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3 | BDB - Asynchronous Berkeley DB access |
3 | BDB - Asynchronous Berkeley DB access |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | use BDB; |
7 | use BDB; |
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8 | |
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9 | my $env = db_env_create; |
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10 | |
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11 | mkdir "bdtest", 0700; |
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12 | db_env_open |
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13 | $env, |
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14 | "bdtest", |
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15 | BDB::INIT_LOCK | BDB::INIT_LOG | BDB::INIT_MPOOL |
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16 | | BDB::INIT_TXN | BDB::RECOVER | BDB::USE_ENVIRON | BDB::CREATE, |
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17 | 0600; |
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18 | |
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19 | $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1); |
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20 | |
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21 | my $db = db_create $env; |
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22 | db_open $db, undef, "table", undef, BDB::BTREE, BDB::AUTO_COMMIT | BDB::CREATE |
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23 | | BDB::READ_UNCOMMITTED, 0600; |
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24 | db_put $db, undef, "key", "data", 0, sub { |
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25 | db_del $db, undef, "key"; |
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26 | }; |
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27 | db_sync $db; |
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28 | |
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29 | # when you also use Coro, management is easy: |
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30 | use Coro::BDB; |
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31 | |
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32 | # automatic event loop intergration with AnyEvent: |
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33 | use AnyEvent::BDB; |
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34 | |
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35 | # automatic result processing with EV: |
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36 | my $WATCHER = EV::io BDB::poll_fileno, EV::READ, \&BDB::poll_cb; |
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37 | |
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38 | # with Glib: |
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39 | add_watch Glib::IO BDB::poll_fileno, |
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40 | in => sub { BDB::poll_cb; 1 }; |
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41 | |
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42 | # or simply flush manually |
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43 | BDB::flush; |
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44 | |
8 | |
45 | |
9 | =head1 DESCRIPTION |
46 | =head1 DESCRIPTION |
10 | |
47 | |
11 | See the BerkeleyDB documentation (L<http://www.oracle.com/technology/documentation/berkeley-db/db/index.html>). |
48 | See the BerkeleyDB documentation (L<http://www.oracle.com/technology/documentation/berkeley-db/db/index.html>). |
12 | The BDB API is very similar to the C API (the translation has been very faithful). |
49 | The BDB API is very similar to the C API (the translation has been very faithful). |
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72 | use strict 'vars'; |
109 | use strict 'vars'; |
73 | |
110 | |
74 | use base 'Exporter'; |
111 | use base 'Exporter'; |
75 | |
112 | |
76 | BEGIN { |
113 | BEGIN { |
77 | our $VERSION = '1.0'; |
114 | our $VERSION = '1.5'; |
78 | |
115 | |
79 | our @BDB_REQ = qw( |
116 | our @BDB_REQ = qw( |
80 | db_env_open db_env_close db_env_txn_checkpoint db_env_lock_detect |
117 | db_env_open db_env_close db_env_txn_checkpoint db_env_lock_detect |
81 | db_env_memp_sync db_env_memp_trickle |
118 | db_env_memp_sync db_env_memp_trickle |
82 | db_open db_close db_compact db_sync db_put db_get db_pget db_del db_key_range |
119 | db_open db_close db_compact db_sync db_upgrade |
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120 | db_put db_get db_pget db_del db_key_range |
83 | db_txn_commit db_txn_abort |
121 | db_txn_commit db_txn_abort db_txn_finish |
84 | db_c_close db_c_count db_c_put db_c_get db_c_pget db_c_del |
