File: Ace.pm

package info (click to toggle)
libace-perl 1.92-12
  • links: PTS, VCS
  • area: main
  • in suites: sid, trixie
  • size: 2,012 kB
  • sloc: perl: 7,763; ansic: 7,420; makefile: 81
file content (2231 lines) | stat: -rw-r--r-- 68,730 bytes parent folder | download | duplicates (4)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
package Ace;

use strict;
use Carp qw(croak carp cluck);
use Scalar::Util 'weaken';

use vars qw($VERSION @ISA @EXPORT @EXPORT_OK $Error $DEBUG_LEVEL);

use Data::Dumper;
use AutoLoader 'AUTOLOAD';
require Exporter;
use overload 
  '""'  => 'asString',
  'cmp' => 'cmp';

@ISA = qw(Exporter);

# Items to export into callers namespace by default.
@EXPORT = qw(STATUS_WAITING STATUS_PENDING STATUS_ERROR);

# Optional exports
@EXPORT_OK = qw(rearrange ACE_PARSE);
$VERSION = '1.92';

use constant STATUS_WAITING => 0;
use constant STATUS_PENDING => 1;
use constant STATUS_ERROR   => -1;
use constant ACE_PARSE      => 3;

use constant DEFAULT_PORT   => 200005;  # rpc server
use constant DEFAULT_SOCKET => 2005;    # socket server

require Ace::Iterator;
require Ace::Object;
eval qq{use Ace::Freesubs};  # XS file, may not be available

# Map database names to objects (to fix file-caching issue)
my %NAME2DB;

# internal cache of objects
my %MEMORY_CACHE;

my %DEFAULT_CACHE_PARAMETERS = (
				default_expires_in  => '1 day',
				auto_purge_interval => '12 hours',
				);

# Preloaded methods go here.
$Error = '';

# Pseudonyms and deprecated methods.
*list      = \&fetch;
*Ace::ERR  = *Error;

# now completely deprecated and gone
# *find_many = \&fetch_many;
# *models    = \&classes;

sub connect {
  my $class = shift;
  my ($host,$port,$user,$pass,$path,$program,
      $objclass,$timeout,$query_timeout,$database,
      $server_type,$url,$u,$p,$cache,$other);

  # one-argument single "URL" form
  if (@_ == 1) {
    return $class->connect(-url=>shift);
  }

  # multi-argument (traditional) form
  ($host,$port,$user,$pass,
   $path,$objclass,$timeout,$query_timeout,$url,$cache,$other) = 
     rearrange(['HOST','PORT','USER','PASS',
		'PATH',['CLASS','CLASSMAPPER'],'TIMEOUT',
		'QUERY_TIMEOUT','URL','CACHE'],@_);

  ($host,$port,$u,$pass,$p,$server_type) = $class->process_url($url) 
    or croak "Usage:  Ace->connect(-host=>\$host,-port=>\$port [,-path=>\$path]\n"
      if defined $url;

  if ($path) { # local database
    $server_type = 'Ace::Local';
  } else { # either RPC or socket server
    $host      ||= 'localhost';
    $user      ||= $u || '';
    $path      ||= $p || '';
    $port        ||= $server_type eq 'Ace::SocketServer' ? DEFAULT_SOCKET : DEFAULT_PORT;
    $query_timeout = 120 unless defined $query_timeout;
    $server_type ||= 'Ace::SocketServer' if $port <  100000;
    $server_type ||= 'Ace::RPC'          if $port >= 100000;
  }

  # we've normalized parameters, so do the actual connect
  eval "require $server_type" || croak "Module $server_type not loaded: $@";
  if ($path) {
    $database = $server_type->connect(-path=>$path,%$other);
  } else {
    $database = $server_type->connect($host,$port,$query_timeout,$user,$pass,%$other);
  }

  unless ($database) {
    $Ace::Error ||= "Couldn't open database";
    return;
  }

  my $contents = {
		  'database'=> $database,
		  'host'   => $host,
		  'port'   => $port,
		  'path'   => $path,
		  'class'  => $objclass || 'Ace::Object',
		  'timeout' => $query_timeout,
		  'user'    => $user,
		  'pass'    => $pass,
		  'other'  => $other,
		  'date_style' => 'java',
		  'auto_save' => 0,
		 };

  my $self = bless $contents,ref($class)||$class;

  $self->_create_cache($cache) if $cache;
  $self->name2db("$self",$self);
  return $self;
}

sub reopen {
  my $self = shift;
  return 1 if $self->ping;
  my $class = ref($self->{database});
  my $database;
  if ($self->{path}) {
    $database = $class->connect(-path=>$self->{path},%{$self->other});
  } else {
    $database = $class->connect($self->{host},$self->{port}, $self->{timeout},
				$self->{user},$self->{pass},%{$self->{other}});
  }
  unless ($database) {
    $Ace::Error = "Couldn't open database";
    return;
  }
  $self->{database} = $database;
  1;
}

sub class {
  my $self = shift;
  my $d = $self->{class};
  $self->{class} = shift if @_;
  $d;
}

sub class_for {
  my $self = shift;
  my ($class,$id) = @_;
  my $selected_class;

  if (my $selector = $self->class) {
    if (ref $selector eq 'HASH') {
      $selected_class = $selector->{$class} || $selector->{'_DEFAULT_'};
    }
    elsif ($selector->can('class_for')) {
      $selected_class = $selector->class_for($class,$id,$self);
    }
    elsif (!ref $selector) {
      $selected_class = $selector;
    }
    else {
      croak "$selector is neither a scalar, nor a HASH, nor an object that supports the class_for() method";  
    }
  }

  $selected_class ||= 'Ace::Object';

  eval "require $selected_class; 1;" || croak $@
    unless $selected_class->can('new');

  $selected_class;
}

sub process_url {
  my $class = shift;
  my $url = shift;
  my ($host,$port,$user,$pass,$path,$server_type) = ('','','','','','');

  if ($url) {  # look for host:port
    local $_ = $url;
    if (m!^rpcace://([^:]+):(\d+)$!) {  # rpcace://localhost:200005
      ($host,$port) = ($1,$2);
      $server_type = 'Ace::RPC';
    } elsif (m!^sace://([\w:]+)\@([^:]+):(\d+)$!) { # sace://user@localhost:2005
      ($user,$host,$port) = ($1,$2,$3);
      $server_type = 'Ace::SocketServer';
    } elsif (m!^sace://([^:]+):(\d+)$!) { # sace://localhost:2005
      ($host,$port) = ($1,$2);
      $server_type = 'Ace::SocketServer';
    } elsif (m!^tace:(/.+)$!) {           # tace:/path/to/database
      $path = $1;
      $server_type = 'Ace::Local';
    } elsif (m!^(/.+)$!) {                # /path/to/database
      $path = $1;
      $server_type = 'Ace::Local';
    } else {
      return;
    }
  }

  if ($user =~ /:/) {
    ($user,$pass) = split /:/,$user;
  }

  return ($host,$port,$user,$pass,$path,$server_type);  

}

# Return the low-level Ace::AceDB object
sub db {
  return $_[0]->{'database'};
}

# Fetch a model from the database.
# Since there are limited numbers of models, we cache
# the results internally.
sub model {
  my $self = shift;
  require Ace::Model;
  my $model       = shift;
  my $break_cycle = shift;  # for breaking cycles when following #includes
  my $key = join(':',$self,'MODEL',$model);
  $self->{'models'}{$model} ||= eval{$self->cache->get($key)};
  unless ($self->{models}{$model}) {
    $self->{models}{$model} =
      Ace::Model->new($self->raw_query("model \"$model\""),$self,$break_cycle);
    eval {$self->cache->set($key=>$self->{models}{$model})};
  }
  return $self->{'models'}{$model};
}

# cached get
# pass "1" for fill to get a full fill
# pass any other true value to get a tag fill
sub get {
  my $self = shift;
  my ($class,$name,$fill) = @_;

  # look in caches first
  my $obj = $self->memory_cache_fetch($class=>$name) 
    || $self->file_cache_fetch($class=>$name);
  return $obj if $obj;

  # _acedb_get() does the caching
  $obj = $self->_acedb_get($class,$name,$fill) or return;
  $obj;
}

sub _acedb_get {
  my $self = shift;
  my ($class,$name,$filltag) = @_;
  return unless $self->count($class,$name) >= 1;

  #return $self->{class}->new($class,$name,$self,1) unless $filltag;
  return ($self->_list)[0] unless $filltag;

  if (defined $filltag && $filltag eq '1') {  # full fill
    return $self->_fetch();
  } else {
    return $self->_fetch(undef,undef,$filltag);
  }
}


