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

Comparing BDB/BDB.pm (file contents):
Revision 1.1 by root, Mon Feb 5 18:40:55 2007 UTC vs.
Revision 1.11 by root, Mon Aug 13 12:04:41 2007 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	BDB::AIO - Asynchronous Berkeley DB access	3	BDB - Asynchronous Berkeley DB access
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use BDB::AIO;	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 ahs 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.
55		64
56	=back	65	=back
57		66
58	=cut	67	=cut
59		68
60	package BDB::AIO;	69	package BDB;
61		70
62	no warnings;	71	no warnings;
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 = '1.0';
69		78
70	our @BDB_REQ = qw();	79	our @BDB_REQ = qw(
		80	db_env_open db_env_close db_env_txn_checkpoint db_env_lock_detect
		81	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
		83	db_txn_commit db_txn_abort
		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
		87	);
		88	our @EXPORT = (@BDB_REQ, qw(dbreq_pri dbreq_nice db_env_create db_create));
		89	our @EXPORT_OK = qw(
71	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	90	poll_fileno poll_cb poll_wait flush
72	min_parallel max_parallel max_idle	91	min_parallel max_parallel max_idle
73	nreqs nready npending nthreads	92	nreqs nready npending nthreads
74	max_poll_time max_poll_reqs);	93	max_poll_time max_poll_reqs
		94	);
75		95
76	require XSLoader;	96	require XSLoader;
77	XSLoader::load ("BDB::AIO", $VERSION);	97	XSLoader::load ("BDB", $VERSION);
78	}	98	}
79		99
		100	=head2 BERKELEYDB FUNCTIONS
		101
		102	All of these are functions. The create functions simply return a new
		103	object and never block. All the remaining functions all take an optional
		104	callback as last argument. If it is missing, then the fucntion will be
		105	executed synchronously.
		106
		107	BDB functions that cannot block (mostly functions that manipulate
		108	settings) are method calls on the relevant objects, so the rule of thumb
		109	is: if its a method, its not blocking, if its a function, it takes a
		110	callback as last argument.
		111
		112	In the following, C<$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
		132	db_env_open (DB_ENV env, octetstring db_home, U32 open_flags, int mode, SV callback = &PL_sv_undef)
		133	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)
		135	db_env_lock_detect (DB_ENV env, U32 flags = 0, U32 atype = DB_LOCK_DEFAULT, SV dummy = 0, SV *callback = &PL_sv_undef)
		136	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)
		138
		139	$db = db_create (DB_ENV *env = 0, U32 flags = 0)
		140
		141	db_open (DB db, DB_TXN_ornull txnid, octetstring file, octetstring database, int type, U32 flags, int mode, SV *callback = &PL_sv_undef)
		142	db_close (DB db, 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_unde
		144	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)
		146	db_put (DB db, DB_TXN_ornull txn, SV key, SV data, U32 flags = 0, SV *callback = &PL_sv_undef)
		147	db_get (DB db, DB_TXN_ornull txn, SV key, SV data, U32 flags = 0, SV *callback = &PL_sv_undef)
		148	db_pget (DB db, DB_TXN_ornull txn, SV key, SV pkey, SV data, U32 flags = 0, SV callback = &PL_sv_undef)
		149	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)
		151	db_txn_abort (DB_TXN txn, SV callback = &PL_sv_undef)
		152	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)
		154	db_c_put (DBC dbc, SV key, SV data, U32 flags = 0, SV callback = &PL_sv_undef)
