--- BDB/BDB.pm	2007/12/10 04:57:14	1.24
+++ BDB/BDB.pm	2011/12/26 01:46:33	1.64
@@ -26,9 +26,11 @@
  };
  db_sync $db;
 
- # automatic result processing with AnyEvent:
- our $FH; open $FH, "<&=" . BDB::poll_fileno;
- our $WATCHER = AnyEvent->io (fh => $FH, poll => 'r', cb => \&BDB::poll_cb);
+ # when you also use Coro, management is easy:
+ use Coro::BDB;
+
+ # automatic event loop integration with AnyEvent:
+ use AnyEvent::BDB;
 
  # automatic result processing with EV:
  my $WATCHER = EV::io BDB::poll_fileno, EV::READ, \&BDB::poll_cb;
@@ -103,18 +105,21 @@
 
 package BDB;
 
-no warnings;
-use strict 'vars';
+use common::sense;
 
 use base 'Exporter';
 
+our $VERSION;
+
 BEGIN {
-   our $VERSION = '1.3';
+   $VERSION = '1.9';
 
    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_open db_close db_compact db_sync db_put db_get db_pget db_del db_key_range
+      db_env_memp_sync db_env_memp_trickle db_env_dbrename db_env_dbremove
+      db_env_log_archive
+      db_open db_close db_compact db_sync db_verify 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
@@ -132,90 +137,118 @@
    XSLoader::load ("BDB", $VERSION);
 }
 
-=head2 BERKELEYDB FUNCTIONS
+=head1 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 function will be
 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
-indices >255), C<U32> is an unsigned 32 bit integer, C<int> is some
-integer, C<NV> is a floating point value.
-
-The 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
-when the request is completed.
+C<bdb_filename> is a "filename" (octets on unix, madness on windows),
+C<U32> is an unsigned 32 bit integer, C<int> is some integer, C<NV> is a
+floating point value.
+
+Most C<SV *> types are generic perl scalars (for input and output of data
+values).
 
 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.
 
-=head3 BDB functions
+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;
+
+=head2 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 = 0)
       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)
+   db_env_close (DB_ENV *env, U32 flags = 0, SV *callback = 0)
+   db_env_txn_checkpoint (DB_ENV *env, U32 kbyte = 0, U32 min = 0, U32 flags = 0, SV *callback = 0)
       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)
+   db_env_lock_detect (DB_ENV *env, U32 flags = 0, U32 atype = DB_LOCK_DEFAULT, SV *dummy = 0, SV *callback = 0)
       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_memp_sync (DB_ENV *env, SV *dummy = 0, SV *callback = 0)
+   db_env_memp_trickle (DB_ENV *env, int percent, SV *dummy = 0, SV *callback = 0)
+   db_env_dbremove (DB_ENV *env, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, U32 flags = 0, SV *callback = 0)
+   db_env_dbrename (DB_ENV *env, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, bdb_filename newname, U32 flags = 0, SV *callback = 0)
+   db_env_log_archive (DB_ENV *env, SV *listp, U32 flags = 0, SV *callback = 0)
 
    $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 = 0)
       flags: AUTO_COMMIT CREATE EXCL MULTIVERSION NOMMAP RDONLY READ_UNCOMMITTED THREAD TRUNCATE
-   db_close (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef)
+   db_close (DB *db, U32 flags = 0, SV *callback = 0)
       flags: DB_NOSYNC
-   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)
+   db_verify (DB *db, bdb_filename file, bdb_filename database = 0, SV *dummy = 0, U32 flags = 0, SV *callback = 0)
+   db_upgrade (DB *db, bdb_filename file, U32 flags = 0, SV *callback = 0)
+   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 = 0)
       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)
+   db_sync (DB *db, U32 flags = 0, SV *callback = 0)
+   db_key_range (DB *db, DB_TXN_ornull *txn, SV *key, SV *key_range, U32 flags = 0, SV *callback = 0)
+   db_put (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = 0)
       flags: APPEND NODUPDATA NOOVERWRITE
-   db_get (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
+   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 = 0)
       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)
+   db_pget (DB *db, DB_TXN_ornull *txn, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = 0)
       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)
-   db_txn_commit (DB_TXN *txn, U32 flags = 0, SV *callback = &PL_sv_undef)
+   db_del (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = 0)
+   db_txn_commit (DB_TXN *txn, U32 flags = 0, SV *callback = 0)
       flags: TXN_NOSYNC TXN_SYNC
-   db_txn_abort (DB_TXN *txn, SV *callback = &PL_sv_undef)
+   db_txn_abort (DB_TXN *txn, SV *callback = 0)
 