#### CACHE AND CARRY CODE ####
# Be very careful here.  The key used for the memory cache is in the format
# db:class:name, but the key used for the file cache is in the format class:name.
# The difference is that the filecache has a built-in namespace but the memory
# cache doesn't.
sub memory_cache_fetch {
  my $self = shift;
  my ($class,$name) = @_;
  my $key = join ":",$self,$class,$name;
  return unless defined $MEMORY_CACHE{$key};
  carp "memory_cache hit on $class:$name"
    if Ace->debug;
  return $MEMORY_CACHE{$key};
}

sub memory_cache_store {
  my $self = shift;
  croak "Usage: memory_cache_store(\$obj)" unless @_ == 1;
  my $obj = shift;
  my $key = join ':',$obj->db,$obj->class,$obj->name;
  return if exists $MEMORY_CACHE{$key};
  carp "memory_cache store on ",$obj->class,":",$obj->name if Ace->debug;
  weaken($MEMORY_CACHE{$key} = $obj);
}

sub memory_cache_clear {
    my $self = shift;
    %MEMORY_CACHE = ();
}

sub memory_cache_delete {
  my $package = shift;
  my $obj = shift or croak "Usage: memory_cache_delete(\$obj)";
  my $key = join ':',$obj->db,$obj->class,$obj->name;
  delete $MEMORY_CACHE{$key};
}

# Call as:
# $ace->file_cache_fetch($class=>$id)
sub file_cache_fetch {
  my $self = shift;
  my ($class,$name) = @_;
  my $key = join ':',$class,$name;
  my $cache = $self->cache or return;
  my $obj   = $cache->get($key);
  if ($obj && !exists $obj->{'.root'}) {  # consistency checks
    require Data::Dumper;
    warn "CACHE BUG! Discarding inconsistent object $obj\n";
    warn Data::Dumper->Dump([$obj],['obj']);
    $cache->remove($key);
    return;
  }
  warn "cache ",$obj?'hit':'miss'," on '$key'\n" if Ace->debug;
  $self->memory_cache_store($obj) if $obj;
  $obj;
}

# call as
# $ace->file_cache_store($obj);
sub file_cache_store {
  my $self = shift;
  my $obj  = shift;

  return unless $obj->name;

  my $key = join ':',$obj->class,$obj->name;
  my $cache = $self->cache or return;

  warn "caching $key obj=",overload::StrVal($obj),"\n" if Ace->debug;
  if ($key eq ':') {  # something badly wrong
    cluck "NULL OBJECT";
  }
  $cache->set($key,$obj);
}

sub file_cache_delete {
  my $self = shift;
  my $obj = shift;
  my $key = join ':',$obj->class,$obj->name;
  my $cache = $self->cache or return;

  carp "deleting $key obj=",overload::StrVal($obj),"\n" if Ace->debug;
  $cache->remove($key,$obj);
}

#### END: CACHE AND CARRY CODE ####


# Fetch one or a group of objects from the database
sub fetch {
  my $self = shift;
  my ($class,$pattern,$count,$offset,$query,$filled,$total,$filltag) =  
    rearrange(['CLASS',['NAME','PATTERN'],'COUNT','OFFSET','QUERY',
	       ['FILL','FILLED'],'TOTAL','FILLTAG'],@_);

  if (defined $class
      && defined $pattern
      && $pattern !~ /[\?\*]/
#      && !wantarray
     )  {
    return $self->get($class,$pattern,$filled);
  }

  $offset += 0;
  $pattern ||= '*';
  $pattern = Ace->freeprotect($pattern);
  if (defined $query) {
    $query = "query $query" unless $query=~/^query\s/;
  } elsif (defined $class) {
    $query = qq{find $class $pattern};
  } else {
    croak "must call fetch() with the -class or -query arguments";
  }


  my $r = $self->raw_query($query);

  my ($cnt) = $r =~ /Found (\d+) objects/m;
  $$total = $cnt if defined $total;

  # Scalar context and a pattern match operation.  Return the
  # object count without bothering to fetch the objects
  return $cnt if !wantarray and $pattern =~ /(?:[^\\]|^)[*?]/;

  my(@h);
  if ($filltag) {
    @h = $self->_fetch($count,$offset,$filltag);
  } else {
    @h = $filled ? $self->_fetch($count,$offset) : $self->_list($count,$offset);
  }

  return wantarray ? @h : $h[0];
}

sub cache    { 
  my $self = shift;
  my $d    = $self->{filecache};
  $self->{filecache} = shift if @_;
  $d;
}

sub _create_cache {
  my $self   = shift;
  my $params = shift;
  $params    = {} if $params and !ref $params;

  return unless eval {require Cache::SizeAwareFileCache};  # not installed

  (my $namespace = "$self") =~ s!/!_!g;
  my %cache_params = (
		      namespace    => $namespace,
		      %DEFAULT_CACHE_PARAMETERS,
		      %$params,
		     );
  my $cache_obj = Cache::SizeAwareFileCache->new(\%cache_params);
  $self->cache($cache_obj);
}

# class method
sub name2db {
  shift;
  my $name = shift;
  return unless defined $name;
  my $d = $NAME2DB{$name};
  # weaken($NAME2DB{$name} = shift) if @_;
  $NAME2DB{$name} = shift if @_;
  $d;
}

# make a new object using indicated class and name pattern
sub new {
  my $self = shift;
  my ($class,$pattern) = rearrange([['CLASS'],['NAME','PATTERN']],@_);
  croak "You must provide -class and -pattern arguments" 
    unless $class && $pattern;
  # escape % signs in the string
  $pattern = Ace->freeprotect($pattern);
  $pattern =~ s/(?<!\\)%/\\%/g;
  my $r = $self->raw_query("new $class $pattern");
  if (defined($r) and $r=~/write access/im) {  # this keeps changing
    $Ace::Error = "Write access denied";
    return;
  }

  unless ($r =~ /($class)\s+\"([^\"]+)\"$/im) {
    $Ace::Error = $r;
    return;
  }
  $self->fetch($1 => $2);
}

# perform an AQL query
sub aql {
  my $self = shift;
  my $query = shift;
  my $db = $self->db;
  my $r = $self->raw_query("aql -j $query");
  if ($r =~ /(AQL error.*)/) {
    $self->error($1);
    return;
  }
  my @r;
  foreach (split "\n",$r) {
    next if m!^//!;
    next if m!^\0!;
    my ($class,$id) = Ace->split($_);
    my @objects = map { $self->class_for($class,$id)->new(Ace->split($_),$self,1)} split "\t";
    push @r,\@objects;
  }
  return @r;
}

# Return the contents of a keyset.  Pattern matches are allowed, in which case
# the keysets will be merged.
sub keyset {
  my $self = shift;
  my $pattern = shift;
  $self->raw_query (qq{find keyset "$pattern"});
  $self->raw_query (qq{follow});
  return $self->_list;
}


#########################################################
# These functions are for low-level (non OO) access only.
# This is for low-level access only.
sub show {
    my ($self,$class,$pattern,$tag) = @_;
    $Ace::Error = '';
    return unless $self->count($class,$pattern);

    # if we get here, then we've got some data to return.
    my @result;
    my $ts = $self->{'timestamps'} ? '-T' : '';
    $self->{database}->query("show -j $ts $tag");
    my $result = $self->read_object;
    unless ($result =~ /(\d+) object dumped/m) {
	$Ace::Error = 'Unexpected close during show';
	return;
    }
    return grep (!m!^//!,split("\n\n",$result));
}

sub read_object {
    my $self = shift;
    return unless $self->{database};
    my $result;
    while ($self->{database}->status == STATUS_PENDING()) {
      my $data = $self->{database}->read();
#      $data =~ s/\0//g;  # get rid of nulls in the buffer
      $result .= $data if defined $data;
    }
    return $result;
}

# do a query, and return the result immediately
sub raw_query {
  my ($self,$query,$no_alert,$parse) = @_;
  $self->_alert_iterators unless $no_alert;
  $self->{database}->query($query, $parse ? ACE_PARSE : () );
  return $self->read_object;
}

# return the last error
sub error {
  my $class = shift;
  $Ace::Error = shift() if defined($_[0]);
  $Ace::Error=~s/\0//g;  # get rid of nulls
  return $Ace::Error;
}