		155	db_c_get (DBC dbc, SV key, SV data, U32 flags = 0, SV callback = &PL_sv_undef)
		156	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)
		158
		159	db_sequence_open (DB_SEQUENCE seq, DB_TXN_ornull txnid, SV key, U32 flags = 0, SV callback = &PL_sv_undef)
		160	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)
		162	db_sequence_remove (DB_SEQUENCE seq, DB_TXN_ornull txnid = 0, U32 flags = 0, SV *callback = &PL_sv_undef)
		163
		164
		165	=head3 DB_ENV/database environment methods
		166
		167	Methods available on DB_ENV/$env handles:
		168
		169	DESTROY (DB_ENV_ornull *env)
		170	CODE:
		171	if (env)
		172	env->close (env, 0);
		173
		174	$int = $env->set_data_dir (const char *dir)
		175	$int = $env->set_tmp_dir (const char *dir)
		176	$int = $env->set_lg_dir (const char *dir)
		177	$int = $env->set_shm_key (long shm_key)
		178	$int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0)
		179	$int = $env->set_flags (U32 flags, int onoff)
		180	$env->set_errfile (FILE *errfile = 0)
		181	$env->set_msgfile (FILE *msgfile = 0)
		182	$int = $env->set_verbose (U32 which, int onoff = 1)
		183	$int = $env->set_encrypt (const char *password, U32 flags = 0)
		184	$int = $env->set_timeout (NV timeout, U32 flags)
		185	$int = $env->set_mp_max_openfd (int maxopenfd);
		186	$int = $env->set_mp_max_write (int maxwrite, int maxwrite_sleep);
		187	$int = $env->set_mp_mmapsize (int mmapsize_mb)
		188	$int = $env->set_lk_detect (U32 detect = DB_LOCK_DEFAULT)
		189	$int = $env->set_lk_max_lockers (U32 max)
		190	$int = $env->set_lk_max_locks (U32 max)
		191	$int = $env->set_lk_max_objects (U32 max)
		192	$int = $env->set_lg_bsize (U32 max)
		193	$int = $env->set_lg_max (U32 max)
		194
		195	$txn = $env->txn_begin (DB_TXN_ornull *parent = 0, U32 flags = 0)
		196
		197	=head4 example
		198
		199	use AnyEvent;
		200	use BDB;
		201
		202	our $FH; open $FH, "<&=" . BDB::poll_fileno;
		203	our $WATCHER = AnyEvent->io (fh => $FH, poll => 'r', cb => \&BDB::poll_cb);
		204
		205	BDB::min_parallel 8;
		206
		207	my $env = db_env_create;
		208
		209	mkdir "bdtest", 0700;
		210	db_env_open
		211	$env,
		212	"bdtest",
		213	BDB::INIT_LOCK \| BDB::INIT_LOG \| BDB::INIT_MPOOL \| BDB::INIT_TXN \| BDB::RECOVER \| BDB::USE_ENVIRON \| BDB::CREATE,
		214	0600;
		215
		216	$env->set_flags (BDB::AUTO_COMMIT \| BDB::TXN_NOSYNC, 1);
		217
		218
		219	=head3 DB/database methods
		220
		221	Methods available on DB/$db handles:
		222
		223	DESTROY (DB_ornull *db)
		224	CODE:
		225	if (db)
		226	{
		227	SV env = (SV )db->app_private;
		228	db->close (db, 0);
		229	SvREFCNT_dec (env);
		230	}
		231
		232	$int = $db->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0)
		233	$int = $db->set_flags (U32 flags)
		234	$int = $db->set_encrypt (const char *password, U32 flags)
		235	$int = $db->set_lorder (int lorder)
		236	$int = $db->set_bt_minkey (U32 minkey)
		237	$int = $db->set_re_delim (int delim)
		238	$int = $db->set_re_pad (int re_pad)
		239	$int = $db->set_re_source (char *source)
		240	$int = $db->set_re_len (U32 re_len)
		241	$int = $db->set_h_ffactor (U32 h_ffactor)
		242	$int = $db->set_h_nelem (U32 h_nelem)
		243	$int = $db->set_q_extentsize (U32 extentsize)
		244
		245	$dbc = $db->cursor (DB_TXN_ornull *txn = 0, U32 flags = 0)
		246	$seq = $db->sequence (U32 flags = 0)
		247
		248	=head4 example
		249
		250	my $db = db_create $env;
