Deliantra-Client/DC/DB.pm

=head1 NAME

DC::DB - async. database and filesystem access for deliantra

=head1 SYNOPSIS

 use DC::DB;

=head1 DESCRIPTION

=over 4

=cut

package DC::DB;

use strict;
use utf8;

use File::Path ();
use Carp ();
use Storable ();
use AnyEvent::Util ();
use Config;
use BDB;

use DC;

our $ODBDIR  = "cfplus-" . BDB::VERSION_MAJOR . "." . BDB::VERSION_MINOR . "-$Config{archname}";
our $DBDIR   = "client-" . BDB::VERSION_MAJOR . "." . BDB::VERSION_MINOR . "-$Config{archname}";
our $DB_HOME = "$Deliantra::VARDIR/$DBDIR";

sub FIRST_TILE_ID () { 64 }

unless (-d $DB_HOME) {
   if (-d "$Deliantra::VARDIR/$ODBDIR") {
      rename "$Deliantra::VARDIR/$ODBDIR", $DB_HOME;
      print STDERR "INFO: moved old database from $Deliantra::VARDIR/$ODBDIR to $DB_HOME\n";
   } elsif (-d "$Deliantra::OLDDIR/$ODBDIR") {
      rename "$Deliantra::OLDDIR/$DBDIR", $DB_HOME;
      print STDERR "INFO: moved old database from $Deliantra::OLDDIR/$ODBDIR to $DB_HOME\n";
   } else {
      File::Path::mkpath [$DB_HOME]
         or die "unable to create database directory $DB_HOME: $!";
   }
}

BDB::max_poll_time 0.03;
BDB::max_parallel 1;

our $DB_ENV;
our $DB_STATE;
our %DB_TABLE;
our $TILE_SEQ;

sub try_open_db {
   File::Path::mkpath [$DB_HOME];

   my $env = db_env_create;

   $env->set_errfile (\*STDERR);
   $env->set_msgfile (\*STDERR);
   $env->set_verbose (-1, 1);

   $env->set_flags (BDB::AUTO_COMMIT | BDB::REGION_INIT);
   $env->set_flags      (&BDB::LOG_AUTOREMOVE ) if BDB::VERSION v0, v4.7;
   $env->log_set_config (&BDB::LOG_AUTO_REMOVE) if BDB::VERSION v4.7;

   $env->set_timeout (3, BDB::SET_TXN_TIMEOUT);
   $env->set_timeout (3, BDB::SET_LOCK_TIMEOUT);

   $env->set_cachesize (0, 2048 * 1024, 0);

   db_env_open $env, $DB_HOME,
               BDB::CREATE | BDB::REGISTER | BDB::RECOVER | BDB::INIT_MPOOL | BDB::INIT_LOCK | BDB::INIT_TXN,
               0666;

   $! and die "cannot open database environment $DB_HOME: " . BDB::strerror;

   $DB_ENV = $env;

   1
}

sub table($) {
   $DB_TABLE{$_[0]} ||= do {
      my ($table) = @_;

      $table =~ s/([^a-zA-Z0-9_\-])/sprintf "=%x=", ord $1/ge;

      $DB_ENV#d#
         or return ::clienterror ("trying to create table $_[0] with empty db_env $DB_ENV" => 1);#d#

      my $db = db_create $DB_ENV;
      $db->set_flags (BDB::CHKSUM);

      db_open $db, undef, $table, undef, BDB::BTREE,
              BDB::AUTO_COMMIT | BDB::CREATE | BDB::READ_UNCOMMITTED, 0666;

      $! and "unable to open/create database table $_[0]: ". BDB::strerror;

      $db
   }
}

#############################################################################

our $WATCHER;
our $SYNC;
our $facemap;

sub exists($$$) {
   my ($db, $key, $cb) = @_;

   my $data;
   db_get table $db, undef, $key, $data, 0, sub {
      $cb->($! ? () : length $data);
   };
}

sub get($$$) {
   my ($db, $key, $cb) = @_;

   my $data;
   db_get table $db, undef, $key, $data, 0, sub {
      $cb->($! ? () : $data);
   };
}

sub put($$$$) {
   my ($db, $key, $data, $cb) = @_;

   db_put table $db, undef, $key, $data, 0, sub {
      $cb->($!);
      $SYNC->again unless $SYNC->is_active;
   };
}

sub do_table {
   my ($db, $cb) = @_;