122 | db_c_close db_c_count db_c_put db_c_get db_c_pget db_c_del |
85 | db_sequence_open db_sequence_close |
123 | db_sequence_open db_sequence_close |
86 | db_sequence_get db_sequence_remove |
124 | db_sequence_get db_sequence_remove |
87 | ); |
125 | ); |
88 | our @EXPORT = (@BDB_REQ, qw(dbreq_pri dbreq_nice db_env_create db_create)); |
126 | our @EXPORT = (@BDB_REQ, qw(dbreq_pri dbreq_nice db_env_create db_create)); |
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95 | |
133 | |
96 | require XSLoader; |
134 | require XSLoader; |
97 | XSLoader::load ("BDB", $VERSION); |
135 | XSLoader::load ("BDB", $VERSION); |
98 | } |
136 | } |
99 | |
137 | |
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138 | =head2 WIN32 FILENAMES/DATABASE NAME MESS |
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139 | |
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140 | Perl on Win32 supports only ASCII filenames (the reason is that it abuses |
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141 | an internal flag to store wether a filename is Unicode or ANSI, but that |
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142 | flag is used for somethign else in the perl core, so there is no way to |
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143 | detect wether a filename is ANSI or Unicode-encoded). The BDB module |
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144 | tries to work around this issue by assuming that the filename is an ANSI |
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145 | filename and BDB was built for unicode support. |
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146 | |
100 | =head2 BERKELEYDB FUNCTIONS |
147 | =head2 BERKELEYDB FUNCTIONS |
101 | |
148 | |
102 | All of these are functions. The create functions simply return a new |
149 | All of these are functions. The create functions simply return a new |
103 | object and never block. All the remaining functions all take an optional |
150 | object and never block. All the remaining functions take an optional |
104 | callback as last argument. If it is missing, then the fucntion will be |
151 | callback as last argument. If it is missing, then the function will be |
105 | executed synchronously. |
152 | executed synchronously. In both cases, C<$!> will reflect the return value |
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153 | of the function. |
106 | |
154 | |
107 | BDB functions that cannot block (mostly functions that manipulate |
155 | BDB functions that cannot block (mostly functions that manipulate |
108 | settings) are method calls on the relevant objects, so the rule of thumb |
156 | settings) are method calls on the relevant objects, so the rule of thumb |
109 | is: if its a method, its not blocking, if its a function, it takes a |
157 | is: if it's a method, it's not blocking, if it's a function, it takes a |
110 | callback as last argument. |
158 | callback as last argument. |
111 | |
159 | |
112 | In the following, C<$int> signifies an integer return value, |
160 | In the following, C<$int> signifies an integer return value, |
113 | C<octetstring> is a "binary string" (i.e. a perl string with no character |
161 | C<octetstring> is a "binary string" (i.e. a perl string with no character |
114 | indices >255), C<U32> is an unsigned 32 bit integer, C<int> is some |
162 | indices >255), C<U32> is an unsigned 32 bit integer, C<int> is some |
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126 | =head3 BDB functions |
174 | =head3 BDB functions |
127 | |
175 | |
128 | Functions in the BDB namespace, exported by default: |
176 | Functions in the BDB namespace, exported by default: |
129 | |
177 | |
130 | $env = db_env_create (U32 env_flags = 0) |
178 | $env = db_env_create (U32 env_flags = 0) |
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179 | flags: RPCCLIENT |
131 | |
180 | |
132 | db_env_open (DB_ENV *env, octetstring db_home, U32 open_flags, int mode, SV *callback = &PL_sv_undef) |
181 | db_env_open (DB_ENV *env, octetstring db_home, U32 open_flags, int mode, SV *callback = &PL_sv_undef) |
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182 | open_flags: INIT_CDB INIT_LOCK INIT_LOG INIT_MPOOL INIT_REP INIT_TXN RECOVER RECOVER_FATAL USE_ENVIRON USE_ENVIRON_ROOT CREATE LOCKDOWN PRIVATE REGISTER SYSTEM_MEM |
133 | db_env_close (DB_ENV *env, U32 flags = 0, SV *callback = &PL_sv_undef) |
183 | db_env_close (DB_ENV *env, U32 flags = 0, SV *callback = &PL_sv_undef) |
134 | db_env_txn_checkpoint (DB_ENV *env, U32 kbyte = 0, U32 min = 0, U32 flags = 0, SV *callback = &PL_sv_undef) |
184 | db_env_txn_checkpoint (DB_ENV *env, U32 kbyte = 0, U32 min = 0, U32 flags = 0, SV *callback = &PL_sv_undef) |