-   db_c_close (DBC *dbc, SV *callback = &PL_sv_undef)
-   db_c_count (DBC *dbc, SV *count, U32 flags = 0, SV *callback = &PL_sv_undef)
-   db_c_put (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
+   db_c_close (DBC *dbc, SV *callback = 0)
+   db_c_count (DBC *dbc, SV *count, U32 flags = 0, SV *callback = 0)
+   db_c_put (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = 0)
       flags: AFTER BEFORE CURRENT KEYFIRST KEYLAST NODUPDATA
-   db_c_get (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
+   db_c_get (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = 0)
       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
-   db_c_pget (DBC *dbc, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
-   db_c_del (DBC *dbc, U32 flags = 0, SV *callback = &PL_sv_undef)
+   db_c_pget (DBC *dbc, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = 0)
+   db_c_del (DBC *dbc, U32 flags = 0, SV *callback = 0)
 
-   db_sequence_open (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef)
+   db_sequence_open (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, SV *key, U32 flags = 0, SV *callback = 0)
       flags: CREATE EXCL
-   db_sequence_close (DB_SEQUENCE *seq, U32 flags = 0, SV *callback = &PL_sv_undef)
-   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)
+   db_sequence_close (DB_SEQUENCE *seq, U32 flags = 0, SV *callback = 0)
+   db_sequence_get (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, int delta, SV *seq_value, U32 flags = DB_TXN_NOSYNC, SV *callback = 0)
       flags: TXN_NOSYNC
-   db_sequence_remove (DB_SEQUENCE *seq, DB_TXN_ornull *txnid = 0, U32 flags = 0, SV *callback = &PL_sv_undef)
+   db_sequence_remove (DB_SEQUENCE *seq, DB_TXN_ornull *txnid = 0, U32 flags = 0, SV *callback = 0)
       flags: TXN_NOSYNC
 
-=head4 db_txn_finish (DB_TXN *txn, U32 flags = 0, SV *callback = &PL_sv_undef)
+=head3 db_txn_finish (DB_TXN *txn, U32 flags = 0, SV *callback = 0)
 
 This is not actually a Berkeley DB function but a BDB module
 extension. The background for this exytension is: It is very annoying to
@@ -251,7 +284,8 @@
 has failed in this way and abort further processing (excluding
 C<db_txn_finish>).
 
-=head3 DB_ENV/database environment methods
+
+=head2 DB_ENV/database environment methods
 
 Methods available on DB_ENV/$env handles:
 
@@ -265,7 +299,9 @@
    $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)
@@ -287,8 +323,9 @@
 
    $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:
+=head3 Example:
 
    use AnyEvent;
    use BDB;
@@ -310,7 +347,7 @@
    $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1);
 
 
-=head3 DB/database methods
+=head2 DB/database methods
 
 Methods available on DB/$db handles:
 
@@ -346,7 +383,7 @@
       flags: READ_COMMITTED READ_UNCOMMITTED WRITECURSOR TXN_SNAPSHOT
    $seq = $db->sequence (U32 flags = 0)
 
-=head4 Example:
+=head3 Example:
 
    my $db = db_create $env;
    db_open $db, undef, "table", undef, BDB::BTREE, BDB::AUTO_COMMIT | BDB::CREATE | BDB::READ_UNCOMMITTED, 0600;
@@ -363,7 +400,7 @@
    db_sync $db;
 
 
-=head3 DB_TXN/transaction methods
+=head2 DB_TXN/transaction methods
 
 Methods available on DB_TXN/$txn handles:
 
@@ -379,7 +416,7 @@
    # see db_txn_finish documentation, above
 
 
-=head3 DBC/cursor methods
+=head2 DBC/cursor methods
 
 Methods available on DBC/$dbc handles:
 
@@ -388,7 +425,9 @@
            if (dbc)
              dbc->c_close (dbc);
 
-=head4 Example:
+   $int = $cursor->set_priority ($priority = PRIORITY_*) (v4.6)
+
+=head3 Example:
 
    my $c = $db->cursor;
 
@@ -401,7 +440,7 @@
    db_c_close $c;
 
 
-=head3 DB_SEQUENCE/sequence methods
+=head2 DB_SEQUENCE/sequence methods
 
 Methods available on DB_SEQUENCE/$seq handles:
 
@@ -416,7 +455,7 @@
       flags: SEQ_DEC SEQ_INC SEQ_WRAP
    $int = $seq->set_range (db_seq_t min, db_seq_t max)
 
-=head4 Example:
+=head3 Example:
 
    my $seq = $db->sequence;
       
@@ -424,9 +463,9 @@
    db_sequence_get $seq, undef, 1, my $value;
 
 
-=head2 SUPPORT FUNCTIONS
+=head1 SUPPORT FUNCTIONS
 
-=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
+=head2 EVENT PROCESSING AND EVENT LOOP INTEGRATION
 