# close the database
sub close {
  my $self = shift;
  $self->raw_query('save') if $self->auto_save;
  foreach (keys %{$self->{iterators}}) {
    $self->_unregister_iterator($_);
  }
  delete $self->{database};
}

sub DESTROY { 
  my $self = shift;
  return if caller() =~ /^Cache\:\:/;
  warn "$self->DESTROY at ", join ' ',caller() if Ace->debug;
  $self->close;
}


#####################################################################
###################### private routines #############################
sub rearrange {
    my($order,@param) = @_;
    return unless @param;
    my %param;

    if (ref $param[0] eq 'HASH') {
      %param = %{$param[0]};
    } else {
      return @param unless (defined($param[0]) && substr($param[0],0,1) eq '-');

      my $i;
      for ($i=0;$i<@param;$i+=2) {
        $param[$i]=~s/^\-//;     # get rid of initial - if present
        $param[$i]=~tr/a-z/A-Z/; # parameters are upper case
      }

      %param = @param;                # convert into associative array
    }

    my(@return_array);

    local($^W) = 0;
    my($key)='';
    foreach $key (@$order) {
        my($value);
        if (ref($key) eq 'ARRAY') {
            foreach (@$key) {
                last if defined($value);
                $value = $param{$_};
                delete $param{$_};
            }
        } else {
            $value = $param{$key};
            delete $param{$key};
        }
        push(@return_array,$value);
    }
    push (@return_array,\%param) if %param;
    return @return_array;
}

# do a query, but don't return the result
sub _query {
  my ($self,@query) = @_;
  $self->_alert_iterators;
  $self->{'database'}->query("@query");
}

# return a portion of the active list
sub _list {
  my $self = shift;
  my ($count,$offset) = @_;
  my (@result);
  my $query = 'list -j';
  $query .= " -b $offset" if defined $offset;
  $query .= " -c $count"  if defined $count;
  my $result = $self->raw_query($query);
  $result =~ s/\0//g;  # get rid of &$#&@( nulls
  foreach (split("\n",$result)) {
    my ($class,$name) = Ace->split($_);
    next unless $class and $name;
    my $obj = $self->memory_cache_fetch($class,$name);
    $obj  ||= $self->file_cache_fetch($class,$name);
    unless ($obj) {
      $obj = $self->class_for($class,$name)->new($class,$name,$self,1);
      $self->memory_cache_store($obj);
      $self->file_cache_store($obj);
    }
    push @result,$obj;
  }
  return @result;
}

# return a portion of the active list
sub _fetch {
  my $self = shift;
  my ($count,$start,$tag) = @_;
  my (@result);
  $tag = '' unless defined $tag;
  my $query = "show -j $tag";
  $query .= ' -T' if $self->{timestamps};
  $query .= " -b $start"  if defined $start;
  $query .= " -c $count"  if defined $count;
  $self->{database}->query($query);
  while (my @objects = $self->_fetch_chunk) {
    push (@result,@objects);
  }
  # copy tag into a portion of the tree
  if ($tag) {
    for my $tree (@result) {
      my $obj = $self->class_for($tree->class,$tree->name)->new($tree->class,$tree->name,$self,1);
      $obj->_attach_subtree($tag=>$tree);
      $tree = $obj;
    }
  }
  # now recache 'em
  for (@result) {
    if (my $obj = $self->memory_cache_store($_)) {
      %$obj = %$_ unless $obj->filled;  # contents copy -- replace partial object with full object
      $_ = $obj;
    } else {
      $self->memory_cache_store($_);
    }
  }
  return wantarray ? @result : $result[0];
}

sub _fetch_chunk {
  my $self = shift;
  return unless $self->{database}->status == STATUS_PENDING();
  my $result = $self->{database}->read();
  $result =~ s/\0//g;  # get rid of &$#&@!! nulls
  my @chunks = split("\n\n",$result);
  my @result;
  foreach (@chunks) {
    next if m!^//!;
    next unless /\S/;  # occasional empty lines
    my ($class,$id) = Ace->split($_); # /^\?([^?]+)\?([^?]+)\?/m;
    push(@result,$self->class_for($class,$id)->newFromText($_,$self));
  }
  return @result;
}

sub _alert_iterators {
  my $self = shift;
  foreach (keys %{$self->{iterators}}) {
    $self->{iterators}{$_}->invalidate if $self->{iterators}{$_};
  }
  undef $self->{active_list};
}

sub asString {
  my $self = shift;
  return "tace://$self->{path}" if $self->{'path'};
  my $server = $self->db && $self->db->isa('Ace::SocketServer') ? 'sace' : 'rpcace';
  return "$server://$self->{host}:$self->{port}" if $self->{'host'};
  return ref $self;
}

sub cmp {
  my ($self,$arg,$reversed) = @_;
  my $cmp;
  if (ref($arg) and $arg->isa('Ace')) {
    $cmp = $self->asString cmp $arg->asString;
  } else {
    $cmp = $self->asString cmp $arg;
  }
  return $reversed ? -$cmp : $cmp;
}


# Count the objects matching pattern without fetching them.
sub count {
  my $self = shift;
  my ($class,$pattern,$query) = rearrange(['CLASS',
					   ['NAME','PATTERN'],
					   'QUERY'],@_);
  $Ace::Error = '';

  # A special case occurs when we have already fetched this
  # object and it is already on the active list.  In this
  # case, we do not need to recount.
  $query   = '' unless defined $query;
  $pattern = '' unless defined $pattern;
  $class   = '' unless defined $class;

  my $active_tag = "$class$pattern$query";
  if (defined $self->{'active_list'} &&
      defined ($self->{'active_list'}->{$active_tag})) {
    return $self->{'active_list'}->{$active_tag};
  }

  if ($query) {
    $query = "query $query" unless $query=~/^query\s/;
  } else {
    $pattern =~ tr/\n//d;
    $pattern ||= '*';
    $pattern = Ace->freeprotect($pattern);
    $query = "find $class $pattern";
  }
  my $result = $self->raw_query($query);
#  unless ($result =~ /Found (\d+) objects/m) {
  unless ($result =~ /(\d+) Active Objects/m) {
    $Ace::Error = 'Unexpected close during find';
    return;
  }
  return $self->{'active_list'}->{$active_tag} = $1;
}

1;

__END__

=head1 NAME

Ace - Object-Oriented Access to ACEDB Databases

=head1 SYNOPSIS

    use Ace;
    # open a remote database connection
    $db = Ace->connect(-host => 'beta.crbm.cnrs-mop.fr',
                       -port => 20000100);

    # open a local database connection
    $local = Ace->connect(-path=>'~acedb/my_ace');

    # simple queries
    $sequence  = $db->fetch(Sequence => 'D12345');
    $count     = $db->count(Sequence => 'D*');
    @sequences = $db->fetch(Sequence => 'D*');
    $i         = $db->fetch_many(Sequence=>'*');  # fetch a cursor
    while ($obj = $i->next) {
       print $obj->asTable;
    }

    # complex queries
    $query = <<END;
    find Annotation Ready_for_submission ; follow gene ; 
    follow derived_sequence ; >DNA
    END
    @ready_dnas= $db->fetch(-query=>$query);

    $ready = $db->fetch_many(-query=>$query);
    while ($obj = $ready->next) {
        # do something with obj
    }

    # database cut and paste
    $sequence = $db->fetch(Sequence => 'D12345');
    $local_db->put($sequence);
    @sequences = $db->fetch(Sequence => 'D*');
    $local_db->put(@sequences);

    # Get errors
    print Ace->error;
    print $db->error;

=head1 DESCRIPTION

AcePerl provides an interface to the ACEDB object-oriented database.
Both read and write access is provided, and ACE objects are returned
as similarly-structured Perl objects.  Multiple databases can be
opened simultaneously.

You will interact with several Perl classes: I<Ace>, I<Ace::Object>,
I<Ace::Iterator>, I<Ace::Model>.  I<Ace> is the database accessor, and
can be used to open both remote Ace databases (running aceserver or
gifaceserver), and local ones.

I<Ace::Object> is the superclass for all objects returned from the
database.  I<Ace> and I<Ace::Object> are linked: if you retrieve an
Ace::Object from a particular database, it will store a reference to
the database and use it to fetch any subobjects contained within it.
You may make changes to the I<Ace::Object> and have those changes
written into the database.  You may also create I<Ace::Object>s from
scratch and store them in the database.

I<Ace::Iterator> is a utility class that acts as a database cursor for
long-running ACEDB queries.  I<Ace::Model> provides object-oriented
access to ACEDB's schema.