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185 | flags: FORCE |
135 | db_env_lock_detect (DB_ENV *env, U32 flags = 0, U32 atype = DB_LOCK_DEFAULT, SV *dummy = 0, SV *callback = &PL_sv_undef) |
186 | db_env_lock_detect (DB_ENV *env, U32 flags = 0, U32 atype = DB_LOCK_DEFAULT, SV *dummy = 0, SV *callback = &PL_sv_undef) |
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187 | atype: LOCK_DEFAULT LOCK_EXPIRE LOCK_MAXLOCKS LOCK_MAXWRITE LOCK_MINLOCKS LOCK_MINWRITE LOCK_OLDEST LOCK_RANDOM LOCK_YOUNGEST |
136 | db_env_memp_sync (DB_ENV *env, SV *dummy = 0, SV *callback = &PL_sv_undef) |
188 | db_env_memp_sync (DB_ENV *env, SV *dummy = 0, SV *callback = &PL_sv_undef) |
137 | db_env_memp_trickle (DB_ENV *env, int percent, SV *dummy = 0, SV *callback = &PL_sv_undef) |
189 | db_env_memp_trickle (DB_ENV *env, int percent, SV *dummy = 0, SV *callback = &PL_sv_undef) |
138 | |
190 | |
139 | $db = db_create (DB_ENV *env = 0, U32 flags = 0) |
191 | $db = db_create (DB_ENV *env = 0, U32 flags = 0) |
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192 | flags: XA_CREATE |
140 | |
193 | |
141 | db_open (DB *db, DB_TXN_ornull *txnid, octetstring file, octetstring database, int type, U32 flags, int mode, SV *callback = &PL_sv_undef) |
194 | db_open (DB *db, DB_TXN_ornull *txnid, octetstring file, octetstring database, int type, U32 flags, int mode, SV *callback = &PL_sv_undef) |
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195 | flags: AUTO_COMMIT CREATE EXCL MULTIVERSION NOMMAP RDONLY READ_UNCOMMITTED THREAD TRUNCATE |
142 | db_close (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) |
196 | db_close (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) |
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197 | flags: DB_NOSYNC |
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198 | db_upgrade (DB *db, octetstring file, U32 flags = 0, SV *callback = &PL_sv_undef) |
143 | db_compact (DB *db, DB_TXN_ornull *txn = 0, SV *start = 0, SV *stop = 0, SV *unused1 = 0, U32 flags = DB_FREE_SPACE, SV *unused2 = 0, SV *callback = &PL_sv_undef) |
199 | db_compact (DB *db, DB_TXN_ornull *txn = 0, SV *start = 0, SV *stop = 0, SV *unused1 = 0, U32 flags = DB_FREE_SPACE, SV *unused2 = 0, SV *callback = &PL_sv_undef) |
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200 | flags: FREELIST_ONLY FREE_SPACE |
144 | db_sync (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) |
201 | db_sync (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) |
145 | db_key_range (DB *db, DB_TXN_ornull *txn, SV *key, SV *key_range, U32 flags = 0, SV *callback = &PL_sv_undef) |
202 | db_key_range (DB *db, DB_TXN_ornull *txn, SV *key, SV *key_range, U32 flags = 0, SV *callback = &PL_sv_undef) |
146 | db_put (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
203 | db_put (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
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204 | flags: APPEND NODUPDATA NOOVERWRITE |
147 | db_get (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
205 | db_get (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
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206 | flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW |
148 | db_pget (DB *db, DB_TXN_ornull *txn, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
207 | db_pget (DB *db, DB_TXN_ornull *txn, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
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208 | flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW |
149 | db_del (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef) |
209 | db_del (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef) |
150 | db_txn_commit (DB_TXN *txn, U32 flags = 0, SV *callback = &PL_sv_undef) |
210 | db_txn_commit (DB_TXN *txn, U32 flags = 0, SV *callback = &PL_sv_undef) |
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211 | flags: TXN_NOSYNC TXN_SYNC |
151 | db_txn_abort (DB_TXN *txn, SV *callback = &PL_sv_undef) |
212 | db_txn_abort (DB_TXN *txn, SV *callback = &PL_sv_undef) |
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213 | |
152 | db_c_close (DBC *dbc, SV *callback = &PL_sv_undef) |
214 | db_c_close (DBC *dbc, SV *callback = &PL_sv_undef) |
153 | db_c_count (DBC *dbc, SV *count, U32 flags = 0, SV *callback = &PL_sv_undef) |
215 | db_c_count (DBC *dbc, SV *count, U32 flags = 0, SV *callback = &PL_sv_undef) |
154 | db_c_put (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
216 | db_c_put (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
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217 | flags: AFTER BEFORE CURRENT KEYFIRST KEYLAST NODUPDATA |
