggregatepost"
 208         }
 209         $feed->{template}=$params{template} . ".tmpl";
 210         delete $feed->{unseen};
 211         $feed->{lastupdate}=0 unless defined $feed->{lastupdate};
 212         $feed->{numposts}=0 unless defined $feed->{numposts};
 213         $feed->{newposts}=0 unless defined $feed->{newposts};
 214         $feed->{message}=gettext("new feed") unless defined $feed->{message};
 215         $feed->{error}=0 unless defined $feed->{error};
 216         $feed->{tags}=[];
 217         while (@_) {
 218                 my $key=shift;
 219                 my $value=shift;
 220                 if ($key eq 'tag') {
 221                         push @{$feed->{tags}}, $value;
 222                 }
 223         }
 224
 225         return "<a href=\"".$feed->{url}."\">".$feed->{name}."</a>: ".
 226                ($feed->{error} ? "<em>" : "").$feed->{message}.
 227                ($feed->{error} ? "</em>" : "").
 228                " (".$feed->{numposts}." ".gettext("posts").
 229                ($feed->{newposts} ? "; ".$feed->{newposts}.
 230                                     " ".gettext("new") : "").
 231                ")";
 232 } # }}}
 233
 234 sub delete (@) { #{{{
 235         my @files=@_;
 236
 237         # Remove feed data for removed pages.
 238         foreach my $file (@files) {
 239                 my $page=pagename($file);
 240                 markunseen($page);
 241         }
 242 } #}}}
 243
 244 sub markunseen ($) { #{{{
 245         my $page=shift;
 246
 247         foreach my $id (keys %feeds) {
 248                 if ($feeds{$id}->{sourcepage} eq $page) {
 249                         $feeds{$id}->{unseen}=1;
 250                 }
 251         }
 252 } #}}}
 253
 254 my $state_loaded=0;
 255
 256 sub loadstate () { #{{{
 257         return if $state_loaded;
 258         $state_loaded=1;
 259         if (-e "$config{wikistatedir}/aggregate") {
 260                 open(IN, "$config{wikistatedir}/aggregate") ||
 261                         die "$config{wikistatedir}/aggregate: $!";
 262                 while (<IN>) {
 263                         $_=IkiWiki::possibly_foolish_untaint($_);
 264                         chomp;
 265                         my $data={};
 266                         foreach my $i (split(/ /, $_)) {
 267                                 my ($field, $val)=split(/=/, $i, 2);
 268                                 if ($field eq "name" || $field eq "feed" ||
 269                                     $field eq "guid" || $field eq "message") {
 270                                         $data->{$field}=decode_entities($val, " \t\n");
 271                                 }
 272                                 elsif ($field eq "tag") {
 273                                         push @{$data->{tags}}, $val;
 274                                 }
 275                                 else {
 276                                         $data->{$field}=$val;
 277                                 }
 278                         }
 279
 280                         if (exists $data->{name}) {
 281                                 $feeds{$data->{name}}=$data;
 282                         }
 283                         elsif (exists $data->{guid}) {
 284                                 $guids{$data->{guid}}=$data;
 285                         }
 286                 }
 287
 288                 close IN;
 289         }
 290 } #}}}
 291
 292 sub savestate () { #{{{
 293         return unless $state_loaded;
 294         garbage_collect();
 295         my $newfile="$config{wikistatedir}/aggregate.new";
 296         my $cleanup = sub { unlink($newfile) };
 297         open (OUT, ">$newfile") || error("open $newfile: $!", $cleanup);
 298         foreach my $data (values %feeds, values %guids) {
 299                 my @line;
 300                 foreach my $field (keys %$data) {
 301                         if ($field eq "name" || $field eq "feed" ||
 302                             $field eq "guid" || $field eq "message") {
 303                                 push @line, "$field=".encode_entities($data->{$field}, " \t\n");
 304                         }
 305                         elsif ($field eq "tags") {
 306                                 push @line, "tag=$_" foreach @{$data->{tags}};
 307                         }
 308                         else {
 309                                 push @line, "$field=".$data->{$field};
 310                         }
 311                 }
 312                 print OUT join(" ", @line)."\n" || error("write $newfile: $!", $cleanup);
 313         }
 314         close OUT || error("save $newfile: $!", $cleanup);
 315         rename($newfile, "$config{wikistatedir}/aggregate") ||
 316                 error("rename $newfile: $!", $cleanup);
 317 } #}}}
 318
 319 sub garbage_collect () { #{{{
 320         foreach my $name (keys %feeds) {
 321                 # remove any feeds that were not seen while building the pages
 322                 # that used to contain them
 323                 if ($feeds{$name}->{unseen}) {
 324                         delete $feeds{$name};
 325                 }
 326         }
 327
 328         foreach my $guid (values %guids) {
 329                 # any guid whose feed is gone should be removed
 330                 if (! exists $feeds{$guid->{feed}}) {
 331                         unlink pagefile($guid->{page})
 332                                 if exists $guid->{page};
 333                         delete $guids{$guid->{guid}};
 334                 }
 335                 # handle expired guids
 336                 elsif ($guid->{expired} && exists $guid->{page}) {
 337                         unlink pagefile($guid->{page});
 338                         delete $guid->{page};
 339                         delete $guid->{md5};
 340                 }
 341         }
 342 } #}}}
 343
 344 sub mergestate () { #{{{
 345         # Load the current state in from disk, and merge into it
 346         # values from the state in memory that might have changed
 347         # during aggregation.