Internally, I<Ace> uses the I<Ace::Local> class for access to local
databases and I<Ace::AceDB> for access to remote databases.
Ordinarily you will not need to interact directly with either of these
classes.

=head1 CREATING NEW DATABASE CONNECTIONS

=head2 connect() -- multiple argument form

    # remote database
    $db = Ace->connect(-host  =>  'beta.crbm.cnrs-mop.fr',
                       -port  =>  20000100);

    # local (non-server) database
    $db = Ace->connect(-path  =>  '/usr/local/acedb);

Use Ace::connect() to establish a connection to a networked or local
AceDB database.  To establish a connection to an AceDB server, use the
B<-host> and/or B<-port> arguments.  For a local server, use the
B<-port> argument.  The database must be up and running on the
indicated host and port prior to connecting to an AceDB server.  The
full syntax is as follows:

    $db = Ace->connect(-host  =>  $host,
                       -port  =>  $port,
		       -path  =>  $database_path,
		       -program     => $local_connection_program
                       -classmapper =>  $object_class,
		       -timeout     => $timeout,
		       -query_timeout => $query_timeout
		       -cache        => {cache parameters},
		      );

The connect() method uses a named argument calling style, and
recognizes the following arguments:

=over 4

=item B<-host>, B<-port>

These arguments point to the host and port of an AceDB server.
AcePerl will use its internal compiled code to establish a connection
to the server unless explicitly overridden with the B<-program>
argument.

=item B<-path>

This argument indicates the path of an AceDB directory on the local
system.  It should point to the directory that contains the I<wspec>
subdirectory.  User name interpolations (~acedb) are OK.

=item B<-user>

Name of user to log in as (when using socket server B<only>).  If not
provided, will attempt an anonymous login.

=item B<-pass>

Password to log in with (when using socket server).

=item B<-url>

An Acedb URL that combines the server type, host, port, user and
password in a single string.  See the connect() method's "single
argument form" description.

=item B<-cache>

AcePerl can use the Cache::SizeAwareFileCache module to cache objects
to disk. This can result in dramatically increased performance in
environments such as web servers in which the same Acedb objects are
frequently reused.  To activate this mechanism, the
Cache::SizeAwareFileCache module must be installed, and you must pass
the -cache argument during the connect() call.

The value of -cache is a hash reference containing the arguments to be
passed to Cache::SizeAwareFileCache.  For example:

   -cache => {
              cache_root         => '/usr/tmp/acedb',
              cache_depth        => 4,
              default_expires_in => '1 hour'
              }

If not otherwise specified, the following cache parameters are assumed:

       Parameter               Default Value
       ---------               -------------
       namespace               Server URL (e.g. sace://localhost:2005)
       cache_root              /tmp/FileCache (dependent on system temp directory)
       default_expires_in      1 day
       auto_purge_interval     12 hours

By default, the cache is not size limited (the "max_size" property is
set to $NO_MAX_SIZE).  To adjust the size you may consider calling the
Ace object's cache() method to retrieve the physical cache and then
calling the cache object's limit_size($max_size) method from time to
time.  See L<Cache::SizeAwareFileCache> for more details.

=item B<-program>

By default AcePerl will use its internal compiled code calls to
establish a connection to Ace servers, and will launch a I<tace>
subprocess to communicate with local Ace databases.  The B<-program>
argument allows you to customize this behavior by forcing AcePerl to
use a local program to communicate with the database.  This argument
should point to an executable on your system.  You may use either a
complete path or a bare command name, in which case the PATH
environment variable will be consulted.  For example, you could force
AcePerl to use the I<aceclient> program to connect to the remote host
by connecting this way:

  $db = Ace->connect(-host => 'beta.crbm.cnrs-mop.fr',
                     -port => 20000100,
                     -program=>'aceclient');

=item B<-classmapper>

The optional B<-classmapper> argument (alias B<-class>) points to the
class you would like to return from database queries.  It is provided
for your use if you subclass Ace::Object.  For example, if you have
created a subclass of Ace::Object called Ace::Object::Graphics, you
can have the database return this subclass by default by connecting
this way:

  $db = Ace->connect(-host => 'beta.crbm.cnrs-mop.fr',
                     -port => 20000100,
	             -class=>'Ace::Object::Graphics');

The value of B<-class> can be a hash reference consisting of AceDB
class names as keys and Perl class names as values.  If a class name
does not exist in the hash, a key named _DEFAULT_ will be looked for.
If that does not exist, then Ace will default to Ace::Object.

The value of B<-class> can also be an object or a classname that
implements a class_for() method.  This method will receive three
arguments containing the AceDB class name, object ID and database
handle.  It should return a string indicating the perl class to
create.

=item B<-timeout>

If no response from the server is received within $timeout seconds,
the call will return an undefined value.  Internally timeout sets an
alarm and temporarily intercepts the ALRM signal.  You should be aware
of this if you use ALRM for your own purposes.

NOTE: this feature is temporarily disabled (as of version 1.40)
because it is generating unpredictable results when used with
Apache/mod_perl.

=item B<-query_timeout>

If any query takes longer than $query_timeout seconds, will return an
undefined value.  This value can only be set at connect time, and cannot
be changed once set.

=back

If arguments are omitted, they will default to the following values:

    -host          localhost
    -port          200005;
    -path          no default
    -program       tace
    -class         Ace::Object
    -timeout       25
    -query_timeout 120

If you prefer to use a more Smalltalk-like message-passing syntax, you
can open a connection this way too:

  $db = connect Ace -host=>'beta.crbm.cnrs-mop.fr',-port=>20000100;

The return value is an Ace handle to use to access the database, or
undef if the connection fails.  If the connection fails, an error
message can be retrieved by calling Ace->error.

You may check the status of a connection at any time with ping().  It
will return a true value if the database is still connected.  Note
that Ace will timeout clients that have been inactive for any length
of time.  Long-running clients should attempt to reestablish their 
connection if ping() returns false.

    $db->ping() || die "not connected";

You may perform low-level calls using the Ace client C API by calling
db().  This fetches an Ace::AceDB object.  See THE LOW LEVEL C API for
details on using this object.
 
    $low_level = $db->db();

=head2 connect() -- single argument form

  $db = Ace->connect('sace://stein.cshl.org:1880')

Ace->connect() also accepts a single argument form using a URL-type
syntax.  The general syntax is:

   protocol://hostname:port/path

The I<:port> and I</path> parts are protocol-dependent as described
above.

Protocols:

=over 4

=item sace://hostname:port

Connect to a socket server at the indicated hostname and port.  Example:

   sace://stein.cshl.org:1880

If not provided, the port defaults to 2005.

=item rpcace://hostname:port

Connect to an RPC server at the indicated hostname and RPC service number.  Example:

  rpcace://stein.cshl.org:400000

If not provided, the port defaults to 200005

=item tace:/path/to/database

Open up the local database at F</path/to/database> using tace.  Example:

  tace:/~acedb/elegans

=item /path/to/database

Same as the previous.

=back

=head2 close() Method

You can explicitly close a database by calling its close() method:

   $db->close();

This is not ordinarily necessary because the database will be
automatically close when it -- and all objects retrieved from it -- go
out of scope.

=head2 reopen() Method

The ACeDB socket server can time out.  The reopen() method will ping
the server and if it is not answering will reopen the connection.  If
the database is live (or could be resurrected), this method returns
true.

=head1 RETRIEVING ACEDB OBJECTS

Once you have established a connection and have an Ace databaes
handle, several methods can be used to query the ACE database to
retrieve objects.  You can then explore the objects, retrieve specific
fields from them, or update them using the I<Ace::Object> methods.
Please see L<Ace::Object>.

=head2 fetch() method

    $count   = $db->fetch($class,$name_pattern);
    $object  = $db->fetch($class,$name);
    @objects = $db->fetch($class,$name_pattern,[$count,$offset]);
    @objects = $db->fetch(-name=>$name_pattern,
                          -class=>$class
			  -count=>$count,
			  -offset=>$offset,
                          -fill=>$fill,
			  -filltag=>$tag,
	                  -total=>\$total);
    @objects = $db->fetch(-query=>$query);

Ace::fetch() retrieves objects from the database based on their class
and name.  You may retrieve a single object by requesting its name, or
a group of objects by fetching a name I<pattern>.  A pattern contains
one or more wildcard characters, where "*" stands for zero or more
characters, and "?" stands for any single character.

This method behaves differently depending on whether it is called in a
scalar or a list context, and whether it is asked to search for a name
pattern or a simple name.