		251	db_open $db, undef, "table", undef, BDB::BTREE, BDB::AUTO_COMMIT \| BDB::CREATE \| BDB::READ_UNCOMMITTED, 0600;
		252
		253	for (1..1000) {
		254	db_put $db, undef, "key $_", "data $_";
		255
		256	db_key_range $db, undef, "key $_", my $keyrange;
		257	my ($lt, $eq, $gt) = @$keyrange;
		258	}
		259
		260	db_del $db, undef, "key $_" for 1..1000;
		261
		262	db_sync $db;
		263
		264
		265	=head3 DB_TXN/transaction methods
		266
		267	Methods available on DB_TXN/$txn handles:
		268
		269	DESTROY (DB_TXN_ornull *txn)
		270	CODE:
		271	if (txn)
		272	txn->abort (txn);
		273
		274	$int = $txn->set_timeout (NV timeout, U32 flags)
		275
		276
		277	=head3 DBC/cursor methods
		278
		279	Methods available on DBC/$dbc handles:
		280
		281	DESTROY (DBC_ornull *dbc)
		282	CODE:
		283	if (dbc)
		284	dbc->c_close (dbc);
		285
		286	=head4 example
		287
		288	my $c = $db->cursor;
		289
		290	for (;;) {
		291	db_c_get $c, my $key, my $data, BDB::NEXT;
		292	warn "<$!,$key,$data>";
		293	last if $!;
		294	}
		295
		296	db_c_close $c;
		297
		298	=head3 DB_SEQUENCE/sequence methods
		299
		300	Methods available on DB_SEQUENCE/$seq handles:
		301
		302	DESTROY (DB_SEQUENCE_ornull *seq)
		303	CODE:
		304	if (seq)
		305	seq->close (seq, 0);
		306
		307	$int = $seq->initial_value (db_seq_t value)
		308	$int = $seq->set_cachesize (U32 size)
		309	$int = $seq->set_flags (U32 flags)
		310	$int = $seq->set_range (db_seq_t min, db_seq_t max)
		311
		312	=head4 example
		313
		314	my $seq = $db->sequence;
		315
		316	db_sequence_open $seq, undef, "seq", BDB::CREATE;
		317	db_sequence_get $seq, undef, 1, my $value;
		318
		319
80	=head2 SUPPORT FUNCTIONS	320	=head2 SUPPORT FUNCTIONS
81		321
82	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	322	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
83		323
84	=over 4	324	=over 4
85		325
86	=item $fileno = BDB::AIO::poll_fileno	326	=item $fileno = BDB::poll_fileno
87		327
88	Return the I<request result pipe file descriptor>. This filehandle must be	328	Return the I<request result pipe file descriptor>. This filehandle must be
89	polled for reading by some mechanism outside this module (e.g. Event or	329	polled for reading by some mechanism outside this module (e.g. Event or
90	select, see below or the SYNOPSIS). If the pipe becomes readable you have	330	select, see below or the SYNOPSIS). If the pipe becomes readable you have
91	to call C<poll_cb> to check the results.	331	to call C<poll_cb> to check the results.
92		332
93	See C<poll_cb> for an example.	333	See C<poll_cb> for an example.
94		334
95	=item BDB::AIO::poll_cb	335	=item BDB::poll_cb
96		336
97	Process some outstanding events on the result pipe. You have to call this	337	Process some outstanding events on the result pipe. You have to call this
98	regularly. Returns the number of events processed. Returns immediately	338	regularly. Returns the number of events processed. Returns immediately
99	when no events are outstanding. The amount of events processed depends on	339	when no events are outstanding. The amount of events processed depends on
100	the settings of C<BDB::AIO::max_poll_req> and C<BDB::AIO::max_poll_time>.	340	the settings of C<BDB::max_poll_req> and C<BDB::max_poll_time>.
101		341
102	If not all requests were processed for whatever reason, the filehandle	342	If not all requests were processed for whatever reason, the filehandle
103	will still be ready when C<poll_cb> returns.	343	will still be ready when C<poll_cb> returns.