 348         my %myfeeds=%feeds;
 349         my %myguids=%guids;
 350         clearstate();
 351         loadstate();
 352
 353         # All that can change in feed state during aggregation is a few
 354         # fields.
 355         foreach my $name (keys %myfeeds) {
 356                 if (exists $feeds{$name}) {
 357                         foreach my $field (qw{message lastupdate numposts
 358                                               newposts error}) {
 359                                 $feeds{$name}->{$field}=$myfeeds{$name}->{$field};
 360                         }
 361                 }
 362         }
 363
 364         # New guids can be created during aggregation.
 365         # It's also possible that guids were removed from the on-disk state
 366         # while the aggregation was in process. That would only happen if
 367         # their feed was also removed, so any removed guids added back here
 368         # will be garbage collected later.
 369         foreach my $guid (keys %myguids) {
 370                 if (! exists $guids{$guid}) {
 371                         $guids{$guid}=$myguids{$guid};
 372                 }
 373         }
 374 } #}}}
 375
 376 sub clearstate () { #{{{
 377         %feeds=();
 378         %guids=();
 379         $state_loaded=0;
 380 } #}}}
 381
 382 sub expire () { #{{{
 383         foreach my $feed (values %feeds) {
 384                 next unless $feed->{expireage} || $feed->{expirecount};
 385                 my $count=0;
 386                 my %seen;
 387                 foreach my $item (sort { $IkiWiki::pagectime{$b->{page}} <=> $IkiWiki::pagectime{$a->{page}} }
 388                                   grep { exists $_->{page} && $_->{feed} eq $feed->{name} && $IkiWiki::pagectime{$_->{page}} }
 389                                   values %guids) {
 390                         if ($feed->{expireage}) {
 391                                 my $days_old = (time - $IkiWiki::pagectime{$item->{page}}) / 60 / 60 / 24;
 392                                 if ($days_old > $feed->{expireage}) {
 393                                         debug(sprintf(gettext("expiring %s (%s days old)"),
 394                                                 $item->{page}, int($days_old)));
 395                                         $item->{expired}=1;
 396                                 }
 397                         }
 398                         elsif ($feed->{expirecount} &&
 399                                $count >= $feed->{expirecount}) {
 400                                 debug(sprintf(gettext("expiring %s"), $item->{page}));
 401                                 $item->{expired}=1;
 402                         }
 403                         else {
 404                                 if (! $seen{$item->{page}}) {
 405                                         $seen{$item->{page}}=1;
 406                                         $count++;
 407                                 }
 408                         }
 409                 }
 410         }
 411 } #}}}
 412
 413 sub needsaggregate () { #{{{
 414         return values %feeds if $config{rebuild};
 415         return grep { time - $_->{lastupdate} >= $_->{updateinterval} } values %feeds;
 416 } #}}}
 417
 418 sub aggregate (@) { #{{{
 419         eval q{use XML::Feed};
 420         error($@) if $@;
 421         eval q{use URI::Fetch};
 422         error($@) if $@;
 423
 424         foreach my $feed (@_) {
 425                 $feed->{lastupdate}=time;
 426                 $feed->{newposts}=0;
 427                 $feed->{message}=sprintf(gettext("processed ok at %s"),
 428                         displaytime($feed->{lastupdate}));
 429                 $feed->{error}=0;
 430
 431                 debug(sprintf(gettext("checking feed %s ..."), $feed->{name}));
 432
 433                 if (! length $feed->{feedurl}) {
 434                         my @urls=XML::Feed->find_feeds($feed->{url});
 435                         if (! @urls) {
 436                                 $feed->{message}=sprintf(gettext("could not find feed at %s"), $feed->{url});
 437                                 $feed->{error}=1;
 438                                 debug($feed->{message});
 439                                 next;
 440                         }
 441                         $feed->{feedurl}=pop @urls;
 442                 }
 443                 my $res=URI::Fetch->fetch($feed->{feedurl});
 444                 if (! $res) {
 445                         $feed->{message}=URI::Fetch->errstr;
 446                         $feed->{error}=1;
 447                         debug($feed->{message});
 448                         next;
 449                 }
 450                 if ($res->status == URI::Fetch::URI_GONE()) {
 451                         $feed->{message}=gettext("feed not found");
 452                         $feed->{error}=1;
 453                         debug($feed->{message});
 454                         next;
 455                 }
 456                 my $content=$res->content;
 457                 my $f=eval{XML::Feed->parse(\$content)};
 458                 if ($@) {
 459                         # One common cause of XML::Feed crashing is a feed
 460                         # that contains invalid UTF-8 sequences. Convert
 461                         # feed to ascii to try to work around.