 =over 4
 
@@ -435,6 +474,9 @@
 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
@@ -520,7 +562,73 @@
 
 =back
 
-=head3 CONTROLLING THE NUMBER OF THREADS
+=head2 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 <v4.7 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;
+   $DB_ENV->log_set_config (&BDB::LOG_AUTO_REMOVE) if BDB::VERSION v4.7;
+
+=over 4
+
+=item BDB::VERSION
+
+The C<BDB::VERSION> function, when called without arguments, returns the
+Berkeley DB version as a v-string (usually with 3 components). You should
+use C<lt> and C<ge> operators exclusively to make comparisons.
+
+Example: check for at least version 4.7.
+
+   BDB::VERSION ge v4.7 or die;
+
+=item BDB::VERSION min-version
+
+Returns true if the BDB version is at least the given version (specified
+as a v-string), false otherwise.
+
+Example: check for at least version 4.5.
+
+   BDB::VERSION v4.7 or die;
+
+=item BDB::VERSION min-version, max-version
+
+Returns true of the BDB version is at least version C<min-version> (specify C<undef> or C<v0> for any minimum version)
+and less then C<max-version>.
+
+Example: check wether version is strictly less then v4.7.
+
+   BDB::VERSION v0, v4.7
+      or die "version 4.7 is not yet supported";
+
+=back
+
+=cut
+
+sub VERSION {
+   # I was dumb enough to override the VERSION method here, so let's try
+   # to fix it up.
+
+   if ($_[0] eq __PACKAGE__) {
+      $VERSION
+   } else {
+      if (@_ > 0) {
+         return undef if VERSION_v lt $_[0];
+         if (@_ > 1) {
+            return undef if VERSION_v ge $_[1];
+         }
+      }
+
+      VERSION_v
+   }
+}
+
+=head2 CONTROLLING THE NUMBER OF THREADS
 
 =over 4
 
@@ -591,12 +699,19 @@
 C<max_oustsanding> is mainly useful in simple scripts (with low values) or
 as a stop gap to shield against fatal memory overflow (with large values).
 
-=item BDB::set_sync_prepare $cb
+=item $old_cb = 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
-callback has been called. The default implementation works like this:
+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<Coro::BDB>.
+
+To allow other, callback-based, events to be executed while callback-less
+ones are run, you could use this sync prepare function:
 
    sub {
       my $status;
@@ -606,9 +721,17 @@
       )
    }
 
+It works by polling for results till the request has finished and then
+sets C<$!> to the return value. This means that if you don't use a
+callback, BDB would simply fall back to synchronous operations.
+
+By default, or if the sync prepare function is set to C<undef>, is to
+execute callback-less BDB requests in the foreground thread, setting C<$!>
+to the return value, without polling for other events.
+
 =back
 
-=head3 STATISTICAL INFORMATION
+=head2 STATISTICAL INFORMATION
 
 =over 4
 
@@ -636,18 +759,7 @@
 
 =cut
 
-set_sync_prepare {
-   my $status;
-   (
-      sub {
-         $status = $!;
-      },
-      sub {
-         BDB::poll while !defined $status;
-         $! = $status;
-      },
-   )
-};
+set_sync_prepare (undef);
 
 min_parallel 8;
 
@@ -655,7 +767,30 @@
 
 1;
 
-=head2 FORK BEHAVIOUR
+=head1 COMMON PITFALLS
+
+=head2 Unexpected Crashes
+
+Remember that, by default, BDB will execute requests in parallel, in
+somewhat random order. That means that it is easy to run a C<db_get>
+request on thesa me database as a concurrent C<db_close> request, leading
+to a crash, silent data corruption, eventually the next world war on
+terrorism.
+
+If you only ever use foreground requests (without a callback), this will
+not be an issue.
+
+=head2 Unexpected Freezes or Deadlocks
+
+Remember that, by default, BDB will execute requests in parallel, which
+easily leads to deadlocks (even concurrent put's on the same database can
+deadlock).
+
+You either need to run deadlock detection (and handle the resulting
+errors), or make sure only one process ever updates the database, ine one
+thread, e.g. by using only foreground requests (without a callback).
+
+=head1 FORK BEHAVIOUR
 
 This module should do "the right thing" when the process using it forks:
 
@@ -671,7 +806,11 @@
 not been called, while the child will act as if BDB has not been used
 yet.
 
-=head2 MEMORY USAGE
+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.
+
+=head1 MEMORY USAGE
 
 Per-request usage:
 
@@ -690,6 +829,15 @@
 temporary buffers, and each thread requires a stack and other data
 structures (usually around 16k-128k, depending on the OS).
 
+=head1 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.
+
 =head1 KNOWN BUGS
 
 Known bugs will be fixed in the next release, except:
@@ -701,7 +849,8 @@
 
 =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