155 | db_c_get (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
218 | db_c_get (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
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219 | flags: CURRENT FIRST GET_BOTH GET_BOTH_RANGE GET_RECNO JOIN_ITEM LAST NEXT NEXT_DUP NEXT_NODUP PREV PREV_DUP PREV_NODUP SET SET_RANGE SET_RECNO READ_UNCOMMITTED MULTIPLE MULTIPLE_KEY RMW |
156 | db_c_pget (DBC *dbc, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
220 | db_c_pget (DBC *dbc, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
157 | db_c_del (DBC *dbc, U32 flags = 0, SV *callback = &PL_sv_undef) |
221 | db_c_del (DBC *dbc, U32 flags = 0, SV *callback = &PL_sv_undef) |
158 | |
222 | |
159 | db_sequence_open (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef) |
223 | db_sequence_open (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef) |
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224 | flags: CREATE EXCL |
160 | db_sequence_close (DB_SEQUENCE *seq, U32 flags = 0, SV *callback = &PL_sv_undef) |
225 | db_sequence_close (DB_SEQUENCE *seq, U32 flags = 0, SV *callback = &PL_sv_undef) |
161 | db_sequence_get (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, int delta, SV *seq_value, U32 flags = DB_TXN_NOSYNC, SV *callback = &PL_sv_undef) |
226 | db_sequence_get (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, int delta, SV *seq_value, U32 flags = DB_TXN_NOSYNC, SV *callback = &PL_sv_undef) |
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227 | flags: TXN_NOSYNC |
162 | db_sequence_remove (DB_SEQUENCE *seq, DB_TXN_ornull *txnid = 0, U32 flags = 0, SV *callback = &PL_sv_undef) |
228 | db_sequence_remove (DB_SEQUENCE *seq, DB_TXN_ornull *txnid = 0, U32 flags = 0, SV *callback = &PL_sv_undef) |
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229 | flags: TXN_NOSYNC |
163 | |
230 | |
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231 | =head4 db_txn_finish (DB_TXN *txn, U32 flags = 0, SV *callback = &PL_sv_undef) |
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232 | |
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233 | This is not actually a Berkeley DB function but a BDB module |
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234 | extension. The background for this exytension is: It is very annoying to |
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235 | have to check every single BDB function for error returns and provide a |
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236 | codepath out of your transaction. While the BDB module still makes this |
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237 | possible, it contains the following extensions: |
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238 | |
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239 | When a transaction-protected function returns any operating system |
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240 | error (errno > 0), BDB will set the C<TXN_DEADLOCK> flag on the |
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241 | transaction. This flag is also set by Berkeley DB functions themselves |
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242 | when an operation fails with LOCK_DEADLOCK, and it causes all further |
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243 | operations on that transaction (including C<db_txn_commit>) to fail. |
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244 | |
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245 | The C<db_txn_finish> request will look at this flag, and, if it is set, |
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246 | will automatically call C<db_txn_abort> (setting errno to C<LOCK_DEADLOCK> |
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247 | if it isn't set to something else yet). If it isn't set, it will call |
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248 | C<db_txn_commit> and return the error normally. |
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249 | |
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250 | How to use this? Easy: just write your transaction normally: |
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251 | |
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252 | my $txn = $db_env->txn_begin; |
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253 | db_get $db, $txn, "key", my $data; |
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254 | db_put $db, $txn, "key", $data + 1 unless $! == BDB::NOTFOUND; |
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255 | db_txn_finish $txn; |
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256 | die "transaction failed" if $!; |
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257 | |
