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

Comparing BDB/BDB.pm (file contents):
Revision 1.18 by root, Tue Dec 4 11:07:39 2007 UTC vs.
Revision 1.45 by root, Wed Jul 9 21:16:14 2008 UTC

 BDB - Asynchronous Berkeley DB access
 =head1 SYNOPSIS
  use BDB;
+ my $env = db_env_create;
+ mkdir "bdtest", 0700;
+ db_env_open
+    $env,
+    "bdtest",
+    BDB::INIT_LOCK | BDB::INIT_LOG | BDB::INIT_MPOOL
+    | BDB::INIT_TXN | BDB::RECOVER | BDB::USE_ENVIRON | BDB::CREATE,
+    0600;
+ $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1);
+ my $db = db_create $env;
+ db_open $db, undef, "table", undef, BDB::BTREE, BDB::AUTO_COMMIT | BDB::CREATE
+                                     | BDB::READ_UNCOMMITTED, 0600;
+ db_put $db, undef, "key", "data", 0, sub {
+    db_del $db, undef, "key";
+ };
+ db_sync $db;
+ # when you also use Coro, management is easy:
+ use Coro::BDB;
+ # automatic event loop intergration with AnyEvent:
+ use AnyEvent::BDB;
+ # automatic result processing with EV:
+ my $WATCHER = EV::io BDB::poll_fileno, EV::READ, \&BDB::poll_cb;
+ # with Glib:
+ add_watch Glib::IO BDB::poll_fileno,
+           in => sub { BDB::poll_cb; 1 };
+ # or simply flush manually
+ BDB::flush;
 =head1 DESCRIPTION
 See the BerkeleyDB documentation (L<http://www.oracle.com/technology/documentation/berkeley-db/db/index.html>).
 The BDB API is very similar to the C API (the translation has been very faithful).
 use strict 'vars';
 use base 'Exporter';
 BEGIN {
-   our $VERSION = '1.2';
+   our $VERSION = '1.7';
    our @BDB_REQ = qw(
       db_env_open db_env_close db_env_txn_checkpoint db_env_lock_detect
-      db_env_memp_sync db_env_memp_trickle
+      db_env_memp_sync db_env_memp_trickle db_env_dbrename db_env_dbremove
-      db_open db_close db_compact db_sync db_put db_get db_pget db_del db_key_range
+      db_open db_close db_compact db_sync db_upgrade
+      db_put db_exists db_get db_pget db_del db_key_range
       db_txn_commit db_txn_abort db_txn_finish
       db_c_close db_c_count db_c_put db_c_get db_c_pget db_c_del
       db_sequence_open db_sequence_close
       db_sequence_get db_sequence_remove
    );
    require XSLoader;
    XSLoader::load ("BDB", $VERSION);
 }
+=head2 WIN32 FILENAMES/DATABASE NAME MESS
+Perl on Win32 supports only ASCII filenames (the reason is that it abuses
+an internal flag to store wether a filename is Unicode or ANSI, but that
+flag is used for somethign else in the perl core, so there is no way to
+detect wether a filename is ANSI or Unicode-encoded). The BDB module
+tries to work around this issue by assuming that the filename is an ANSI
+filename and BDB was built for unicode support.
 =head2 BERKELEYDB FUNCTIONS
 All of these are functions. The create functions simply return a new
-object and never block. All the remaining functions all take an optional
+object and never block. All the remaining functions take an optional
-callback as last argument. If it is missing, then the fucntion will be
+callback as last argument. If it is missing, then the function will be
-executed synchronously.
+executed synchronously. In both cases, C<$!> will reflect the return value
+of the function.
 BDB functions that cannot block (mostly functions that manipulate
 settings) are method calls on the relevant objects, so the rule of thumb
-is: if its a method, its not blocking, if its a function, it takes a
+is: if it's a method, it's not blocking, if it's a function, it takes a
 callback as last argument.
