[ViewVC] Diff of: cvs/BDB/BDB.pm

Comparing BDB/BDB.pm (file contents):
Revision 1.4 by root, Mon Feb 5 23:46:15 2007 UTC vs.
Revision 1.15 by root, Thu Sep 13 21:34:00 2007 UTC

…		…
6		6
7	use BDB;	7	use BDB;
8		8
9	=head1 DESCRIPTION	9	=head1 DESCRIPTION
10		10
11	=head2 EXAMPLE	11	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).
		13
		14	See also the example sections in the document below and possibly the eg/
		15	subdirectory of the BDB distribution. Last not least see the IO::AIO
		16	documentation, as that module uses almost the same asynchronous request
		17	model as this module.
		18
		19	I know this is woefully inadequate documentation. Send a patch!
		20
12		21
13	=head1 REQUEST ANATOMY AND LIFETIME	22	=head1 REQUEST ANATOMY AND LIFETIME
14		23
15	Every request method creates a request. which is a C data structure not	24	Every request method creates a request. which is a C data structure not
16	directly visible to Perl.	25	directly visible to Perl.
…		…
63	use strict 'vars';	72	use strict 'vars';
64		73
65	use base 'Exporter';	74	use base 'Exporter';
66		75
67	BEGIN {	76	BEGIN {
68	our $VERSION = '0.1';	77	our $VERSION = '1.1';
69		78
70	our @BDB_REQ = qw(	79	our @BDB_REQ = qw(
71	db_env_create db_env_open db_env_close	80	db_env_open db_env_close db_env_txn_checkpoint db_env_lock_detect
		81	db_env_memp_sync db_env_memp_trickle
72	db_create db_open db_close db_compact db_sync db_put db_get db_pget	82	db_open db_close db_compact db_sync db_put db_get db_pget db_del db_key_range
73	db_txn_commit db_txn_abort	83	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
		85	db_sequence_open db_sequence_close
		86	db_sequence_get db_sequence_remove
74	);	87	);
75	our @EXPORT = (@BDB_REQ, qw(dbreq_pri dbreq_nice));	88	our @EXPORT = (@BDB_REQ, qw(dbreq_pri dbreq_nice db_env_create db_create));
		89	our @EXPORT_OK = qw(
76	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	90	poll_fileno poll_cb poll_wait flush
77	min_parallel max_parallel max_idle	91	min_parallel max_parallel max_idle
78	nreqs nready npending nthreads	92	nreqs nready npending nthreads
79	max_poll_time max_poll_reqs);	93	max_poll_time max_poll_reqs
		94	);
80		95
81	require XSLoader;	96	require XSLoader;
82	XSLoader::load ("BDB", $VERSION);	97	XSLoader::load ("BDB", $VERSION);
83	}	98	}
		99
		100	=head2 BERKELEYDB FUNCTIONS
		101
		102	All of these are functions. The create functions simply return a new
		103	object and never block. All the remaining functions all take an optional
		104	callback as last argument. If it is missing, then the fucntion will be
		105	executed synchronously.
		106
		107	BDB functions that cannot block (mostly functions that manipulate
		108	settings) are method calls on the relevant objects, so the rule of thumb
		109	is: if its a method, its not blocking, if its a function, it takes a
		110	callback as last argument.
		111
		112	In the following, C<$int> signifies an integer return value,
		113	C<octetstring> is a "binary string" (i.e. a perl string with no character
		114	indices >255), C<U32> is an unsigned 32 bit integer, C<int> is some
		115	integer, C<NV> is a floating point value.
		116
		117	The C<SV *> types are generic perl scalars (for input and output of data
		118	values), and the C<SV *callback> is the optional callback function to call
		119	when the request is completed.
		120
		121	The various C<DB_ENV> etc. arguments are handles return by
		122	C<db_env_create>, C<db_create>, C<txn_begin> and so on. If they have an
		123	appended C<_ornull> this means they are optional and you can pass C<undef>
		124	for them, resulting a NULL pointer on the C level.