   $db = table $db;

   my $cursor = $db->cursor;
   my %kv;

   for (;;) {
      db_c_get $cursor, my $k, my $v, BDB::NEXT;
      last if $!;
      $kv{$k} = $v;
   }

   $cb->(\%kv);
}

sub do_get_tile_id {
   my ($name, $cb) = @_;

   my $table = table "facemap";
   my $id;

   db_get $table, undef, $name => $id, 0;
   $! or return $cb->($id);

   unless ($TILE_SEQ) {
      $TILE_SEQ = $table->sequence;
      $TILE_SEQ->initial_value (FIRST_TILE_ID);
      $TILE_SEQ->set_cachesize (0);
      db_sequence_open $TILE_SEQ, undef, "id", BDB::CREATE;
   }

   db_sequence_get $TILE_SEQ, undef, 1, my $id;

   die "unable to allocate tile id: $!"
      if $!;
   
   db_put $table, undef, $name => $id, 0;
   $cb->($id);

}

sub get_tile_id_sync($) {
   my ($name) = @_;

   $facemap->{$name} ||= do {
      my $id;
      do_get_tile_id $name, sub {
         $id = $_[0];
      };
      BDB::flush;
      $id
   }
}

#############################################################################

sub path_of_res($) {
   utf8::downgrade $_[0]; # bug in unpack "H*"
   "$DB_HOME/res-data-" . unpack "H*", $_[0]
}

sub sync {
   # for debugging
   #DC::DB::Server::req (sync => sub { });
   DC::DB::Server::sync ();
}

sub unlink($$) {
   DC::DB::Server::req (unlink => @_);
}

sub read_file($$) {
   DC::DB::Server::req (read_file => @_);
}

sub write_file($$$) {
   DC::DB::Server::req (write_file => @_);
}

sub prefetch_file($$$) {
   DC::DB::Server::req (prefetch_file => @_);
}

sub logprint($$$) {
   DC::DB::Server::req (logprint => @_);
}

#############################################################################

package DC::DB::Server;

use strict;

use EV ();
use Fcntl;

our %CB;
our $FH;
our $ID = "aaa0";
our ($fh_r_watcher, $fh_w_watcher);
our $sync_timer;
our $write_buf;
our $read_buf;

sub fh_write {
   my $len = syswrite $FH, $write_buf;

   substr $write_buf, 0, $len, "";

   $fh_w_watcher->stop
      unless length $write_buf;
}

sub fh_read {
   my $status = sysread $FH, $read_buf, 16384, length $read_buf;

   die "FATAL: database process died\n"
      if $status == 0 && defined $status;

   while () {
      return if 4 > length $read_buf;
      my $len = unpack "N", $read_buf;

      return if $len + 4 > length $read_buf;

      substr $read_buf, 0, 4, "";
      my $res = Storable::thaw substr $read_buf, 0, $len, "";

      my ($id, @args) = @$res;
      (delete $CB{$id})->(@args);
   }
}

sub sync {
   # biggest mess evarr
   my $fds; (vec $fds, fileno $FH, 1) =  1;

   while (1 < scalar keys %CB) {
      my $r = $fds;
      my $w = length $write_buf ? $fds : undef;
      select $r, $w, undef, undef;

      fh_write if vec $w, fileno $FH, 1;
      fh_read  if vec $r, fileno $FH, 1;
   }
}

sub req {
   my ($type, @args) = @_;
   my $cb = pop @args;

   my $id = ++$ID;
   $write_buf .= pack "N/a*", Storable::freeze [$id, $type, @args];
   $CB{$id} = $cb;

   $fh_w_watcher->start;
}

sub do_unlink {
   unlink $_[0];
}

sub do_read_file {
   my ($path) = @_;

   utf8::downgrade $path;
   open my $fh, "<:raw", $path
      or return;
   sysread $fh, my $buf, -s $fh;

   $buf
}

sub do_write_file {
   my ($path, $data) = @_;

   utf8::downgrade $path;
   utf8::downgrade $data;
   open my $fh, ">:raw", $path
      or return;
   syswrite $fh, $data;
   close $fh;

   1
}

sub do_prefetch_file {
   my ($path, $size) = @_;

   utf8::downgrade $path;
   open my $fh, "<:raw", $path
      or return;
   sysread $fh, my $buf, $size;

   1
}

our %LOG_FH;

sub do_logprint {
   my ($path, $line) = @_;