104		344
105	Example: Install an Event watcher that automatically calls	345	Example: Install an Event watcher that automatically calls
106	BDB::AIO::poll_cb with high priority:	346	BDB::poll_cb with high priority:
107		347
108	Event->io (fd => BDB::AIO::poll_fileno,	348	Event->io (fd => BDB::poll_fileno,
109	poll => 'r', async => 1,	349	poll => 'r', async => 1,
110	cb => \&BDB::AIO::poll_cb);	350	cb => \&BDB::poll_cb);
111		351
112	=item BDB::AIO::max_poll_reqs $nreqs	352	=item BDB::max_poll_reqs $nreqs
113		353
114	=item BDB::AIO::max_poll_time $seconds	354	=item BDB::max_poll_time $seconds
115		355
116	These set the maximum number of requests (default C<0>, meaning infinity)	356	These set the maximum number of requests (default C<0>, meaning infinity)
117	that are being processed by C<BDB::AIO::poll_cb> in one call, respectively	357	that are being processed by C<BDB::poll_cb> in one call, respectively
118	the maximum amount of time (default C<0>, meaning infinity) spent in	358	the maximum amount of time (default C<0>, meaning infinity) spent in
119	C<BDB::AIO::poll_cb> to process requests (more correctly the mininum amount	359	C<BDB::poll_cb> to process requests (more correctly the mininum amount
120	of time C<poll_cb> is allowed to use).	360	of time C<poll_cb> is allowed to use).
121		361
122	Setting C<max_poll_time> to a non-zero value creates an overhead of one	362	Setting C<max_poll_time> to a non-zero value creates an overhead of one
123	syscall per request processed, which is not normally a problem unless your	363	syscall per request processed, which is not normally a problem unless your
124	callbacks are really really fast or your OS is really really slow (I am	364	callbacks are really really fast or your OS is really really slow (I am
…		…
129	time.	369	time.
130		370
131	For interactive programs, values such as C<0.01> to C<0.1> should be fine.	371	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
132		372
133	Example: Install an Event watcher that automatically calls	373	Example: Install an Event watcher that automatically calls
134	BDB::AIO::poll_cb with low priority, to ensure that other parts of the	374	BDB::poll_cb with low priority, to ensure that other parts of the
135	program get the CPU sometimes even under high AIO load.	375	program get the CPU sometimes even under high AIO load.
136		376
137	# try not to spend much more than 0.1s in poll_cb	377	# try not to spend much more than 0.1s in poll_cb
138	BDB::AIO::max_poll_time 0.1;	378	BDB::max_poll_time 0.1;
139		379
140	# use a low priority so other tasks have priority	380	# use a low priority so other tasks have priority
141	Event->io (fd => BDB::AIO::poll_fileno,	381	Event->io (fd => BDB::poll_fileno,
142	poll => 'r', nice => 1,	382	poll => 'r', nice => 1,
143	cb => &BDB::AIO::poll_cb);	383	cb => &BDB::poll_cb);
144		384
145	=item BDB::AIO::poll_wait	385	=item BDB::poll_wait
146		386
147	If there are any outstanding requests and none of them in the result	387	If there are any outstanding requests and none of them in the result
148	phase, wait till the result filehandle becomes ready for reading (simply	388	phase, wait till the result filehandle becomes ready for reading (simply
149	does a C<select> on the filehandle. This is useful if you want to	389	does a C<select> on the filehandle. This is useful if you want to
150	synchronously wait for some requests to finish).	390	synchronously wait for some requests to finish).
151		391
152	See C<nreqs> for an example.	392	See C<nreqs> for an example.
153		393
154	=item BDB::AIO::poll	394	=item BDB::poll
155		395
156	Waits until some requests have been handled.	396	Waits until some requests have been handled.
157		397
158	Returns the number of requests processed, but is otherwise strictly	398	Returns the number of requests processed, but is otherwise strictly
159	equivalent to:	399	equivalent to:
160		400
161	BDB::AIO::poll_wait, BDB::AIO::poll_cb	401	BDB::poll_wait, BDB::poll_cb
162		402
163	=item BDB::AIO::flush	403	=item BDB::flush
164		404
165	Wait till all outstanding AIO requests have been handled.	405	Wait till all outstanding AIO requests have been handled.