		125
		126	=head3 BDB functions
		127
		128	Functions in the BDB namespace, exported by default:
		129
		130	$env = db_env_create (U32 env_flags = 0)
		131	flags: RPCCLIENT
		132
		133	db_env_open (DB_ENV env, octetstring db_home, U32 open_flags, int mode, SV callback = &PL_sv_undef)
		134	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
		135	db_env_close (DB_ENV env, U32 flags = 0, SV callback = &PL_sv_undef)
		136	db_env_txn_checkpoint (DB_ENV env, U32 kbyte = 0, U32 min = 0, U32 flags = 0, SV callback = &PL_sv_undef)
		137	flags: FORCE
		138	db_env_lock_detect (DB_ENV env, U32 flags = 0, U32 atype = DB_LOCK_DEFAULT, SV dummy = 0, SV *callback = &PL_sv_undef)
		139	atype: LOCK_DEFAULT LOCK_EXPIRE LOCK_MAXLOCKS LOCK_MAXWRITE LOCK_MINLOCKS LOCK_MINWRITE LOCK_OLDEST LOCK_RANDOM LOCK_YOUNGEST
		140	db_env_memp_sync (DB_ENV env, SV dummy = 0, SV *callback = &PL_sv_undef)
		141	db_env_memp_trickle (DB_ENV env, int percent, SV dummy = 0, SV *callback = &PL_sv_undef)
		142
		143	$db = db_create (DB_ENV *env = 0, U32 flags = 0)
		144	flags: XA_CREATE
		145
		146	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
		148	db_close (DB db, U32 flags = 0, SV callback = &PL_sv_undef)
		149	flags: DB_NOSYNC
		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)
		151	flags: FREELIST_ONLY FREE_SPACE
		152	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)
		154	db_put (DB db, DB_TXN_ornull txn, SV key, SV data, U32 flags = 0, SV *callback = &PL_sv_undef)
		155	flags: APPEND NODUPDATA NOOVERWRITE
		156	db_get (DB db, DB_TXN_ornull txn, SV key, SV data, U32 flags = 0, SV *callback = &PL_sv_undef)
		157	flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW
		158	db_pget (DB db, DB_TXN_ornull txn, SV key, SV pkey, SV data, U32 flags = 0, SV callback = &PL_sv_undef)
		159	flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW
		160	db_del (DB db, DB_TXN_ornull txn, SV key, U32 flags = 0, SV callback = &PL_sv_undef)
		161	db_txn_commit (DB_TXN txn, U32 flags = 0, SV callback = &PL_sv_undef)
		162	flags: TXN_NOSYNC TXN_SYNC
		163	db_txn_abort (DB_TXN txn, SV callback = &PL_sv_undef)
		164
		165	db_c_close (DBC dbc, SV callback = &PL_sv_undef)
		166	db_c_count (DBC dbc, SV count, U32 flags = 0, SV *callback = &PL_sv_undef)
		167	db_c_put (DBC dbc, SV key, SV data, U32 flags = 0, SV callback = &PL_sv_undef)
		168	flags: AFTER BEFORE CURRENT KEYFIRST KEYLAST NODUPDATA
		169	db_c_get (DBC dbc, SV key, SV data, U32 flags = 0, SV callback = &PL_sv_undef)
		170	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
		171	db_c_pget (DBC dbc, SV key, SV pkey, SV data, U32 flags = 0, SV *callback = &PL_sv_undef)
		172	db_c_del (DBC dbc, U32 flags = 0, SV callback = &PL_sv_undef)
		173
		174	db_sequence_open (DB_SEQUENCE seq, DB_TXN_ornull txnid, SV key, U32 flags = 0, SV callback = &PL_sv_undef)
		175	flags: CREATE EXCL
		176	db_sequence_close (DB_SEQUENCE seq, U32 flags = 0, SV callback = &PL_sv_undef)
		177	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)
		178	flags: TXN_NOSYNC
		179	db_sequence_remove (DB_SEQUENCE seq, DB_TXN_ornull txnid = 0, U32 flags = 0, SV *callback = &PL_sv_undef)
		180	flags: TXN_NOSYNC
		181
		182	=head4 db_txn_finish (DB_TXN txn, U32 flags = 0, SV callback = &PL_sv_undef)
		183
		184	This is not a Berkeley DB function but a BDB module extension. It is very
		185	annoying to have to check every single BDB function for error returns and
		186	provide a codepath out of your transaction. While the BDB module still
		187	makes this possible, it contains the following extensions:
		188
		189	When a transaction-protected function returns any operating system
		190	error (errno > 0), BDB will set the C<TXN_DEADLOCK> flag on the
		191	transaction. This flag is also set by Berkeley DB functions externally
		192	when an operation fails with LOCK_DEADLOCK, and it causes all further
		193	operations on that transaction (including C<db_txn_commit>) to fail.