When called with a class and a simple name, it returns the object
referenced by that time, or undef, if no such object exists.  In an
array context, it will return an empty list.

When called with a class and a name pattern in a list context, fetch()
returns the list of objects that match the name.  When called with a
pattern in a scalar context, fetch() returns the I<number> of objects
that match without actually retrieving them from the database.  Thus,
it is similar to count().

In the examples below, the first line of code will fetch the Sequence
object whose database ID is I<D12345>.  The second line will retrieve
all objects matching the pattern I<D1234*>.  The third line will
return the count of objects that match the same pattern.

   $object =  $db->fetch(Sequence => 'D12345');
   @objects = $db->fetch(Sequence => 'D1234*');
   $cnt =     $db->fetch(Sequence =>'D1234*');

A variety of communications and database errors may occur while
processing the request.  When this happens, undef or an empty list
will be returned, and a string describing the error can be retrieved
by calling Ace->error.

When retrieving database objects, it is possible to retrieve a
"filled" or an "unfilled" object.  A filled object contains the entire
contents of the object, including all tags and subtags.  In the case
of certain Sequence objects, this may be a significant amount of data.
Unfilled objects consist just of the object name.  They are filled in
from the database a little bit at a time as tags are requested.  By
default, fetch() returns the unfilled object.  This is usually a
performance win, but if you know in advance that you will be needing
the full contents of the retrieved object (for example, to display
them in a tree browser) it can be more efficient to fetch them in
filled mode. You do this by calling fetch() with the argument of
B<-fill> set to a true value.

The B<-filltag> argument, if provided, asks the database to fill in
the subtree anchored at the indicated tag.  This will improve
performance for frequently-accessed subtrees.  For example:

   @objects = $db->fetch(-name    => 'D123*',
                         -class   => 'Sequence',
                         -filltag => 'Visible');

This will fetch all Sequences named D123* and fill in their Visible
trees in a single operation.

Other arguments in the named parameter calling form are B<-count>, to
retrieve a certain maximum number of objects, and B<-offset>, to
retrieve objects beginning at the indicated offset into the list.  If
you want to limit the number of objects returned, but wish to learn
how many objects might have been retrieved, pass a reference to a
scalar variable in the B<-total> argument.  This will return the
object count.  This example shows how to fetch 100 Sequence
objects, starting at Sequence number 500:

  @some_sequences = $db->fetch('Sequence','*',100,500);

The next example uses the named argument form to fetch 100 Sequence
objects starting at Sequence number 500, and leave the total number of
Sequences in $total:

  @some_sequences = $db->fetch(-class  => 'Sequence',
	                       -count  => 100,
	                       -offset => 500,
	                       -total  => \$total);

Notice that if you leave out the B<-name> argument the "*" wildcard is 
assumed.

You may also pass an arbitrary Ace query string with the B<-query>
argument.  This will supersede any name and class you provide.
Example: 

  @ready_dnas= $db->fetch(-query=>
      'find Annotation Ready_for_submission ; follow gene ; 
       follow derived_sequence ; >DNA');

If your request is likely to retrieve very many objects, fetch() many
consume a lot of memory, even if B<-fill> is false.  Consider using
B<fetch_many()> instead (see below).  Also see the get() method, which
is equivalent to the simple two-argument form of fetch().

=item get() method

   $object = $db->get($class,$name [,$fill]);

The get() method will return one and only one AceDB object
identified by its class and name.  The optional $fill argument can be
used to control how much data is retrieved from the database. If $fill
is absent or undefined, then the method will return a lightweight
"stub" object that is filled with information as requested in a lazy
fashion. If $fill is the number "1" then the retrieved object contains
all the relevant information contained within the database.  Any other
true value of $fill will be treated as a tag name: the returned object
will be prefilled with the subtree to the right of that tag.

Examples:

   # return lightweight stub for Author object "Sulston JE."
   $author = $db->get(Author=>'Sulston JE');

   # return heavyweight object
   $author = $db->get(Author=>'Sulston JE',1);

   # return object containing the Address subtree
   $author = $db->get(Author=>'Sulston JE','Address');

The get() method is equivalent to this form of the fetch()
method:

   $object = $db->fetch($class=>$name);

=head2 aql() method

    $count   = $db->aql($aql_query);
    @objects = $db->aql($aql_query);

Ace::aql() will perform an AQL query on the database.  In a scalar
context it returns the number of rows returned.  In an array context
it returns a list of rows.  Each row is an anonymous array containing
the columns returned by the query as an Ace::Object.

If an AQL error is encountered, will return undef or an empty list and
set Ace->error to the error message.

Note that this routine is not optimized -- there is no iterator
defined.  All results are returned synchronously, leading to large
memory consumption for certain queries.

=head2 put() method

   $cnt = $db->put($obj1,$obj2,$obj3);

This method will put the list of objects into the database,
overwriting like-named objects if they are already there.  This can
be used to copy an object from one database to another, provided that
the models are compatible.

The method returns the count of objects successfully written into the
database.  In case of an error, processing will stop at the last
object successfully written and an error message will be placed in
Ace->error();

=head2 parse() method

  $object = $db->parse('data to parse');

This will parse the Ace tags contained within the "data to parse"
string, convert it into an object in the database, and return the
resulting Ace::Object.  In case of a parse error, the undefined value
will be returned and a (hopefully informative) description of the
error will be returned by Ace->error().

For example:

  $author = $db->parse(<<END);
  Author : "Glimitz JR"
  Full_name "Jonathan R. Glimitz"
  Mail	"128 Boylston Street"
  Mail	"Boston, MA"
  Mail	"USA"
  Laboratory GM
  END

This method can also be used to parse several objects, but only the
last object successfully parsed will be returned.

=head2 parse_longtext() method

  $object = $db->parse($title,$text);

This will parse the long text (which may contain carriage returns and
other funny characters) and place it into the database with the given
title.  In case of a parse error, the undefined value will be returned
and a (hopefully informative) description of the error will be
returned by Ace->error(); otherwise, a LongText object will be returned.

For example:

  $author = $db->parse_longtext('A Novel Inhibitory Domain',<<END);
  We have discovered a novel inhibitory domain that inhibits
  many classes of proteases, including metallothioproteins.
  This inhibitory domain appears in three different gene families studied
  to date...
  END

=head2 parse_file() method

  @objects = $db->parse_file('/path/to/file');
  @objects = $db->parse_file('/path/to/file',1);

This will call parse() to parse each of the objects found in the
indicated .ace file, returning the list of objects successfully loaded
into the database.

By default, parsing will stop at the first object that causes a parse
error.  If you wish to forge on after an error, pass a true value as
the second argument to this method.

Any parse error messages are accumulated in Ace->error().

=head2 new() method

  $object = $db->new($class => $name);

This method creates a new object in the database of type $class and
name $name.  If successful, it returns the newly-created object.
Otherwise it returns undef and sets $db->error().

$name may contain sprintf()-style patterns.  If one of the patterns is
%d (or a variant), Acedb uses a class-specific unique numbering to return
a unique name.  For example:

  $paper = $db->new(Paper => 'wgb%06d');

The object is created in the database atomically.  There is no chance to rollback as there is
in Ace::Object's object editing methods.

See also the Ace::Object->add() and replace() methods.

=head2 list() method

    @objects = $db->list(class,pattern,[count,offset]);
    @objects = $db->list(-class=>$class,
                         -name=>$name_pattern,
                         -count=>$count,
                         -offset=>$offset);

This is a deprecated method.  Use fetch() instead.

=head2 count() method

    $count = $db->count($class,$pattern);
    $count = $db->count(-query=>$query);

This function queries the database for a list of objects matching the
specified class and pattern, and returns the object count.  For large
sets of objects this is much more time and memory effective than
fetching the entire list.

The class and name pattern are the same as the list() method above.

You may also provide a B<-query> argument to instead specify an
arbitrary ACE query such as "find Author COUNT Paper > 80".  See
find() below.

=head2 find() method

    @objects = $db->find($query_string);
    @objects = $db->find(-query => $query_string,
                         -offset=> $offset,
                         -count => $count
                         -fill  => $fill);

This allows you to pass arbitrary Ace query strings to the server and
retrieve all objects that are returned as a result.  For example, this
code fragment retrieves all papers written by Jean and Danielle
Thierry-Mieg.

    @papers = $db->find('author IS "Thierry-Mieg *" ; >Paper');

You can find the full query syntax reference guide plus multiple
examples at http://probe.nalusda.gov:8000/acedocs/index.html#query.