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258 | That is, handle only the expected errors. If something unexpected happens |
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259 | (EIO, LOCK_NOTGRANTED or a deadlock in either db_get or db_put), then the remaining |
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260 | requests (db_put in this case) will simply be skipped (they will fail with |
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261 | LOCK_DEADLOCK) and the transaction will be aborted. |
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262 | |
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263 | You can use the C<< $txn->failed >> method to check wether a transaction |
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264 | has failed in this way and abort further processing (excluding |
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265 | C<db_txn_finish>). |
164 | |
266 | |
165 | =head3 DB_ENV/database environment methods |
267 | =head3 DB_ENV/database environment methods |
166 | |
268 | |
167 | Methods available on DB_ENV/$env handles: |
269 | Methods available on DB_ENV/$env handles: |
168 | |
270 | |
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179 | $int = $env->set_flags (U32 flags, int onoff) |
281 | $int = $env->set_flags (U32 flags, int onoff) |
180 | $env->set_errfile (FILE *errfile = 0) |
282 | $env->set_errfile (FILE *errfile = 0) |
181 | $env->set_msgfile (FILE *msgfile = 0) |
283 | $env->set_msgfile (FILE *msgfile = 0) |
182 | $int = $env->set_verbose (U32 which, int onoff = 1) |
284 | $int = $env->set_verbose (U32 which, int onoff = 1) |
183 | $int = $env->set_encrypt (const char *password, U32 flags = 0) |
285 | $int = $env->set_encrypt (const char *password, U32 flags = 0) |
184 | $int = $env->set_timeout (NV timeout, U32 flags) |
286 | $int = $env->set_timeout (NV timeout_seconds, U32 flags = SET_TXN_TIMEOUT) |
185 | $int = $env->set_mp_max_openfd (int maxopenfd); |
287 | $int = $env->set_mp_max_openfd (int maxopenfd); |
186 | $int = $env->set_mp_max_write (int maxwrite, int maxwrite_sleep); |
288 | $int = $env->set_mp_max_write (int maxwrite, int maxwrite_sleep); |
187 | $int = $env->set_mp_mmapsize (int mmapsize_mb) |
289 | $int = $env->set_mp_mmapsize (int mmapsize_mb) |
188 | $int = $env->set_lk_detect (U32 detect = DB_LOCK_DEFAULT) |
290 | $int = $env->set_lk_detect (U32 detect = DB_LOCK_DEFAULT) |
189 | $int = $env->set_lk_max_lockers (U32 max) |
291 | $int = $env->set_lk_max_lockers (U32 max) |
190 | $int = $env->set_lk_max_locks (U32 max) |
292 | $int = $env->set_lk_max_locks (U32 max) |
191 | $int = $env->set_lk_max_objects (U32 max) |
293 | $int = $env->set_lk_max_objects (U32 max) |
192 | $int = $env->set_lg_bsize (U32 max) |
294 | $int = $env->set_lg_bsize (U32 max) |
193 | $int = $env->set_lg_max (U32 max) |
295 | $int = $env->set_lg_max (U32 max) |
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296 | $int = $env->mutex_set_increment (U32 increment) |
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297 | $int = $env->mutex_set_tas_spins (U32 tas_spins) |
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298 | $int = $env->mutex_set_max (U32 max) |
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299 | $int = $env->mutex_set_align (U32 align) |
194 | |
300 | |
195 | $txn = $env->txn_begin (DB_TXN_ornull *parent = 0, U32 flags = 0) |
301 | $txn = $env->txn_begin (DB_TXN_ornull *parent = 0, U32 flags = 0) |
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302 | flags: READ_COMMITTED READ_UNCOMMITTED TXN_NOSYNC TXN_NOWAIT TXN_SNAPSHOT TXN_SYNC TXN_WAIT TXN_WRITE_NOSYNC |
196 | |
303 | |
197 | =head4 Example: |
304 | =head4 Example: |
198 | |
305 | |
199 | use AnyEvent; |
306 | use AnyEvent; |
200 | use BDB; |
307 | use BDB; |
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229 | SvREFCNT_dec (env); |
336 | SvREFCNT_dec (env); |
230 | } |
337 | } |
231 | |
338 | |
232 | $int = $db->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0) |
339 | $int = $db->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0) |
233 | $int = $db->set_flags (U32 flags) |
340 | $int = $db->set_flags (U32 flags) |
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341 | flags: CHKSUM ENCRYPT TXN_NOT_DURABLE |
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342 | Btree: DUP DUPSORT RECNUM REVSPLITOFF |
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343 | Hash: DUP DUPSORT |
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344 | Queue: INORDER |
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345 | Recno: RENUMBER SNAPSHOT |
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346 | |
