[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 1.13 by root, Mon Aug 13 12:07:55 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 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.
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_undef)
		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 $c;
		297
		298
		299	=head3 DB_SEQUENCE/sequence methods
		300
		301	Methods available on DB_SEQUENCE/$seq handles:
		302
		303	DESTROY (DB_SEQUENCE_ornull *seq)
		304	CODE:
		305	if (seq)
		306	seq->close (seq, 0);
		307
		308	$int = $seq->initial_value (db_seq_t value)
		309	$int = $seq->set_cachesize (U32 size)
		310	$int = $seq->set_flags (U32 flags)
		311	$int = $seq->set_range (db_seq_t min, db_seq_t max)
		312
		313	=head4 Example:
		314
		315	my $seq = $db->sequence;
		316
		317	db_sequence_open $seq, undef, "seq", BDB::CREATE;
		318	db_sequence_get $seq, undef, 1, my $value;
		319
		320
80	=head2 SUPPORT FUNCTIONS	321	=head2 SUPPORT FUNCTIONS
81		322
82	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION	323	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
83		324
84	=over 4	325	=over 4
85		326
86	=item $fileno = BDB::AIO::poll_fileno	327	=item $fileno = BDB::poll_fileno
87		328
88	Return the I<request result pipe file descriptor>. This filehandle must be	329	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	330	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	331	select, see below or the SYNOPSIS). If the pipe becomes readable you have
91	to call C<poll_cb> to check the results.	332	to call C<poll_cb> to check the results.
92		333
93	See C<poll_cb> for an example.	334	See C<poll_cb> for an example.
94		335
95	=item BDB::AIO::poll_cb	336	=item BDB::poll_cb
96		337
97	Process some outstanding events on the result pipe. You have to call this	338	Process some outstanding events on the result pipe. You have to call this
98	regularly. Returns the number of events processed. Returns immediately	339	regularly. Returns the number of events processed. Returns immediately
99	when no events are outstanding. The amount of events processed depends on	340	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>.	341	the settings of C<BDB::max_poll_req> and C<BDB::max_poll_time>.
101		342
102	If not all requests were processed for whatever reason, the filehandle	343	If not all requests were processed for whatever reason, the filehandle
103	will still be ready when C<poll_cb> returns.	344	will still be ready when C<poll_cb> returns.
104		345
105	Example: Install an Event watcher that automatically calls	346	Example: Install an Event watcher that automatically calls
106	BDB::AIO::poll_cb with high priority:	347	BDB::poll_cb with high priority:
107		348
108	Event->io (fd => BDB::AIO::poll_fileno,	349	Event->io (fd => BDB::poll_fileno,
109	poll => 'r', async => 1,	350	poll => 'r', async => 1,
110	cb => \&BDB::AIO::poll_cb);	351	cb => \&BDB::poll_cb);
111		352
112	=item BDB::AIO::max_poll_reqs $nreqs	353	=item BDB::max_poll_reqs $nreqs
113		354
114	=item BDB::AIO::max_poll_time $seconds	355	=item BDB::max_poll_time $seconds
115		356
116	These set the maximum number of requests (default C<0>, meaning infinity)	357	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	358	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	359	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	360	C<BDB::poll_cb> to process requests (more correctly the mininum amount
120	of time C<poll_cb> is allowed to use).	361	of time C<poll_cb> is allowed to use).
121		362
122	Setting C<max_poll_time> to a non-zero value creates an overhead of one	363	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	364	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	365	callbacks are really really fast or your OS is really really slow (I am
…		…
129	time.	370	time.
130		371
131	For interactive programs, values such as C<0.01> to C<0.1> should be fine.	372	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
132		373
133	Example: Install an Event watcher that automatically calls	374	Example: Install an Event watcher that automatically calls
134	BDB::AIO::poll_cb with low priority, to ensure that other parts of the	375	BDB::poll_cb with low priority, to ensure that other parts of the
135	program get the CPU sometimes even under high AIO load.	376	program get the CPU sometimes even under high AIO load.