 462                         $feed->{message}.=" ".sprintf(gettext("(invalid UTF-8 stripped from feed)"));
 463                         $content=Encode::decode_utf8($content, 0);
 464                         $f=eval{XML::Feed->parse(\$content)};
 465                 }
 466                 if ($@) {
 467                         # Another possibility is badly escaped entities.
 468                         $feed->{message}.=" ".sprintf(gettext("(feed entities escaped)"));
 469                         $content=~s/\&(?!amp)(\w+);/&amp;$1;/g;
 470                         $content=Encode::decode_utf8($content, 0);
 471                         $f=eval{XML::Feed->parse(\$content)};
 472                 }
 473                 if ($@) {
 474                         $feed->{message}=gettext("feed crashed XML::Feed!")." ($@)";
 475                         $feed->{error}=1;
 476                         debug($feed->{message});
 477                         next;
 478                 }
 479                 if (! $f) {
 480                         $feed->{message}=XML::Feed->errstr;
 481                         $feed->{error}=1;
 482                         debug($feed->{message});
 483                         next;
 484                 }
 485
 486                 foreach my $entry ($f->entries) {
 487                         add_page(
 488                                 feed => $feed,
 489                                 copyright => $f->copyright,
 490                                 title => defined $entry->title ? decode_entities($entry->title) : "untitled",
 491                                 link => $entry->link,
 492                                 content => defined $entry->content->body ? $entry->content->body : "",
 493                                 guid => defined $entry->id ? $entry->id : time."_".$feed->{name},
 494                                 ctime => $entry->issued ? ($entry->issued->epoch || time) : time,
 495                         );
 496                 }
 497         }
 498 } #}}}
 499
 500 sub add_page (@) { #{{{
 501         my %params=@_;
 502
 503         my $feed=$params{feed};
 504         my $guid={};
 505         my $mtime;
 506         if (exists $guids{$params{guid}}) {
 507                 # updating an existing post
 508                 $guid=$guids{$params{guid}};
 509                 return if $guid->{expired};
 510         }
 511         else {
 512                 # new post
 513                 $guid->{guid}=$params{guid};
 514                 $guids{$params{guid}}=$guid;
 515                 $mtime=$params{ctime};
 516                 $feed->{numposts}++;
 517                 $feed->{newposts}++;
 518
 519                 # assign it an unused page
 520                 my $page=IkiWiki::titlepage($params{title});
 521                 # escape slashes and periods in title so it doesn't specify
 522                 # directory name or trigger ".." disallowing code.
 523                 $page=~s!([/.])!"__".ord($1)."__"!eg;
 524                 $page=$feed->{dir}."/".$page;
 525                 ($page)=$page=~/$config{wiki_file_regexp}/;
 526                 if (! defined $page || ! length $page) {
 527                         $page=$feed->{dir}."/item";
 528                 }
 529                 my $c="";
 530                 while (exists $IkiWiki::pagecase{lc $page.$c} ||
 531                        -e pagefile($page.$c)) {
 532                         $c++
 533                 }
 534
 535                 # Make sure that the file name isn't too long.
 536                 # NB: This doesn't check for path length limits.
 537                 my $max=POSIX::pathconf($config{srcdir}, &POSIX::_PC_NAME_MAX);
 538                 if (defined $max && length(htmlfn($page)) >= $max) {
 539                         $c="";
 540                         $page=$feed->{dir}."/item";
 541                         while (exists $IkiWiki::pagecase{lc $page.$c} ||
 542                                -e pagefile($page.$c)) {
 543                                 $c++
 544                         }
 545                 }
 546
 547                 $guid->{page}=$page;
 548                 debug(sprintf(gettext("creating new page %s"), $page));
 549         }
 550         $guid->{feed}=$feed->{name};
 551
 552         # To write or not to write? Need to avoid writing unchanged pages
 553         # to avoid unneccessary rebuilding. The mtime from rss cannot be
 554         # trusted; let's use a digest.
 555         eval q{use Digest::MD5 'md5_hex'};
 556         error($@) if $@;
 557         require Encode;
 558         my $digest=md5_hex(Encode::encode_utf8($params{content}));
 559         return unless ! exists $guid->{md5} || $guid->{md5} ne $digest || $config{rebuild};
 560         $guid->{md5}=$digest;
 561
 562         # Create the page.