234 | $int = $db->set_encrypt (const char *password, U32 flags) |
347 | $int = $db->set_encrypt (const char *password, U32 flags) |
235 | $int = $db->set_lorder (int lorder) |
348 | $int = $db->set_lorder (int lorder) |
236 | $int = $db->set_bt_minkey (U32 minkey) |
349 | $int = $db->set_bt_minkey (U32 minkey) |
237 | $int = $db->set_re_delim (int delim) |
350 | $int = $db->set_re_delim (int delim) |
238 | $int = $db->set_re_pad (int re_pad) |
351 | $int = $db->set_re_pad (int re_pad) |
… | |
… | |
241 | $int = $db->set_h_ffactor (U32 h_ffactor) |
354 | $int = $db->set_h_ffactor (U32 h_ffactor) |
242 | $int = $db->set_h_nelem (U32 h_nelem) |
355 | $int = $db->set_h_nelem (U32 h_nelem) |
243 | $int = $db->set_q_extentsize (U32 extentsize) |
356 | $int = $db->set_q_extentsize (U32 extentsize) |
244 | |
357 | |
245 | $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0) |
358 | $dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0) |
|
|
359 | flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT |
246 | $seq = $db->sequence (U32 flags = 0) |
360 | $seq = $db->sequence (U32 flags = 0) |
247 | |
361 | |
248 | =head4 Example: |
362 | =head4 Example: |
249 | |
363 | |
250 | my $db = db_create $env; |
364 | my $db = db_create $env; |
… | |
… | |
269 | DESTROY (DB_TXN_ornull *txn) |
383 | DESTROY (DB_TXN_ornull *txn) |
270 | CODE: |
384 | CODE: |
271 | if (txn) |
385 | if (txn) |
272 | txn->abort (txn); |
386 | txn->abort (txn); |
273 | |
387 | |
274 | $int = $txn->set_timeout (NV timeout, U32 flags) |
388 | $int = $txn->set_timeout (NV timeout_seconds, U32 flags = SET_TXN_TIMEOUT) |
|
|
389 | flags: SET_LOCK_TIMEOUT SET_TXN_TIMEOUT |
|
|
390 | |
|
|
391 | $bool = $txn->failed |
|
|
392 | # see db_txn_finish documentation, above |
275 | |
393 | |
276 | |
394 | |
277 | =head3 DBC/cursor methods |
395 | =head3 DBC/cursor methods |
278 | |
396 | |
279 | Methods available on DBC/$dbc handles: |
397 | Methods available on DBC/$dbc handles: |
280 | |
398 | |
281 | DESTROY (DBC_ornull *dbc) |
399 | DESTROY (DBC_ornull *dbc) |
282 | CODE: |
400 | CODE: |
283 | if (dbc) |
401 | if (dbc) |
284 | dbc->c_close (dbc); |
402 | dbc->c_close (dbc); |
|
|
403 | |
|
|
404 | $int = $cursor->set_priority ($priority = PRIORITY_*) |
285 | |
405 | |
286 | =head4 Example: |
406 | =head4 Example: |
287 | |
407 | |
288 | my $c = $db->cursor; |
408 | my $c = $db->cursor; |
289 | |
409 | |
… | |
… | |
306 | seq->close (seq, 0); |
426 | seq->close (seq, 0); |
307 | |
427 | |
308 | $int = $seq->initial_value (db_seq_t value) |
428 | $int = $seq->initial_value (db_seq_t value) |
309 | $int = $seq->set_cachesize (U32 size) |
429 | $int = $seq->set_cachesize (U32 size) |
310 | $int = $seq->set_flags (U32 flags) |
430 | $int = $seq->set_flags (U32 flags) |
|
|
431 | flags: SEQ_DEC SEQ_INC SEQ_WRAP |
311 | $int = $seq->set_range (db_seq_t min, db_seq_t max) |
432 | $int = $seq->set_range (db_seq_t min, db_seq_t max) |
312 | |
433 | |
313 | =head4 Example: |
434 | =head4 Example: |
314 | |
435 | |
315 | my $seq = $db->sequence; |
436 | my $seq = $db->sequence; |
… | |
… | |
321 | =head2 SUPPORT FUNCTIONS |
442 | =head2 SUPPORT FUNCTIONS |
322 | |
443 | |
323 | =head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION |
444 | =head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION |
324 | |
445 | |
325 | =over 4 |
446 | =over 4 |
|
|
447 | |
|
|
448 | =item $msg = BDB::strerror [$errno] |
|
|
449 | |
|
|
450 | Returns the string corresponding to the given errno value. If no argument |
|
|
451 | is given, use C<$!>. |
|
|
452 | |
|
|
453 | Note that the BDB module also patches the C<$!> variable directly, so you |
|
|
454 | should be able to get a bdb error string by simply stringifying C<$!>. |
326 | |
455 | |
327 | =item $fileno = BDB::poll_fileno |
456 | =item $fileno = BDB::poll_fileno |
328 | |
457 | |
329 | Return the I<request result pipe file descriptor>. This filehandle must be |
458 | Return the I<request result pipe file descriptor>. This filehandle must be |
330 | polled for reading by some mechanism outside this module (e.g. Event or |
459 | polled for reading by some mechanism outside this module (e.g. Event or |
… | |
… | |
369 | interactiveness when perl is not fast enough to process all requests in |
498 | interactiveness when perl is not fast enough to process all requests in |
370 | time. |
499 | time. |
371 | |
500 | |
372 | For interactive programs, values such as C<0.01> to C<0.1> should be fine. |
501 | For interactive programs, values such as C<0.01> to C<0.1> should be fine. |
373 | |
502 | |
374 | Example: Install an Event watcher that automatically calls |
503 | Example: Install an EV watcher that automatically calls |