In the named parameter calling form, B<-count>, B<-offset>, and
B<-fill> have the same meanings as in B<fetch()>.

=head2 fetch_many() method

    $obj = $db->fetch_many($class,$pattern);

    $obj = $db->fetch_many(-class=>$class,
                           -name =>$pattern,
                           -fill =>$filled,
                           -chunksize=>$chunksize);

    $obj = $db->fetch_many(-query=>$query);

If you expect to retrieve many objects, you can fetch an iterator
across the data set.  This is friendly both in terms of network
bandwidth and memory consumption.  It is simple to use:

    $i = $db->fetch_many(Sequence,'*');  # all sequences!!!!
    while ($obj = $i->next) {
       print $obj->asTable;
    }

The iterator will return undef when it has finished iterating, and
cannot be used again.  You can have multiple iterators open at once
and they will operate independently of each other.

Like B<fetch()>, B<fetch_many()> takes an optional B<-fill> (or
B<-filled>) argument which retrieves the entire object rather than
just its name.  This is efficient on a network with high latency if 
you expect to be touching many parts of the object (rather than
just retrieving the value of a few tags).

B<fetch_many()> retrieves objects from the database in groups of a
certain maximum size, 40 by default.  This can be tuned using the
optional B<-chunksize> argument.  Chunksize is only a hint to the
database.  It may return fewer objects per transaction, particularly
if the objects are large.

You may provide raw Ace query string with the B<-query> argument.  If
present the B<-name> and B<-class> arguments will be ignored.

=head2 find_many() method

This is an alias for fetch_many().  It is now deprecated.

=head2 keyset() method

    @objects = $db->keyset($keyset_name);

This method returns all objects in a named keyset.  Wildcard
characters are accepted, in which case all keysets that match the
pattern will be retrieved and merged into a single list of unique
objects.

=head2 grep() method

    @objects = $db->grep($grep_string);
    $count   = $db->grep($grep_string);
    @objects = $db->grep(-pattern => $grep_string,
                         -offset=> $offset,
                         -count => $count,
                         -fill  => $fill,
                         -filltag => $filltag,
			 -total => \$total,
                         -long  => 1,
			);

This performs a "grep" on the database, returning all object names or
text that contain the indicated grep pattern.  In a scalar context
this call will return the number of matching objects.  In an array
context, the list of matching objects are retrieved.  There is also a
named-parameter form of the call, which allows you to specify the
number of objects to retrieve, the offset from the beginning of the
list to retrieve from, whether the retrieved objects should be filled
initially.  You can use B<-total> to discover the total number of
objects that match, while only retrieving a portion of the list.

By default, grep uses a fast search that only examines class names and
lexiques.  By providing a true value to the B<-long> parameter, you
can search inside LongText and other places that are not usually
touched on, at the expense of much more CPU time.

Due to "not listable" objects that may match during grep, the list of
objects one can retrieve may not always match the count.

=head2 model() method

  $model = $db->model('Author');

This will return an I<Ace::Model> object corresponding to the
indicated class.

=head2 new() method

   $obj = $db->new($class,$name);
   $obj = $db->new(-class=>$class,
                   -name=>$name);

Create a new object in the database with the indicated class and name
and return a pointer to it.  Will return undef if the object already
exists in the database.  The object isn't actually written into the database
until you call Ace::Object::commit().

=head2 raw_query() method

    $r = $db->raw_query('Model');

Send a command to the database and return its unprocessed output.
This method is necessary to gain access to features that are not yet
implemented in this module, such as model browsing and complex
queries.

=head2 classes() method

   @classes = $db->classes();
   @all_classes = $db->classes(1);

This method returns a list of all the object classes known to the
server.  In a list context it returns an array of class names.  In a
scalar context, it the number of classes defined in the database.

Ordinarily I<classes()> will return only those classes that are
exposed to the user interface for browsing, the so-called "visible"
classes.  Pass a true argument to the call to retrieve non-visible
classes as well.

=head2 class_count() method

   %classes = $db->class_count()

This returns a hash in which the keys are the class names and the
values are the total number of objects in that class.  All classes
are returned, including invisible ones.  Use this method if you need
to count all classes simultaneously.  If you only want to count one
or two classes, it may be more efficient to call I<count($class_name)>
instead.

This method transiently uses a lot of memory.  It should not be used
with Ace 4.5 servers, as they contain a memory leak in the counting
routine.

=head2 status() method

    %status = $db->status;
    $status = $db->status;

Returns various bits of status information from the server.  In an
array context, returns a hash of hashes.  In a scalar context, returns a
reference to a hash of hashes.  Keys and subkeys are as follows

   code
           program     name of acedb binary
           version     version of acedb binary
           build       build date of acedb binary in format Jan 25 2003 16:21:24

   database
           title       name of the database
           version     version of the database
           dbformat    database format version number
           directory   directory in which the database is stored
           session     session number
           user        user under which server is running
           write       whether the server has write access
           address     global address - not known if this is useful

   resources
           classes     number of classes defined
           keys        number of keys defined
           memory      amount of memory used by acedb objects (bytes)

For example, to get the program version:

   my $version = $db->status->{code}{version};

=head2 title() method

    my $title = $db->title

Returns the version of the current database, equivalent
to $db->status->{database}{title};

=head2 version() method

    my $version = $db->version;

Returns the version of the current database, equivalent 
to $db->status->{database}{version};

=head2 date_style() method

  $style = $db->date_style();
  $style = $db->date_style('ace');
  $style = $db->date_style('java');

For historical reasons, AceDB can display dates using either of two
different formats.  The first format, which I call "ace" style, puts
the year first, as in "1997-10-01".  The second format, which I call
"java" style, puts the day first, as in "01 Oct 1997 00:00:00" (this
is also the style recommended for Internet dates).  The default is to
use the latter notation.

B<date_style()> can be used to set or retrieve the current style.
Called with no arguments, it returns the current style, which will be
one of "ace" or "java."  Called with an argument, it will set the
style to one or the other.

=head2 timestamps() method

  $timestamps_on = $db->timestamps();
  $db->timestamps(1);

Whenever a data object is updated, AceDB records the time and date of
the update, and the user ID it was running under.  Ordinarily, the
retrieval of timestamp information is suppressed to conserve memory
and bandwidth.  To turn on timestamps, call the B<timestamps()> method 
with a true value.  You can retrieve the current value of the setting
by calling the method with no arguments.

Note that activating timestamps disables some of the speed
optimizations in AcePerl.  Thus they should only be activated if you
really need the information.

=head2 auto_save()

Sets or queries the I<auto_save> variable.  If true, the "save"
command will be issued automatically before the connection to the
database is severed.  The default is true.

Examples:

   $db->auto_save(1);
   $flag = $db->auto_save;

=head2 error() method

    Ace->error;

This returns the last error message.  Like UNIX errno, this variable
is not reset between calls, so its contents are only valid after a
method call has returned a result value indicating a failure.

For your convenience, you can call error() in any of several ways:

    print Ace->error();
    print $db->error();  # $db is an Ace database handle
    print $obj->error(); # $object is an Ace::Object

There's also a global named $Ace::Error that you are free to use.

=head2 datetime() and date()

  $datetime = Ace->datetime($time);
  $today    = Ace->datetime();
  $date     = Ace->date($time);
  $today    = Ace->date([$time]);

These convenience functions convert the UNIX timestamp given by $time
(seconds since the epoch) into a datetime string in the format that
ACEDB requires.  date() will truncate the time portion.

If not provided, $time defaults to localtime().

=head1 OTHER METHODS

=head2 debug()

  $debug_level = Ace->debug([$new_level])

This class method gets or sets the debug level.  Higher integers
increase verbosity.  0 or undef turns off debug messages.

=head2 name2db()

 $db = Ace->name2db($name [,$database])

This class method associates a database URL with an Ace database
object. This is used internally by the Ace::Object class in order to
discover what database they "belong" to.

=head2 cache()

Get or set the Cache::SizeAwareFileCache object, if one has been
created.

=head2 memory_cache_fetch()

  $obj = $db->memory_cache_fetch($class,$name)

Given an object class and name return a copy of the object from the
in-memory cache.  The object will only be cached if a copy of the
object already exists in memory space.  This is ordinarily called
internally.

=head2 memory_cache_store($obj)

Store an object into the memory cache.  This is ordinarily called
internally.

=head2 memory_cache_delete($obj)

Delete an object from the memory cache. This is ordinarily called
internally.

=head2 memory_cache_clear()

Completely clears the memory cache.