166		406
167	Strictly equivalent to:	407	Strictly equivalent to:
168		408
169	BDB::AIO::poll_wait, BDB::AIO::poll_cb	409	BDB::poll_wait, BDB::poll_cb
170	while BDB::AIO::nreqs;	410	while BDB::nreqs;
		411
		412	=back
171		413
172	=head3 CONTROLLING THE NUMBER OF THREADS	414	=head3 CONTROLLING THE NUMBER OF THREADS
173		415
		416	=over 4
		417
174	=item BDB::AIO::min_parallel $nthreads	418	=item BDB::min_parallel $nthreads
175		419
176	Set the minimum number of AIO threads to C<$nthreads>. The current	420	Set the minimum number of AIO threads to C<$nthreads>. The current
177	default is C<8>, which means eight asynchronous operations can execute	421	default is C<8>, which means eight asynchronous operations can execute
178	concurrently at any one time (the number of outstanding requests,	422	concurrently at any one time (the number of outstanding requests,
179	however, is unlimited).	423	however, is unlimited).
180		424
181	BDB::AIO starts threads only on demand, when an AIO request is queued and	425	BDB starts threads only on demand, when an AIO request is queued and
182	no free thread exists. Please note that queueing up a hundred requests can	426	no free thread exists. Please note that queueing up a hundred requests can
183	create demand for a hundred threads, even if it turns out that everything	427	create demand for a hundred threads, even if it turns out that everything
184	is in the cache and could have been processed faster by a single thread.	428	is in the cache and could have been processed faster by a single thread.
185		429
186	It is recommended to keep the number of threads relatively low, as some	430	It is recommended to keep the number of threads relatively low, as some
…		…
189	versions, 4-32 threads should be fine.	433	versions, 4-32 threads should be fine.
190		434
191	Under most circumstances you don't need to call this function, as the	435	Under most circumstances you don't need to call this function, as the
192	module selects a default that is suitable for low to moderate load.	436	module selects a default that is suitable for low to moderate load.
193		437
194	=item BDB::AIO::max_parallel $nthreads	438	=item BDB::max_parallel $nthreads
195		439
196	Sets the maximum number of AIO threads to C<$nthreads>. If more than the	440	Sets the maximum number of AIO threads to C<$nthreads>. If more than the
197	specified number of threads are currently running, this function kills	441	specified number of threads are currently running, this function kills
198	them. This function blocks until the limit is reached.	442	them. This function blocks until the limit is reached.
199		443
…		…
203	This module automatically runs C<max_parallel 0> at program end, to ensure	447	This module automatically runs C<max_parallel 0> at program end, to ensure
204	that all threads are killed and that there are no outstanding requests.	448	that all threads are killed and that there are no outstanding requests.
205		449
206	Under normal circumstances you don't need to call this function.	450	Under normal circumstances you don't need to call this function.
207		451
208	=item BDB::AIO::max_idle $nthreads	452	=item BDB::max_idle $nthreads
209		453
210	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	454	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
211	threads that did not get a request to process within 10 seconds). That	455	threads that did not get a request to process within 10 seconds). That
212	means if a thread becomes idle while C<$nthreads> other threads are also	456	means if a thread becomes idle while C<$nthreads> other threads are also
213	idle, it will free its resources and exit.	457	idle, it will free its resources and exit.
…		…
218		462
219	The default is probably ok in most situations, especially if thread	463	The default is probably ok in most situations, especially if thread
220	creation is fast. If thread creation is very slow on your system you might	464	creation is fast. If thread creation is very slow on your system you might
221	want to use larger values.	465	want to use larger values.