   $LOG_FH{$path} ||= do {
      open my $fh, ">>:utf8", $path
         or warn "Couldn't open logfile $path: $!";

      $fh->autoflush (1);

      $fh
   };

   my ($sec, $min, $hour, $mday, $mon, $year) = localtime time;

   my $ts = sprintf "%04d-%02d-%02d %02d:%02d:%02d",
               $year + 1900, $mon + 1, $mday, $hour, $min, $sec;

   print { $LOG_FH{$path} } "$ts $line\n"
}

sub run {
   ($FH, my $fh) = AnyEvent::Util::portable_socketpair
     or die "unable to create database socketpair: $!";

   my $oldfh = select $FH; $| = 1; select $oldfh;
   my $oldfh = select $fh; $| = 1; select $oldfh;

   my $pid = fork;
   
   if (defined $pid && !$pid) {
      local $SIG{QUIT} = "IGNORE";
      local $SIG{__DIE__};
      local $SIG{__WARN__};
      eval {
         close $FH;

         while () {
            4 == read $fh, my $len, 4
               or last;
            $len = unpack "N", $len;
            $len == read $fh, my $req, $len
               or die "unexpected eof while reading request";

            $req = Storable::thaw $req;

            my ($id, $type, @args) = @$req;
            my $cb = DC::DB::Server->can ("do_$type")
               or die "$type: unknown database request type\n";
            my $res = pack "N/a*", Storable::freeze [$id, $cb->(@args)];
            (syswrite $fh, $res) == length $res
               or die "DB::write: $!";
         }
      };

      my $error = $@;

      eval {
         Storable::store_fd [die => $error], $fh;
      };

      warn $error
         if $error;

      DC::_exit 0;
   }

   close $fh;
   DC::fh_nonblocking $FH, 1;

   $CB{die} = sub { die shift };

   $fh_r_watcher = EV::io $FH, EV::READ , \&fh_read;
   $fh_w_watcher = EV::io $FH, EV::WRITE, \&fh_write;
}

sub stop {
   close $FH;
}

package DC::DB;

sub nuke_db {
   File::Path::mkpath [$DB_HOME];
   eval { File::Path::rmtree $DB_HOME };
}

sub open_db {
   unless (eval { try_open_db }) {
      warn "$@";#d#
      eval { nuke_db };
      try_open_db;
   }

   # fetch the full face table first
   unless ($facemap) {
      do_table facemap => sub {
         $facemap = $_[0];
         delete $facemap->{id};
         my %maptile = reverse %$facemap;#d#
         if ((scalar keys %$facemap) != (scalar keys %maptile)) {#d#
            $facemap = { };#d#
            DC::error "FATAL: facemap is not a 1:1 mapping, please report this and delete your $DB_HOME directory!\n";#d#
         }#d#
      };
   }

   $WATCHER = EV::io BDB::poll_fileno, EV::READ, \&BDB::poll_cb;
   $SYNC = EV::timer_ns 0, 60, sub {
      $_[0]->stop;
      db_env_txn_checkpoint $DB_ENV, 0, 0, 0, sub { };
   };
}

END {
   db_env_txn_checkpoint $DB_ENV, 0, 0, 0
      if $DB_ENV;

   undef $TILE_SEQ;
   %DB_TABLE = ();
   undef $DB_ENV;
}

1;