=head2 file_cache_fetch()

  $obj = $db->file_cache_fetch($class,$name)

Given an object class and name return a copy of the object from the
file cache.  This is ordinarily called internally.

=head2 file_cache_store($obj)

Store an object into the file cache.  This is ordinarily called
internally.

=head2 file_cache_delete($obj)

Delete an object from the file cache.  This is ordinarily called
internally.

=head1 THE LOW LEVEL C API

Internally Ace.pm makes C-language calls to libace to send query
strings to the server and to retrieve the results.  The class that
exports the low-level calls is named Ace::AceDB.

The following methods are available in Ace::AceDB:

=over 4

=item new($host,$port,$query_timeout)

Connect to the host $host at port $port. Queries will time out after
$query_timeout seconds.  If timeout is not specified, it defaults to
120 (two minutes).

If successful, this call returns an Ace::AceDB connection object.
Otherwise, it returns undef.  Example:

  $acedb = Ace::AceDB->new('localhost',200005,5) 
           || die "Couldn't connect";

The Ace::AceDB object can also be accessed from the high-level Ace
interface by calling the ACE::db() method:

  $db = Ace->new(-host=>'localhost',-port=>200005);
  $acedb = $db->db();

=item query($request)

Send the query string $request to the server and return a true value
if successful.  You must then call read() repeatedly in order to fetch
the query result.

=item read()

Read the result from the last query sent to the server and return it
as a string.  ACE may return the result in pieces, breaking between
whole objects.  You may need to read repeatedly in order to fetch the
entire result.  Canonical example:

  $acedb->query("find Sequence D*");
  die "Got an error ",$acedb->error() if $acedb->status == STATUS_ERROR;
  while ($acedb->status == STATUS_PENDING) {
     $result .= $acedb->read;
  }

=item status()

Return the status code from the last operation.  Status codes are
exported by default when you B<use> Ace.pm.  The status codes you may
see are:

  STATUS_WAITING    The server is waiting for a query.
  STATUS_PENDING    A query has been sent and Ace is waiting for
                    you to read() the result.
  STATUS_ERROR      A communications or syntax error has occurred

=item error()

Returns a more detailed error code supplied by the Ace server.  Check
this value when STATUS_ERROR has been returned.  These constants are
also exported by default.  Possible values:

 ACE_INVALID
 ACE_OUTOFCONTEXT
 ACE_SYNTAXERROR
 ACE_UNRECOGNIZED

Please see the ace client library documentation for a full description
of these error codes and their significance.

=item encore()

This method may return true after you have performed one or more
read() operations, and indicates that there is more data to read.  You
will not ordinarily have to call this method.

=back

=head1 BUGS

1. The ACE model should be consulted prior to updating the database.

2. There is no automatic recovery from connection errors.

3. Debugging has only one level of verbosity, despite the best
of intentions.

4. Performance is poor when fetching big objects, because of 
many object references that must be created.  This could be
improved.

5. When called in an array context at("tag[0]") should return the
current tag's entire column.  It returns the current subtree instead.

6. There is no way to add comments to objects.

7. When timestamps are active, many optimizations are disabled. 

8. Item number eight is still missing.

=head1 SEE ALSO

L<Ace::Object>, L<Ace::Local>, L<Ace::Model>,
L<Ace::Sequence>,L<Ace::Sequence::Multi>.

=head1 AUTHOR

Lincoln Stein <lstein@cshl.org> with extensive help from Jean
Thierry-Mieg <mieg@kaa.crbm.cnrs-mop.fr>

Copyright (c) 1997-1998 Cold Spring Harbor Laboratory

This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.  See DISCLAIMER.txt for
disclaimers of warranty.

=cut

# -------------------- AUTOLOADED SUBS ------------------

sub debug {
  my $package = shift;
  my $d = $DEBUG_LEVEL;
  $DEBUG_LEVEL = shift if @_;
  $d;
}

# Return true if the database is still connected.  This is oddly convoluted
# because there are numerous things that can go wrong, including:
#   1. server has gone away
#   2. server has timed out our connection! (grrrrr)
#   3. communications channel contains unread garbage and is in an inconsistent state
sub ping {
  my $self = shift;
  local($SIG{PIPE})='IGNORE';  # so we don't get a fatal exception during the check
  my $result = $self->raw_query('');
  return unless $result;  # server has gone away
  return if $result=~/broken connection|client time out/;  # server has timed us out  
  return unless $self->{database}->status() == STATUS_WAITING(); #communications oddness
  return 1;
}

# Get or set the display style for dates
sub date_style {
  my $self = shift;
  $self->{'date_style'} = $_[0] if defined $_[0];
  return $self->{'date_style'};
}

# Get or set whether we retrieve timestamps
sub timestamps {
  my $self = shift;
  $self->{'timestamps'} = $_[0] if defined $_[0];
  return $self->{'timestamps'};
}

# Add one or more objects to the database
sub put {
  my $self = shift;
  my @objects = @_;
  my $count = 0;
  $Ace::Error = '';
  foreach my $object (@objects) {
    croak "Can't put a non-Ace object into an Ace database"
      unless $object->isa('Ace::Object');
    croak "Can't put a non-object into a database"
      unless $object->isObject;
    $object = $object->fetch unless $object->isRoot;  # make sure we're putting root object
    my $data = $object->asAce;
    $data =~ s/\n/; /mg;
    my $result = $self->raw_query("parse = $data");
    $Ace::Error = $result if $result =~ /sorry|parse error/mi;
    return $count if $Ace::Error;
    $count++;  # bump if succesful
  }
  return $count;
}

# Parse a single object and return the result as an object
sub parse {
  my $self = shift;
  my $ace_data = shift;
  my @lines = split("\n",$ace_data);
  foreach (@lines) { s/;/\\;/;  } # protect semicolons  
  my $query = join("; ",@lines);
  my $result = $self->raw_query("parse = $query");
  $Ace::Error = $result=~/sorry|parse error/mi ? $result : '';
  my @results = $self->_list(1,0);
  return $results[0];
}

# Parse a single object as longtext and return the result
# as an object
sub parse_longtext {
  my $self  = shift;
  my ($title,$body) = @_;
      my $mm = "parse =
Longtext $title
$body
***LongTextEnd***
" ;
  $mm =~ s/\//\\\//g ;
  $mm =~ s/\n/\\n/g ;
  $mm .= "\n" ;
  my $result = $self->raw_query($mm) ;
  $Ace::Error = $result=~/sorry|parse error/mi ? $result : '';
  my @results = $self->_list(1,0);
  return $results[0];
}


# Parse a file and return all the results
sub parse_file {
  my $self = shift;
  my ($file,$keepgoing) = @_;
  local(*ACE);
  local($/) = '';  # paragraph mode
  my(@objects,$errors);
  open(ACE,$file) || croak "$file: $!";
  while (<ACE>) {
    chomp;
    my $obj = $self->parse($_);
    unless ($obj) {
      $errors .= $Ace::Error;  # keep track of errors
      last unless $keepgoing;
    }
    push(@objects,$obj);
  }
  close ACE;
  $Ace::Error = $errors;
  return @objects;
}

# Create a new Ace::Object in the indicated database
# (doesn't actually write into database until you do a commit)
sub new {
  my $self = shift;
  my ($class,$name) = rearrange([qw/CLASS NAME/],@_);
  return if $self->fetch($class,$name);
  my $obj = $self->class_for($class,$name)->new($class,$name,$self);
  return $obj;
}

# Return the layout, which contains classes that should be displayed
sub layout {
  my $self = shift;
  my $result = $self->raw_query('layout');
  $result=~s{\n(\s*\n|//.*\n|\0)+\Z}{}m;  # get rid of extraneous information
  $result;
}

# Return a hash of all the classes and the number of objects in each
sub class_count {
  my $self = shift;
  return $self->raw_query('classes') =~ /^\s+(\S+) (\d+)/gm;
}

# Return a hash of miscellaneous status information from the server
# (to be expanded later)
sub status {
  my $self = shift;
  my $data = $self->raw_query('status');
  study $data;

  my %status;

  # -Code section
  my ($program)    = $data=~/Program:\s+(.+)/m;
  my ($aceversion) = $data=~/Version:\s+(.+)/m;
  my ($build)      = $data=~/Build:\s+(.+)/m;
  $status{code}    = { program=>$program,
		       version=>$aceversion,
		       build  =>$build};