222		466
223	=item $oldmaxreqs = BDB::AIO::max_outstanding $maxreqs	467	=item $oldmaxreqs = BDB::max_outstanding $maxreqs
224		468
225	This is a very bad function to use in interactive programs because it	469	This is a very bad function to use in interactive programs because it
226	blocks, and a bad way to reduce concurrency because it is inexact: Better	470	blocks, and a bad way to reduce concurrency because it is inexact: Better
227	use an C<aio_group> together with a feed callback.	471	use an C<aio_group> together with a feed callback.
228		472
…		…
236		480
237	You can still queue as many requests as you want. Therefore,	481	You can still queue as many requests as you want. Therefore,
238	C<max_oustsanding> is mainly useful in simple scripts (with low values) or	482	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
239	as a stop gap to shield against fatal memory overflow (with large values).	483	as a stop gap to shield against fatal memory overflow (with large values).
240		484
		485	=item BDB::set_sync_prepare $cb
		486
		487	Sets a callback that is called whenever a request is created without an
		488	explicit callback. It has to return two code references. The first is used
		489	as the request callback, and the second is called to wait until the first
		490	callback has been called. The default implementation works like this:
		491
		492	sub {
		493	my $status;
		494	(
		495	sub { $status = $! },
		496	sub { BDB::poll while !defined $status; $! = $status },
		497	)
		498	}
		499
		500	=back
		501
241	=head3 STATISTICAL INFORMATION	502	=head3 STATISTICAL INFORMATION
242		503
		504	=over 4
		505
243	=item BDB::AIO::nreqs	506	=item BDB::nreqs
244		507
245	Returns the number of requests currently in the ready, execute or pending	508	Returns the number of requests currently in the ready, execute or pending
246	states (i.e. for which their callback has not been invoked yet).	509	states (i.e. for which their callback has not been invoked yet).
247		510
248	Example: wait till there are no outstanding requests anymore:	511	Example: wait till there are no outstanding requests anymore:
249		512
250	BDB::AIO::poll_wait, BDB::AIO::poll_cb	513	BDB::poll_wait, BDB::poll_cb
251	while BDB::AIO::nreqs;	514	while BDB::nreqs;
252		515
253	=item BDB::AIO::nready	516	=item BDB::nready
254		517
255	Returns the number of requests currently in the ready state (not yet	518	Returns the number of requests currently in the ready state (not yet
256	executed).	519	executed).
257		520
258	=item BDB::AIO::npending	521	=item BDB::npending
259		522
260	Returns the number of requests currently in the pending state (executed,	523	Returns the number of requests currently in the pending state (executed,
261	but not yet processed by poll_cb).	524	but not yet processed by poll_cb).
262		525
263	=back	526	=back
264		527
265	=cut	528	=cut
266		529
267	# support function to convert a fd into a perl filehandle	530	set_sync_prepare {
268	sub _fd2fh {	531	my $status;
269	return undef if $_[0] < 0;	532	(
270		533	sub {
271	# try to generate nice filehandles	534	$status = $!;
272	my $sym = "BDB::AIO::fd#$_[0]";	535	},
273	local *$sym;	536	sub {
274		537	BDB::poll while !defined $status;
275	open *$sym, "+<&=$_[0]" # usually works under any unix	538	$! = $status;
276	or open *$sym, "<&=$_[0]" # cygwin needs this	539	},
277	or open *$sym, ">&=$_[0]" # or this	540	)
278	or return undef;	541	};
279
280	*$sym
281	}
282		542
283	min_parallel 8;	543	min_parallel 8;
284		544
285	END { flush }	545	END { flush }
286		546

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Comparing BDB/BDB.pm (file contents): Revision 1.1 by root, Mon Feb 5 18:40:55 2007 UTC vs. Revision 1.11 by root, Mon Aug 13 12:04:41 2007 UTC

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Comparing BDB/BDB.pm (file contents):
Revision 1.1 by root, Mon Feb 5 18:40:55 2007 UTC vs.
Revision 1.11 by root, Mon Aug 13 12:04:41 2007 UTC