 In the following, C<$int> signifies an integer return value,
-C<octetstring> is a "binary string" (i.e. a perl string with no character
+C<bdb_filename> is a "filename" (octets on unix, madness on windows),
-indices >255), C<U32> is an unsigned 32 bit integer, C<int> is some
+C<U32> is an unsigned 32 bit integer, C<int> is some integer, C<NV> is a
-integer, C<NV> is a floating point value.
+floating point value.
-The C<SV *> types are generic perl scalars (for input and output of data
+Most C<SV *> types are generic perl scalars (for input and output of data
-values), and the C<SV *callback> is the optional callback function to call
+values).
-when the request is completed.
 The various C<DB_ENV> etc. arguments are handles return by
 C<db_env_create>, C<db_create>, C<txn_begin> and so on. If they have an
 appended C<_ornull> this means they are optional and you can pass C<undef>
 for them, resulting a NULL pointer on the C level.
+The C<SV *callback> is the optional callback function to call when the
+request is completed. This last callback argument is special: the callback
+is simply the last argument passed. If there are "optional" arguments
+before the callback they can be left out. The callback itself can be left
+out or specified as C<undef>, in which case the function will be executed
+synchronously.
+For example, C<db_env_txn_checkpoint> usually is called with all integer
+arguments zero. These can be left out, so all of these specify a call
+to C<< DB_ENV->txn_checkpoint >>, to be executed asynchronously with a
+callback to be called:
+   db_env_txn_checkpoint $db_env, 0, 0, 0, sub { };
+   db_env_txn_checkpoint $db_env, 0, 0, sub { };
+   db_env_txn_checkpoint $db_env, sub { };
+While these all specify a call to C<< DB_ENV->txn_checkpoint >> to be
+executed synchronously:
+   db_env_txn_checkpoint $db_env, 0, 0, 0, undef;
+   db_env_txn_checkpoint $db_env, 0, 0, 0;
+   db_env_txn_checkpoint $db_env, 0;
 =head3 BDB functions
 Functions in the BDB namespace, exported by default:
    $env = db_env_create (U32 env_flags = 0)
       flags: RPCCLIENT
-   db_env_open (DB_ENV *env, octetstring db_home, U32 open_flags, int mode, SV *callback = &PL_sv_undef)
+   db_env_open (DB_ENV *env, bdb_filename db_home, U32 open_flags, int mode, SV *callback = &PL_sv_undef)
       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
    db_env_close (DB_ENV *env, U32 flags = 0, SV *callback = &PL_sv_undef)
    db_env_txn_checkpoint (DB_ENV *env, U32 kbyte = 0, U32 min = 0, U32 flags = 0, SV *callback = &PL_sv_undef)
       flags: FORCE
    db_env_lock_detect (DB_ENV *env, U32 flags = 0, U32 atype = DB_LOCK_DEFAULT, SV *dummy = 0, SV *callback = &PL_sv_undef)
       atype: LOCK_DEFAULT LOCK_EXPIRE LOCK_MAXLOCKS LOCK_MAXWRITE LOCK_MINLOCKS LOCK_MINWRITE LOCK_OLDEST LOCK_RANDOM LOCK_YOUNGEST
    db_env_memp_sync (DB_ENV *env, SV *dummy = 0, SV *callback = &PL_sv_undef)
    db_env_memp_trickle (DB_ENV *env, int percent, SV *dummy = 0, SV *callback = &PL_sv_undef)
+   db_env_dbremove (DB_ENV *env, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, U32 flags = 0, SV *callback = &PL_sv_undef)
+   db_env_dbrename (DB_ENV *env, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, bdb_filename newname, U32 flags = 0, SV *callback = &PL_sv_undef)
    $db = db_create (DB_ENV *env = 0, U32 flags = 0)
       flags: XA_CREATE
-   db_open (DB *db, DB_TXN_ornull *txnid, octetstring file, octetstring database, int type, U32 flags, int mode, SV *callback = &PL_sv_undef)
+   db_open (DB *db, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, int type, U32 flags, int mode, SV *callback = &PL_sv_undef)