375 | BDB::poll_cb with low priority, to ensure that other parts of the |
504 | BDB::poll_cb with low priority, to ensure that other parts of the |
376 | program get the CPU sometimes even under high AIO load. |
505 | program get the CPU sometimes even under high load. |
377 | |
506 | |
378 | # try not to spend much more than 0.1s in poll_cb |
507 | # try not to spend much more than 0.1s in poll_cb |
379 | BDB::max_poll_time 0.1; |
508 | BDB::max_poll_time 0.1; |
380 | |
509 | |
381 | # use a low priority so other tasks have priority |
510 | my $bdb_poll = EV::io BDB::poll_fileno, EV::READ, \&BDB::poll_cb); |
382 | Event->io (fd => BDB::poll_fileno, |
|
|
383 | poll => 'r', nice => 1, |
|
|
384 | cb => &BDB::poll_cb); |
|
|
385 | |
511 | |
386 | =item BDB::poll_wait |
512 | =item BDB::poll_wait |
387 | |
513 | |
388 | If there are any outstanding requests and none of them in the result |
514 | If there are any outstanding requests and none of them in the result |
389 | phase, wait till the result filehandle becomes ready for reading (simply |
515 | phase, wait till the result filehandle becomes ready for reading (simply |
… | |
… | |
401 | |
527 | |
402 | BDB::poll_wait, BDB::poll_cb |
528 | BDB::poll_wait, BDB::poll_cb |
403 | |
529 | |
404 | =item BDB::flush |
530 | =item BDB::flush |
405 | |
531 | |
406 | Wait till all outstanding AIO requests have been handled. |
532 | Wait till all outstanding BDB requests have been handled. |
407 | |
533 | |
408 | Strictly equivalent to: |
534 | Strictly equivalent to: |
409 | |
535 | |
410 | BDB::poll_wait, BDB::poll_cb |
536 | BDB::poll_wait, BDB::poll_cb |
411 | while BDB::nreqs; |
537 | while BDB::nreqs; |
… | |
… | |
416 | |
542 | |
417 | =over 4 |
543 | =over 4 |
418 | |
544 | |
419 | =item BDB::min_parallel $nthreads |
545 | =item BDB::min_parallel $nthreads |
420 | |
546 | |
421 | Set the minimum number of AIO threads to C<$nthreads>. The current |
547 | Set the minimum number of BDB threads to C<$nthreads>. The current |
422 | default is C<8>, which means eight asynchronous operations can execute |
548 | default is C<8>, which means eight asynchronous operations can execute |
423 | concurrently at any one time (the number of outstanding requests, |
549 | concurrently at any one time (the number of outstanding requests, |
424 | however, is unlimited). |
550 | however, is unlimited). |
425 | |
551 | |
426 | BDB starts threads only on demand, when an AIO request is queued and |
552 | BDB starts threads only on demand, when an BDB request is queued and |
427 | no free thread exists. Please note that queueing up a hundred requests can |
553 | no free thread exists. Please note that queueing up a hundred requests can |
428 | create demand for a hundred threads, even if it turns out that everything |
554 | create demand for a hundred threads, even if it turns out that everything |
429 | is in the cache and could have been processed faster by a single thread. |
555 | is in the cache and could have been processed faster by a single thread. |
430 | |
556 | |
431 | It is recommended to keep the number of threads relatively low, as some |
557 | It is recommended to keep the number of threads relatively low, as some |
… | |
… | |
436 | Under most circumstances you don't need to call this function, as the |
562 | Under most circumstances you don't need to call this function, as the |
437 | module selects a default that is suitable for low to moderate load. |
563 | module selects a default that is suitable for low to moderate load. |
438 | |
564 | |
439 | =item BDB::max_parallel $nthreads |
565 | =item BDB::max_parallel $nthreads |
440 | |
566 | |
441 | Sets the maximum number of AIO threads to C<$nthreads>. If more than the |
567 | Sets the maximum number of BDB threads to C<$nthreads>. If more than the |
442 | specified number of threads are currently running, this function kills |
568 | specified number of threads are currently running, this function kills |
443 | them. This function blocks until the limit is reached. |
569 | them. This function blocks until the limit is reached. |
444 | |
570 | |
445 | While C<$nthreads> are zero, aio requests get queued but not executed |
571 | While C<$nthreads> are zero, aio requests get queued but not executed |
446 | until the number of threads has been increased again. |
572 | until the number of threads has been increased again. |
… | |
… | |
485 | |
611 | |
486 | =item BDB::set_sync_prepare $cb |
612 | =item BDB::set_sync_prepare $cb |
487 | |
613 | |
488 | Sets a callback that is called whenever a request is created without an |
614 | Sets a callback that is called whenever a request is created without an |
489 | explicit callback. It has to return two code references. The first is used |