		194
		195	The C<db_txn_finish> request will look at this flag, and, if it is set,
		196	will automatically call C<db_txn_abort> (setting errno to C<LOCK_DEADLOCK>
		197	if it isn't set). If it isn't set, it will call C<db_txn_commit> and
		198	return the error normally.
		199
		200	How to use this? Easy: just write your transaction normally:
		201
		202	my $txn = $db_env->txn_begin;
		203	db_get $db, $txn, "key", my $data;
		204	db_put $db, $txn, "key", $data + 1 unless $! == BDB::NOTFOUND;
		205	db_txn_finish $txn;
		206	die "transaction failed" if $!;
		207
		208	That is, handle only the expected errors. If something unexpected happens
		209	(EIO, LOCK_NOTGRANTED or a deadlock in either db_get or db_put), then the remaining
		210	requests (db_put in this case) will simply be skipped (they will fail with
		211	LOCK_DEADLOCK) and the transaction will be aborted.
		212
		213	You cna use the C<< $txn->failed >> method to check wether a transaction
		214	has failed in this way and abort further processing (excluding
		215	C<db_txn_finish>).
		216
		217	=head3 DB_ENV/database environment methods
		218
		219	Methods available on DB_ENV/$env handles:
		220
		221	DESTROY (DB_ENV_ornull *env)
		222	CODE:
		223	if (env)
		224	env->close (env, 0);
		225
		226	$int = $env->set_data_dir (const char *dir)
		227	$int = $env->set_tmp_dir (const char *dir)
		228	$int = $env->set_lg_dir (const char *dir)
		229	$int = $env->set_shm_key (long shm_key)
		230	$int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0)
		231	$int = $env->set_flags (U32 flags, int onoff)
		232	$env->set_errfile (FILE *errfile = 0)
		233	$env->set_msgfile (FILE *msgfile = 0)
		234	$int = $env->set_verbose (U32 which, int onoff = 1)
		235	$int = $env->set_encrypt (const char *password, U32 flags = 0)
		236	$int = $env->set_timeout (NV timeout_seconds, U32 flags = SET_TXN_TIMEOUT)
		237	$int = $env->set_mp_max_openfd (int maxopenfd);
		238	$int = $env->set_mp_max_write (int maxwrite, int maxwrite_sleep);
		239	$int = $env->set_mp_mmapsize (int mmapsize_mb)
		240	$int = $env->set_lk_detect (U32 detect = DB_LOCK_DEFAULT)
		241	$int = $env->set_lk_max_lockers (U32 max)
		242	$int = $env->set_lk_max_locks (U32 max)
		243	$int = $env->set_lk_max_objects (U32 max)
		244	$int = $env->set_lg_bsize (U32 max)
		245	$int = $env->set_lg_max (U32 max)
		246
		247	$txn = $env->txn_begin (DB_TXN_ornull *parent = 0, U32 flags = 0)
		248	flags: READ_COMMITTED READ_UNCOMMITTED TXN_NOSYNC TXN_NOWAIT TXN_SNAPSHOT TXN_SYNC TXN_WAIT TXN_WRITE_NOSYNC
		249
		250	=head4 Example:
		251
		252	use AnyEvent;
		253	use BDB;
		254
		255	our $FH; open $FH, "<&=" . BDB::poll_fileno;
		256	our $WATCHER = AnyEvent->io (fh => $FH, poll => 'r', cb => \&BDB::poll_cb);
		257
		258	BDB::min_parallel 8;
		259
		260	my $env = db_env_create;
		261
		262	mkdir "bdtest", 0700;
		263	db_env_open
		264	$env,
		265	"bdtest",
		266	BDB::INIT_LOCK \| BDB::INIT_LOG \| BDB::INIT_MPOOL \| BDB::INIT_TXN \| BDB::RECOVER \| BDB::USE_ENVIRON \| BDB::CREATE,
		267	0600;
		268
		269	$env->set_flags (BDB::AUTO_COMMIT \| BDB::TXN_NOSYNC, 1);