       flags: AUTO_COMMIT CREATE EXCL MULTIVERSION NOMMAP RDONLY READ_UNCOMMITTED THREAD TRUNCATE
    db_close (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef)
       flags: DB_NOSYNC
+   db_upgrade (DB *db, bdb_filename file, U32 flags = 0, SV *callback = &PL_sv_undef)
    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)
       flags: FREELIST_ONLY FREE_SPACE
    db_sync (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef)
    db_key_range (DB *db, DB_TXN_ornull *txn, SV *key, SV *key_range, U32 flags = 0, SV *callback = &PL_sv_undef)
    db_put (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
       flags: APPEND NODUPDATA NOOVERWRITE
+   db_exists (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = 0) (v4.6)
    db_get (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
       flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW
    db_pget (DB *db, DB_TXN_ornull *txn, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
       flags: CONSUME CONSUME_WAIT GET_BOTH SET_RECNO MULTIPLE READ_COMMITTED READ_UNCOMMITTED RMW
    db_del (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef)
    $int = $env->set_data_dir (const char *dir)
    $int = $env->set_tmp_dir (const char *dir)
    $int = $env->set_lg_dir (const char *dir)
    $int = $env->set_shm_key (long shm_key)
    $int = $env->set_cachesize (U32 gbytes, U32 bytes, int ncache = 0)
-   $int = $env->set_flags (U32 flags, int onoff)
+   $int = $env->set_flags (U32 flags, int onoff = 1)
+   $int = $env->log_set_config (U32 flags, int onoff = 1) (v4.7)
+   $int = $env->set_intermediate_dir_mode (const char *modestring) (v4.7)
    $env->set_errfile (FILE *errfile = 0)
    $env->set_msgfile (FILE *msgfile = 0)
    $int = $env->set_verbose (U32 which, int onoff = 1)
    $int = $env->set_encrypt (const char *password, U32 flags = 0)
    $int = $env->set_timeout (NV timeout_seconds, U32 flags = SET_TXN_TIMEOUT)
    $int = $env->set_lk_max_lockers (U32 max)
    $int = $env->set_lk_max_locks (U32 max)
    $int = $env->set_lk_max_objects (U32 max)
    $int = $env->set_lg_bsize (U32 max)
    $int = $env->set_lg_max (U32 max)
+   $int = $env->mutex_set_increment (U32 increment)
+   $int = $env->mutex_set_tas_spins (U32 tas_spins)
+   $int = $env->mutex_set_max (U32 max)
+   $int = $env->mutex_set_align (U32 align)
    $txn = $env->txn_begin (DB_TXN_ornull *parent = 0, U32 flags = 0)
       flags: READ_COMMITTED READ_UNCOMMITTED TXN_NOSYNC TXN_NOWAIT TXN_SNAPSHOT TXN_SYNC TXN_WAIT TXN_WRITE_NOSYNC
+   $txn = $env->cdsgroup_begin; (v4.5)
 =head4 Example:
    use AnyEvent;
    use BDB;
    DESTROY (DBC_ornull *dbc)
            CODE:
            if (dbc)
              dbc->c_close (dbc);
+   $int = $cursor->set_priority ($priority = PRIORITY_*) (v4.6)
 =head4 Example:
    my $c = $db->cursor;
    for (;;) {
 =head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
 =over 4
+=item $msg = BDB::strerror [$errno]
+Returns the string corresponding to the given errno value. If no argument
+is given, use C<$!>.
+Note that the BDB module also patches the C<$!> variable directly, so you
+should be able to get a bdb error string by simply stringifying C<$!>.
 =item $fileno = BDB::poll_fileno
 Return the I<request result pipe file descriptor>. This filehandle must be
 polled for reading by some mechanism outside this module (e.g. Event or
 select, see below or the SYNOPSIS). If the pipe becomes readable you have
    BDB::poll_wait, BDB::poll_cb
       while BDB::nreqs;
 =back
+=head3 VERSION CHECKING
+BerkeleyDB comes in various versions, many of them have minor
+incompatibilities. This means that traditional "at least version x.x"
+checks are often not sufficient.