=back

=head1 AUTHOR

 Marc Lehmann <schmorp@schmorp.de>
 http://home.schmorp.de/

=cut

Revision:	1.42
Committed:	Sun Jan 4 10:22:19 2009 UTC (15 years, 5 months ago) by root
Branch:	MAIN
Changes since 1.41:	+3 -1 lines
Log Message:	* empty log message *
#	Content
1	=head1 NAME
2
3	DC::DB - async. database and filesystem access for deliantra
4
5	=head1 SYNOPSIS
6
7	use DC::DB;
8
9	=head1 DESCRIPTION
10
11	=over 4
12
13	=cut
14
15	package DC::DB;
16
17	use strict;
18	use utf8;
19
20	use File::Path ();
21	use Carp ();
22	use Storable ();
23	use AnyEvent::Util ();
24	use Config;
25	use BDB;
26
27	use DC;
28
29	our $ODBDIR = "cfplus-" . BDB::VERSION_MAJOR . "." . BDB::VERSION_MINOR . "-$Config{archname}";
30	our $DBDIR = "client-" . BDB::VERSION_MAJOR . "." . BDB::VERSION_MINOR . "-$Config{archname}";
31	our $DB_HOME = "$Deliantra::VARDIR/$DBDIR";
32
33	sub FIRST_TILE_ID () { 64 }
34
35	unless (-d $DB_HOME) {
36	if (-d "$Deliantra::VARDIR/$ODBDIR") {
37	rename "$Deliantra::VARDIR/$ODBDIR", $DB_HOME;
38	print STDERR "INFO: moved old database from $Deliantra::VARDIR/$ODBDIR to $DB_HOME\n";
39	} elsif (-d "$Deliantra::OLDDIR/$ODBDIR") {
40	rename "$Deliantra::OLDDIR/$DBDIR", $DB_HOME;
41	print STDERR "INFO: moved old database from $Deliantra::OLDDIR/$ODBDIR to $DB_HOME\n";
42	} else {
43	File::Path::mkpath [$DB_HOME]
44	or die "unable to create database directory $DB_HOME: $!";
45	}
46	}
47
48	BDB::max_poll_time 0.03;
49	BDB::max_parallel 1;
50
51	our $DB_ENV;
52	our $DB_STATE;
53	our %DB_TABLE;
54	our $TILE_SEQ;
55
56	sub try_open_db {
57	File::Path::mkpath [$DB_HOME];
58
59	my $env = db_env_create;
60
61	$env->set_errfile (\*STDERR);
62	$env->set_msgfile (\*STDERR);
63	$env->set_verbose (-1, 1);
64
65	$env->set_flags (BDB::AUTO_COMMIT \| BDB::REGION_INIT);
66	$env->set_flags (&BDB::LOG_AUTOREMOVE ) if BDB::VERSION v0, v4.7;
67	$env->log_set_config (&BDB::LOG_AUTO_REMOVE) if BDB::VERSION v4.7;
68
69	$env->set_timeout (3, BDB::SET_TXN_TIMEOUT);
70	$env->set_timeout (3, BDB::SET_LOCK_TIMEOUT);
71
72	$env->set_cachesize (0, 2048 * 1024, 0);
73
74	db_env_open $env, $DB_HOME,
75	BDB::CREATE \| BDB::REGISTER \| BDB::RECOVER \| BDB::INIT_MPOOL \| BDB::INIT_LOCK \| BDB::INIT_TXN,
76	0666;
77
78	$! and die "cannot open database environment $DB_HOME: " . BDB::strerror;
79
80	$DB_ENV = $env;
81
82	1
83	}
84
85	sub table($) {
86	$DB_TABLE{$_[0]} \|\|= do {
87	my ($table) = @_;
88
89	$table =~ s/([^a-zA-Z0-9_\-])/sprintf "=%x=", ord $1/ge;
90
91	$DB_ENV#d#
92	or return ::clienterror ("trying to create table $_[0] with empty db_env $DB_ENV" => 1);#d#
93
94	my $db = db_create $DB_ENV;
95	$db->set_flags (BDB::CHKSUM);
96
97	db_open $db, undef, $table, undef, BDB::BTREE,
98	BDB::AUTO_COMMIT \| BDB::CREATE \| BDB::READ_UNCOMMITTED, 0666;
99
100	$! and "unable to open/create database table $_[0]: ". BDB::strerror;
101
102	$db
103	}
104	}
105
106	#############################################################################
107
108	our $WATCHER;
109	our $SYNC;
110	our $facemap;
111
112	sub exists($$$) {
113	my ($db, $key, $cb) = @_;
114
115	my $data;
116	db_get table $db, undef, $key, $data, 0, sub {
117	$cb->($! ? () : length $data);
118	};
119	}
120
121	sub get($$$) {
122	my ($db, $key, $cb) = @_;
123
124	my $data;
125	db_get table $db, undef, $key, $data, 0, sub {
126	$cb->($! ? () : $data);
127	};
128	}
129
130	sub put($$$$) {
131	my ($db, $key, $data, $cb) = @_;
132
133	db_put table $db, undef, $key, $data, 0, sub {