		270
		271
		272	=head3 DB/database methods
		273
		274	Methods available on DB/$db handles:
		275
		276	DESTROY (DB_ornull *db)
		277	CODE:
		278	if (db)
		279	{
		280	SV env = (SV )db->app_private;
		281	db->close (db, 0);
		282	SvREFCNT_dec (env);
		283	}
		284
		285	$int = $db->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0)
		286	$int = $db->set_flags (U32 flags)
		287	flags: CHKSUM ENCRYPT TXN_NOT_DURABLE
		288	Btree: DUP DUPSORT RECNUM REVSPLITOFF
		289	Hash: DUP DUPSORT
		290	Queue: INORDER
		291	Recno: RENUMBER SNAPSHOT
		292
		293	$int = $db->set_encrypt (const char *password, U32 flags)
		294	$int = $db->set_lorder (int lorder)
		295	$int = $db->set_bt_minkey (U32 minkey)
		296	$int = $db->set_re_delim (int delim)
		297	$int = $db->set_re_pad (int re_pad)
		298	$int = $db->set_re_source (char *source)
		299	$int = $db->set_re_len (U32 re_len)
		300	$int = $db->set_h_ffactor (U32 h_ffactor)
		301	$int = $db->set_h_nelem (U32 h_nelem)
		302	$int = $db->set_q_extentsize (U32 extentsize)
		303
		304	$dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0)
		305	flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT
		306	$seq = $db->sequence (U32 flags = 0)
		307
		308	=head4 Example:
		309
		310	my $db = db_create $env;
		311	db_open $db, undef, "table", undef, BDB::BTREE, BDB::AUTO_COMMIT \| BDB::CREATE \| BDB::READ_UNCOMMITTED, 0600;
		312
		313	for (1..1000) {
		314	db_put $db, undef, "key $_", "data $_";
		315
		316	db_key_range $db, undef, "key $_", my $keyrange;
		317	my ($lt, $eq, $gt) = @$keyrange;
		318	}
		319
		320	db_del $db, undef, "key $_" for 1..1000;
		321
		322	db_sync $db;
		323
		324
		325	=head3 DB_TXN/transaction methods
		326
		327	Methods available on DB_TXN/$txn handles:
		328
		329	DESTROY (DB_TXN_ornull *txn)
		330	CODE:
		331	if (txn)
		332	txn->abort (txn);
		333
		334	$int = $txn->set_timeout (NV timeout_seconds, U32 flags = SET_TXN_TIMEOUT)
		335	flags: SET_LOCK_TIMEOUT SET_TXN_TIMEOUT
		336
		337	$bool = $txn->failed
		338	# see db_txn_finish documentation, above
		339
		340
		341	=head3 DBC/cursor methods
		342
		343	Methods available on DBC/$dbc handles:
		344
		345	DESTROY (DBC_ornull *dbc)
		346	CODE:
		347	if (dbc)
		348	dbc->c_close (dbc);
		349
		350	=head4 Example:
		351
		352	my $c = $db->cursor;
		353
		354	for (;;) {
		355	db_c_get $c, my $key, my $data, BDB::NEXT;
		356	warn "<$!,$key,$data>";
		357	last if $!;
		358	}
		359
		360	db_c_close $c;
		361
		362
		363	=head3 DB_SEQUENCE/sequence methods
		364
		365	Methods available on DB_SEQUENCE/$seq handles:
		366
		367	DESTROY (DB_SEQUENCE_ornull *seq)
		368	CODE:
		369	if (seq)
		370	seq->close (seq, 0);
		371
		372	$int = $seq->initial_value (db_seq_t value)
		373	$int = $seq->set_cachesize (U32 size)
		374	$int = $seq->set_flags (U32 flags)
		375	flags: SEQ_DEC SEQ_INC SEQ_WRAP
		376	$int = $seq->set_range (db_seq_t min, db_seq_t max)
		377
		378	=head4 Example:
		379
		380	my $seq = $db->sequence;
		381
		382	db_sequence_open $seq, undef, "seq", BDB::CREATE;