136		377
137	# try not to spend much more than 0.1s in poll_cb	378	# try not to spend much more than 0.1s in poll_cb
138	BDB::AIO::max_poll_time 0.1;	379	BDB::max_poll_time 0.1;
139		380
140	# use a low priority so other tasks have priority	381	# use a low priority so other tasks have priority
141	Event->io (fd => BDB::AIO::poll_fileno,	382	Event->io (fd => BDB::poll_fileno,
142	poll => 'r', nice => 1,	383	poll => 'r', nice => 1,
143	cb => &BDB::AIO::poll_cb);	384	cb => &BDB::poll_cb);
144		385
145	=item BDB::AIO::poll_wait	386	=item BDB::poll_wait
146		387
147	If there are any outstanding requests and none of them in the result	388	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	389	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	390	does a C<select> on the filehandle. This is useful if you want to
150	synchronously wait for some requests to finish).	391	synchronously wait for some requests to finish).
151		392
152	See C<nreqs> for an example.	393	See C<nreqs> for an example.
153		394
154	=item BDB::AIO::poll	395	=item BDB::poll
155		396
156	Waits until some requests have been handled.	397	Waits until some requests have been handled.
157		398
158	Returns the number of requests processed, but is otherwise strictly	399	Returns the number of requests processed, but is otherwise strictly
159	equivalent to:	400	equivalent to:
160		401
161	BDB::AIO::poll_wait, BDB::AIO::poll_cb	402	BDB::poll_wait, BDB::poll_cb
162		403
163	=item BDB::AIO::flush	404	=item BDB::flush
164		405
165	Wait till all outstanding AIO requests have been handled.	406	Wait till all outstanding AIO requests have been handled.
166		407
167	Strictly equivalent to:	408	Strictly equivalent to:
168		409
169	BDB::AIO::poll_wait, BDB::AIO::poll_cb	410	BDB::poll_wait, BDB::poll_cb
170	while BDB::AIO::nreqs;	411	while BDB::nreqs;
		412
		413	=back
171		414
172	=head3 CONTROLLING THE NUMBER OF THREADS	415	=head3 CONTROLLING THE NUMBER OF THREADS
173		416
		417	=over 4
		418
174	=item BDB::AIO::min_parallel $nthreads	419	=item BDB::min_parallel $nthreads
175		420
176	Set the minimum number of AIO threads to C<$nthreads>. The current	421	Set the minimum number of AIO threads to C<$nthreads>. The current
177	default is C<8>, which means eight asynchronous operations can execute	422	default is C<8>, which means eight asynchronous operations can execute
178	concurrently at any one time (the number of outstanding requests,	423	concurrently at any one time (the number of outstanding requests,
179	however, is unlimited).	424	however, is unlimited).
180		425
181	BDB::AIO starts threads only on demand, when an AIO request is queued and	426	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	427	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	428	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.	429	is in the cache and could have been processed faster by a single thread.
185		430
186	It is recommended to keep the number of threads relatively low, as some	431	It is recommended to keep the number of threads relatively low, as some
…		…
189	versions, 4-32 threads should be fine.	434	versions, 4-32 threads should be fine.
190		435
191	Under most circumstances you don't need to call this function, as the	436	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.	437	module selects a default that is suitable for low to moderate load.
193		438
194	=item BDB::AIO::max_parallel $nthreads	439	=item BDB::max_parallel $nthreads
195		440
196	Sets the maximum number of AIO threads to C<$nthreads>. If more than the	441	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	442	specified number of threads are currently running, this function kills
198	them. This function blocks until the limit is reached.	443	them. This function blocks until the limit is reached.
199		444
…		…
203	This module automatically runs C<max_parallel 0> at program end, to ensure	448	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.	449	that all threads are killed and that there are no outstanding requests.
205		450
206	Under normal circumstances you don't need to call this function.	451	Under normal circumstances you don't need to call this function.
207		452
208	=item BDB::AIO::max_idle $nthreads	453	=item BDB::max_idle $nthreads
209		454
210	Limit the number of threads (default: 4) that are allowed to idle (i.e.,	455	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
211	threads that did not get a request to process within 10 seconds). That	456	threads that did not get a request to process within 10 seconds). That
212	means if a thread becomes idle while C<$nthreads> other threads are also	457	means if a thread becomes idle while C<$nthreads> other threads are also
213	idle, it will free its resources and exit.	458	idle, it will free its resources and exit.