134	$cb->($!);
135	$SYNC->again unless $SYNC->is_active;
136	};
137	}
138
139	sub do_table {
140	my ($db, $cb) = @_;
141
142	$db = table $db;
143
144	my $cursor = $db->cursor;
145	my %kv;
146
147	for (;;) {
148	db_c_get $cursor, my $k, my $v, BDB::NEXT;
149	last if $!;
150	$kv{$k} = $v;
151	}
152
153	$cb->(\%kv);
154	}
155
156	sub do_get_tile_id {
157	my ($name, $cb) = @_;
158
159	my $table = table "facemap";
160	my $id;
161
162	db_get $table, undef, $name => $id, 0;
163	$! or return $cb->($id);
164
165	unless ($TILE_SEQ) {
166	$TILE_SEQ = $table->sequence;
167	$TILE_SEQ->initial_value (FIRST_TILE_ID);
168	$TILE_SEQ->set_cachesize (0);
169	db_sequence_open $TILE_SEQ, undef, "id", BDB::CREATE;
170	}
171
172	db_sequence_get $TILE_SEQ, undef, 1, my $id;
173
174	die "unable to allocate tile id: $!"
175	if $!;
176
177	db_put $table, undef, $name => $id, 0;
178	$cb->($id);
179
180	}
181
182	sub get_tile_id_sync($) {
183	my ($name) = @_;
184
185	$facemap->{$name} \|\|= do {
186	my $id;
187	do_get_tile_id $name, sub {
188	$id = $_[0];
189	};
190	BDB::flush;
191	$id
192	}
193	}
194
195	#############################################################################
196
197	sub path_of_res($) {
198	utf8::downgrade $_[0]; # bug in unpack "H*"
199	"$DB_HOME/res-data-" . unpack "H*", $_[0]
200	}
201
202	sub sync {
203	# for debugging
204	#DC::DB::Server::req (sync => sub { });
205	DC::DB::Server::sync ();
206	}
207
208	sub unlink($$) {
209	DC::DB::Server::req (unlink => @_);
210	}
211
212	sub read_file($$) {
213	DC::DB::Server::req (read_file => @_);
214	}
215
216	sub write_file($$$) {
217	DC::DB::Server::req (write_file => @_);
218	}
219
220	sub prefetch_file($$$) {
221	DC::DB::Server::req (prefetch_file => @_);
222	}
223
224	sub logprint($$$) {
225	DC::DB::Server::req (logprint => @_);
226	}
227
228	#############################################################################
229
230	package DC::DB::Server;
231
232	use strict;
233
234	use EV ();
235	use Fcntl;
236
237	our %CB;
238	our $FH;
239	our $ID = "aaa0";
240	our ($fh_r_watcher, $fh_w_watcher);
241	our $sync_timer;
242	our $write_buf;
243	our $read_buf;
244
245	sub fh_write {
246	my $len = syswrite $FH, $write_buf;
247
248	substr $write_buf, 0, $len, "";
249
250	$fh_w_watcher->stop
251	unless length $write_buf;
252	}
253
254	sub fh_read {
255	my $status = sysread $FH, $read_buf, 16384, length $read_buf;
256
257	die "FATAL: database process died\n"
258	if $status == 0 && defined $status;
259
260	while () {
261	return if 4 > length $read_buf;
262	my $len = unpack "N", $read_buf;
263
264	return if $len + 4 > length $read_buf;
265
266	substr $read_buf, 0, 4, "";
267	my $res = Storable::thaw substr $read_buf, 0, $len, "";
268
269	my ($id, @args) = @$res;
270	(delete $CB{$id})->(@args);
271	}
272	}
273
274	sub sync {
275	# biggest mess evarr
276	my $fds; (vec $fds, fileno $FH, 1) = 1;
277
278	while (1 < scalar keys %CB) {
279	my $r = $fds;
280	my $w = length $write_buf ? $fds : undef;
281	select $r, $w, undef, undef;
282
283	fh_write if vec $w, fileno $FH, 1;
284	fh_read if vec $r, fileno $FH, 1;
285	}
286	}
287
288	sub req {
289	my ($type, @args) = @_;
290	my $cb = pop @args;
291
292	my $id = ++$ID;
293	$write_buf .= pack "N/a*", Storable::freeze [$id, $type, @args];
294	$CB{$id} = $cb;
295
296	$fh_w_watcher->start;
297	}
298
299	sub do_unlink {
300	unlink $_[0];
301	}
302
303	sub do_read_file {
304	my ($path) = @_;