		383	db_sequence_get $seq, undef, 1, my $value;
		384
84		385
85	=head2 SUPPORT FUNCTIONS	386	=head2 SUPPORT FUNCTIONS
86		387
87	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	388	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
88		389
…		…
172	Strictly equivalent to:	473	Strictly equivalent to:
173		474
174	BDB::poll_wait, BDB::poll_cb	475	BDB::poll_wait, BDB::poll_cb
175	while BDB::nreqs;	476	while BDB::nreqs;
176		477
		478	=back
		479
177	=head3 CONTROLLING THE NUMBER OF THREADS	480	=head3 CONTROLLING THE NUMBER OF THREADS
		481
		482	=over 4
178		483
179	=item BDB::min_parallel $nthreads	484	=item BDB::min_parallel $nthreads
180		485
181	Set the minimum number of AIO threads to C<$nthreads>. The current	486	Set the minimum number of AIO threads to C<$nthreads>. The current
182	default is C<8>, which means eight asynchronous operations can execute	487	default is C<8>, which means eight asynchronous operations can execute
…		…
331	bytes of memory. In addition, stat requests need a stat buffer (possibly	636	bytes of memory. In addition, stat requests need a stat buffer (possibly
332	a few hundred bytes), readdir requires a result buffer and so on. Perl	637	a few hundred bytes), readdir requires a result buffer and so on. Perl
333	scalars and other data passed into aio requests will also be locked and	638	scalars and other data passed into aio requests will also be locked and
334	will consume memory till the request has entered the done state.	639	will consume memory till the request has entered the done state.
335		640
336	This is now awfully much, so queuing lots of requests is not usually a	641	This is not awfully much, so queuing lots of requests is not usually a
337	problem.	642	problem.
338		643
339	Per-thread usage:	644	Per-thread usage:
340		645
341	In the execution phase, some aio requests require more memory for	646	In the execution phase, some aio requests require more memory for
342	temporary buffers, and each thread requires a stack and other data	647	temporary buffers, and each thread requires a stack and other data
343	structures (usually around 16k-128k, depending on the OS).	648	structures (usually around 16k-128k, depending on the OS).
344		649
345	=head1 KNOWN BUGS	650	=head1 KNOWN BUGS
346		651
347	Known bugs will be fixed in the next release.	652	Known bugs will be fixed in the next release, except:
		653
		654	If you use a transaction in any request, and the request returns
		655	with an operating system error or DB_LOCK_NOTGRANTED, the internal
		656	TXN_DEADLOCK flag will be set on the transaction. See C<db_txn_finish>,
		657	above.
348		658
349	=head1 SEE ALSO	659	=head1 SEE ALSO
350		660
351	L<Coro::AIO>.	661	L<Coro::AIO>.
352		662

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Comparing BDB/BDB.pm (file contents): Revision 1.4 by root, Mon Feb 5 23:46:15 2007 UTC vs. Revision 1.15 by root, Thu Sep 13 21:34:00 2007 UTC

Diff Legend

Comparing BDB/BDB.pm (file contents):
Revision 1.4 by root, Mon Feb 5 23:46:15 2007 UTC vs.
Revision 1.15 by root, Thu Sep 13 21:34:00 2007 UTC