615 | explicit callback. It has to return two code references. The first is used |
490 | as the request callback, and the second is called to wait until the first |
616 | as the request callback (it should save the return status), and the second |
|
|
617 | is called to wait until the first callback has been called (it must set |
|
|
618 | C<$!> to the return status). |
|
|
619 | |
|
|
620 | This mechanism can be used to include BDB into other event mechanisms, |
|
|
621 | such as L<AnyEvent::BDB> or L<Coro::BDB>. |
|
|
622 | |
491 | callback has been called. The default implementation works like this: |
623 | The default implementation works like this: |
492 | |
624 | |
493 | sub { |
625 | sub { |
494 | my $status; |
626 | my $status; |
495 | ( |
627 | ( |
496 | sub { $status = $! }, |
628 | sub { $status = $! }, |
497 | sub { BDB::poll while !defined $status; $! = $status }, |
629 | sub { BDB::poll while !defined $status; $! = $status }, |
498 | ) |
630 | ) |
499 | } |
631 | } |
|
|
632 | |
|
|
633 | It simply blocks the process till the request has finished and then sets |
|
|
634 | C<$!> to the return value. This means that if you don't use a callback, |
|
|
635 | BDB will simply fall back to synchronous operations. |
500 | |
636 | |
501 | =back |
637 | =back |
502 | |
638 | |
503 | =head3 STATISTICAL INFORMATION |
639 | =head3 STATISTICAL INFORMATION |
504 | |
640 | |
… | |
… | |
549 | |
685 | |
550 | =head2 FORK BEHAVIOUR |
686 | =head2 FORK BEHAVIOUR |
551 | |
687 | |
552 | This module should do "the right thing" when the process using it forks: |
688 | This module should do "the right thing" when the process using it forks: |
553 | |
689 | |
554 | Before the fork, IO::AIO enters a quiescent state where no requests |
690 | Before the fork, BDB enters a quiescent state where no requests |
555 | can be added in other threads and no results will be processed. After |
691 | can be added in other threads and no results will be processed. After |
556 | the fork the parent simply leaves the quiescent state and continues |
692 | the fork the parent simply leaves the quiescent state and continues |
557 | request/result processing, while the child frees the request/result queue |
693 | request/result processing, while the child frees the request/result queue |
558 | (so that the requests started before the fork will only be handled in the |
694 | (so that the requests started before the fork will only be handled in the |
559 | parent). Threads will be started on demand until the limit set in the |
695 | parent). Threads will be started on demand until the limit set in the |
560 | parent process has been reached again. |
696 | parent process has been reached again. |
561 | |
697 | |
562 | In short: the parent will, after a short pause, continue as if fork had |
698 | In short: the parent will, after a short pause, continue as if fork had |
563 | not been called, while the child will act as if IO::AIO has not been used |
699 | not been called, while the child will act as if BDB has not been used |
564 | yet. |
700 | yet. |
|
|
701 | |
|
|
702 | Win32 note: there is no fork on win32, and perls emulation of it is too |
|
|
703 | broken to be supported, so do not use BDB in a windows pseudo-fork, better |
|
|
704 | yet, switch to a more capable platform. |
565 | |
705 | |
566 | =head2 MEMORY USAGE |
706 | =head2 MEMORY USAGE |
567 | |
707 | |
568 | Per-request usage: |
708 | Per-request usage: |
569 | |
709 | |
… | |
… | |
582 | temporary buffers, and each thread requires a stack and other data |
722 | temporary buffers, and each thread requires a stack and other data |
583 | structures (usually around 16k-128k, depending on the OS). |
723 | structures (usually around 16k-128k, depending on the OS). |
584 | |
724 | |
585 | =head1 KNOWN BUGS |
725 | =head1 KNOWN BUGS |
586 | |
726 | |
587 | Known bugs will be fixed in the next release. |
727 | Known bugs will be fixed in the next release, except: |
|
|
728 | |
|
|
729 | If you use a transaction in any request, and the request returns |
|
|
730 | with an operating system error or DB_LOCK_NOTGRANTED, the internal |
|
|
731 | TXN_DEADLOCK flag will be set on the transaction. See C<db_txn_finish>, |
|
|
732 | above. |
588 | |
733 | |
589 | =head1 SEE ALSO |
734 | =head1 SEE ALSO |
590 | |
735 | |
591 | L<Coro::AIO>. |
736 | L<AnyEvent::BDB> (event loop integration), L<Coro::BDB> (more natural |
|
|
737 | syntax), L<IO::AIO> (nice to have). |
592 | |
738 | |
593 | =head1 AUTHOR |
739 | =head1 AUTHOR |
594 | |
740 | |
595 | Marc Lehmann <schmorp@schmorp.de> |
741 | Marc Lehmann <schmorp@schmorp.de> |
596 | http://home.schmorp.de/ |
742 | http://home.schmorp.de/ |