…		…
218		463
219	The default is probably ok in most situations, especially if thread	464	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	465	creation is fast. If thread creation is very slow on your system you might
221	want to use larger values.	466	want to use larger values.
222		467
223	=item $oldmaxreqs = BDB::AIO::max_outstanding $maxreqs	468	=item $oldmaxreqs = BDB::max_outstanding $maxreqs
224		469
225	This is a very bad function to use in interactive programs because it	470	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	471	blocks, and a bad way to reduce concurrency because it is inexact: Better
227	use an C<aio_group> together with a feed callback.	472	use an C<aio_group> together with a feed callback.
228		473
…		…
236		481
237	You can still queue as many requests as you want. Therefore,	482	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	483	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).	484	as a stop gap to shield against fatal memory overflow (with large values).
240		485
		486	=item BDB::set_sync_prepare $cb
		487
		488	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
		490	as the request callback, and the second is called to wait until the first
		491	callback has been called. The default implementation works like this:
		492
		493	sub {
		494	my $status;
		495	(
		496	sub { $status = $! },
		497	sub { BDB::poll while !defined $status; $! = $status },
		498	)
		499	}
		500
		501	=back
		502
241	=head3 STATISTICAL INFORMATION	503	=head3 STATISTICAL INFORMATION
242		504
		505	=over 4
		506
243	=item BDB::AIO::nreqs	507	=item BDB::nreqs
244		508
245	Returns the number of requests currently in the ready, execute or pending	509	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).	510	states (i.e. for which their callback has not been invoked yet).
247		511
248	Example: wait till there are no outstanding requests anymore:	512	Example: wait till there are no outstanding requests anymore:
249		513
250	BDB::AIO::poll_wait, BDB::AIO::poll_cb	514	BDB::poll_wait, BDB::poll_cb
251	while BDB::AIO::nreqs;	515	while BDB::nreqs;
252		516
253	=item BDB::AIO::nready	517	=item BDB::nready
254		518
255	Returns the number of requests currently in the ready state (not yet	519	Returns the number of requests currently in the ready state (not yet
256	executed).	520	executed).
257		521
258	=item BDB::AIO::npending	522	=item BDB::npending
259		523
260	Returns the number of requests currently in the pending state (executed,	524	Returns the number of requests currently in the pending state (executed,
261	but not yet processed by poll_cb).	525	but not yet processed by poll_cb).
262		526
263	=back	527	=back
264		528
265	=cut	529	=cut
266		530
267	# support function to convert a fd into a perl filehandle	531	set_sync_prepare {
268	sub _fd2fh {	532	my $status;
269	return undef if $_[0] < 0;	533	(
270		534	sub {
271	# try to generate nice filehandles	535	$status = $!;
272	my $sym = "BDB::AIO::fd#$_[0]";	536	},
273	local *$sym;	537	sub {
274		538	BDB::poll while !defined $status;
275	open *$sym, "+<&=$_[0]" # usually works under any unix	539	$! = $status;
276	or open *$sym, "<&=$_[0]" # cygwin needs this	540	},
277	or open *$sym, ">&=$_[0]" # or this	541	)
278	or return undef;	542	};
279
280	*$sym
281	}
282		543
283	min_parallel 8;	544	min_parallel 8;
284		545
285	END { flush }	546	END { flush }
286		547
…		…
310	bytes of memory. In addition, stat requests need a stat buffer (possibly	571	bytes of memory. In addition, stat requests need a stat buffer (possibly
311	a few hundred bytes), readdir requires a result buffer and so on. Perl	572	a few hundred bytes), readdir requires a result buffer and so on. Perl
312	scalars and other data passed into aio requests will also be locked and	573	scalars and other data passed into aio requests will also be locked and
313	will consume memory till the request has entered the done state.	574	will consume memory till the request has entered the done state.
314		575
315	This is now awfully much, so queuing lots of requests is not usually a	576	This is not awfully much, so queuing lots of requests is not usually a
316	problem.	577	problem.
317		578
318	Per-thread usage:	579	Per-thread usage:
319		580
320	In the execution phase, some aio requests require more memory for	581	In the execution phase, some aio requests require more memory for

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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 1.13 by root, Mon Aug 13 12:07:55 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 1.13 by root, Mon Aug 13 12:07:55 2007 UTC