 563         my $template=template($feed->{template}, blind_cache => 1);
 564         $template->param(title => $params{title})
 565                 if defined $params{title} && length($params{title});
 566         $template->param(content => htmlescape(htmlabs($params{content}, $feed->{feedurl})));
 567         $template->param(name => $feed->{name});
 568         $template->param(url => $feed->{url});
 569         $template->param(copyright => $params{copyright})
 570                 if defined $params{copyright} && length $params{copyright};
 571         $template->param(permalink => urlabs($params{link}, $feed->{feedurl}))
 572                 if defined $params{link};
 573         if (ref $feed->{tags}) {
 574                 $template->param(tags => [map { tag => $_ }, @{$feed->{tags}}]);
 575         }
 576         writefile(htmlfn($guid->{page}), $config{srcdir},
 577                 $template->output);
 578
 579         # Set the mtime, this lets the build process get the right creation
 580         # time on record for the new page.
 581         utime $mtime, $mtime, pagefile($guid->{page})
 582                 if defined $mtime && $mtime <= time;
 583 } #}}}
 584
 585 sub htmlescape ($) { #{{{
 586         # escape accidental wikilinks and preprocessor stuff
 587         my $html=shift;
 588         $html=~s/(?<!\\)\[\[/\\\[\[/g;
 589         return $html;
 590 } #}}}
 591
 592 sub urlabs ($$) { #{{{
 593         my $url=shift;
 594         my $urlbase=shift;
 595
 596         URI->new_abs($url, $urlbase)->as_string;
 597 } #}}}
 598
 599 sub htmlabs ($$) { #{{{
 600         # Convert links in html from relative to absolute.
 601         # Note that this is a heuristic, which is not specified by the rss
 602         # spec and may not be right for all feeds. Also, see Debian
 603         # bug #381359.
 604         my $html=shift;
 605         my $urlbase=shift;
 606
 607         my $ret="";
 608         my $p = HTML::Parser->new(api_version => 3);
 609         $p->handler(default => sub { $ret.=join("", @_) }, "text");
 610         $p->handler(start => sub {
 611                 my ($tagname, $pos, $text) = @_;
 612                 if (ref $HTML::Tagset::linkElements{$tagname}) {
 613                         while (4 <= @$pos) {
 614                                 # use attribute sets from right to left
 615                                 # to avoid invalidating the offsets
 616                                 # when replacing the values
 617                                 my($k_offset, $k_len, $v_offset, $v_len) =
 618                                         splice(@$pos, -4);
 619                                 my $attrname = lc(substr($text, $k_offset, $k_len));
 620                                 next unless grep { $_ eq $attrname } @{$HTML::Tagset::linkElements{$tagname}};
 621                                 next unless $v_offset; # 0 v_offset means no value
 622                                 my $v = substr($text, $v_offset, $v_len);
 623                                 $v =~ s/^([\'\"])(.*)\1$/$2/;
 624                                 my $new_v=urlabs($v, $urlbase);
 625                                 $new_v =~ s/\"/&quot;/g; # since we quote with ""
 626                                 substr($text, $v_offset, $v_len) = qq("$new_v");
 627                         }
 628                 }
 629                 $ret.=$text;
 630         }, "tagname, tokenpos, text");
 631         $p->parse($html);
 632         $p->eof;
 633
 634         return $ret;
 635 } #}}}
 636
 637 sub pagefile ($) { #{{{
 638         my $page=shift;
 639
 640         return "$config{srcdir}/".htmlfn($page);
 641 } #}}}
 642
 643 sub htmlfn ($) { #{{{
 644         return shift().".".($config{aggregateinternal} ? "_" : "").$config{htmlext};
 645 } #}}}
 646
 647 my $aggregatelock;
 648
 649 sub lockaggregate () { #{{{
 650         # Take an exclusive lock to prevent multiple concurrent aggregators.
 651         # Returns true if the lock was aquired.
 652         if (! -d $config{wikistatedir}) {
 653                 mkdir($config{wikistatedir});
 654         }
 655         open($aggregatelock, '>', "$config{wikistatedir}/aggregatelock") ||
 656                 error ("cannot open to $config{wikistatedir}/aggregatelock: $!");
 657         if (! flock($aggregatelock, 2 | 4)) { # LOCK_EX | LOCK_NB
 658                 close($aggregatelock) || error("failed closing aggregatelock: $!");
 659                 return 0;
 660         }
 661         return 1;
 662 } #}}}
 663
 664 sub unlockaggregate () { #{{{
 665         return close($aggregatelock) if $aggregatelock;
 666         return;
 667 } #}}}
 668
 669 1