+Example: set the log_autoremove option in a way compatible with <v.47 and
+v4.7. Note the use of & on the constants to avoid triggering a compiletime
+bug when the symbol isn't available.
+   $DB_ENV->set_flags      (&BDB::LOG_AUTOREMOVE ) if BDB::VERSION v0, v4.7;
+   $DB_ENV->log_set_config (&BDB::LOG_AUTO_REMOVE) if BDB::VERSION v4.7;
+=over 4
+=item BDB::VERSION
+The C<BDB::VERSION> function, when called without arguments, returns the
+Berkeley DB version as a v-string (usually with 3 components). You should
+use C<lt> and C<ge> operators exclusively to make comparisons.
+Example: check for at least version 4.7.
+   BDB::VERSION ge v4.7 or die;
+=item BDB::VERSION min-version
+Returns true if the BDB version is at least the given version (specified
+as a v-string), false otherwise.
+Example: check for at least version 4.5.
+   BDB::VERSION v4.7 or die;
+=item BDB::VERSION min-version, max-version
+Returns true of the BDB version is at least version C<min-version> (specify C<undef> or C<v0> for any minimum version)
+and less then C<max-version>.
+Example: check wether version is strictly less then v4.7.
+   BDB::VERSION v0, v4.7
+      or die "version 4.7 is not yet supported";
+=back
+=cut
+sub VERSION {
+   if (@_ > 0) {
+      return undef if VERSION_v lt $_[0];
+      if (@_ > 1) {
+         return undef if VERSION_v ge $_[1];
+      }
+   }
+   VERSION_v
+}
 =head3 CONTROLLING THE NUMBER OF THREADS
 =over 4
 =item BDB::min_parallel $nthreads
 =item BDB::set_sync_prepare $cb
 Sets a callback that is called whenever a request is created without an
 explicit callback. It has to return two code references. The first is used
-as the request callback, and the second is called to wait until the first
+as the request callback (it should save the return status), and the second
+is called to wait until the first callback has been called (it must set
+C<$!> to the return status).
+This mechanism can be used to include BDB into other event mechanisms,
+such as L<AnyEvent::BDB> or L<Coro::BDB>.
-callback has been called. The default implementation works like this:
+The default implementation works like this:
    sub {
       my $status;
       (
          sub { $status = $! },
          sub { BDB::poll while !defined $status; $! = $status },
       )
    }
+It simply blocks the process till the request has finished and then sets
+C<$!> to the return value. This means that if you don't use a callback,
+BDB will simply fall back to synchronous operations.
 =back
 =head3 STATISTICAL INFORMATION
 In short: the parent will, after a short pause, continue as if fork had
 not been called, while the child will act as if BDB has not been used
 yet.
+Win32 note: there is no fork on win32, and perls emulation of it is too
+broken to be supported, so do not use BDB in a windows pseudo-fork, better
+yet, switch to a more capable platform.
 =head2 MEMORY USAGE
 Per-request usage:
 Each aio request uses - depending on your architecture - around 100-200
    TXN_DEADLOCK flag will be set on the transaction. See C<db_txn_finish>,
    above.
 =head1 SEE ALSO
-L<Coro::BDB>, L<IO::AIO>.
+L<AnyEvent::BDB> (event loop integration), L<Coro::BDB> (more natural
+syntax), L<IO::AIO> (nice to have).
 =head1 AUTHOR
  Marc Lehmann <schmorp@schmorp.de>
  http://home.schmorp.de/

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing BDB/BDB.pm (file contents): Revision 1.18 by root, Tue Dec 4 11:07:39 2007 UTC vs. Revision 1.45 by root, Wed Jul 9 21:16:14 2008 UTC

Diff Legend

Comparing BDB/BDB.pm (file contents):
Revision 1.18 by root, Tue Dec 4 11:07:39 2007 UTC vs.
Revision 1.45 by root, Wed Jul 9 21:16:14 2008 UTC