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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 = '1.2'; |
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 db_txn_finish |
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 | ); |
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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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145 | |
193 | |
146 | 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) |
147 | flags: AUTO_COMMIT CREATE EXCL MULTIVERSION NOMMAP RDONLY READ_UNCOMMITTED THREAD TRUNCATE |
195 | flags: AUTO_COMMIT CREATE EXCL MULTIVERSION NOMMAP RDONLY READ_UNCOMMITTED THREAD TRUNCATE |
148 | 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) |
149 | flags: DB_NOSYNC |
197 | flags: DB_NOSYNC |
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198 | db_upgrade (DB *db, octetstring file, U32 flags = 0, SV *callback = &PL_sv_undef) |
150 | 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) |
151 | flags: FREELIST_ONLY FREE_SPACE |
200 | flags: FREELIST_ONLY FREE_SPACE |
152 | 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) |
153 | 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) |
154 | 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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242 | $int = $env->set_lk_max_lockers (U32 max) |
291 | $int = $env->set_lk_max_lockers (U32 max) |
243 | $int = $env->set_lk_max_locks (U32 max) |
292 | $int = $env->set_lk_max_locks (U32 max) |
244 | $int = $env->set_lk_max_objects (U32 max) |
293 | $int = $env->set_lk_max_objects (U32 max) |
245 | $int = $env->set_lg_bsize (U32 max) |
294 | $int = $env->set_lg_bsize (U32 max) |
246 | $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) |
247 | |
300 | |
248 | $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) |
249 | flags: READ_COMMITTED READ_UNCOMMITTED TXN_NOSYNC TXN_NOWAIT TXN_SNAPSHOT TXN_SYNC TXN_WAIT TXN_WRITE_NOSYNC |
302 | flags: READ_COMMITTED READ_UNCOMMITTED TXN_NOSYNC TXN_NOWAIT TXN_SNAPSHOT TXN_SYNC TXN_WAIT TXN_WRITE_NOSYNC |
250 | |
303 | |
251 | =head4 Example: |
304 | =head4 Example: |
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346 | DESTROY (DBC_ornull *dbc) |
399 | DESTROY (DBC_ornull *dbc) |
347 | CODE: |
400 | CODE: |
348 | if (dbc) |
401 | if (dbc) |
349 | dbc->c_close (dbc); |
402 | dbc->c_close (dbc); |
350 | |
403 | |
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404 | $int = $cursor->set_priority ($priority = PRIORITY_*) |
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405 | |
351 | =head4 Example: |
406 | =head4 Example: |
352 | |
407 | |
353 | my $c = $db->cursor; |
408 | my $c = $db->cursor; |
354 | |
409 | |
355 | for (;;) { |
410 | for (;;) { |
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387 | =head2 SUPPORT FUNCTIONS |
442 | =head2 SUPPORT FUNCTIONS |
388 | |
443 | |
389 | =head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION |
444 | =head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION |
390 | |
445 | |
391 | =over 4 |
446 | =over 4 |
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447 | |
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448 | =item $msg = BDB::strerror [$errno] |
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449 | |
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450 | Returns the string corresponding to the given errno value. If no argument |
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451 | is given, use C<$!>. |
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452 | |
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453 | Note that the BDB module also patches the C<$!> variable directly, so you |
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454 | should be able to get a bdb error string by simply stringifying C<$!>. |
392 | |
455 | |
393 | =item $fileno = BDB::poll_fileno |
456 | =item $fileno = BDB::poll_fileno |
394 | |
457 | |
395 | 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 |
396 | 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 |
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624 | |
687 | |
625 | In short: the parent will, after a short pause, continue as if fork had |
688 | In short: the parent will, after a short pause, continue as if fork had |
626 | not been called, while the child will act as if BDB has not been used |
689 | not been called, while the child will act as if BDB has not been used |
627 | yet. |
690 | yet. |
628 | |
691 | |
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692 | Win32 note: there is no fork on win32, and perls emulation of it is too |
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693 | broken to be supported, so do not use BDB in a windows pseudo-fork, better |
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694 | yet, switch to a more capable platform. |
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695 | |
629 | =head2 MEMORY USAGE |
696 | =head2 MEMORY USAGE |
630 | |
697 | |
631 | Per-request usage: |
698 | Per-request usage: |
632 | |
699 | |
633 | Each aio request uses - depending on your architecture - around 100-200 |
700 | Each aio request uses - depending on your architecture - around 100-200 |
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654 | TXN_DEADLOCK flag will be set on the transaction. See C<db_txn_finish>, |
721 | TXN_DEADLOCK flag will be set on the transaction. See C<db_txn_finish>, |
655 | above. |
722 | above. |
656 | |
723 | |
657 | =head1 SEE ALSO |
724 | =head1 SEE ALSO |
658 | |
725 | |
659 | L<Coro::BDB>, L<IO::AIO>. |
726 | L<AnyEvent::BDB> (event loop integration), L<Coro::BDB> (more natural |
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727 | syntax), L<IO::AIO> (nice to have). |
660 | |
728 | |
661 | =head1 AUTHOR |
729 | =head1 AUTHOR |
662 | |
730 | |
663 | Marc Lehmann <schmorp@schmorp.de> |
731 | Marc Lehmann <schmorp@schmorp.de> |
664 | http://home.schmorp.de/ |
732 | http://home.schmorp.de/ |