305
306	utf8::downgrade $path;
307	open my $fh, "<:raw", $path
308	or return;
309	sysread $fh, my $buf, -s $fh;
310
311	$buf
312	}
313
314	sub do_write_file {
315	my ($path, $data) = @_;
316
317	utf8::downgrade $path;
318	utf8::downgrade $data;
319	open my $fh, ">:raw", $path
320	or return;
321	syswrite $fh, $data;
322	close $fh;
323
324	1
325	}
326
327	sub do_prefetch_file {
328	my ($path, $size) = @_;
329
330	utf8::downgrade $path;
331	open my $fh, "<:raw", $path
332	or return;
333	sysread $fh, my $buf, $size;
334
335	1
336	}
337
338	our %LOG_FH;
339
340	sub do_logprint {
341	my ($path, $line) = @_;
342
343	$LOG_FH{$path} \|\|= do {
344	open my $fh, ">>:utf8", $path
345	or warn "Couldn't open logfile $path: $!";
346
347	$fh->autoflush (1);
348
349	$fh
350	};
351
352	my ($sec, $min, $hour, $mday, $mon, $year) = localtime time;
353
354	my $ts = sprintf "%04d-%02d-%02d %02d:%02d:%02d",
355	$year + 1900, $mon + 1, $mday, $hour, $min, $sec;
356
357	print { $LOG_FH{$path} } "$ts $line\n"
358	}
359
360	sub run {
361	($FH, my $fh) = AnyEvent::Util::portable_socketpair
362	or die "unable to create database socketpair: $!";
363
364	my $oldfh = select $FH; $\| = 1; select $oldfh;
365	my $oldfh = select $fh; $\| = 1; select $oldfh;
366
367	my $pid = fork;
368
369	if (defined $pid && !$pid) {
370	local $SIG{QUIT} = "IGNORE";
371	local $SIG{__DIE__};
372	local $SIG{__WARN__};
373	eval {
374	close $FH;
375
376	while () {
377	4 == read $fh, my $len, 4
378	or last;
379	$len = unpack "N", $len;
380	$len == read $fh, my $req, $len
381	or die "unexpected eof while reading request";
382
383	$req = Storable::thaw $req;
384
385	my ($id, $type, @args) = @$req;
386	my $cb = DC::DB::Server->can ("do_$type")
387	or die "$type: unknown database request type\n";
388	my $res = pack "N/a*", Storable::freeze [$id, $cb->(@args)];
389	(syswrite $fh, $res) == length $res
390	or die "DB::write: $!";
391	}
392	};
393
394	my $error = $@;
395
396	eval {
397	Storable::store_fd [die => $error], $fh;
398	};
399
400	warn $error
401	if $error;
402
403	DC::_exit 0;
404	}
405
406	close $fh;
407	DC::fh_nonblocking $FH, 1;
408
409	$CB{die} = sub { die shift };
410
411	$fh_r_watcher = EV::io $FH, EV::READ , \&fh_read;
412	$fh_w_watcher = EV::io $FH, EV::WRITE, \&fh_write;
413	}
414
415	sub stop {
416	close $FH;
417	}
418
419	package DC::DB;
420
421	sub nuke_db {
422	File::Path::mkpath [$DB_HOME];
423	eval { File::Path::rmtree $DB_HOME };
424	}
425
426	sub open_db {
427	unless (eval { try_open_db }) {
428	warn "$@";#d#
429	eval { nuke_db };
430	try_open_db;
431	}
432
433	# fetch the full face table first
434	unless ($facemap) {
435	do_table facemap => sub {
436	$facemap = $_[0];
437	delete $facemap->{id};
438	my %maptile = reverse %$facemap;#d#
439	if ((scalar keys %$facemap) != (scalar keys %maptile)) {#d#
440	$facemap = { };#d#
441	DC::error "FATAL: facemap is not a 1:1 mapping, please report this and delete your $DB_HOME directory!\n";#d#
442	}#d#
443	};
444	}
445
446	$WATCHER = EV::io BDB::poll_fileno, EV::READ, \&BDB::poll_cb;
447	$SYNC = EV::timer_ns 0, 60, sub {
448	$_[0]->stop;
449	db_env_txn_checkpoint $DB_ENV, 0, 0, 0, sub { };
450	};
451	}
452
453	END {
454	db_env_txn_checkpoint $DB_ENV, 0, 0, 0
455	if $DB_ENV;
456
457	undef $TILE_SEQ;
458	%DB_TABLE = ();
459	undef $DB_ENV;
460	}
461
462	1;
463
464	=back
465
466	=head1 AUTHOR
467
468	Marc Lehmann <schmorp@schmorp.de>
469	http://home.schmorp.de/
470
471	=cut
472