  # -Database section
  my ($title)      = $data=~/Title:\s+(.+)/m;
  my ($name)       = $data=~/Name:\s+(.+)/m;
  my ($release)    = $data=~/Release:\s+(.+)/m;
  my ($directory)  = $data=~/Directory:\s+(.+)/m;
  my ($session)    = $data=~/Session:\s+(\d+)/m;
  my ($user)       = $data=~/User:\s+(.+)/m;
  my ($write)      = $data=~/Write Access:\s+(.+)/m;
  my ($address)    = $data=~/Global Address:\s+(\d+)/m;
  $status{database} = {
		       title     => $title,
		       version   => $name,
		       dbformat  => $release,
		       directory => $directory,
		       session   => $session,
		       user      => $user,
		       write     => $write,
		       address   => $address,
		       };

  # other info - not all
  my ($classes)   = $data=~/classes:\s+(\d+)/;
  my ($keys)      = $data=~/keys:\s+(\d+)/;
  my ($memory)    = $data=~/blocks:\s+\d+,\s+allocated \(kb\):\s+(\d+)/;
  $status{resources} = {
		      classes => $classes,
		      keys    => $keys,
		      memory  => $memory * 1024,
		      };
  return wantarray ? %status : \%status;
}

sub title {
  my $self = shift;
  my $status= $self->status;
  $status->{database}{title};
}

sub version {
  my $self = shift;
  my $status= $self->status;
  $status->{database}{version};
}

sub auto_save {
  my $self = shift;
  if ($self->db && $self->db->can('auto_save')) {
    $self->db->auto_save;
  } else {
    $self->{'auto_save'} = $_[0] if defined $_[0];
    return $self->{'auto_save'};
  }
}

# Perform an ace query and return the result
sub find {
  my $self = shift;
  my ($query,$count,$offset,$filled,$total) = rearrange(['QUERY','COUNT',
							 'OFFSET',['FILL','FILLED'],'TOTAL'],@_);
  $offset += 0;
  $query = "find $query" unless $query=~/^find/i;
  my $cnt = $self->count(-query=>$query);
  $$total = $cnt if defined $total;
  return $cnt unless wantarray;
  $filled ? $self->_fetch($count,$offset) : $self->_list($count,$offset);
}

#########################################################
# Grep function returns count in a scalar context, list
# of retrieved objects in a list context.
sub grep {
  my $self = shift;
  my ($pattern,$count,$offset,$filled,$filltag,$total,$long) = 
      rearrange(['PATTERN','COUNT','OFFSET',['FILL','FILLED'],'FILLTAG','TOTAL','LONG'],@_);
  $offset += 0;
  my $grep = defined($long) && $long ? 'LongGrep' : 'grep';
  my $r = $self->raw_query("$grep $pattern");
  my ($cnt) = $r =~ /Found (\d+) objects/m;
  $$total = $cnt if defined $total;
  return $cnt if !wantarray;
  if ($filltag) {
    @h = $self->_fetch($count,$offset,$filltag);
  } else {
    @h = $filled ? $self->_fetch($count,$offset) : $self->_list($count,$offset);
  }
  @h;
}

sub pick {
    my ($self,$class,$item) = @_;
    $Ace::Error = '';
    # assumption of uniqueness of name is violated by some classes!
    #    return () unless $self->count($class,$item) == 1;
    return unless $self->count($class,$item) >= 1;

    # if we get here, then we've got some data to return.
    # yes, we're repeating code slightly...
    my @result;
    my $ts = $self->{'timestamps'} ? '-T' : '';
    my $result = $self->raw_query("show -j $ts");
    unless ($result =~ /(\d+) object dumped/m) {
	$Ace::Error = 'Unexpected close during pick';
	return;
    }

    @result = grep (!m!^\s*//!,split("\n\n",$result));
    return $result[0];
}


# these two only get loaded if the Ace::Freesubs .XS isn't compiled
sub freeprotect {
  my $class = shift;
  my $text = shift;
  $text =~ s/\n/\\n/g;
  $text =~ s/\t/\\t/g;
  $text =~ s/"/\\"/g;
  return qq("$text");
}

sub split {
  my $class = shift;
  my $text = shift;
  $text =~ s/\\n/\n/g;
  $text =~ s/\\t/\t/g;
  my ($id,$ts);
  ($class,$id,$ts) = $text=~m/^\?(.+)(?<!\\)\?(.+)(?<!\\)\?([^?]*)$/s;
  $class ||= '';  # fix uninitialized variable warnings
  $id    ||= '';
  $class =~ s/\\\?/?/g;
  $id =~  s/\\\?/?/g;
  return ($class,$id) unless $ts;
  return ($class,$id,$ts);  # return timestamp
}

# Return a list of all the classes known to the server.
sub classes {
  my ($self,$invisible) = @_;
  my $query = defined($invisible) && $invisible ?
    "query find class !buried" 
      :
    "query find class visible AND !buried";
  $self->raw_query($query);
  return $self->_list;
}

################## iterators ##################
# Fetch many objects in iterative style
sub fetch_many {
  my $self = shift;
  my ($class,$pattern,$filled,$query,$chunksize) = rearrange( ['CLASS',
							       ['PATTERN','NAME'],
							       ['FILL','FILLED'],
							       'QUERY',
							       'CHUNKSIZE'],@_);
  $pattern ||= '*';
  $pattern = Ace->freeprotect($pattern);
  if (defined $query) {
    $query = "query $query" unless $query=~/^query\s/;
  } elsif (defined $class) {
    $query = qq{query find $class $pattern};
  } else {
    croak "must call fetch_many() with the -class or -query arguments";
  }
  my $iterator = Ace::Iterator->new($self,$query,$filled,$chunksize);
  return $iterator;
}

sub _register_iterator {
  my ($self,$iterator) = @_;
  $self->{iterators}{$iterator} = $iterator;
}

sub _unregister_iterator {
  my ($self,$iterator) = @_;
  $self->_restore_iterator($iterator);
  delete $self->{iterators}{$iterator};
}

sub _save_iterator {
  my $self = shift;
  my $iterator = shift;
  return unless $self->{iterators}{$iterator};
  $self->{iterator_stack} ||= [];
  return 1 if grep { $_ eq $iterator } @{$self->{iterator_stack}};
  $self->raw_query("spush",'no_alert');
  unshift @{$self->{iterator_stack}},$iterator;
  1;  # result code -- CHANGE THIS LATER
}

# horrid method that keeps the database's view of
# iterators in synch with our view
sub _restore_iterator {
  my $self = shift;
  my $iterator = shift;

  # no such iterator known, return false
  return unless $self->{iterators}{$iterator};

  # make other iterators save themselves
  $self->_alert_iterators;

  # fetch the list of iterators stored on the stack
  my $list = $self->{iterator_stack};
  # spick not supported. Abandon ship
  return if @$list > 1 and $self->{no_spick};

  # Find the iterator in our list. This mirrors the
  # position in the server stack
  my $i;
  for ($i=0; $i<@$list; $i++) {
    last if $list->[$i] eq $iterator;
  }
  return unless $i < @$list;

  # Sse spop if the list size is 1.  Otherwise use spick, which is
  # only supported in hacked versions of the server.
  my $result = $i == 0 ? $self->raw_query("spop",'no_alert') 
                       : $self->raw_query("spick $i",'no_alert');
  
  if ($result =~ /Keyword spick does not match/) {
    # _restore_iterator will now only work for a single iterator (non-reentrantly)
    $self->{no_spick}++;
    $self->raw_query('spop','no_alert') foreach @$list;  # empty database stack
    $self->{iterator_stack} = [];             # and local copy
    return;
  }

  unless (($result =~ /The stack now holds (\d+) keyset/ && ($1 == (@$list-1) ))
	  or 
	  ($result =~ /stack is (now )?empty/ && @$list == 1)
	 ) {
    $Ace::Error = 'Unexpected result from spick: $result';
    return;
  }

  splice(@$list,$i,1);   # remove from position
  return 1;
}

sub datetime {
  my $self = shift;
  my $time = shift || time;
  my ($sec,$min,$hour,$day,$mon,$year) = localtime($time);
  $year += 1900;   # avoid Y3K bug
  sprintf("%4d-%02d-%02d %02d:%02d:%02d",$year,$mon+1,$day,$hour,$min,$sec);
}

sub date {
  my $self = shift;
  my $time = shift || time;
  my ($sec,$min,$hour,$day,$mon,$year) = localtime($time);
  $year += 1900;   # avoid Y3K bug
  sprintf("%4d-%02d-%02d",$year,$mon+1,$day);
}